NanoHTTPD源码阅读

package fi.iki.elonen;

import java.io.*;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.net.URLDecoder;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TimeZone;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * A simple, tiny, nicely embeddable HTTP server in Java
 * <p/>
 * <p/>
 * NanoHTTPD
 * <p></p>Copyright (c) 2012-2013 by Paul S. Hawke, 2001,2005-2013 by Jarno Elonen, 2010 by Konstantinos Togias</p>
 * <p/>
 * <p/>
 * <b>Features + limitations: </b>
 * <ul>
 * <p/>
 * <li>Only one Java file</li>
 * <li>Java 5 compatible</li>
 * <li>Released as open source, Modified BSD licence</li>
 * <li>No fixed config files, logging, authorization etc. (Implement yourself if you need them.)</li>
 * <li>Supports parameter parsing of GET and POST methods (+ rudimentary PUT support in 1.25)</li>
 * <li>Supports both dynamic content and file serving</li>
 * <li>Supports file upload (since version 1.2, 2010)</li>
 * <li>Supports partial content (streaming)</li>
 * <li>Supports ETags</li>
 * <li>Never caches anything</li>
 * <li>Doesn't limit bandwidth, request time or simultaneous connections</li>
 * <li>Default code serves files and shows all HTTP parameters and headers</li>
 * <li>File server supports directory listing, index.html and index.htm</li>
 * <li>File server supports partial content (streaming)</li>
 * <li>File server supports ETags</li>
 * <li>File server does the 301 redirection trick for directories without '/'</li>
 * <li>File server supports simple skipping for files (continue download)</li>
 * <li>File server serves also very long files without memory overhead</li>
 * <li>Contains a built-in list of most common mime types</li>
 * <li>All header names are converted lowercase so they don't vary between browsers/clients</li>
 * <p/>
 * </ul>
 * <p/>
 * <p/>
 * <b>How to use: </b>
 * <ul>
 * <p/>
 * <li>Subclass and implement serve() and embed to your own program</li>
 * <p/>
 * </ul>
 * <p/>
 * See the separate "LICENSE.md" file for the distribution license (Modified BSD licence)
 */
public abstract class NanoHTTPD {
    /**
     * Maximum time to wait on Socket.getInputStream().read() (in milliseconds)
     * This is required as the Keep-Alive HTTP connections would otherwise
     * block the socket reading thread forever (or as long the browser is open).
     * <p/>
     * Socket过期时间，这里的过期时间，主要指服务器等待客户端输入的过期时间
     */
    public static final int SOCKET_READ_TIMEOUT = 5000;
    /**
     * Common mime type for dynamic content: plain text
     * <p/>
     * 设置：Content-Type: text/plain;
     */
    public static final String MIME_PLAINTEXT = "text/plain";
    /**
     * Common mime type for dynamic content: html
     * <p/>
     * 设置：Content-Type: text/html;
     */
    public static final String MIME_HTML = "text/html";
    /**
     * Pseudo-Parameter to use to store the actual query string in the parameters map for later re-processing.
     * <p/>
     * 预处理当时，以这个字段为key，以查询字符串为value放在Map当中。
     */
    private static final String QUERY_STRING_PARAMETER = "NanoHttpd.QUERY_STRING";
    /**
     * 主机IP
     */
    private final String hostname;
    /**
     * 监听的端口，不一定是80
     */
    private final int myPort;
    /**
     * 服务器端抗在最前端的socket，用于接收客户端的socket请求。
     */
    private ServerSocket myServerSocket;
    /**
     * 在服务器端存放与客户端Socket链接
     */
    private Set<Socket> openConnections = new HashSet<Socket>();
    /**
     * 在服务器端抗在最前面的线程。
     */
    private Thread myThread;
    /**
     * Pluggable strategy for asynchronously executing requests.
     * 当服务器接收到socket后，新开线程进行处理。此接口主要定义了处理的方法。
     */
    private AsyncRunner asyncRunner;
    /**
     * Pluggable strategy for creating and cleaning up temporary files.
     * <p/>
     * 创建和清除临时文件的策略工厂
     */
    private TempFileManagerFactory tempFileManagerFactory;

    /**
     * Constructs an HTTP server on given port.
     * <p/>
     * 构造函数
     */
    public NanoHTTPD(int port) {
        this(null, port);
    }

    /**
     * Constructs an HTTP server on given hostname and port.
     * <p/>
     * 构造函数
     */
    public NanoHTTPD(String hostname, int port) {
        this.hostname = hostname;
        this.myPort = port;
        //设置文件管理器工厂
        setTempFileManagerFactory(new DefaultTempFileManagerFactory());
        //设置异步处理线程
        setAsyncRunner(new DefaultAsyncRunner());
    }

    /**
     * 安全关闭Closeable
     *
     * @param closeable
     */
    private static final void safeClose(Closeable closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
            }
        }
    }

    /**
     * 安全关闭  Socket
     *
     * @param closeable
     */
    private static final void safeClose(Socket closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
            }
        }
    }

    /**
     * 安全关闭   ServerSocket
     *
     * @param closeable
     */
    private static final void safeClose(ServerSocket closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
            }
        }
    }

    /**
     * Start the server.
     *
     * @throws IOException if the socket is in use.
     *                     打开服务器
     *                     |
     *                     用户----> |---->新socket，建立新线程1处理
     *                     服务器端线程myThread
     *                     用户----> |---->新socket，建立新线程2处理
     *                     用户----> |---->新socket，建立新线程3处理
     *                     用户----> |---->新socket，建立新线程4处理
     *                     用户----> |---->新socket，建立新线程5处理
     *                     用户----> |---->新socket，建立新线程6处理
     *                     用户----> |---->新socket，建立新线程7处理
     *                     服务器端线程myThread
     *                     用户----> |---->新socket，建立新线程8处理
     *                     |
     */
    public void start() throws IOException {
        //创建服务器端Socket
        myServerSocket = new ServerSocket();
        myServerSocket.bind((hostname != null) ? new InetSocketAddress(hostname, myPort) : new InetSocketAddress(myPort));
        //服务器端主线程抗着用户的请求。
        myThread = new Thread(new Runnable() {
            @Override
            public void run() {
                do {
                    try {
                        //阻塞，直到新的Socket到来。
                        final Socket finalAccept = myServerSocket.accept();
                        //注册用户请求，
                        registerConnection(finalAccept);
                        //设置Socket超时时间
                        finalAccept.setSoTimeout(SOCKET_READ_TIMEOUT);
                        //得到Socket入口引用
                        final InputStream inputStream = finalAccept.getInputStream();
                        //分发用户请求，开启新的线程对用户进行响应
                        asyncRunner.exec(new Runnable() {
                            @Override
                            public void run() {
                                OutputStream outputStream = null;
                                try {
                                    //得到Socket出口引用
                                    outputStream = finalAccept.getOutputStream();
                                    //创建文件工厂
                                    TempFileManager tempFileManager = tempFileManagerFactory.create();
                                    //新建 HTTPSession实例，主要用户请求的处理类。
                                    HTTPSession session = new HTTPSession(tempFileManager, inputStream, outputStream, finalAccept.getInetAddress());
                                    while (!finalAccept.isClosed()) {
                                        //处理用户请求
                                        session.execute();
                                    }
                                } catch (Exception e) {
                                    // When the socket is closed by the client, we throw our own SocketException
                                    // to break the  "keep alive" loop above.
                                    if (!(e instanceof SocketException && "NanoHttpd Shutdown".equals(e.getMessage()))) {
                                        e.printStackTrace();
                                    }
                                } finally {
                                    safeClose(outputStream);
                                    safeClose(inputStream);
                                    safeClose(finalAccept);
                                    //将用户请求Socket
                                    unRegisterConnection(finalAccept);
                                }
                            }
                        });
                    } catch (IOException e) {
                    }
                } while (!myServerSocket.isClosed());
            }
        });
        //设置为守护线程，当JVM当中全部是守护线程时，JVM会退出，GC就是守护线程。
        myThread.setDaemon(true);
        myThread.setName("NanoHttpd Main Listener");
        myThread.start();
    }

