http协议:超文本传输协议
http协议规定，响应与请求一样，有3部分组成，分别是
1.http协议版本、状态代码、描述
2.响应头（response head）
3.响应文本（response content）
实例
http/1.1 200 ok
server:apache tomcat/6.0.12
date:mon,6oct2012 16:35:42 gmt
content-type:text/html;charset=gbk;
content-length:112

 

下面示例在浏览器中输入http://localhost:8888可以得到响应

package httpserver;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Date;

public class Server {
    private ServerSocket  server;
    public static final String CRLF = "\r\n";
    public static final String BLANK=" ";
    public static void main(String[] args) {
        Server server = new Server();
        server.start();
    }

    /*
     * 启动方法
     */
    public void start(){
        try {
            server = new ServerSocket(8888);
            
            this.receive();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /*
     * 接受客户端
     */
    private void receive(){
        try {
            Socket client = server.accept();
            byte[] data = new byte[20480];
            
            int len = client.getInputStream().read(data);
            //接受客户端的请求信息
            String requestInfo = new String(data,0,len);
            System.out.println(requestInfo);
            
            //响应
            StringBuilder responseContext = new StringBuilder();
            responseContext.append("<html><head><title>HTTP响应示例</title></head><body>hello tomcat!</body></html");
            
            StringBuilder response = new StringBuilder();
            //1)http协议版本、状态代码、描述
            response.append("HTTP/1.1").append(BLANK).append("200").append(BLANK).append("OK").append(CRLF);
            //2)响应头（response head）
            response.append("server:apache tomcat/6.0.12").append(CRLF);
            response.append("Date:").append(new Date()).append(CRLF);
            //3.响应文本（response  content）
            response.append("content-type:text/html;charset=gbk;").append(CRLF);
            //正文长度
            response.append("Content-Length;").append(responseContext.toString().getBytes().length).append(CRLF);
            //正文之前
            response.append(CRLF);
            //正文
            response.append(responseContext);
            
            //输出了
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));
            bw.write(response.toString());
            bw.flush();
            bw.close();
            
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /*
     * 停止
     */
    public void stop(){
        
    }
}



请求头