网络编程小例子

TCP实现聊天

public class TcpClientDemo01 {
   public static void main(String[] args) {
      InetAddress serverIP = null;
      Socket socket = null;
      OutputStream os = null;
      try {
         //1.服务器地址、端口号
         serverIP = InetAddress.getByName("localhost");
         int port = 9999;
         //2.创建一个socket连接
         socket = new Socket(serverIP,port);
         //3.发送信息 IO流
         os = socket.getOutputStream();
         os.write("hello".getBytes());
      } catch (IOException e) {
         e.printStackTrace();
      } finally {
         if(null != os) {
            try {
               os.close();
            } catch (IOException e) {
               e.printStackTrace();
            }
         }

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

public class TcpServerDemo01 {
   public static void main(String[] args) {

      ServerSocket serverSocket = null;
      Socket socket = null;
      InputStream is = null;
      //管道流
      ByteArrayOutputStream baos = null;

      try {
         //1.给自己一个地址
         serverSocket = new ServerSocket(9999);
         //2.等待客户端连接
         socket = serverSocket.accept();
         //3.读取客户端消息
         is = socket.getInputStream();
         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 {
         if(null != baos) {
            try {
               baos.close();
            } catch (IOException e) {
               e.printStackTrace();
            }
         }

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

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

TCP文件上传

public class TcpClientDemo02 {

   public static void main(String[] args) throws Exception {

      Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9000);
      OutputStream os = socket.getOutputStream();

      FileInputStream fis = new FileInputStream(new File("exit.png"));
      byte[] buffer = new byte[1024];
      int len;
      while ((len = fis.read(buffer)) != -1){
         os.write(buffer,0,len);
      }

//    //通知服务器我已经传输完了
//    socket.shutdownOutput();
//
//    //确定服务带接收完毕才能断开连接
//    InputStream is = socket.getInputStream();
//    ByteArrayOutputStream baos = new ByteArrayOutputStream();
//    byte[] buffer2=new byte[1024];
//    int len2;
//    while ((len2 = fis.read(buffer)) != -1){
//       baos.write(buffer2,0,len2);
//    }
//
//    System.out.println(baos.toString());

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

   }
}

public class TcpServerDemo02 {

   public static void main(String[] args) throws IOException {

      ServerSocket serverSocket = new ServerSocket(9000);
      Socket socket = serverSocket.accept();
      InputStream is = socket.getInputStream();

      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);
      }

//    //通知客户端我接收完毕了
//    OutputStream os = socket.getOutputStream();
//    os.write("我接受完毕了，你可以断开了".getBytes());
//
//    os.close();
      fos.close();
      is.close();
      socket.close();
      serverSocket.close();
   }
}

UDP 多线程在线聊天实现

public class TalkSend implements Runnable {
   //UDP 套接字
   DatagramSocket socket = null;
   BufferedReader reader = null;

   //发送端口
   private int fromPort;
   //目的IP
   private String toIP;
   //目的端口
   private int toPort;

   public TalkSend(int fromPort, String toIP, int toPort) {
      this.fromPort = fromPort;
      this.toIP = toIP;
      this.toPort = toPort;

      try {
         //给自己一个端口
         socket = new DatagramSocket(fromPort);
         //读取控制台信息输入的信息
         reader = new BufferedReader(new InputStreamReader(System.in));
      } catch (SocketException e) {
         e.printStackTrace();
      }
   }


   @Override
   public void run() {
      while (true) {
         String data = null;
         try {
            data = reader.readLine();
            byte[] datas = data.getBytes();
            //封装数据报
            DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, 
                                      new InetSocketAddress(this.toIP, this.toPort));
            //发送
            socket.send(packet);
             
            //从控制台读取到 bye 退出循环
            if(data.equals("bye")) {
               break;
            }
         } catch (IOException e) {
            e.printStackTrace();
         }
      }
      try {
         reader.close();
      } catch (IOException e) {
         e.printStackTrace();
      }

      socket.close();
   }
}

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 {
         //给自己一个端口
         socket = new DatagramSocket(port);
      } catch (SocketException e) {
         e.printStackTrace();
      }
   }

   @Override
   public void run() {
      while (true) {
         try {
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container, 0, container.length);
            //接收数据报
            socket.receive(packet);
            byte[] data = packet.getData();
            String receiveData = new String(data, 0, packet.getLength());

            System.out.println(msgFrom + ":" + receiveData);

            //读取到 bye 就退出循环
            if ("bye".equals(receiveData)) {
               break;
            }
         } catch (IOException e) {
            e.printStackTrace();
         }
      }
      socket.close();
   }
}

public class TalkStudent {
   public static void main(String[] args) {
      //开启两个线程，一发一收
      new Thread(new TalkSend(7777,"localhost",9999)).start();
      new Thread(new TalkReceive(8888,"teacher")).start();
   }
}

public class TalkTeacher {
   public static void main(String[] args) {
      //开启两个线程，一发一收
      new Thread(new TalkSend(6666,"localhost",8888)).start();
      new Thread(new TalkReceive(9999,"student")).start();
   }
}

URL下载网络资源

public class UrlDown {

   public static void main(String[] args) throws Exception {
      //创建 URL
      URL url = new URL("https://www.cnblogs.com/hzyuan/p/13872923.html");
      //建立URL连接
      HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
　　
      InputStream inputStream = urlConnection.getInputStream();

      FileOutputStream fos = new FileOutputStream("aa.html");

      byte[] buffer = new byte[1024];
      int len;
      while ((len = inputStream.read(buffer)) != -1) {
         fos.write(buffer,0,len);
      }

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