    /**
     * Stop the server.
     */
    public void stop() {
        try {
            safeClose(myServerSocket);
            closeAllConnections();
            if (myThread != null) {
                myThread.join();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Registers that a new connection has been set up.
     *
     * @param socket the {@link Socket} for the connection.
     *               <p/>
     *               将Socket放入到集合中，因为是Set集合，而非CopyOnWriteArraySet或者ConcurrentSkipListSet，因此在
     *               多线程操作时，需要注意线程安全问题。同时又多个用户访问服务器，需要加入Socket集合中。
     */
    public synchronized void registerConnection(Socket socket) {
        openConnections.add(socket);
    }

    /**
     * Registers that a connection has been closed
     *
     * @param socket the {@link Socket} for the connection.
     *               <p/>
     *               将用户请求Socket从Socket集合当中取出来。加synchronized的原因看 @see registerConnection。
     */
    public synchronized void unRegisterConnection(Socket socket) {
        openConnections.remove(socket);
    }

    /**
     * Forcibly closes all connections that are open.
     * <p/>
     * 关闭所有的Socket，加synchronized的原因看 @see registerConnection。
     */
    public synchronized void closeAllConnections() {
        for (Socket socket : openConnections) {
            safeClose(socket);
        }
    }

    /**
     * 得到服务器监听的端口
     *
     * @return
     */
    public final int getListeningPort() {
        return myServerSocket == null ? -1 : myServerSocket.getLocalPort();
    }

    /**
     * 检查服务器是否已经启动。
     *
     * @return
     */
    public final boolean wasStarted() {
        return myServerSocket != null && myThread != null;
    }

    /**
     * 服务器是否可用
     *
     * @return
     */
    public final boolean isAlive() {
        return wasStarted() && !myServerSocket.isClosed() && myThread.isAlive();
    }

    /**
     * Override this to customize the server.
     * <p/>
     * <p/>
     * (By default, this delegates to serveFile() and allows directory listing.)
     *
     * @param uri     Percent-decoded URI without parameters, for example "/index.cgi"
     * @param method  "GET", "POST" etc.
     * @param parms   Parsed, percent decoded parameters from URI and, in case of POST, data.
     * @param headers Header entries, percent decoded
     * @return HTTP response, see class Response for details
     *         <p/>
     *         已经过期，
     */
    @Deprecated
    public Response serve(String uri, Method method, Map<String, String> headers, Map<String, String> parms,
                          Map<String, String> files) {
        return new Response(Response.Status.NOT_FOUND, MIME_PLAINTEXT, "Not Found");
    }

    /**
     * Override this to customize the server.
     * <p/>
     * <p/>
     * (By default, this delegates to serveFile() and allows directory listing.)
     *
     * @param session The HTTP session
     * @return HTTP response, see class Response for details
     *         <p/>
     *         可以重写这个方法以自定义服务。
     */
    public Response serve(IHTTPSession session) {
        Map<String, String> files = new HashMap<String, String>();
        Method method = session.getMethod();
        //当请求的方法是put或者post方法时。
        if (Method.PUT.equals(method) || Method.POST.equals(method)) {
            try {
                //
                session.parseBody(files);
            } catch (IOException ioe) {
                return new Response(Response.Status.INTERNAL_ERROR, MIME_PLAINTEXT, "SERVER INTERNAL ERROR: IOException: " + ioe.getMessage());
            } catch (ResponseException re) {
                return new Response(re.getStatus(), MIME_PLAINTEXT, re.getMessage());
            }
        }

        Map<String, String> parms = session.getParms();
        parms.put(QUERY_STRING_PARAMETER, session.getQueryParameterString());
        return serve(session.getUri(), method, session.getHeaders(), parms, files);
    }

    /**
     * Decode percent encoded <code>String</code> values.
     *
     * @param str the percent encoded <code>String</code>
     * @return expanded form of the input, for example "foo%20bar" becomes "foo bar"
     */
    protected String decodePercent(String str) {
        String decoded = null;
        try {
            decoded = URLDecoder.decode(str, "UTF8");
        } catch (UnsupportedEncodingException ignored) {
        }
        return decoded;
    }

    /**
     * Decode parameters from a URL, handing the case where a single parameter name might have been
     * supplied several times, by return lists of values.  In general these lists will contain a single
     * element.
     *
     * @param parms original <b>NanoHttpd</b> parameters values, as passed to the <code>serve()</code> method.
     * @return a map of <code>String</code> (parameter name) to <code>List<String></code> (a list of the values supplied).
     */
    protected Map<String, List<String>> decodeParameters(Map<String, String> parms) {
        return this.decodeParameters(parms.get(QUERY_STRING_PARAMETER));
    }

    /**
     * Decode parameters from a URL, handing the case where a single parameter name might have been
     * supplied several times, by return lists of values.  In general these lists will contain a single
     * element.
     *
     * @param queryString a query string pulled from the URL.
     * @return a map of <code>String</code> (parameter name) to <code>List<String></code> (a list of the values supplied).
     */
    protected Map<String, List<String>> decodeParameters(String queryString) {
        Map<String, List<String>> parms = new HashMap<String, List<String>>();
        if (queryString != null) {
            StringTokenizer st = new StringTokenizer(queryString, "&");
            while (st.hasMoreTokens()) {
                String e = st.nextToken();
                int sep = e.indexOf('=');
                String propertyName = (sep >= 0) ? decodePercent(e.substring(0, sep)).trim() : decodePercent(e).trim();
                if (!parms.containsKey(propertyName)) {
                    parms.put(propertyName, new ArrayList<String>());
                }
                String propertyValue = (sep >= 0) ? decodePercent(e.substring(sep + 1)) : null;
                if (propertyValue != null) {
                    parms.get(propertyName).add(propertyValue);
                }
            }
        }
        return parms;
    }

    // ------------------------------------------------------------------------------- //
    //
    // Threading Strategy.
    //
    // ------------------------------------------------------------------------------- //

    /**
     * Pluggable strategy for asynchronously executing requests.
     *
     * @param asyncRunner new strategy for handling threads.
     */
    public void setAsyncRunner(AsyncRunner asyncRunner) {
        this.asyncRunner = asyncRunner;
    }

    // ------------------------------------------------------------------------------- //
    //
    // Temp file handling strategy.
    //
    // ------------------------------------------------------------------------------- //

    /**
     * Pluggable strategy for creating and cleaning up temporary files.
     *
     * @param tempFileManagerFactory new strategy for handling temp files.
     */
    public void setTempFileManagerFactory(TempFileManagerFactory tempFileManagerFactory) {
        this.tempFileManagerFactory = tempFileManagerFactory;
    }

    /**
     * HTTP Request methods, with the ability to decode a <code>String</code> back to its enum value.
     */
    public enum Method {
        GET, PUT, POST, DELETE, HEAD, OPTIONS;

        static Method lookup(String method) {
            for (Method m : Method.values()) {
                if (m.toString().equalsIgnoreCase(method)) {
                    return m;
                }
            }
            return null;
        }
    }

