java学习日记 网络编程

1、编写服务器端程序

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

public class HelloServer {
    public static void main(String[] args) throws Exception{
        ServerSocket server = new ServerSocket(9999); //所有服务器都必须有端口
        System.out.println("等待客户连接");
        Socket client = server.accept();
        PrintStream out = new PrintStream(client.getOutputStream());  //实例化打印流对象，输出信息
        out.println("hello world");
        out.close();
        client.close();
        server.close();
    }
}

2、编写客户端程序

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

public class HelloServer {
    public static void main(String[] args) throws Exception{
        ServerSocket server = new ServerSocket(9999); //所有服务器都必须有端口
        System.out.println("等待客户连接");
        Socket client = server.accept();
        PrintStream out = new PrintStream(client.getOutputStream());  //实例化打印流对象，输出信息
        out.println("hello world");
        out.close();
        client.close();
        server.close();
    }
}

将客户端程序拷贝到d盘，并将第一行的导入包删除，在命令窗口执行。

 3、Echo程序

import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class EchoServer {
    public static void main(String[] args) throws Exception {
        ServerSocket server = new ServerSocket(8888);
        Socket client = server.accept();  //等待连接
        //得到客户端输入数据以及向客户端输出数据的对象
        Scanner scanner = new Scanner(client.getInputStream());
        PrintStream out = new PrintStream(client.getOutputStream());
        boolean flag = true;
        while (flag){
            if (scanner.hasNext()){
                String str = scanner.next().trim();
                if (str.equalsIgnoreCase("byebye")){
                    flag=false;
                }else {
                    out.println("Echo:"+str);
                }
            }
        }
        client.close();
        server.close();
    }
}

客户端：

import java.io.PrintStream;
import java.net.Socket;
import java.util.Scanner;

public class EchoClient {
    public static void main(String[] args) throws Exception{
        Socket client = new Socket("localhost",8888);
        Scanner input = new Scanner(System.in);  //键盘输入数据
        Scanner scanner = new Scanner(client.getInputStream());
        input.useDelimiter("
");
        scanner.useDelimiter("
");  //换行为分隔符
        PrintStream out = new PrintStream(client.getOutputStream());
        boolean flag =true;
        while (flag){
            System.out.println("输入信息：");
            if (input.hasNext()){
                String str = input.next().trim();
                out.println(str);
                if ("byebye".equalsIgnoreCase(str)){
                    flag = false;
                }
                if (scanner.hasNext()){
                    System.out.println(scanner.next());
                }
            }
        }
        client.close();
    }
}

4、EchoThread

import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

class EchoThread implements Runnable{
    private Socket client = null;
    public EchoThread(Socket client){
        this.client = client;
    }
    @Override
    public void run() {
       try{
           //得到客户端输入数据以及向客户端输出数据的对象
           Scanner scanner = new Scanner(client.getInputStream());
           PrintStream out = new PrintStream(client.getOutputStream());
           boolean flag = true;
           while (flag){
               if (scanner.hasNext()){
                   String str = scanner.next().trim();
                   if (str.equalsIgnoreCase("byebye")){
                       out.println("***关闭***下次再回***");
                       flag=false;
                   }else {
                       out.println("Echo:"+str);
                   }
               }
           }
           client.close();

       }catch (Exception e){
           System.err.println(e);
       }

    }
}
public class EchoServer {
    public static void main(String[] args) throws Exception {
        ServerSocket server = new ServerSocket(8888);
        boolean flag =true;
        while (flag){
            Socket client = server.accept();  //等待连接
            new Thread(new EchoThread(client)).start();
        }
    }
}