try {
//新建server,监听本地8080端口
serverSocket=new ServerSocket(8080, 1, InetAddress.getByName("127.0.0.1"));
System.out.println("....server start...");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
while(!shutdown){
try {
Socket socket=serverSocket.accept();
in=socket.getInputStream();
out=socket.getOutputStream();
Request request=new Request(in);
//解析请求http请求
request.parse();
Response response=new Response(out);
response.setRequest(request);
response.sendStaticResource();
socket.close();
shutdown=request.getUri().equals(SHUTDOWN_COMMAND);
} Request.java
public void parse(){
StringBuffer request=new StringBuffer(2048);
int i;
byte[] buffer=new byte[2048];
try {
i=input.read(buffer);
} catch (Exception e) {
e.printStackTrace();
i=-1;
}
for (int j = 0; j < i; j++) {
request.append((char)buffer[j]);
}
System.out.println(request.toString());
uri=parseUri(request.toString());
}
public String getUri(){
return uri;
}
/**
* http请求第一行格式 <p/>
* 请求方法 uri 协议
* @param requestString
* @return
*/
private String parseUri(String requestString){
int index1,index2;
index1=requestString.indexOf(" ");
if(index1 != -1){
index2 = requestString.indexOf(" ",index1+1);
if(index2 > index1){
return requestString.substring(index1 + 1,index2);
}
}
return null;
} Response.java
public void sendStaticResource(){
byte[] bytes=new byte[BUFFER_SIZE];
FileInputStream fis=null;
try {
File file=new File(HttpServer.WEB_ROOT,request.getUri());
if(file.exists()){
fis=new FileInputStream(file);
int ch=fis.read(bytes, 0, BUFFER_SIZE);
while(ch!=-1){
out.write(bytes,0,ch);
ch=fis.read(bytes, 0, BUFFER_SIZE);
}
}else{
String errorMsg="HTTP/1.1 404 File Not Found\r\n"+
"Content-Type: text/html\r\n"+
"Content-Length: 23\r\n"+
"\r\n"+
"<h1>File Not Found</h1>";
out.write(errorMsg.getBytes());
}
} catch (Exception e) {
System.out.println(e.toString());
} 第二部分 在前章处理静态资源的基础上，加入处理servlet请求的方法。成为简单的servlet容器，而不仅仅是一个web服务器。
需要加入的内容：
1.request解析请求头uri后判断检查request是针对servlet还是静态资源
if(request.getUri().startsWith("/servlet/")){
ServletProcessor1 processor=new ServletProcessor1();
processor.process(request,response); 2.实例化ServletProcessor类传入response,request。初始化一个类加载器并加载相关的serlvet类。
URL urls[]=new URL[1];
//根据不用协议流建立不同链接 ftp/http/
URLStreamHandler streamHandler=null;
File classPath=new File(Constants.WEB_ROOT);
String repository=(new URL("file",null,classPath.getCanonicalPath()+File.separator)).toString();
//指定第三个参数编译器才知道调用哪个构造函数，不然报错
urls[0]=new URL(null,repository,streamHandler);
//如果ULR以/结尾则是目录，否则是jar,这里查找工作目录下的webroot
System.out.println(repository);
loader=new URLClassLoader(urls);
.....
Class myClass=null;
try {
myClass=loader.loadClass(servletName);
} catch (Exception e) {
System.out.println(e.toString());
}
Servlet servlet=null;
try {
servlet=(Servlet)myClass.newInstance();
servlet.service((ServletRequest)request, (ServletResponse)response);
} catch (Exception e) {
e.printStackTrace();
}
3.PrimitiveServlet类收到请求后调用service方法并打印输出结果。
public class PrimitiveServlet implements Servlet {
......
@Override
public void service(ServletRequest arg0, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
System.out.println("from service");
PrintWriter out=response.getWriter();
out.println("Hello .ROses are red");
out.println("violets are blue");
out.flush();
}
} 4. Request和Response类分别需要实现ServletRequest，ServletResponse接口。这里我们先把需要实现的方法均留空不处理。需要处理的：
public class Response implements ServletResponse {
...
public PrintWriter getWriter() throws IOException {
// TODO Auto-generated method stub
return new PrintWriter(out);
}
...
} 5.加入门面模式Facade来区别tomcat系统开发人员和用户对request,reponse方法的使用提高安全性，拿出部分方法对使用者可见。大家可以看看很多源码都采用了Facade模式，比如代码生成器:rapid_framework，spring -quartz等。思考下HttpProcessor在每次请求时候都需要新建一个Processor来处理请求，可以利用对象池进行优化。每个Processor可以使用新的线程来处理，防止线程阻塞等。后面将说明这些问题。
/** * 定义外观类，所有方法在servlet中可见的，<p/> * 只是Request中的部分方法，其它方法不可访问,这样方法才更安全 * @author greenn [email protected] * CopyRight Huawei 2013-11-20 * */ public class HttpRequestFacade implements ServletRequest{ private HttpRequest request; public HttpRequestFacade(HttpRequest request) { // TODO Auto-generated constructor stub this.request=request; } @Override public AsyncContext getAsyncContext() { // TODO Auto-generated method stub return request.getAsyncContext(); } ....
try {
servlet=(Servlet)myClass.newInstance();
servlet.service(new HttpRequestFacade(request), new HttpResponseFacade(response));
} catch (Exception e) {
e.printStackTrace();
} 第三部分 模拟Tomcat默认连接器，罗列一些优化性能的思路方法。 1.HttpConnector及HttpProcessor类均实现Runable接口来运行在自己的线程中无需等待某个HttpProcessor实例完成解析。
2.容器类均实现了LifeCycle接口。当创建一个HttpConnector实例后，就会调用其initialize()方法和start()方法。在组件的整个生命周期内，这两个方法均被调用一次。
3.HttpConnector维护HttpProcessor池。