    /**
     * Pluggable strategy for asynchronously executing requests.
     */
    public interface AsyncRunner {
        void exec(Runnable code);
    }

    /**
     * Factory to create temp file managers.
     */
    public interface TempFileManagerFactory {
        TempFileManager create();
    }

    // ------------------------------------------------------------------------------- //

    /**
     * Temp file manager.
     * <p/>
     * <p>Temp file managers are created 1-to-1 with incoming requests, to create and cleanup
     * temporary files created as a result of handling the request.</p>
     */
    public interface TempFileManager {
        TempFile createTempFile() throws Exception;

        void clear();
    }

    /**
     * A temp file.
     * <p/>
     * <p>Temp files are responsible for managing the actual temporary storage and cleaning
     * themselves up when no longer needed.</p>
     */
    public interface TempFile {
        OutputStream open() throws Exception;

        void delete() throws Exception;

        String getName();
    }

    /**
     * Default threading strategy for NanoHttpd.
     * <p/>
     * <p>By default, the server spawns a new Thread for every incoming request.  These are set
     * to <i>daemon</i> status, and named according to the request number.  The name is
     * useful when profiling the application.</p>
     */
    public static class DefaultAsyncRunner implements AsyncRunner {
        private long requestCount;

        @Override
        public void exec(Runnable code) {
            ++requestCount;
            Thread t = new Thread(code);
            t.setDaemon(true);
            t.setName("NanoHttpd Request Processor (#" + requestCount + ")");
            t.start();
        }
    }

    /**
     * Default strategy for creating and cleaning up temporary files.
     * <p/>
     * <p></p>This class stores its files in the standard location (that is,
     * wherever <code>java.io.tmpdir</code> points to).  Files are added
     * to an internal list, and deleted when no longer needed (that is,
     * when <code>clear()</code> is invoked at the end of processing a
     * request).</p>
     *
     *创建和清理临时文件的默认策略。本类将文件存放在标准目录java.io.tmpdir下。
     *文件被保存在内部的目录，不再使用时会删除这个文件。在request处理结束时会调用本类的clear()方法。
     */
    public static class DefaultTempFileManager implements TempFileManager {
        //临时文件路径
        private final String tmpdir;
        //保存临时文件的List容器。
        private final List<TempFile> tempFiles;

        public DefaultTempFileManager() {
            //默认文件目录是  java.io.tmpdir
            tmpdir = System.getProperty("java.io.tmpdir");
            tempFiles = new ArrayList<TempFile>();
        }

        /**
         * 创建临时文件，并将其加入到 tempFiles容器当中。
         * @return
         * @throws Exception
         */
        @Override
        public TempFile createTempFile() throws Exception {
            DefaultTempFile tempFile = new DefaultTempFile(tmpdir);
            tempFiles.add(tempFile);
            return tempFile;
        }

        /**
         * 清除文件
         */
        @Override
        public void clear() {
            for (TempFile file : tempFiles) {
                try {
                    file.delete();
                } catch (Exception ignored) {
                }
            }
            tempFiles.clear();
        }
    }

    /**
     * Default strategy for creating and cleaning up temporary files.
     * <p/>
     * <p></p></[>By default, files are created by <code>File.createTempFile()</code> in
     * the directory specified.</p>
     *
     *创建和清理临时文件的默认策略。默认情况下，使用 File.createTempFile()创建文件。
     */
    public static class DefaultTempFile implements TempFile {
        private File file;
        private OutputStream fstream;

        public DefaultTempFile(String tempdir) throws IOException {
            file = File.createTempFile("NanoHTTPD-", "", new File(tempdir));
            fstream = new FileOutputStream(file);
        }

        @Override
        public OutputStream open() throws Exception {
            return fstream;
        }

        @Override
        public void delete() throws Exception {
            safeClose(fstream);
            file.delete();
        }

        @Override
        public String getName() {
            return file.getAbsolutePath();
        }
    }

    /**
     * HTTP response. Return one of these from serve().
     * <p/>
     * 服务器返回值。由serve()返回。
     */
    public static class Response {
        /**
         * HTTP status code after processing, e.g. "200 OK", HTTP_OK
         * <p/>
         * 返回状态
         */
        private IStatus status;
        /**
         * MIME type of content, e.g. "text/html"
         * <p/>
         * MIME值，content-type:
         */
        private String mimeType;
        /**
         * Data of the response, may be null.
         * <p/>
         * response的返回值。最终由outputStream写出。。
         */
        private InputStream data;
        /**
         * Headers for the HTTP response. Use addHeader() to add lines.
         * 返回值得头信息
         * 如：
         * <p/>
         * HTTP/1.1 200 OK
         * Date: Mon, 18 Aug 2014 12:51:32 GMT
         * Content-Type: text/html; charset=utf-8
         * Transfer-Encoding: chunked
         * Connection: Keep-Alive
         * Vary: Accept-Encoding
         * Cache-Control: private
         * Cxy_all: baidu+6c00a4386fa893e998b0e8342d8aaa65
         * Expires: Mon, 18 Aug 2014 12:51:31 GMT
         * X-Powered-By: HPHP
         * Server: BWS/1.1
         * BDPAGETYPE: 1
         * BDQID: 0x81c8781b000244bc
         * BDUSERID: 0
         * Set-Cookie: BDSVRTM=0; path=/
         * Set-Cookie: BD_HOME=0; path=/
         * Content-Encoding: gzip
         */
        private Map<String, String> header = new HashMap<String, String>();
        /**
         * The request method that spawned this response.
         * <p/>
         * 引起服务器返回这个response的请求方式
         */
        private Method requestMethod;
        /**
         * Use chunkedTransfer
         * <p/>
         * 是否采用块传输的方式，即没有content-length而使用Transfer-encoding=chunked代替。
         * HTTP协议的chunked编码 http://www.cnblogs.com/zhaozhan/archive/2010/08/24/1807639.html
         */
        private boolean chunkedTransfer;

        /**
         * Default constructor: response = HTTP_OK, mime = MIME_HTML and your supplied message
         * 默认构造函数
         */
        public Response(String msg) {
            this(Status.OK, MIME_HTML, msg);
        }

        /**
         * Basic constructor.
         * 基础构造函数
         */
        public Response(IStatus status, String mimeType, InputStream data) {
            this.status = status;
            this.mimeType = mimeType;
            this.data = data;
        }

        /**
         * Convenience method that makes an InputStream out of given text.
         * 返回txt类型
         */
        public Response(IStatus status, String mimeType, String txt) {
            this.status = status;
            this.mimeType = mimeType;
            try {
                this.data = txt != null ? new ByteArrayInputStream(txt.getBytes("UTF-8")) : null;
            } catch (java.io.UnsupportedEncodingException uee) {
                uee.printStackTrace();
            }
        }

        /**
         * Adds given line to the header.
         * 增加头部信息
         */
        public void addHeader(String name, String value) {
            header.put(name, value);
        }

        /**
         * 得到头部信息
         *
         * @param name
         * @return
         */
        public String getHeader(String name) {
            return header.get(name);
        }

