tomcat源码编写计划连载(1)

 以前没实在的接触过tomcat这个东西,对于应用服务器和服务器的概念也一直都很模糊,于是我决定抽时间出来去实现以下tomcat源码.tomcat的流程网上一堆,大家自己去熟悉一下就行了,我直接先实现一个简单的java http服务器。这样大家可以熟悉一下服务器的最基本的工作原理,当然也是tomcat的最基本的工作原理,tomcat原比这个复杂多了,后期会进行更新代码一共包含四个类,Client(发起请求) Server(接收请求) Request(类似于Servlet的Request Response ,类似于Servlet的Response),tomcat的处理流程是1.Server接收到Client发送的请求,交给Request解析HTTP请求,然后把Request和Response对象交给你写的Service处理。1.Client发送请求代码

import java.io.*;
import java.net.InetAddress;
import java.net.Socket;

/**
* Created by user1013 on 2016/7/1.
*/
public class Client {

public static void main(String[] args){
try {
Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 8080);
OutputStream os = socket.getOutputStream(); //获取输入流
boolean autoflush = false; //socket的缓冲区
PrintWriter out = new PrintWriter(socket.getOutputStream(), autoflush);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

//发送一个HTTP请求到web服务器
out.println("GET /index.jsp HTTP/1.1");
out.println("Host: localhost:8080");
out.println("Connection: Close");
out.println();
out.flush();

//同步获取服务器返回的信息,最长接收8096个字节的东西
boolean loop = true;
StringBuffer sb = new StringBuffer(8096);
while(loop){
System.out.println("準備讀取返回");
if(in.ready()){
int i = 0;
while(i != -1){
i = in.read();
sb.append((char)i);
}
loop = false;
}
Thread.currentThread().sleep(500);
}

System.out.println(sb.toString());
socket.close();
} catch (IOException e) {
e.printStackTrace();
System.out.println(e.getMessage());
} catch (InterruptedException e) {
e.printStackTrace();
System.out.println(e.getMessage());
}

}
}

2.Server接收请求代码

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;

/**
* Created by user1013 on 2016/7/1.
*/
public class Server {

public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webRoot";
public static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
private boolean shutdown = false;

public static void main(String[] args) throws IOException {
Server server = new Server();
server.await();
}
//
private void await() {
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(8080, 1, InetAddress.getByName("127.0.0.1"));
} catch (IOException e) {
e.printStackTrace();
}
while( !this.shutdown){
try {
System.out.print("等待接收消息。。。。");
Socket socket = null;
InputStream input = null;
OutputStream output = null;
socket = serverSocket.accept();
input = socket.getInputStream();
output = socket.getOutputStream();

//1.解析请求 ,注意这两步的初始化Request和Response对象
Request request = new Request(input);
request.parse();

//2.发送信息回去
Response response = new Response(output);
response.setRequset(request);
response.SendStaticResource(); //发送静态文件资源

socket.close();
this.shutdown = request.getUri().equals(Server.SHUTDOWN_COMMAND);
} catch (IOException e) {
e.printStackTrace();
continue;
}
}

}
}

3.Request 解析处理请求

import java.io.IOException;import java.io.InputStream;/*** Created by user1013 on 2016/7/1.*/public class Request {private InputStream input = null ;private String uri ;public Request(InputStream input){this.input = input;}public void parse(){StringBuffer request = new StringBuffer(2048);int i;byte[] buffer = new byte[2048];try {i = this.input.read(buffer);} catch (IOException e) {e.printStackTrace();i = -1;}for (int j = 0; j < i; j++) {request.append((char) buffer[j]);}System.out.print(request.toString());uri = this.parseUri(request.toString());}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;}public String getUri(){return this.uri;}}

4.Response返回信息

import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.OutputStream;/*** Created by user1013 on 2016/7/1.*/public class Response {private static final int BUFFER_SIZE = 1024;private OutputStream output;private Request requset;public Response(OutputStream output){this.output = output;}public void SendStaticResource() throws IOException {byte[] bytes = new byte[Response.BUFFER_SIZE];FileInputStream fin = null;File file = new File(Server.WEB_ROOT, requset.getUri());if(file.exists()){fin = new FileInputStream(file);int ch = fin.read(bytes, 0, Response.BUFFER_SIZE);while(ch != -1){this.output.write(bytes);ch = fin.read(bytes, 0, Response.BUFFER_SIZE);}}else{String errorMessage = "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>";try {this.output.write(errorMessage.getBytes());} catch (IOException e) {} finally {if (fin!=null)fin.close();}}}public void setRequset(Request requset) {this.requset = requset;}}

上面这段代码是处理一个HTTP请求并返回一个静态资源的信息,你可以认为这个tomcat最最基本的实现。以上代码如果不懂Socket的自行学习一下，Socket可以关联很多东西.

个人感觉是比较重要的基础知识吧,其实它的本质只是一个TCP UDP操作的封装集合而已。可以牵扯到一些RPC之类的东西，反正网络之前的进程通信都是用这个。