java网络编程笔记

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特殊说明，本节笔记，是我学习马士兵java课程记录，所用某些ppt图片也是马士兵教育的课件截图

1、InetAddress对象，处理IP地址

package com.company;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class Main{

    public static void main(String[] args) {
        InetAddress localHost = null;
        InetAddress byName = null;
        try {
            localHost = InetAddress.getLocalHost();//获取本机ip地址，结果为XXXXXXX-XXXXXXX/xxx.xxx.xx.xxx，其中前面一串是本机名称,后面是ip
            System.out.println(localHost);

            byName = InetAddress.getByName("XXXXXXX-XXXXXXX");//根据主机名获取ip地址,我这里用的XXX代表一切字符，毕竟我不能暴露我的主机名给你
            System.out.println(byName+"--------"+byName.getHostAddress()+"---------------"+byName.getHostName());

        } catch (UnknownHostException e) {
            e.printStackTrace();
        }

    }
}

2、传输协议和Socket套接字

1、基于TCP的Socket编程

1、基本客户端—服务器案例

注意shutdownInput()这些方法

package com.company;

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

/**
 * 服务端
 */
public class ServerSocketTest {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket server = null;
        InputStream inputStream = null;
        DataInputStream dataInputStream = null;
        OutputStream outputStream = null;
        try {
            //服务端需要用serverSocket开放本地端口，这样别人就可以通过ip地址和端口号找到你
            serverSocket = new ServerSocket(10086);
            //要想接受client传过来的数据，也需要Socket对象，不过此对象需要用serverSocket.accept()方法返回
            server = serverSocket.accept();
            //获取输入流
            inputStream = server.getInputStream();
            //包装输入流
            dataInputStream = new DataInputStream(inputStream);
            //读取对应的数据
            String s = dataInputStream.readUTF();
            System.out.println(s);

            server.shutdownInput();//关闭流对象，如果不关，尽管程序执行结束，也依旧占用内存


            //获取输出流，给客户端反馈信息
            outputStream = server.getOutputStream();

            outputStream.write("你好客户端，我收到你的请求了".getBytes());

            server.shutdownOutput();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                dataInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                server.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

package com.company;

import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

/**
 * 客户端
 */
public class Main{

    public static void main(String[] args) {
        Socket client = null;
        OutputStream outputStream = null;
        DataOutputStream dataOutputStream = null;
        InputStream inputStream = null;
        try {
            //创建Socket对象，实际上是开启实现io的虚拟接口，此接口不是java接口，而是网络接口，可以与网络通信
            //需要指定接收方的ip地址和端口号，这里localhost是本机ip的意思，10086是一个端口号
            client  = new Socket("localhost", 10086);
            //获取输出流，向服务端发送数据
            outputStream = client.getOutputStream();
            //包装输出流，简化代码
            dataOutputStream = new DataOutputStream(outputStream);
            //传输数据
            dataOutputStream.writeUTF("服务端您好！！！我是客户端发来的请求");

            client.shutdownOutput();//关闭流对象，如果不关，尽管程序执行结束，也依旧占用内存

            //获取输入流对象，用来接收服务端反馈
            inputStream = client.getInputStream();
            byte[] buf = new byte[1024];
            int readLength = inputStream.read(buf);
            System.out.println(new String(buf,0,readLength));
            client.shutdownInput();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭这些流
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                dataOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                client.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }
}

2、基于UDP的Socket编程（应用场景不多，简单了解一下即可）

package com.company;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Scanner;

/**
 * 客户端
 */
public class Main{

    public static void main(String[] args) throws Exception {
        //创建UDP通信Socket，随便指定一个自己的端口10000
        DatagramSocket datagramSocket = new DatagramSocket(10000);
        //从控制台接收数据
        System.out.println("请输入要给服务端发送的数据：");
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();
        //构造一个发送指定长度的分组数据包，并指定服务端的端口号
        DatagramPacket localhost = new DatagramPacket(str.getBytes(), str.getBytes().length, InetAddress.getByName("localhost"), 9857);

        //将分组数据包发送出去
        datagramSocket.send(localhost);

        datagramSocket.close();

    }
}

package com.company;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

/**
 * 服务端
 */
public class ServerSocketTest {
    public static void main(String[] args) throws Exception {
        DatagramSocket datagramSocket = new DatagramSocket(9857);
        byte[] buf = new byte[1024];
        // 创建数据包对象
        DatagramPacket datagramPacket = new DatagramPacket(buf,buf.length);

        // 利用数据包对象接收数据
        datagramSocket.receive(datagramPacket);

        System.out.println("客户端发来数据："+new String(datagramPacket.getData(),0,datagramPacket.getLength()));

        datagramSocket.close();
    }
}

本文地址：https://blog.csdn.net/grd_java/article/details/109862876