TCP与UDP

谁践踏了优雅 2021-11-27 06:20 356阅读 0赞

###### TCP传输控制协议 ######

1.  使用TCP协议前，须先建立TCP连接，形成数据传输通道
2.  传输前，采用**三次握手**方式，点对点通信，**是可靠的**
3.  TCP协议进行通信的两个应用进程：客户端、服务端
4.  在连接中可**进行大量数据的传输**
5.  传输完毕，需**释放已建立的连接，效率低**

###### UDP用户数据包协议 ######

1.  将数据、源、目的封装成数据包，**不需要建立连接**
2.  每个数据包的大小限制在64K内
3.  发送不管对方是否准备好，接收方收到也不确认，**故是不可靠的**
4.  可以广播发送
5.  发送数据结束后**无需释放资源、开销小，速度快**

TCP

//TCP
    public class Demo{ 
    
        //客户端
       @Test
        public void client(){ 
           Socket socket=null;
           OutputStream os=null;
           try { 
               //指明ip以及端口
               socket = new Socket(InetAddress.getLocalHost(),9999);
               os = socket.getOutputStream();
               os.write("客户端".getBytes());
           } catch (IOException 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();
                   }
               }
           }
       }
    
       //服务端
        @Test
        public void server(){ 
           ServerSocket serverSocket = null;
           Socket socket = null;
           InputStream is = null;
            try { 
                serverSocket = new ServerSocket(9999);
                socket = serverSocket.accept();
                is = socket.getInputStream();
                byte b[]=new byte[1024];
                int len;
                while((len=is.read(b))!=-1){ 
                    System.out.println(new String(b,0,len));
                }
            } catch (IOException e) { 
                e.printStackTrace();
            }finally{ 
                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();
                    }
                }
            }
        }
    }

UDP

//UDP
    public class Demo{ 
    
        //发送端
        @Test
        public void sender(){ 
            DatagramSocket datagramSocket = null;
            try { 
                datagramSocket = new DatagramSocket();
                String message = "发送端";
                byte[] message_b = message.getBytes();
                DatagramPacket datagramPacket = new DatagramPacket(message_b,0,message_b.length, InetAddress.getLocalHost(),9999);
                datagramSocket.send(datagramPacket);
            } catch (Exception e) { 
                e.printStackTrace();
            }finally{ 
                if(datagramSocket!=null){ 
                    datagramSocket.close();
                }
            }
        }
    
        //接收端
        @Test
        public void receiver(){ 
            DatagramSocket datagramSocket = null;
            try { 
                datagramSocket = new DatagramSocket(9999);
                byte[] message = new byte[100];
                DatagramPacket datagramPacket = new DatagramPacket(message,0,message.length);
                datagramSocket.receive(datagramPacket);
                System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));
            } catch (Exception e) { 
                e.printStackTrace();
            }finally{ 
                if(datagramSocket!=null){ 
                    datagramSocket.close();
                }
            }
        }
    }