02--Java TCP Socket编程

一、基础知识

1. TCP状态转换知识，可参考：

http://www.cnblogs.com/qlee/archive/2011/07/12/2104089.html

2. TCP/IP五层模型

应用层：HTTP、FTP、SMTP、Telnet等

传输层：TCP/IP

网络层：

数据链路层：

物理层：网线、双绞线、网卡等

3. 常用类,java.net.*

此包下主要类结构图如下：

3.1 InetAddress

InetAddress类用于标识网络上的硬件资源，标识互联网协议(IP)地址。 该类没有构造方法，由于涉及DNS解析，该类一般用单例模式。

1 //获取本机的InetAddress实例
2 InetAddress address =InetAddress.getLocalHost();
3 address.getHostName();//获取计算机名
4 address.getHostAddress();//获取IP地址
5 byte[] bytes = address.getAddress();//获取字节数组形式的IP地址,以点分隔的四部分
6
7 //获取其他主机的InetAddress实例
8 InetAddress address2 =InetAddress.getByName("其他主机名");
9 InetAddress address3 =InetAddress.getByName("IP地址");

3.2 URL类

URL(Uniform Resource Locator)统一资源定位符，表示Internet上某一资源的地址，协议名：资源名称

 1 //创建一个URL的实例
 2 URL baidu =new URL("http://www.baidu.com");
 3 URL url =new URL(baidu,"/index.html?username=tom#test");//？表示参数，#表示锚点
 4 url.getProtocol();//获取协议
 5 url.getHost();//获取主机
 6 url.getPort();//如果没有指定端口号，根据协议不同使用默认端口。此时getPort()方法的返回值为 -1
 7 url.getPath();//获取文件路径
 8 url.getFile();//文件名，包括文件路径+参数
 9 url.getRef();//相对路径，就是锚点，即#号后面的内容
10 url.getQuery();//查询字符串，即参数

3.3 Socket类

代表通讯过程中的客户端。

3.4 ServerSocket类

代表通讯过程中的服务器端。

二、Socket编程模型及步骤

1. Socket模型图

2. ServerSocket工作步骤

① 创建ServerSocket对象，绑定监听端口
② 通过accept()方法监听客户端请求，此处会堵塞。
③ 连接建立后，通过输入流读取客户端发送的请求信息
④ 通过输出流向客户端发送乡音信息
⑤ 关闭相关资源

3. Socket工作步骤

① 创建ServerSocket和Socket
② 打开连接到Socket的输入/输出流
③ 按照协议对Socket进行读/写操作
④ 关闭输入输出流、关闭Socket

三、常用工作模型

1. 服务器单线程监听和处理服务，客户端单线程，2个文件

package com.yyn.io.net;

import java.io.BufferedOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.sql.Date;

public class SingleThreadServer extends Thread{
 /**
  *  单线程的,仅仅是能够应答连接的客户就立即断开连接了
  */
    private static ServerSocket serverSocket;

    public SingleThreadServer(){
        super();
        try{
            serverSocket = new ServerSocket(1112);
            System.out.println("SingleThreadSocket creating....");
        }catch (Exception e) {
            System.out.println("SingleThreadSocket create failed....");
            System.exit(1);
        }
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub
        Socket client = null;
        while (true) {
            if (serverSocket == null) {
                return;
            }
            try{
                client = serverSocket.accept();
                InputStream in = client.getInputStream();
                OutputStream out = client.getOutputStream();
                BufferedOutputStream bos = new BufferedOutputStream(out);
                PrintWriter writer = new PrintWriter(bos);
                Date now = new Date(System.currentTimeMillis());
                writer.write(now.toString());
                System.out.println("New Connection Accepted:"+client.getRemoteSocketAddress());
                writer.flush();
                client.close();

            }catch (Exception e) {
                // TODO: handle exception
            }
        }
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        SingleThreadServer server = new SingleThreadServer();
        server.start();
    }
}

package com.yyn.io.net;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.Buffer;

public class SingleThreadClient {

    public static void main(String[] args) throws UnknownHostException, IOException {
        // TODO Auto-generated method stub
        Socket server = new Socket("127.0.0.1", 1112);
        OutputStream out = server.getOutputStream();
        BufferedOutputStream bos = new BufferedOutputStream(out);
        PrintWriter writer = new PrintWriter(bos);
        writer.write("Hello server!!!");

