Java-网络编程_随笔

Java-网络编程 1、IP

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

//测试IP
public class TestInetAddress {
    public static void main(String[] args) {
        try {
            //查询本机地址
            InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress1);
            InetAddress inetAddress2 = InetAddress.getByName("localhost");
            System.out.println(inetAddress2);
            InetAddress inetAddress3 = InetAddress.getLocalHost();
            System.out.println(inetAddress3);

            //查询网站地址
            InetAddress inetAddress4 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress4);

            //常用方法
            //System.out.println(inetAddress4.getAddress());
            System.out.println(inetAddress4.getCanonicalHostName());//规范的名字
            System.out.println(inetAddress4.getHostAddress());//ip
            System.out.println(inetAddress4.getHostName());//域名或者自己电脑的名字
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }

    }
}

2、端口

端口表示一个计算机的进程

不同进程有不同的端口号。

规定端口号的范围为0~65535（每个协议）tcp（0~65535）、udp（0~65535），总共65525*2

单个写一下端口号不可以相同，不同协议之间端口号的以重复。

端口分类：

公有端口：0~1023 尽量不要用
HTTP：80
HTTPS：443
FTP：21
Telent：23
程序注册端口：1024~49151，分配给用户或程序。
Tomcat：8080
MySQL：3306
Oracle：1521
动态、私有：49152~65525 尽量不要用

常见 *** 作：

netstat -ano #查看所有的端口
netstat -ano | findstr "5900" #查看指定的端口
tasklist/findstr "8696" #查看指定端口的进程
ctr1+ shift + ESC  #打开任务管理器的快捷键

import java.net.InetSocketAddress;

//套接字
public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress socketAddress1 = new InetSocketAddress("127.0.0.1", 8080);
        InetSocketAddress socketAddress2 = new InetSocketAddress("localhost", 8080);
        System.out.println(socketAddress1);
        System.out.println(socketAddress2);

        System.out.println(socketAddress2.getAddress());
        System.out.println(socketAddress2.getHostName());//地址
        System.out.println(socketAddress2.getPort());//端口
    }
}

3、通信协议

协议：约定，就好比我们现在说的是普通话。
网络通信协议：速率，传输码奉，i代码结构，传输控制.…...问题:非常的复杂?
大事化小：分层!
TCP/IP协议簇：实际上是一组协议。

重要:
TCP：用户传输协议。 UDP：用户数据报协议。

主要协议:
TCP：用户传输协议。 IP︰网络互连协议。

TCP与UDP

TCP：

连接、稳定
三次握手、四次挥手
客户端、服务端
传输完成、释放连接、效率低

UDP：

不连接、不稳定
客户端、服务端：没有明确的界面
直接发送
好比导d攻击
DDOS：洪水攻击（饱和攻击）：强行发送大量垃圾数据包，堵塞网络。

4、TCP

客户端：

连接服务器 Socket
发送消息

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;

//客户端01
public class TcpClientDemo01 {
    public static void main(String[] args) {
        Socket socket = null;
        OutputStream os =null;
        try {
            //1、需要知道服务器的地址、端口号
            InetAddress serverIp = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2、建立Socket连接
            socket = new Socket(serverIp, port);
            //3、发送消息IO流
            os = socket.getOutputStream();
            os.write("你好，网络世界".getBytes());
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (os!=null) {
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket!=null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

服务器：

建立服务端口 ServerSocket
等待客户链接 accept
接受消息

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

//服务器
public class TcpServerDemo01 {
    public static void main(String[] args) {
        ServerSocket serverSocket =null;
        Socket socket =null;
        InputStream is =null;
        ByteArrayOutputStream baos =null;
        try {
            //1、需要有一个地址
            serverSocket = new ServerSocket(9999);
            //2、等待客户连接
            while (true) {
                socket = serverSocket.accept();
                //3、读取客户端消息
                is = socket.getInputStream();
            
                //管道流
                baos = new ByteArrayOutputStream();
                byte[] buffer = new byte[1024];
                int len;
                while ((len = is.read(buffer)) != -1) {
                    baos.write(buffer, 0, len);
                }
                System.out.println(baos.toString());
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭资源
            if (baos!=null) {
                try {
                    baos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (is!=null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket!=null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (serverSocket!=null) {
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

文件上传

客户端

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;

public class TcpClientDemo02 {
    public static void main(String[] args) throws Exception {
        //1、建立连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);
        //2、创建输出流
        OutputStream os = socket.getOutputStream();
        //3、读取文件
        FileInputStream fis = new FileInputStream("up.png");
        //4、写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len= fis.read(buffer))!=-1){
            os.write(buffer,0,len);
        }
        //通知服务器我已经结束了
        socket.shutdownOutput();

        //确定服务端接收完了,才能断开连接
        InputStream inputStream = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        byte[] buffer2 = new byte[1024];
        int len2;
        while ((len2=inputStream.read(buffer2))!=-1){
            baos.write(buffer2,0,len2);
        }
        System.out.println(baos.toString());

        //5、关闭资源
        baos.close();
        inputStream.close();
        fis.close();
        os.close();
        socket.close();
    }
}

