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Java小白第一次就能看懂的網(wǎng)絡(luò)編程

更新時間：2021年08月30日 11:56:11 作者：扛麻袋的少年

網(wǎng)絡(luò)編程是指編寫運行在多個設(shè)備（計算機）的程序，這些設(shè)備都通過網(wǎng)絡(luò)連接起來。本文介紹了一些網(wǎng)絡(luò)編程基礎(chǔ)的概念，并用Java來實現(xiàn)TCP和UDP的Socket的編程，來讓讀者更好的了解其原理

一、網(wǎng)絡(luò)基礎(chǔ)

二、網(wǎng)絡(luò)協(xié)議

 實現(xiàn)TCP的網(wǎng)絡(luò)編程
 例子1：客戶端發(fā)送信息給服務(wù)端，服務(wù)端將數(shù)據(jù)顯示在控制臺上
public class TCPTest1 {
    //客戶端
    @Test
    public void client() {
        Socket socket = null;
        OutputStream os = null;
        try {
            //1.創(chuàng)建Socket對象，指明服務(wù)器端的ip和端口號
            InetAddress inet = InetAddress.getByName("127.0.0.1");
            socket = new Socket(inet, 8899);
            //2.獲取一個輸出流，用于輸出數(shù)據(jù)
            os = socket.getOutputStream();
            //3.寫出數(shù)據(jù)的操作
            os.write("你好，我是客戶端mm".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //4.資源的關(guān)閉
            if(os != null){
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
 
    }
    //服務(wù)端
    @Test
    public void server(){
        ServerSocket ss = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;
        try {
            //1.創(chuàng)建服務(wù)器的ServerSocket,指明自己的端口號
            ss = new ServerSocket(8899);
            //2.調(diào)用accept()表示接收來自于客戶端的socket
            socket = ss.accept();
            //3.獲取輸入流
            is = socket.getInputStream();
            //不建議這樣寫，可能會有亂碼
//        byte[] buffer = new byte[1024];
//        int len;
//        while((len = is.read(buffer)) != -1){
//            String str = new String(buffer,0,len);
//            System.out.println(str);
//        }
            //4.讀取輸入流中的數(shù)據(jù)
            baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[5];
            int len;
            while((len = is.read(buffer)) != -1){
                baos.write(buffer,0,len);
            }
            System.out.println(baos.toString());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //5.關(guān)閉資源
            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(ss != null){
                try {
                    ss.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

 實現(xiàn)TCP的網(wǎng)絡(luò)編程
 例題2：客戶端發(fā)送文件給服務(wù)端，服務(wù)端將文件保存在本地。
public class TCPTest2 {
    //這里異常處理的方式應(yīng)該使用try-catch-finally
    @Test
    public void client() throws IOException {
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9090);
        OutputStream os = socket.getOutputStream();
        FileInputStream fis = new FileInputStream(new File("beauty.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while((len = fis.read(buffer)) != -1){
            os.write(buffer,0,len);
        }
        fis.close();
        os.close();
        socket.close();
    }
    //這里異常處理的方式應(yīng)該使用try-catch-finally
    @Test
    public void server() throws IOException {
        ServerSocket ss = new ServerSocket(9090);
        Socket socket = ss.accept();
        InputStream is = socket.getInputStream();
        FileOutputStream fos = new FileOutputStream(new File("beauty1.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while((len = is.read(buffer)) != -1){
            fos.write(buffer,0,len);
        }
        fos.close();
        is.close();
        socket.close();
        ss.close();
    }
}

 實現(xiàn)TCP的網(wǎng)絡(luò)編程
 例題3：從客戶端發(fā)送文件給服務(wù)端，服務(wù)端保存到本地，并返回"發(fā)送成功"給客戶端。并關(guān)閉相應(yīng)的連接
 
public class TCPTest3 {
    @Test
    public void client() throws IOException {
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9090);
        OutputStream os = socket.getOutputStream();
        FileInputStream fis = new FileInputStream(new File("beauty.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while((len = fis.read(buffer)) != -1){
            os.write(buffer,0,len);
        }
        //服務(wù)區(qū)端給予客戶端反饋
        OutputStream os1 = socket.getOutputStream();
        os.write("你好，美女，照片我以收到，非常漂亮！".getBytes());
        fis.close();
        os.close();
        socket.close();
        os1.close();
 
    }
    //這里異常處理的方式應(yīng)該使用try-catch-finally
    @Test
    public void server() throws IOException {
        ServerSocket ss = new ServerSocket(9090);
        Socket socket = ss.accept();
        InputStream is = socket.getInputStream();
        FileOutputStream fos = new FileOutputStream(new File("beauty2.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while((len = is.read(buffer)) != -1){
            fos.write(buffer,0,len);
        }
        //接受來自于服務(wù)器端的數(shù)據(jù)，并顯示到控制臺上
        InputStream is1 = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] bufferr = new byte[20];
        int len1;
        while((len1 = is1.read(buffer)) != -1){
            baos.write(buffer,0,len1);
        }
        System.out.println(baos.toString());
        fos.close();
        is.close();
        socket.close();
        ss.close();
        baos.close();
    }
}

UDP協(xié)議的網(wǎng)絡(luò)編程
public class UDPTest {
    @Test
    public void sender() throws IOException {
        DatagramSocket socket = new DatagramSocket();
 
        String str = "我是UDP方式發(fā)送的導(dǎo)彈";
        byte[] data = str.getBytes();
        InetAddress inet = InetAddress.getLocalHost();
        DatagramPacket packet = new DatagramPacket(data,0,data.length,inet,9090);
        socket.send(packet);
        socket.close();
    }
    @Test
    public void receiver() throws IOException {
        DatagramSocket socket = new DatagramSocket(9090);
        byte[] buffer = new byte[100];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
        socket.receive(packet);
        System.out.println(new String(packet.getData(),0,packet.getLength()));
    }

URL類

  URL網(wǎng)絡(luò)編程
  1.URL:統(tǒng)一資源定位符，對應(yīng)著互聯(lián)網(wǎng)的某一資源地址
  2.格式：
    http://localhost:8080/examples/beauty.jpg?username=Tom
    協(xié)議   主機名     端口號    資源地址       參數(shù)列表
 
public class URLTest {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://localhost:8080/examples/beauty.jpg?username=Tom");
//            public String getProtocol()       獲取該URL的協(xié)議名
            System.out.println(url.getProtocol());// http
//            public String getHost()           獲取該URL的主機名
            System.out.println(url.getHost());//localhost
//            public String getPort()           獲取該URL的端口號
            System.out.println(url.getPort());// 8080
//            public String getPath()           獲取該URL的文件路徑
            System.out.println(url.getPath());//examples/beauty.jpg
//            public String getFile()           獲取該URL的文件名
            System.out.println(url.getFile());//examples/beauty.jpg?username=Tom
//            public String getQuery()          獲取該URL的查詢名
            System.out.println(url.getQuery());//username=Tom
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
    }
}

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