        InputStream in = server.getInputStream();
        InputStreamReader isr = new InputStreamReader(in);
        BufferedReader reader = new BufferedReader(isr);
        String info = null;
        info = reader.readLine();
        System.out.println("####Server Message: " + info);

        reader.close();
        isr.close();
        in.close();
        writer.close();
        bos.close();
        out.close();
        server.close();

    }

}

2. 服务器单线程监听，连接客户端后(ACCEPT成功后)，启动新线程处理服务。

package com.yyn.io.net;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

//获取用户连接请求，请求成功后，调用MultiThreadSeverThread进行服务
public class MultiThreadServerReceiver {

    public static final int PORT = 12002;

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        init();
    }

    public static void init() throws Exception{
        ServerSocket server = new ServerSocket(PORT);
        System.out.println("Server is started");
        int count = 0;
        while(true){
            Socket client = server.accept();
            System.out.println("Accepted at: " + client.getRemoteSocketAddress());
            MultiThreadSeverThread serverThread = new MultiThreadSeverThread(client);
            System.out.println("Start Thread to process!!!");
            serverThread.start();
            count++;
            while (count >=3) {
                return;
            }
        }
    }

}

package com.yyn.io.net;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;

//请求连接后，accept成功后，负责服务的线程类
public class MultiThreadSeverThread extends Thread{
        private Socket client = null;
        private PrintWriter writer = null;
        private BufferedReader reader = null;
        public static final String CHARSET = "UTF-8";

        public MultiThreadSeverThread(Socket client) throws Exception{
            this.client = client;
            try{
                // Init writer
                OutputStreamWriter osw = new OutputStreamWriter(client.getOutputStream(),CHARSET);
                BufferedWriter bw = new BufferedWriter(osw);
                this.writer = new PrintWriter(bw);

                // Init reader
                InputStreamReader isr = new InputStreamReader(client.getInputStream(),CHARSET);
                this.reader = new BufferedReader(isr);
            }catch(Exception e){
                e.printStackTrace();
                throw new Exception("Init MultiThreadServerThread failed!!!");
            }
            System.out.println("#######Welcome to server,input commands please!!!");
        }

        @Override
        public void run(){
            String command = null;
            boolean flag = true;
            System.out.println("thread to process!!!");
            while (flag) {
                try {
                    command = this.reader.readLine();
                    System.out.println("client command:" + command);
                } catch (Exception e) {
                    e.printStackTrace();
                    flag = false;
                }
                if (command == null) {
                    return ;
                }
                // if command is not null ,then trim it and change to upper case
                command = command.trim().toUpperCase();
                if(command.equals("QUIT")){
                    flag = false;
                }else if (command.equals("HELP")) {
                    this.writer.println("本服务器可收到的请求有：");
                    this.writer.println("list");
                    this.writer.println("push");
                    this.writer.println("pop");
                }else if(command.equals("LIST") || command.equals("PUSH") || command.equals("POP")) {
                    this.writer.println("输入命令正确");
                }else{
                    this.writer.println("输入命令有误，请重新输入！！！");
                }
                writer.flush();
            }
            // close socket connection
            try {
                this.client.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
}

package com.yyn.io.net;

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Iterator;
import java.util.stream.Stream;

public class MultiThreadServerClient {

    public static final int PORT = 12002;

    public static void main(String[] args) throws UnknownHostException, IOException {
        // TODO Auto-generated method stub
        Socket socket = new Socket("127.0.0.1",PORT);
        // in stream from console
        InputStreamReader isr = new InputStreamReader(System.in,"UTF-8");
        BufferedReader in = new BufferedReader(isr);
        // out stream from socket
        OutputStreamWriter osw =
                new OutputStreamWriter(new BufferedOutputStream(socket.getOutputStream()), "UTF-8");
        PrintWriter out = new PrintWriter(osw);

        String command = null;
        while(true){
            System.out.println("#######################");
            command = in.readLine();
            if (command == null) {
                socket.shutdownInput();
                break;
            }
            command = command.trim().toUpperCase();
            if (command.equals("EXIT")) {
                socket.shutdownInput();
                break;
            }
            out.println(command); //必须用println方法，不能用write，否则服务端无法获取数据，会堵塞
            out.flush();
            System.out.println("data send to server:"+command);
        }
    }

}

3. 服务器一次向多个客户端发送信息