        /**
         * Sends given response to the socket.
         * <p/>
         * 发送response到socket
         * <p/>
         * HTTP/1.1 200 OK
         * Date: Mon, 18 Aug 2014 12:51:32 GMT
         * Content-Type: text/html; charset=utf-8
         * Transfer-Encoding: chunked
         * Connection: Keep-Alive
         * Vary: Accept-Encoding
         * Cache-Control: private
         * Cxy_all: baidu+6c00a4386fa893e998b0e8342d8aaa65
         * Expires: Mon, 18 Aug 2014 12:51:31 GMT
         * X-Powered-By: HPHP
         * Server: BWS/1.1
         * BDPAGETYPE: 1
         * BDQID: 0x81c8781b000244bc
         * BDUSERID: 0
         * Set-Cookie: BDSVRTM=0; path=/
         * Set-Cookie: BD_HOME=0; path=/
         * Content-Encoding: gzip
         */
        protected void send(OutputStream outputStream) {
            String mime = mimeType;
            SimpleDateFormat gmtFrmt = new SimpleDateFormat("E, d MMM yyyy HH:mm:ss 'GMT'", Locale.US);
            gmtFrmt.setTimeZone(TimeZone.getTimeZone("GMT"));

            try {
                if (status == null) {
                    throw new Error("sendResponse(): Status can't be null.");
                }
                //输出流的目的地为outputStream，outputStream为Socket的outputStream。
                PrintWriter pw = new PrintWriter(outputStream);
                // HTTP/1.1 200 OK
                pw.print("HTTP/1.1 " + status.getDescription() + " \r\n");
                // Content-Type: text/html;
                if (mime != null) {
                    pw.print("Content-Type: " + mime + "\r\n");
                }
                // Date: Mon, 18 Aug 2014 12:51:32 GMT
                if (header == null || header.get("Date") == null) {
                    pw.print("Date: " + gmtFrmt.format(new Date()) + "\r\n");
                }
                //其他头部信息
                if (header != null) {
                    for (String key : header.keySet()) {
                        String value = header.get(key);
                        pw.print(key + ": " + value + "\r\n");
                    }
                }
                //如果有connection则Connection: Keep-Alive
                sendConnectionHeaderIfNotAlreadyPresent(pw, header);
                //如果requestMethod不为head方式，同时chunkedTransfer为True时
                if (requestMethod != Method.HEAD && chunkedTransfer) {
                    //以Transfer-Encoding: chunked的方式传输
                    //transfer-encoding:chunked的含义
                    //http://blog.csdn.net/whatday/article/details/7571451
                    sendAsChunked(outputStream, pw);
                } else {
                    //socket要输出的的数据的长度
                    int pending = data != null ? data.available() : 0;
                    //设置Content-Length
                    sendContentLengthHeaderIfNotAlreadyPresent(pw, header, pending);

                    pw.print("\r\n");
                    pw.flush();
                    //按照固定长度发送数据，即发送Content-Length的长度的数据。
                    sendAsFixedLength(outputStream, pending);
                }
                outputStream.flush();
                safeClose(data);
            } catch (IOException ioe) {
                // Couldn't write? No can do.
            }
        }

        /**
         * 发送Content-Length
         * @param pw
         * @param header
         * @param size
         */
        protected void sendContentLengthHeaderIfNotAlreadyPresent(PrintWriter pw, Map<String, String> header, int size) {
            if (!headerAlreadySent(header, "content-length")) {
                pw.print("Content-Length: " + size + "\r\n");
            }
        }

        /**
         * 发送Connection: keep-alive
         * @param pw
         * @param header
         */
        protected void sendConnectionHeaderIfNotAlreadyPresent(PrintWriter pw, Map<String, String> header) {
            if (!headerAlreadySent(header, "connection")) {
                pw.print("Connection: keep-alive\r\n");
            }
        }

        /**
         *
         * @param header
         * @param name
         * @return
         */
        private boolean headerAlreadySent(Map<String, String> header, String name) {
            boolean alreadySent = false;
            for (String headerName : header.keySet()) {
                alreadySent |= headerName.equalsIgnoreCase(name);
            }
            return alreadySent;
        }

        /**
         * 以Transfer-Encoding: chunked方式传输 ，发送到客户端。
         * @param outputStream
         * @param pw
         * @throws IOException
         *
         *
         * BDPAGETYPE:1
        BDQID:0xc483ee8900026bab
        BDUSERID:0
        Cache-Control:private
        Connection:Keep-Alive
        Content-Encoding:gzip
        Content-Type:text/html; charset=utf-8
        Cxy_all:baidu+c865c0ef8e3418bd9f8ffe9a77eb5291
        Date:Mon, 25 Aug 2014 10:01:31 GMT
        Expires:Mon, 25 Aug 2014 10:00:57 GMT
        Server:BWS/1.1
        Set-Cookie:BDSVRTM=0; path=/
        Set-Cookie:BD_HOME=0; path=/
        Transfer-Encoding:chunked
        Vary:Accept-Encoding
        X-Powered-By:HPHP
         */
        private void sendAsChunked(OutputStream outputStream, PrintWriter pw) throws IOException {
            //transfer-encoding:chunked的含义 http://blog.csdn.net/whatday/article/details/7571451
            /**
             *  "Transfer-Encoding: chunked" 是这样编码的：
             HTTP头
             \r\n
             \r\n      --连续的两个\r\n之后就是HTTP体了
             16进制值代表的数据长度
             \r\n
             上面所指的数据长度
             \r\n    --每段数据结束后，以\r\n标识
             16进制代表的第二段数据
             \r\n
             XX长度的数据
             \r\n
             ………… (反复通过这样的方式表示每次传输的数据长度)
             0      --数据结束部分用0表示，然后是连续的两个\r\n
             \r\n
             \r\n
             */
            pw.print("Transfer-Encoding: chunked\r\n");
            pw.print("\r\n");
            //两个\r\n之后就是HTTP体了
            pw.flush();
            int BUFFER_SIZE = 16 * 1024;
            byte[] CRLF = "\r\n".getBytes();
            byte[] buff = new byte[BUFFER_SIZE];
            int read;
            while ((read = data.read(buff)) > 0) {
                outputStream.write(String.format("%x\r\n", read).getBytes());
                outputStream.write(buff, 0, read);
                outputStream.write(CRLF);
            }
            outputStream.write(String.format("0\r\n\r\n").getBytes());
        }

        /**
         * 发送固定大小的数据到客户端，其大小为发送的内容的大小。
         *
         * @param outputStream
         * @param pending
         * @throws IOException
         */
        private void sendAsFixedLength(OutputStream outputStream, int pending) throws IOException {
            //不是head请求，同时data不为空。
            if (requestMethod != Method.HEAD && data != null) {
                int BUFFER_SIZE = 16 * 1024;
                //缓存
                byte[] buff = new byte[BUFFER_SIZE];
                while (pending > 0) {
                    //将inputStream当中的数据读入到buff当中
                    //将输入流中最多 len 个数据字节读入 byte 数组。尝试读取 len 个字节，但读取的字节也可能小于该值。以整数形式返回实际读取的字节数。
                    int read = data.read(buff, 0, ((pending > BUFFER_SIZE) ? BUFFER_SIZE : pending));
                    if (read <= 0) {
                        break;
                    }
                    // 将指定 buff 数组中从偏移量 0 开始的 read 个字节写入此输出流。
                    outputStream.write(buff, 0, read);
                    pending -= read;
                }
            }
        }

        public IStatus getStatus() {
            return status;
        }

        public void setStatus(Status status) {
            this.status = status;
        }

        public String getMimeType() {
            return mimeType;
        }

        public void setMimeType(String mimeType) {
            this.mimeType = mimeType;
        }

        public InputStream getData() {
            return data;
        }

        public void setData(InputStream data) {
            this.data = data;
        }

        public Method getRequestMethod() {
            return requestMethod;
        }

        public void setRequestMethod(Method requestMethod) {
            this.requestMethod = requestMethod;
        }

        public void setChunkedTransfer(boolean chunkedTransfer) {
            this.chunkedTransfer = chunkedTransfer;
        }

        public interface IStatus {
            int getRequestStatus();

