前言
看到网上有很多现成的Web容器:Tomcat、Jetty、Undertow、JBoss、WebLogic、WebSphere等,心里就痒痒的,也想要尝试自己写一个。然后我就从最熟悉的Tomcat下手,先学习了一下它,不过自从上回写了《学Springboot必须要懂的内嵌式Tomcat启动与请求处理》之后,总感觉思路还不是很清晰,毕竟Tomcat是一个较为重量级的容器了,它内部有很多分支在初学时会使得理解变的很困难,索性就边写边理解吧。
一、我的理解
整体流程如下所示:
线程池处理请求的时候需要解析请求报文,然后将请求报文转成请求对象,方便后续处理,最后将执行结果返回给终端
二、代码实现
2.1主函数开启容器
public class Main {
public static void main(String[] args) {
WcfServlet servlet=new WcfServlet();
servlet.start();
}
}
2.2容器的入口,包括端口号和ip的绑定,以及 轮询器的启动
package com.wcf.test;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
/**
* @author wangcanfeng
* @description 服务容器
* @Date Created in 15:44-2019/7/29
*/
public class WcfServlet {
Logger logger = LogManager.getLogger(WcfServlet.class);
/**
* 系统默认端口号
*/
private final static int DEFAULT_PORT = 7528;
/**
* socketChannel
*/
private volatile ServerSocketChannel socketChannel = null;
public WcfServlet() {
try {
// 新建一个channel
socketChannel = ServerSocketChannel.open();
// 绑定一下ip和端口号
socketChannel.socket().bind(new InetSocketAddress(InetAddress.getLocalHost(), DEFAULT_PORT));
//设置ServerSocket以非阻塞方式工作
socketChannel.configureBlocking(false);
} catch (Exception e) {
logger.error("construct servlet failed", e);
}
}
/**
* 功能描述: 启动容器
*
* @param
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/29-16:26
*/
public void start() {
try {
Poller poller=new Poller();
poller.register(this.socketChannel);
poller.start();
} catch (Exception e) {
e.printStackTrace();
}
}
}
2.3轮询器,用于轮询进来的请求,然后将请求交给分配器处理
package com.wcf.test;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.io.IOException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
/**
* @author wangcanfeng
* @description 轮询器,轮询请求
* @Date Created in 16:19-2019/7/29
*/
public class Poller extends Thread {
private Logger logger = LogManager.getLogger(Poller.class);
/**
* 通道选择器
*/
private final Selector selector;
/**
* 可以使用的通道数
*/
private volatile int keyCount = 0;
private volatile ServerSocketChannel socketChannel;
public Poller() throws IOException {
// 新建一个通道选择器
// open的方法实现各个操作系统都是不一样的,需要注意一下
selector = Selector.open();
}
/**
* 功能描述: 给选择器绑定通道
*
* @param ssc 服务器通道
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/29-16:30
*/
public void register(ServerSocketChannel ssc) throws Exception {
// 将通道注册到selector上,当有多个终端连接时,都是由这个selector来管理,实现传说中的多路复用
// 让选择器监听socket的变化
ssc.register(selector, SelectionKey.OP_ACCEPT);
this.socketChannel = ssc;
}
@Override
public void run() {
while (true) {
try {
keyCount = selector.select();
} catch (IOException e) {
logger.error("find selector failed", e);
}
Iterator keys =
keyCount > 0 ? selector.selectedKeys().iterator() : null;
while (keys != null && keys.hasNext()) {
SelectionKey sk = keys.next();
keys.remove();
// ssc需要先处理连接请求
if (sk.isValid() && sk.isAcceptable()) {
accept(sk);
}
// 附件的包装器,把附件绑定到sk上,附件的生命周期和sk一致,但是附件不会随着网络传播
InformationWrapper wrapper = new InformationWrapper();
sk.attach(wrapper);
if (sk.isValid() && sk.isReadable()) {
Dispatcher dispatcher = new Dispatcher(sk);
dispatcher.dispatch();
}
}
}
}
/**
* 功能描述: 接收连接请求,重新绑定通道,并关注读请求
*
* @param sk
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/29-19:28
*/
private void accept(SelectionKey sk) {
try {
ServerSocketChannel serverSocketChannel = (ServerSocketChannel) sk.channel();
SocketChannel sc = serverSocketChannel.accept();
sc.configureBlocking(false);
sc.register(selector, SelectionKey.OP_READ);
//将sk对应的Channel设置成准备接受其他请求
sk.interestOps(SelectionKey.OP_ACCEPT);
} catch (Exception e) {
logger.error("accept information from client failed", e);
}
}
}
2.4分配器将任务分配给处理器去处理
package com.wcf.test;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.io.IOException;
import java.nio.channels.SelectionKey;
