问题概述

实现EchoServer和EchoClient类，其中EchoServer监听某一端口号（启动时，通过参数传入），等待客户端访问；EchoClient根据启动时传入的服务器地址（IP地址或域名）和端口号连接该服务；连接后，读取用户在命令行下的输入，将该输入传输给EchoServer；EchoServer接收后，向EchoClient返回“EchoServer received: ” + 用户输入信息；EchoClient接收到返回信息后输出到命令行，并继续等待用户输入

1、客户端EchoClient.java代码

package cn.wangbaiyuan;
import java.io.;
import java.net.;
import java.util.Scanner;

/**
* socket通信客户端类
*
* @author 王柏元
/

public class EchoClient {

/\*\*
 \* PORT 一个初始化端口
 */
static int PORT = 12340; // 连接端口
/\*\*
 \* HOST一个初始化主机名
 */
static String HOST = "192.168.4.21"; // 连接地址
/\*\*
 \* socket 客户端socket
 \* 
 */
Socket socket;

public EchoClient() throws UnknownHostException, IOException {
    socket = new Socket(HOST, PORT); // 创建客户端套接字
}

/\*\*
 \* 实现发送消息
 */
public void send() {
    try {
        // 客户端输出流，向服务器发消息
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(
                socket.getOutputStream()));
        // 客户端输入流，接收服务器消息
        BufferedReader br = new BufferedReader(new InputStreamReader(
                socket.getInputStream()));
        PrintWriter pw = new PrintWriter(bw, true); // 装饰输出流，及时刷新
        Scanner in = new Scanner(System.in); // 接受用户信息
        String msg = null;
        while ((msg = in.next()) != null) {
            pw.println(msg); // 发送给服务器端
            System.out.println(br.readLine()); // 输出服务器返回的消息
            if (msg.equals("quit")) {
                break; // 退出
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (null != socket) {
            try {
                socket.close(); // 断开连接
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

public static void main(String\[\] args) throws UnknownHostException,
        IOException {
    BufferedReader strin = new BufferedReader(new InputStreamReader(
            System.in));
    System.out.println("请输入连接地址：");
    HOST = strin.readLine();
    System.out.println("请输入连接端口：");
    PORT = Integer.parseInt(strin.readLine());
    new EchoClient().send();
}

}

2、单线程服务器端EchoServer.java代码

package cn.wangbaiyuan;

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.ServerSocket;
import java.net.Socket;

/**
* @author 王柏元
socket通信服务器类 /

public class EchoServer {
/*
*/

ServerSocket serverSocket;
private final int PORT = 12340; // 端口

/**
* 新建EchoServer类时建立一个ServerSocket
* @throws IOException
/
public EchoServer() throws IOException {
serverSocket = new ServerSocket(PORT); // 创建服务器端套接字
System.out.println(“服务器启动。”);
}
/\*
* 启动服务器socket服务，监听客户端消息
*/

public void servic() {
    Socket socket = null;
    while (true) {
        try {
            socket = serverSocket.accept(); // 等待并取出用户连接，并创建套接字
            System.out.println("新连接，连接地址：" + socket.getInetAddress() + "："
                    \+ socket.getPort()); // 客户端信息
            // 输入流，读取客户端信息
            BufferedReader br = new BufferedReader(new InputStreamReader(
                    socket.getInputStream(), "UTF-8"));// 涉及到安卓客户端，为留设置编码
            // 输出流，向客户端写信息
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(
                    socket.getOutputStream(), "UTF-8"));
            PrintWriter pw = new PrintWriter(bw, true); // 装饰输出流，true,每写一行就刷新输出缓冲区，不用flush
            String info = null; // 接收用户输入的信息
            while ((info = br.readLine()) != null) {
                System.out.println(info); // 输出用户发送的消息
                pw.println("you said:" + info); // 向客户端返回用户发送的消息，println输出完后会自动刷新缓冲区
                if (info.equals("quit")) { // 如果用户输入“quit”就退出
                    break;
                }
            }
        } // 如果客户端断开连接，则应捕获该异常，但不应中断整个while循环，使得服务器能继续与其他客户端通信
        catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (null != socket) {
                try {
                    socket.close(); // 断开连接
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

/**
* EchoServer main静态类，启动时开启服务器端服务
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
new EchoServer().servic(); // 启动服务
}
}

3、多线程服务器端代码

ThreadEchoServer.java:

package cn.wangbaiyuan;

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.ServerSocket;
import java.net.Socket;

public class ThreadEchoServer {
ServerSocket serverSocket;
private final int PORT=1245; //端口

public ThreadEchoServer() throws IOException{
serverSocket=new ServerSocket(PORT); //创建服务器端套接字
System.out.println("服务器启动。");
}

//servic()方法
public void service(){
    while(true){
    Socket socket=null;
    try {
    socket=serverSocket.accept();
    Thread work=new Thread(new Handler(socket)); //为客户连接创建工作线程
    work.start();
    } catch (IOException e) {
    e.printStackTrace();
    }
    }
    }

public static void main(String\[\] args) throws IOException {
new ThreadEchoServer().service(); //启动服务
}
}

Handler.java

package cn.wangbaiyuan;

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

public class Handler implements Runnable { // 负责与单个客户通信的线程
private Socket socket;
BufferedReader br;
BufferedWriter bw;
PrintWriter pw;

public Handler(Socket socket) {
    this.socket = socket;
}

public void initStream() throws IOException { // 初始化输入输出流对象方法
    br = new BufferedReader(new InputStreamReader(socket.getInputStream(),"UTF-8"));
    bw = new BufferedWriter(
            new OutputStreamWriter(socket.getOutputStream(),"UTF-8"));
    pw = new PrintWriter(bw, true);
    System.out.println("新连接，连接地址："+socket.getInetAddress()+"："+socket.getPort());

}

public void run() { // 执行的内容
    try {
        initStream(); // 初始化输入输出流对象
        String info = null;
        while (null != (info = br.readLine())) {
            System.out.println(socket.getInetAddress()+"say："+info);
            pw.println("you said:" + info);
            // 返回用户发送的消息
            if (info.equals("quit")) {
                System.out.println(socket.getInetAddress()+"已退出："+info);// 如果用户输入“quit”就退出
                pw.println("你已退出");
                break;
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (null != socket) {
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

}