            String getDescription();
        }

        /**
         * Some HTTP response status codes
         * 消息体
         */
        public enum Status implements IStatus {
            SWITCH_PROTOCOL(101, "Switching Protocols"), OK(200, "OK"), CREATED(201, "Created"), ACCEPTED(202, "Accepted"), NO_CONTENT(204, "No Content"), PARTIAL_CONTENT(206, "Partial Content"), REDIRECT(301,
                    "Moved Permanently"), NOT_MODIFIED(304, "Not Modified"), BAD_REQUEST(400, "Bad Request"), UNAUTHORIZED(401,
                    "Unauthorized"), FORBIDDEN(403, "Forbidden"), NOT_FOUND(404, "Not Found"), METHOD_NOT_ALLOWED(405, "Method Not Allowed"), RANGE_NOT_SATISFIABLE(416,
                    "Requested Range Not Satisfiable"), INTERNAL_ERROR(500, "Internal Server Error");
            private final int requestStatus;
            private final String description;

            Status(int requestStatus, String description) {
                this.requestStatus = requestStatus;
                this.description = description;
            }

            @Override
            public int getRequestStatus() {
                return this.requestStatus;
            }

            @Override
            public String getDescription() {
                return "" + this.requestStatus + " " + description;
            }
        }
    }

    /**
     * 返回异常
     */
    public static final class ResponseException extends Exception {

        private final Response.Status status;

        public ResponseException(Response.Status status, String message) {
            super(message);
            this.status = status;
        }

        public ResponseException(Response.Status status, String message, Exception e) {
            super(message, e);
            this.status = status;
        }

        public Response.Status getStatus() {
            return status;
        }
    }

    /**
     * Default strategy for creating and cleaning up temporary files.
     */
    private class DefaultTempFileManagerFactory implements TempFileManagerFactory {
        @Override
        public TempFileManager create() {
            return new DefaultTempFileManager();
        }
    }

    /**
     * Handles one session, i.e. parses the HTTP request and returns the response.
     */
    public interface IHTTPSession {
        void execute() throws IOException;

        Map<String, String> getParms();

        Map<String, String> getHeaders();

        /**
         * @return the path part of the URL.
         */
        String getUri();

        String getQueryParameterString();

        Method getMethod();

        InputStream getInputStream();

        CookieHandler getCookies();

        /**
         * Adds the files in the request body to the files map.
         *
         * @arg files - map to modify
         */
        void parseBody(Map<String, String> files) throws IOException, ResponseException;
    }

    /**
     * 处理用户http请求的主要类！
     */
    protected class HTTPSession implements IHTTPSession {
        public static final int BUFSIZE = 8192;
        private final TempFileManager tempFileManager;
        private final OutputStream outputStream;
        /**
         * PushbackInputStream 为另一个输入流添加性能，即“推回 (push back)”或“取消读取 (unread)”一个字节的能力。
         * 在代码片段可以很方便地读取由特定字节值分隔的不定数量的数据字节时，这很有用；在读取终止字节后，
         * 代码片段可以“取消读取”该字节，这样，输入流上的下一个读取操作将会重新读取被推回的字节。
         * 例如，表示构成标识符字符的字节可能由表示操作符字符的字节终止；
         * 用于读取一个标识符的方法可以读取到遇到操作符为止，然后将该操作符推回以进行重读。
         */
        private PushbackInputStream inputStream;
        private int splitbyte;
        private int rlen;
        private String uri;
        private Method method;
        private Map<String, String> parms;
        private Map<String, String> headers;
        private CookieHandler cookies;
        private String queryParameterString;

        public HTTPSession(TempFileManager tempFileManager, InputStream inputStream, OutputStream outputStream) {
            this.tempFileManager = tempFileManager;
            this.inputStream = new PushbackInputStream(inputStream, BUFSIZE);
            this.outputStream = outputStream;
        }

        public HTTPSession(TempFileManager tempFileManager, InputStream inputStream, OutputStream outputStream, InetAddress inetAddress) {
            this.tempFileManager = tempFileManager;
            this.inputStream = new PushbackInputStream(inputStream, BUFSIZE);
            this.outputStream = outputStream;
            String remoteIp = inetAddress.isLoopbackAddress() || inetAddress.isAnyLocalAddress() ? "127.0.0.1" : inetAddress.getHostAddress().toString();
            headers = new HashMap<String, String>();

            headers.put("remote-addr", remoteIp);
            headers.put("http-client-ip", remoteIp);
        }

        //处理用户请求的主要入口方法。
        @Override
        public void execute() throws IOException {
            try {
                // Read the first 8192 bytes.
                // The full header should fit in here.
                // Apache's default header limit is 8KB.
                // Do NOT assume that a single read will get the entire header at once!


                //  8192/1024=8 就是说这个header的限制的最大长度为8KB同Apache默认的header长度限制一样
                //imputStream一次性会读入最多BUFSIZE个字节，说明，其是一种尽力的做法，而不是确定的做法。
                //其读取的字节的长度由返回值确定。
                byte[] buf = new byte[BUFSIZE];
                splitbyte = 0; //头信息与内容信息隔断的位置
                rlen = 0; //总共的长度
                {
                    int read = -1;//从inputStream到buf中的数量
                    try {
                        //将inputStream中的内容读到buf中
                        read = inputStream.read(buf, 0, BUFSIZE);
                    } catch (Exception e) {
                        safeClose(inputStream);
                        safeClose(outputStream);
                        throw new SocketException("NanoHttpd Shutdown");
                    }
                    if (read == -1) {
                        // socket was been closed
                        safeClose(inputStream);
                        safeClose(outputStream);
                        throw new SocketException("NanoHttpd Shutdown");
                    }
                    //找到头部信息与内容信息分割的位置  ，因为可能取多次才能获取到那个位置，所以放在while循环当中。
                    while (read > 0) {
                        //rlen为总长度
                        rlen += read;
                        //找到这header与Http内容分割位置
                        splitbyte = findHeaderEnd(buf, rlen);
                        if (splitbyte > 0)
                            break;
                        //从rlen这个偏移读取 BUFSIZE - rlen 长度的数据
                        read = inputStream.read(buf, rlen, BUFSIZE - rlen);
                    }
                }

                if (splitbyte < rlen) {
                    //推回 byte 数组的某一部分：将其复制到推回缓冲区之前。
                    //此方法返回后，要读取的下一个字节的值将为 b[off]，该字节之后的字节的值将为 b[off+1]，依此类推。
                    inputStream.unread(buf, splitbyte, rlen - splitbyte);
                }

                parms = new HashMap<String, String>();
                if (null == headers) {
                    headers = new HashMap<String, String>();
                }

                // Create a BufferedReader for parsing the header.
                //创建解析header的BufferedReader
                BufferedReader hin = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(buf, 0, rlen)));

                // Decode the header into parms and header java properties
                Map<String, String> pre = new HashMap<String, String>();
                //解码Header到parms和header
                decodeHeader(hin, pre, parms, headers);
                     //得到method
                method = Method.lookup(pre.get("method"));
                if (method == null) {
                    throw new ResponseException(Response.Status.BAD_REQUEST, "BAD REQUEST: Syntax error.");
                }
                 //得到uri
                uri = pre.get("uri");

                cookies = new CookieHandler(headers);