/**
* @author wangcanfeng
* @description 任务分配器,分配任务给处理器
* @Date Created in 16:51-2019/7/29
*/
public class Dispatcher {
private final static Logger logger = LogManager.getLogger(Dispatcher.class);
private SelectionKey sk;
public Dispatcher(SelectionKey sk) {
this.sk = sk;
}
/**
* 功能描述: 处理事件内容
*
* @param
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/29-19:58
*/
public void dispatch() {
InformationWrapper wrapper = (InformationWrapper) sk.attachment();
if (wrapper == null) {
cancelledKey(sk);
} else {
processKey(wrapper);
}
}
/**
* 功能描述: 处理包装器中的数据
*
* @param wrapper
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/29-18:40
*/
private void processKey(InformationWrapper wrapper) {
try {
// 将数据读入信息包装器中
wrapper.read(sk);
} catch (IOException e) {
cancelledKey(sk);
logger.error("read information failed", e);
}
ThreadPool.getExecutors().execute(new Handler(wrapper));
}
/**
* 功能描述: 将SelectionKey从select的Set中取消
*
* @param sk
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/29-18:39
*/
public static void cancelledKey(SelectionKey sk) {
try {
if (sk != null) {
sk.attach(null);
if (sk.isValid()) {
sk.cancel();
}
// 虽然被cancel了,但是这个通道还是可以使用的,所以这个通道需要关闭一下
if (sk.channel().isOpen()) {
sk.channel().close();
}
}
} catch (Throwable e) {
logger.error("channelCloseFail", e);
}
}
}
2.5处理器,处理请求内容
package com.wcf.test;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
/**
* @author wangcanfeng
* @description 处理器,具体处理请求内容
* @Date Created in 11:09-2019/7/30
*/
public class Handler implements Runnable {
private final static Logger logger = LogManager.getLogger(Dispatcher.class);
/**
* 请求附件信息
*/
private InformationWrapper wrapper;
/**
* 长连接标识
*/
private final static String PROTOCOL_LONG = "long";
public Handler(InformationWrapper wrapper) {
this.wrapper = wrapper;
}
@Override
public void run() {
// 判断是长连接还是短连接
// 假设长连接请求是有long开头的
try {
if (wrapper.getInfoStr().startsWith(PROTOCOL_LONG)) {
// 长连接只需要写数据到通道中,不需要消除sk
wrapper.write();
} else {
// 处理一下http请求的报文,生成请求对象
HttpRequest request = new HttpRequest();
request.getRequest(wrapper);
// 处理请求
// ......
// 处理完毕
HttpResponse.response(wrapper, "请求已处理".getBytes());
// 短连接用完之后需要消除当前的SelectionKey
Dispatcher.cancelledKey(wrapper.getSelectionKey());
}
} catch (Exception e) {
logger.error("handler information failed", e);
Dispatcher.cancelledKey(wrapper.getSelectionKey());
}
}
}
2.6附件对象,和sk一起消亡
package com.wcf.test;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
/**
* @author wangcanfeng
* @description 信息包装器
* @Date Created in 16:01-2019/7/29
*/
public class InformationWrapper {
/**
* 信息流
*/
private final ByteBuffer information;
/**
* 通道和选择器的绑定键
*/
private SelectionKey selectionKey;
/**
* socket的通道
*/
private SocketChannel socketChannel;
/**
* 编码后的字符串信息
*/
private final StringBuffer stringBuffer;
/**
* 默认的编码格式
*/
private final static Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
/**
* 允许的单次传送最大信息体积
*/
private final static int ALLOW_CONTENT_LENGTH = 2 * 1024 * 1024;
public InformationWrapper() {
information = ByteBuffer.allocate(ALLOW_CONTENT_LENGTH);
stringBuffer = new StringBuffer(ALLOW_CONTENT_LENGTH);
}
/**
* 功能描述: 通过SelectionKey获取到通道,再从通道路面读取流
*
* @param sk
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/29-18:37
*/
public void read(SelectionKey sk) throws IOException {
this.selectionKey = sk;
this.socketChannel = (SocketChannel) sk.channel();
while (socketChannel.read(information) > 0) {
information.flip();
stringBuffer.append(DEFAULT_CHARSET.decode(information));
}
}
/**
* 功能描述: 将指定的信息写到通道中
*
* @param bbf
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/30-11:01
*/
public void write(ByteBuffer bbf) throws IOException {