服务器

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class TcpServerDemo02 {
    public static void main(String[] args) throws Exception {
        //创建服务端口
        ServerSocket serverSocket = new ServerSocket(9000);
        //等待连接
        Socket socket = serverSocket.accept();
        //获取数据
        InputStream is = socket.getInputStream();
        //输出文件
        FileOutputStream fos = new FileOutputStream(new File("receive.png"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len= is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }

        //告诉客户端我接收完了
        OutputStream os = socket.getOutputStream();
        os.write("我接收完毕了，不可以断开了".getBytes());

        //关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();

    }
}

Tomcat

服务器：

自定义 S
Tomcat S

客户端：

自定义 C
浏览器 B

UDP

类似发短信，不需要连接，需要知道对方地址

发送端

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

//不需要建立连接
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1、建立一个Socket
        DatagramSocket socket = new DatagramSocket();
        //2、建立一个包
        String msg = "Hello,Word!";
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;
        // 数据，数据的长度起始，要发给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);
        //3、发送包
        socket.send(packet);
        //关闭流
        socket.close();
    }
}

接收端

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

public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);

        socket.receive(packet);

        System.out.println(packet.getAddress().getHostName());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        //关闭连接
        socket.close();
    }
}

循环发送

发送端：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class UpdateSenderDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);

        //准备数据：控制台读取，System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            String data = reader.readLine();
            byte[] datas = data.getBytes();

            DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress("localhost", 6666));
            socket.send(packet);
            if (data.equals("bye")) break;
        }
        socket.close();
    }
}

接收端：

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

public class UpdateReceiverDemo01 {
    public static void main(String[] args)throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);

        while (true) {
            //准备接受包
            byte[] container = new byte[1024];

            DatagramPacket packet = new DatagramPacket(container, 0, container.length);
            socket.receive(packet);//阻塞式接受

            //bye断开连接
            byte[] data = packet.getData();
            String receiveData = new String(data, 0, packet.getLength());
            System.out.println(receiveData);

            if (receiveData.equals("bye")) break;
        }
        socket.close();


    }
}

简易聊天（相会对话）

TalkSend

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class TalkSend implements Runnable   {
    DatagramSocket socket = null;
    BufferedReader reader =null;

    private int fromPort;
    private String toIP;
    private int toPort;

    public TalkSend(int fromPort, String toIP, int toPort) {
        this.fromPort = fromPort;
        this.toIP = toIP;
        this.toPort = toPort;
        try {
            socket = new DatagramSocket(fromPort);
            reader = new BufferedReader(new InputStreamReader(System.in));
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public void run() {

        while (true) {
            try {
                String data = reader.readLine();
                byte[] datas = data.getBytes();

                DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, this.toPort));
                socket.send(packet);
                if (data.equals("bye")) break;
            }catch (Exception e){
                e.printStackTrace();
            }

        }
        socket.close();
    }
}

TaklReceive

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class TalkReceive implements Runnable{
    DatagramSocket socket =null;
    private int port;
    private String msgFrom;

    public TalkReceive(int port,String msgFrom) {
        this.port = port;
        this.msgFrom = msgFrom;
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while (true) {
            try {
                //准备接受包
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);
                socket.receive(packet);//阻塞式接受

                //bye断开连接
                byte[] data = packet.getData();
                String receiveData = new String(data, 0, packet.getLength());
                System.out.println(this.msgFrom+":"+receiveData);

                if (receiveData.equals("bye")) break;
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

TalkStudent

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(7777,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"老师")).start();
    }
}

TalkTeacher

public class TalkTeacher {
    public static void main(String[] args) {
        new Thread(new TalkSend(5555,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生")).start();
    }
}

URL（统一资源定位符：定位资源、定位互联网上的某一个资源）

协议://ip地址:端口/项目/资源

URL常用方法

import java.net.MalformedURLException;
import java.net.URL;

public class URLDemo01 {
    public static void main(String[] args) throws MalformedURLException {
        URL url = new URL("http://www.baodu.com:8080/helloword/index.jsp?username=yao&password=123");
        System.out.println(url.getProtocol());//协议
        System.out.println(url.getHost());//主机IP
        System.out.println(url.getPort());//端口
        System.out.println(url.getPath());//文件地址
        System.out.println(url.getFile());//文件全路径
        System.out.println(url.getQuery());//参数
    }
}

使用URL下载网络资源

import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class URLDown {
    public static void main(String[] args) throws Exception {
        //下载地址
        URL url = new URL("https://m701.music.126.net/20211124231827/4b608a1bc8ebd9c0293443c48c4e2c9c/jdyyaac/obj/w5rDlsOJwrLDjj7CmsOj/11624482968/5b8b/9912/7c40/3877aa1c480cedeb274dae1b816efbb6.m4a");
        //连接到这个资源
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        InputStream inputStream = urlConnection.getInputStream();

        FileOutputStream fos = new FileOutputStream("a.m4a");
        byte[] buffer = new byte[1024];
        int len;
        while ((len=inputStream.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }
        System.out.println("下载完成");

        fos.close();
        inputStream.close();
        urlConnection.disconnect();
    }
}

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原文地址: https://outofmemory.cn/zaji/5583704.html

Java-网络编程

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