                // Ok, now do the serve()
                Response r = serve(this);
                if (r == null) {
                    throw new ResponseException(Response.Status.INTERNAL_ERROR, "SERVER INTERNAL ERROR: Serve() returned a null response.");
                } else {
                    cookies.unloadQueue(r);
                    r.setRequestMethod(method);
                    r.send(outputStream);
                }
            } catch (SocketException e) {
                // throw it out to close socket object (finalAccept)
                throw e;
            } catch (SocketTimeoutException ste) {
                throw ste;
            } catch (IOException ioe) {
                Response r = new Response(Response.Status.INTERNAL_ERROR, MIME_PLAINTEXT, "SERVER INTERNAL ERROR: IOException: " + ioe.getMessage());
                r.send(outputStream);
                safeClose(outputStream);
            } catch (ResponseException re) {
                Response r = new Response(re.getStatus(), MIME_PLAINTEXT, re.getMessage());
                r.send(outputStream);
                safeClose(outputStream);
            } finally {
                tempFileManager.clear();
            }
        }

        /**
         * parseBody方法中使用了tmpFile的方法保存httpRequest的content信息
         * @param files
         * @throws IOException
         * @throws ResponseException
         */
        @Override
        public void parseBody(Map<String, String> files) throws IOException, ResponseException {
            RandomAccessFile randomAccessFile = null;
            BufferedReader in = null;
            try {
                //创建临时文件
                randomAccessFile = getTmpBucket();

                long size;
                if (headers.containsKey("content-length")) {
                    size = Integer.parseInt(headers.get("content-length"));
                } else if (splitbyte < rlen) {
                    size = rlen - splitbyte;
                } else {
                    size = 0;
                }

                // Now read all the body and write it to f
                byte[] buf = new byte[512];
                while (rlen >= 0 && size > 0) {
                    rlen = inputStream.read(buf, 0, (int) Math.min(size, 512));
                    size -= rlen;
                    if (rlen > 0) {
                        randomAccessFile.write(buf, 0, rlen);
                    }
                }

                // Get the raw body as a byte []
                ByteBuffer fbuf = randomAccessFile.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, randomAccessFile.length());
                randomAccessFile.seek(0);

                // Create a BufferedReader for easily reading it as string.
                InputStream bin = new FileInputStream(randomAccessFile.getFD());
                in = new BufferedReader(new InputStreamReader(bin));

                // If the method is POST, there may be parameters
                // in data section, too, read it:
                if (Method.POST.equals(method)) {
                    String contentType = "";
                    String contentTypeHeader = headers.get("content-type");

                    StringTokenizer st = null;
                    if (contentTypeHeader != null) {
                        st = new StringTokenizer(contentTypeHeader, ",; ");
                        if (st.hasMoreTokens()) {
                            contentType = st.nextToken();
                        }
                    }

                    if ("multipart/form-data".equalsIgnoreCase(contentType)) {
                        // Handle multipart/form-data
                        if (!st.hasMoreTokens()) {
                            throw new ResponseException(Response.Status.BAD_REQUEST, "BAD REQUEST: Content type is multipart/form-data but boundary missing. Usage: GET /example/file.html");
                        }

                        String boundaryStartString = "boundary=";
                        int boundaryContentStart = contentTypeHeader.indexOf(boundaryStartString) + boundaryStartString.length();
                        String boundary = contentTypeHeader.substring(boundaryContentStart, contentTypeHeader.length());
                        if (boundary.startsWith("\"") && boundary.endsWith("\"")) {
                            boundary = boundary.substring(1, boundary.length() - 1);
                        }
                        /*
                        POST http://write.blog.csdn.net/article/uploadimg2?isadd=1 HTTP/1.1
                        Host: write.blog.csdn.net
                        Connection: keep-alive
                        Content-Length: 99634
                        Cache-Control: max-age=0
                        Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,;q=0.8
                        Origin: http://write.blog.csdn.net
                        User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.125 Safari/537.36
                        Content-Type: multipart/form-data; boundary=----WebKitFormBoundarywA8jbCE5nreOTIKG
                        Referer: http://write.blog.csdn.net/article/uploadimg2?isadd=1
                        Accept-Encoding: gzip,deflate,sdch
                        Accept-Language: zh-CN,zh;q=0.8,en;q=0.6,ja;q=0.4,zh-TW;q=0.2,fr;q=0.2
                        Cookie: uuid_tt_dd=6456255936017088876_20140821; UserName=yangzl2008; UserInfo=; UserNick=Snowball; AU=AEB; UN=yangzl2008; UE="[email protected]"; access-token=6; __utma=17226283.1613953559.1408605887.1408967386.1408970302.28; __utmb=17226283.2.10.1408970302; __utmc=17226283; __utmz=17226283.1408961787.26.17.utmcsr=baidu|utmccn=(organic)|utmcmd=organic|utmctr=header%20%E6%9C%80%E5%A4%A7%E9%95%BF%E5%BA%A6; dc_tos=nav4g3; dc_session_id=1408970301842

                                ------WebKitFormBoundarywA8jbCE5nreOTIKG
                        Content-Disposition: form-data; name="file1"; filename="2014-07-31_144229.png"
                        Content-Type: image/png

                        �PNG
                        
                        ���
                         */
                        decodeMultipartData(boundary, fbuf, in, parms, files);
                    } else {
                        String postLine = "";
                        StringBuilder postLineBuffer = new StringBuilder();
                        char pbuf[] = new char[512];
                        int read = in.read(pbuf);
                        while (read >= 0 && !postLine.endsWith("\r\n")) {
                            postLine = String.valueOf(pbuf, 0, read);
                            postLineBuffer.append(postLine);
                            read = in.read(pbuf);
                        }
                        postLine = postLineBuffer.toString().trim();
                        // Handle application/x-www-form-urlencoded
                        if ("application/x-www-form-urlencoded".equalsIgnoreCase(contentType)) {
                            decodeParms(postLine, parms);
                        } else if (postLine.length() != 0) {
                            // Special case for raw POST data => create a special files entry "postData" with raw content data
                            files.put("postData", postLine);
                        }
                    }
                } else if (Method.PUT.equals(method)) {
                    files.put("content", saveTmpFile(fbuf, 0, fbuf.limit()));
                }
            } finally {
                safeClose(randomAccessFile);
                safeClose(in);
            }
        }

        /**
         * Decodes the sent headers and loads the data into Key/value pairs
         * 解码数据到键值对
         *
         *
         * GET http://www.baidu.com/ HTTP/1.1
         Host: www.baidu.com
         Connection: keep-alive
         Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp
        User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.125 Safari/537.36
        Accept-Encoding: gzip,deflate,sdch
        Accept-Language: zh-CN,zh;q=0.8,en;q=0.6,ja;q=0.4,zh-TW;q=0.2,fr;q=0.2
        Cookie: BAIDUID=EDB95C7AF45CA0BEDF26A38E63CD8458:SL=0:NR=10:FG=1; sug=3; ORIGIN=1; bdime=0; sugstore=1; BD_CK_SAM=1; H_PS_PSSID=6459_1446_7801_8234_8225_8057_8220_8211_6017_8251_8262_7476_7607_7798_8036_8319_7963_8113; H_PS_ENCTN=125bkhUTjZXsPCymXy4aLJBui1rjGrs4GbDzEzpe1M5iY%2FPPvg4uNJ3Ywqo; BD_HOME=0

