Java implements TCP (socket) network programming

Java implements TCP (socket) network programming:

• In Java, you can directly use Socket to instantiate a socket object to implement the tcp protocol. The client and server can establish a connection in the local area network through the IP address and port, and transfer data and files.

data transmission:

//客户端
    @Test
    public void client()  {
    
    
        Socket socket = null;
        OutputStream os = null;
        try {
    
    
            //1.创建Socket对象，指明服务器端的ip和端口号
            InetAddress inet = InetAddress.getByName("127.0.0.1");
            socket = new Socket(inet,8899);
            //2.获取一个输出流，用于输出数据
            os = socket.getOutputStream();
            //3.写出数据的操作
            os.write("你好，我是客户端".getBytes());
        } catch (IOException e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            //4.资源的关闭
            if(os != null){
    
    
                try {
    
    
                    os.close();
                } catch (IOException e) {
    
    
                    e.printStackTrace();
                }

            }
            if(socket != null){
    
    
                try {
    
    
                    socket.close();
                } catch (IOException e) {
    
    
                    e.printStackTrace();
                }

            }
        }



    }
    //服务端
    @Test
    public void server()  {
    
    

        ServerSocket ss = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;
        try {
    
    
            //1.创建服务器端的ServerSocket，指明自己的端口号
            ss = new ServerSocket(8899);
            //2.调用accept()表示接收来自于客户端的socket
            socket = ss.accept();
            //3.获取输入流
            is = socket.getInputStream();
            
            //4.读取输入流中的数据
            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());

            System.out.println("收到了来自于：" + socket.getInetAddress().getHostAddress() + "的数据");

        } catch (IOException e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            if(baos != null){
    
    
                //5.关闭资源
                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();
                }
            }

        }

    }

file transfer:

@Test
public void client() throws IOException {
    
    
    //1.
    Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9090);
    //2.
    OutputStream os = socket.getOutputStream();
    //3.
    FileInputStream fis = new FileInputStream(new File("beauty.jpg"));
    //4.
    byte[] buffer = new byte[1024];
    int len;
    while((len = fis.read(buffer)) != -1){
    
    
        os.write(buffer,0,len);
    }
    //关闭数据的输出
    socket.shutdownOutput();

    //5.接收来自于服务器端的数据，并显示到控制台上
    InputStream is = socket.getInputStream();
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] bufferr = new byte[20];
    int len1;
    while((len1 = is.read(buffer)) != -1){
    
    
        baos.write(buffer,0,len1);
    }

    System.out.println(baos.toString());

    //6.
    fis.close();
    os.close();
    socket.close();
    baos.close();
}

/*
这里涉及到的异常，应该使用try-catch-finally处理
 */
@Test
public void server() throws IOException {
    
    
    //1.
    ServerSocket ss = new ServerSocket(9090);
    //2.
    Socket socket = ss.accept();
    //3.
    InputStream is = socket.getInputStream();
    //4.
    FileOutputStream fos = new FileOutputStream(new File("beauty2.jpg"));
    //5.
    byte[] buffer = new byte[1024];
    int len;
    while((len = is.read(buffer)) != -1){
    
    
        fos.write(buffer,0,len);
    }

    System.out.println("图片传输完成");

    //6.服务器端给予客户端反馈
    OutputStream os = socket.getOutputStream();
    os.write("你好，照片我已收到！".getBytes());

    //7.
    fos.close();
    is.close();
    socket.close();
    ss.close();
    os.close();

}