this.socketChannel.write(bbf);
}
/**
* 功能描述: 直接写当前附件中的信息到通道中
*
* @param
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/30-11:01
*/
public void write() throws IOException {
this.socketChannel.write(DEFAULT_CHARSET.encode(stringBuffer.toString()));
}
public SelectionKey getSelectionKey() {
return selectionKey;
}
public ByteBuffer getInformation() {
return information;
}
public String getInfoStr() {
return stringBuffer.toString();
}
public SocketChannel getChannel() {
return socketChannel;
}
}
2.7请求对象
package com.wcf.test;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.HashMap;
import java.util.Map;
/**
* @author wangcanfeng
* @description
* @Date Created in 13:42-2019/7/30
*/
public class HttpRequest {
private final static Logger logger = LogManager.getLogger(HttpRequest.class);
/**
* 请求方法
*/
private String method;
/**
* 请求路径
*/
private String path;
/**
* 请求版本信息
*/
private String version;
/**
* 请求头信息
*/
private Map headers = new HashMap<>();
/**
* 请求体
*/
private String body;
private final static String UTF8 = "UTF-8";
public HttpRequest getRequest(InformationWrapper wrapper) {
String info = wrapper.getInfoStr();
// 首先获取请求方法
if (info == null || info.length() == 0) {
return null;
} else {
// 解析请求报文
// 浏览器中换行符使用了\r\n,估计是为了适配windows和linux
String[] arr = info.split("\r\n");
//
if (arr.length < 2) {
return null;
}
// 解析请求行
try {
resolveRequestLine(arr[0]);
} catch (UnsupportedEncodingException e) {
logger.error("UnsupportedEncodingException", e);
}
int count = 1;
for (; count < arr.length; count++) {
if ("".equals(arr[count])) {
break;
} else {
resolveRequestHeader(arr[count]);
}
}
// 获取请求体
if (count < arr.length) {
resolveRequestBody(arr[count + 1]);
}
return this;
}
}
/**
* 功能描述: 解析请求行,获取请求方法名,请求路径,http协议版本
*
* @param line 请求行
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/30-14:09
*/
private void resolveRequestLine(String line) throws UnsupportedEncodingException {
// 根据空格切割字符串
String[] arr = line.split(" ");
this.method = arr[0];
// 因为在请求中可能存在特殊字符,一般都会做URL编码处理
// 所以这里需要对请求路径需要进行解码
this.path = URLDecoder.decode(arr[1], UTF8);
this.version = arr[2];
}
/**
* 功能描述: 解析请求头
*
* @param header
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/30-14:31
*/
private void resolveRequestHeader(String header) {
// 切割字符串,获取请求头中的字段名和字段值,存入map中
String[] arr = header.split(": ");
if (arr.length > 1) {
headers.put(arr[0], arr[1]);
} else {
logger.warn("this header's format is not right");
}
}
/**
* 功能描述: 解析请求体
*
* @param body
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/30-14:32
*/
private void resolveRequestBody(String body) {
this.body = body;
}
public String getMethod() {
return method;
}
public String getPath() {
return path;
}
public String getVersion() {
return version;
}
public Map getHeaders() {
return headers;
}
}
2.8返回对象
package com.wcf.test;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
* @author wangcanfeng
* @description
* @Date Created in 10:53-2019/7/30
*/
public class HttpResponse {
/**
* 功能描述: 给终端回应
*
* @param wrapper 附件信息
* @param bytes 需要返回的实际内容
* @return:void
* @since: v1.0
* @Author:wangcanfeng
* @Date: 2019/7/30-10:57
*/
public static void response(InformationWrapper wrapper, byte[] bytes) throws IOException {
ByteBuffer buf = ByteBuffer.allocate(1024);
buf.put("HTTP/1.1 200\r\n".getBytes());
buf.put("Content-Type: text/html; charset=utf-8\r\n".getBytes());
buf.put("Date: Thu, 26 Jul 2018 01:54:53 GMT\r\n".getBytes());
buf.put("\r\n".getBytes());
buf.put("Hello ".getBytes());
// 写出指定的信息
buf.put(bytes);
buf.put("
".getBytes());
buf.flip();
wrapper.write(buf);
}
}
最后
到这里我们只需要修改Handler中的处理过程就可以简单的完成我们的容器了,如果需要更好的实现这个容器,还可以对处理器进行复用等优化操作