                */
        private void decodeHeader(BufferedReader in, Map<String, String> pre, Map<String, String> parms, Map<String, String> headers)
                throws ResponseException {
            try {
                // Read the request line
                String inLine = in.readLine();
                if (inLine == null) {
                    return;
                }
                 //以空格分组
                StringTokenizer st = new StringTokenizer(inLine);
                if (!st.hasMoreTokens()) {
                    throw new ResponseException(Response.Status.BAD_REQUEST, "BAD REQUEST: Syntax error. Usage: GET /example/file.html");
                }
                 //得到method
                pre.put("method", st.nextToken());

                if (!st.hasMoreTokens()) {
                    throw new ResponseException(Response.Status.BAD_REQUEST, "BAD REQUEST: Missing URI. Usage: GET /example/file.html");
                }
                  //得到uri
                String uri = st.nextToken();

                // Decode parameters from the URI
                int qmi = uri.indexOf('?');
                if (qmi >= 0) {
                    decodeParms(uri.substring(qmi + 1), parms);
                    uri = decodePercent(uri.substring(0, qmi));
                } else {
                    uri = decodePercent(uri);
                }

                // If there's another token, it's protocol version,
                // followed by HTTP headers. Ignore version but parse headers.
                // NOTE: this now forces header names lowercase since they are
                // case insensitive and vary by client.
                //得到更多的header信息
                if (st.hasMoreTokens()) {
                    String line = in.readLine();
                    while (line != null && line.trim().length() > 0) {
                        int p = line.indexOf(':');
                        if (p >= 0)
                            headers.put(line.substring(0, p).trim().toLowerCase(Locale.US), line.substring(p + 1).trim());
                        line = in.readLine();
                    }
                }

                pre.put("uri", uri);
            } catch (IOException ioe) {
                throw new ResponseException(Response.Status.INTERNAL_ERROR, "SERVER INTERNAL ERROR: IOException: " + ioe.getMessage(), ioe);
            }
        }

        /**
         * Decodes the Multipart Body data and put it into Key/Value pairs.
         */
        private void decodeMultipartData(String boundary, ByteBuffer fbuf, BufferedReader in, Map<String, String> parms,
                                         Map<String, String> files) throws ResponseException {
            try {
                int[] bpositions = getBoundaryPositions(fbuf, boundary.getBytes());
                int boundarycount = 1;
                String mpline = in.readLine();
                while (mpline != null) {
                    if (!mpline.contains(boundary)) {
                        throw new ResponseException(Response.Status.BAD_REQUEST, "BAD REQUEST: Content type is multipart/form-data but next chunk does not start with boundary. Usage: GET /example/file.html");
                    }
                    boundarycount++;
                    Map<String, String> item = new HashMap<String, String>();
                    mpline = in.readLine();
                    while (mpline != null && mpline.trim().length() > 0) {
                        int p = mpline.indexOf(':');
                        if (p != -1) {
                            item.put(mpline.substring(0, p).trim().toLowerCase(Locale.US), mpline.substring(p + 1).trim());
                        }
                        mpline = in.readLine();
                    }
                    if (mpline != null) {
                        String contentDisposition = item.get("content-disposition");
                        if (contentDisposition == null) {
                            throw new ResponseException(Response.Status.BAD_REQUEST, "BAD REQUEST: Content type is multipart/form-data but no content-disposition info found. Usage: GET /example/file.html");
                        }
                        StringTokenizer st = new StringTokenizer(contentDisposition, ";");
                        Map<String, String> disposition = new HashMap<String, String>();
                        while (st.hasMoreTokens()) {
                            String token = st.nextToken().trim();
                            int p = token.indexOf('=');
                            if (p != -1) {
                                disposition.put(token.substring(0, p).trim().toLowerCase(Locale.US), token.substring(p + 1).trim());
                            }
                        }
                        String pname = disposition.get("name");
                        pname = pname.substring(1, pname.length() - 1);

                        String value = "";
                        if (item.get("content-type") == null) {
                            while (mpline != null && !mpline.contains(boundary)) {
                                mpline = in.readLine();
                                if (mpline != null) {
                                    int d = mpline.indexOf(boundary);
                                    if (d == -1) {
                                        value += mpline;
                                    } else {
                                        value += mpline.substring(0, d - 2);
                                    }
                                }
                            }
                        } else {
                            if (boundarycount > bpositions.length) {
                                throw new ResponseException(Response.Status.INTERNAL_ERROR, "Error processing request");
                            }
                            int offset = stripMultipartHeaders(fbuf, bpositions[boundarycount - 2]);
                            String path = saveTmpFile(fbuf, offset, bpositions[boundarycount - 1] - offset - 4);
                            files.put(pname, path);
                            value = disposition.get("filename");
                            value = value.substring(1, value.length() - 1);
                            do {
                                mpline = in.readLine();
                            } while (mpline != null && !mpline.contains(boundary));
                        }
                        parms.put(pname, value);
                    }
                }
            } catch (IOException ioe) {
                throw new ResponseException(Response.Status.INTERNAL_ERROR, "SERVER INTERNAL ERROR: IOException: " + ioe.getMessage(), ioe);
            }
        }

        /**
         * Find byte index separating header from body. It must be the last byte of the first two sequential new lines.
         *
         * 从头开始，找header信息与内容信息间隔的位置。其是第一个 \r\n \r\n 的位置。
         */
        private int findHeaderEnd(final byte[] buf, int rlen) {
            //从头开始，找header信息与内容信息间隔的位置。
            int splitbyte = 0;
            while (splitbyte + 3 < rlen) {
                if (buf[splitbyte] == '\r' && buf[splitbyte + 1] == '\n' && buf[splitbyte + 2] == '\r' && buf[splitbyte + 3] == '\n') {
                    return splitbyte + 4;
                }
                splitbyte++;
            }
            return 0;
        }

        /**
         * Find the byte positions where multipart boundaries start.
         * 这个方法真的没看懂啊。。
         *
        POST http://write.blog.csdn.net/article/uploadimg2?isadd=1 HTTP/1.1
         Host: write.blog.csdn.net
         Connection: keep-alive
         Content-Length: 99634
         Cache-Control: max-age=0
         Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,q=0.8
        Origin: http://write.blog.csdn.net
        User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.125 Safari/537.36
        Content-Type: multipart/form-data; boundary=----WebKitFormBoundarywA8jbCE5nreOTIKG
        Referer: http://write.blog.csdn.net/article/uploadimg2?isadd=1
        Accept-Encoding: gzip,deflate,sdch
        Accept-Language: zh-CN,zh;q=0.8,en;q=0.6,ja;q=0.4,zh-TW;q=0.2,fr;q=0.2
        Cookie: uuid_tt_dd=6456255936017088876_20140821; UserName=yangzl2008; UserInfo=%%%3D%3D; UserNick=Snowball; AU=AEB; UN=yangzl2008; UE="[email protected]"; access-token=602bcdff-49d2-4830-9112-e67084079e70; __utma=17226283.1613953559.1408605887.1408967386.1408970302.28; __utmb=17226283.2.10.1408970302; __utmc=17226283; __utmz=17226283.1408961787.26.17.utmcsr=baidu|utmccn=(organic)|utmcmd=organic|utmctr=header%20%E6%9C%80%E5%A4%A7%E9%95%BF%E5%BA%A6; dc_tos=nav4g3; dc_session_id=1408970301842

