Socket小练习

本例实现了多客户端，当客户端a发送消息，按下回车后，所有的客户端均会收到a的消息。例子十分简单，做socket入门之用：
Myserver.java

package server;import server.ServerThread;import java.io.IOException;import java.net.ServerSocket;import java.net.Socket;import java.util.ArrayList;public class Myserver {    //建立一个socket集合    public static ArrayList<Socket> socketList = new ArrayList<Socket>();    public static void main(String[] args) throws IOException {        ServerSocket serverSocket  = new ServerSocket(30000);        //循环用于不断接收客户端连接        while(true){            Socket s = serverSocket.accept();            socketList.add(s);            //对于每一个客户端都启动一个新的线程            new Thread(new ServerThread(s)).start();        }    }}

ServerThread.java

package server;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintStream;import java.net.Socket;public class ServerThread implements Runnable{    Socket socket = null;    //该线程所处理的Socket 所对应的输入流    BufferedReader br =null;    public ServerThread(Socket s) throws IOException{        this.socket= s;        br  = new BufferedReader(new InputStreamReader(socket.getInputStream()));    }    public void run(){        try {            String content =null;            while((content = readFromClient())!=null){                for(Socket s:Myserver.socketList){                    PrintStream ps = new PrintStream(s.getOutputStream());                    ps.println(content);                }            }        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    private String readFromClient() {        // TODO Auto-generated method stub        try {            return br.readLine();        } catch (IOException e) {            // TODO Auto-generated catch block            Myserver.socketList.remove(socket);        }        return null;    }}

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刚刚开始接触socket对socket的getInputStream( )和getOutputStream( )方法不够理解，查资料后，解析如下：

socket的输入流和输出流
socket提供了InputStream getInputStream( );
OutputStream getOutputStream( ) l两个方法来获取输入流和输出流。
在理解这两个方法之前，首先要理解InputStream 和OutputStream
将流想象成管道，输入流是从别人创建的管道（如客户端创建的管道）里读数据
输出流则是向管道（自己的管道）中放数据
那么socket.getInputStream( )方法意为获取输入流，
SocketThread.java 部分代码解析

br  = new BufferedReader(new InputStreamReader(socket.getInputStream()));

先将客户端发送的数据以字节流的形式从管道中读出，然后用它初始化一个字符流，再用这个字符流初始化一个字符缓冲流；

PrintStream ps = new PrintStream(s.getOutputStream());
意为获取将socket的输出流作为PrintStream的输出流

ps.println(content);

content 定义为从客户端读取的数据，用PrintStream 打印输出。

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Myclient.java

package client;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.PrintStream;import java.net.Socket;import java.net.UnknownHostException;public class MyClient {    public static void main(String[] args) throws UnknownHostException, IOException {        Socket socket = new Socket("127.0.0.1", 30000);        //启动client 线程，不断读取来自服务器的消息        new Thread(new ClientThread(socket)).start();        //获取socket 对象对应的输出流        PrintStream printStream =  new PrintStream(socket.getOutputStream());        String line = null;        //不断从键盘读取输入        BufferedReader bReader = new BufferedReader(new InputStreamReader(System.in));        while((line = bReader.readLine())!=null)            printStream.println(line);    }}

ClientThread.java

package client;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.net.Socket;public class ClientThread implements Runnable {    private Socket socket;    private BufferedReader bf;    public ClientThread(Socket socket) throws IOException {        this.socket = socket;        // ??inputStreamReader        this.bf = new BufferedReader(new InputStreamReader(socket.getInputStream()));    }    @Override    public void run() {        // TODO Auto-generated method stub        try {            String content = null;            while((content = bf.readLine())!=null)                System.out.println(content);        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}

以上代码均测试通过
下一篇将会详细剖析 InputStream 、 InputStreamReader和BufferedReader