黑马程序员---tcp与udp总结

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1.tcp 有连接可靠 对传输大小没限制 像打电话 传输的是socket对象（封装了数据） socket  serversocket    必须先启动服务端

2.udp 无连接 不可靠 对传输有限制64k（一个包）像发短信 传输的是包（真实数据）两个类 datagramsocket datagrampacket   发送端和接收端谁先开都行

最主要的区别 udp 是传输数据包发送和接收是直接操作数据  而tcp传输的是socket对象（封装了数据） 服务器端是操作socket对象间接操作对象 关闭的socket是客户端socket

udp代码

class Send implements Runnable {
    private DatagramSocket ds;

    public Send(DatagramSocket ds) {
        this.ds = ds;
    }
    @Override
    public void run() {
        try {
             BufferedReader br =  new BufferedReader(new InputStreamReader(System.in));
             byte[] buf = new byte[1024*64];
             DatagramPacket  dp = null;
             String line = null;
             while((line = br.readLine())!=null){
                 if("88".equals(line))
                     break;
                 buf = line.getBytes();
                 dp = new DatagramPacket(buf, buf.length, InetAddress.getByName("127.0.0.1"),10001);
                 ds.send(dp);
             }
        } catch (Exception e) {
           throw  new RuntimeException("发送出现错误");
        }
    }
}

class Receive implements Runnable {
    private DatagramSocket ds;

    public Receive(DatagramSocket ds) {
        this.ds = ds;
    }
    @Override
    public void run() {
       
        try {
          
            while(true){
                byte[] buf = new byte[1024*64];
                DatagramPacket dp = new DatagramPacket(buf, buf.length);
                ds.receive(dp);
                
                System.out.println(new String(dp.getData()));
            }
            
            
            
        } catch (Exception e) {
            throw  new RuntimeException("接收出现错误");
        }
    }

}

public class UDPChar {
    public static void main(String[] args) throws Exception {
        DatagramSocket sendSocket = new DatagramSocket();
        DatagramSocket receiveSocket = new DatagramSocket(10001);
        
        new Thread(new Send(sendSocket)).start();
        new Thread(new Receive(receiveSocket)).start();
        
        
        
        
        
    }

}

1.发送端和接收端都有 packet与socket

2.发送的和接收端的socket都应该有一个端口号 接收端必须有 发送端如果没有系统指定

3.packet 发送端和接收端不同 发送的应该指明发送地址与端口号  接收端只需接收就行

TCP代码

客户端 

public class TCPClient {
    
    public static void main(String[] args) throws UnknownHostException, Exception {
        Socket socket = new Socket("127.0.0.1",20000);
        
        InputStream is = socket.getInputStream();
        OutputStream os = socket.getOutputStream();
        os.write("niaho".getBytes());
        
        byte[] arr = new byte[8192];
        int lengh = is.read(arr);
        System.out.println(new String(arr));
        socket.close();
  
    }
    
}

服务器端

public class TCPServer {

    public static void main(String[] args) throws Exception {
        ServerSocket ss = new ServerSocket(20000, 10);
        Socket socket = ss.accept();
        InputStream is = socket.getInputStream();
        OutputStream os = socket.getOutputStream();
        os.write("niaho".getBytes());
        byte[] arr = new byte[8192];
        int lengh = is.read(arr);
        System.out.println(new String(arr));
     
        ss.close(); //关闭客户端

    }

}

1.客户端 是socket 服务器端是serversocket 但操作的都是客户端传过来的socket对象  

2.客户端要指明发送端口和目的ip  服务器端只需指明端口就行

3.操作用的都是io  把数据放到对象中传到服务器端 服务器操作 客户端的socket  

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