                ------WebKitFormBoundarywA8jbCE5nreOTIKG
        Content-Disposition: form-data; name="file1"; filename="2014-07-31_144229.png"
        Content-Type: image/png

        �PNG
        
                ���
         */
        private int[] getBoundaryPositions(ByteBuffer b, byte[] boundary) {
            int matchcount = 0;
            int matchbyte = -1;
            List<Integer> matchbytes = new ArrayList<Integer>();
            for (int i = 0; i < b.limit(); i++) {
                if (b.get(i) == boundary[matchcount]) {
                    if (matchcount == 0)
                        matchbyte = i;
                    matchcount++;
                    if (matchcount == boundary.length) {
                        matchbytes.add(matchbyte);
                        matchcount = 0;
                        matchbyte = -1;
                    }
                } else {
                    i -= matchcount;
                    matchcount = 0;
                    matchbyte = -1;
                }
            }
            int[] ret = new int[matchbytes.size()];
            for (int i = 0; i < ret.length; i++) {
                ret[i] = matchbytes.get(i);
            }
            return ret;
        }

        /**
         * Retrieves the content of a sent file and saves it to a temporary file. The full path to the saved file is returned.
         */
        private String saveTmpFile(ByteBuffer b, int offset, int len) {
            String path = "";
            if (len > 0) {
                FileOutputStream fileOutputStream = null;
                try {
                    TempFile tempFile = tempFileManager.createTempFile();
                    ByteBuffer src = b.duplicate();
                    fileOutputStream = new FileOutputStream(tempFile.getName());
                    FileChannel dest = fileOutputStream.getChannel();
                    src.position(offset).limit(offset + len);
                    dest.write(src.slice());
                    path = tempFile.getName();
                } catch (Exception e) { // Catch exception if any
                    throw new Error(e); // we won't recover, so throw an error
                } finally {
                    safeClose(fileOutputStream);
                }
            }
            return path;
        }

        /**
         * 创建文件。
         * @return
         */
        private RandomAccessFile getTmpBucket() {
            try {
                TempFile tempFile = tempFileManager.createTempFile();
                return new RandomAccessFile(tempFile.getName(), "rw");
            } catch (Exception e) {
                throw new Error(e); // we won't recover, so throw an error
            }
        }

        /**
         * It returns the offset separating multipart file headers from the file's data.
         */
        private int stripMultipartHeaders(ByteBuffer b, int offset) {
            int i;
            for (i = offset; i < b.limit(); i++) {
                if (b.get(i) == '\r' && b.get(++i) == '\n' && b.get(++i) == '\r' && b.get(++i) == '\n') {
                    break;
                }
            }
            return i + 1;
        }

        /**
         * Decodes parameters in percent-encoded URI-format ( e.g. "name=Jack%20Daniels&pass=Single%20Malt" ) and
         * adds them to given Map. NOTE: this doesn't support multiple identical keys due to the simplicity of Map.
         */
        private void decodeParms(String parms, Map<String, String> p) {
            if (parms == null) {
                queryParameterString = "";
                return;
            }

            queryParameterString = parms;
            StringTokenizer st = new StringTokenizer(parms, "&");
            while (st.hasMoreTokens()) {
                String e = st.nextToken();
                int sep = e.indexOf('=');
                if (sep >= 0) {
                    p.put(decodePercent(e.substring(0, sep)).trim(),
                            decodePercent(e.substring(sep + 1)));
                } else {
                    p.put(decodePercent(e).trim(), "");
                }
            }
        }

        @Override
        public final Map<String, String> getParms() {
            return parms;
        }

        public String getQueryParameterString() {
            return queryParameterString;
        }

        @Override
        public final Map<String, String> getHeaders() {
            return headers;
        }

        @Override
        public final String getUri() {
            return uri;
        }

        @Override
        public final Method getMethod() {
            return method;
        }

        @Override
        public final InputStream getInputStream() {
            return inputStream;
        }

        @Override
        public CookieHandler getCookies() {
            return cookies;
        }
    }

    /**
     * Cookie信息
     * Cookie: BAIDUID=EDB95C7AF45CA0BEDF26A38E63CD8458:SL=0:NR=10:FG=1; sug=3; ORIGIN=1; bdime=0; sugstore=1; BD_CK_SAM=1; H_PS_PSSID=6459_1446_7801_8234_8225_8057_8220_8211_6017_8251_8262_7476_7607_7798_8036_8319_7963_8113; H_PS_ENCTN=125bkhUTjZXsPCymXy4aLJBui1rjGrs4GbDzEzpe1M5iY%2FPPvg4uNJ3Ywqo; BD_HOME=0
     */
    public static class Cookie {
        private String n, v, e;

        public Cookie(String name, String value, String expires) {
            n = name;
            v = value;
            e = expires;
        }

        public Cookie(String name, String value) {
            this(name, value, 30);
        }

        public Cookie(String name, String value, int numDays) {
            n = name;
            v = value;
            e = getHTTPTime(numDays);
        }

        public String getHTTPHeader() {
            String fmt = "%s=%s; expires=%s";
            return String.format(fmt, n, v, e);
        }

        public static String getHTTPTime(int days) {
            Calendar calendar = Calendar.getInstance();
            SimpleDateFormat dateFormat = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z", Locale.US);
            dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
            calendar.add(Calendar.DAY_OF_MONTH, days);
            return dateFormat.format(calendar.getTime());
        }
    }

    /**
     * Provides rudimentary support for cookies.
     * Doesn't support 'path', 'secure' nor 'httpOnly'.
     * Feel free to improve it and/or add unsupported features.
     *
     * @author LordFokas
     */
    public class CookieHandler implements Iterable<String> {
        private HashMap<String, String> cookies = new HashMap<String, String>();
        private ArrayList<Cookie> queue = new ArrayList<Cookie>();

        /**
         * 得到cookies信息
         * @param httpHeaders
         */
        public CookieHandler(Map<String, String> httpHeaders) {
            String raw = httpHeaders.get("cookie");
            if (raw != null) {
                String[] tokens = raw.split(";");
                for (String token : tokens) {
                    String[] data = token.trim().split("=");
                    if (data.length == 2) {
                        cookies.put(data[0], data[1]);
                    }
                }
            }
        }

        @Override
        public Iterator<String> iterator() {
            return cookies.keySet().iterator();
        }

        /**
         * Read a cookie from the HTTP Headers.
         *
         * @param name The cookie's name.
         * @return The cookie's value if it exists, null otherwise.
         */
        public String read(String name) {
            return cookies.get(name);
        }

        /**
         * Sets a cookie.
         *
         * @param name    The cookie's name.
         * @param value   The cookie's value.
         * @param expires How many days until the cookie expires.
         */
        public void set(String name, String value, int expires) {
            queue.add(new Cookie(name, value, Cookie.getHTTPTime(expires)));
        }

        public void set(Cookie cookie) {
            queue.add(cookie);
        }

        /**
         * Set a cookie with an expiration date from a month ago, effectively deleting it on the client side.
         *
         * @param name The cookie name.
         */
        public void delete(String name) {
            set(name, "-delete-", -30);
        }

        /**
         * Internally used by the webserver to add all queued cookies into the Response's HTTP Headers.
         *
         * @param response The Response object to which headers the queued cookies will be added.
         */
        public void unloadQueue(Response response) {
            for (Cookie cookie : queue) {
                response.addHeader("Set-Cookie", cookie.getHTTPHeader());
            }
        }
    }
}