今日学习了网络基础和udp(用户数据报协议)编程和tcp(传输控制协议)编程
相比较之下udp 是面向无连接的 信息不可靠 但是效率高
tcp 是面向连接的 信息可靠 但是效率不够高
tcp 也要比udp 学起来复杂一点，现在我还有点没搞明白，还需要继续的复习。
附代码（以下有一些代码是老师课件中下载的，我只是阅读了代码理解大概意思）：
1 import java.net.*; 2 public class UdpRecv 3 { 4 public static void main(String[] args) throws Exception 5 { 6 DatagramSocket ds=new DatagramSocket(3000); 7 byte [] buf=new byte[1024]; 8 DatagramPacket dp=new DatagramPacket(buf,1024); 9 10 System.out.println("UdpRecv: 我在等待信息"); 11 ds.receive(dp); 12 System.out.println("UdpRecv: 我接收到信息"); 13 String strRecv=new String(dp.getData(),0,dp.getLength()) + 14 " from " + dp.getAddress().getHostAddress()+":"+dp.getPort(); 15 System.out.println(strRecv); 16 17 Thread.sleep(1000); 18 System.out.println("UdpRecv: 我要发送信息"); 19 String str="hello world 222"; 20 DatagramPacket dp2=new DatagramPacket(str.getBytes(),str.length(), 21 InetAddress.getByName("127.0.0.1"),dp.getPort()); 22 ds.send(dp2); 23 System.out.println("UdpRecv: 我发送信息结束"); 24 ds.close(); 25 } 26 }
1 import java.net.*; 2 public class UdpSend 3 { 4 public static void main(String [] args) throws Exception 5 { 6 DatagramSocket ds=new DatagramSocket(); 7 String str="hello world"; 8 DatagramPacket dp=new DatagramPacket(str.getBytes(),str.length(), 9 InetAddress.getByName("127.0.0.1"),3000); 10 11 System.out.println("UdpSend: 我要发送信息"); 12 ds.send(dp); 13 System.out.println("UdpSend: 我发送信息结束"); 14 15 Thread.sleep(1000); 16 byte [] buf=new byte[1024]; 17 DatagramPacket dp2=new DatagramPacket(buf,1024); 18 System.out.println("UdpSend: 我在等待信息"); 19 ds.receive(dp2); 20 System.out.println("UdpSend: 我接收到信息"); 21 String str2=new String(dp2.getData(),0,dp2.getLength()) + 22 " from " + dp2.getAddress().getHostAddress()+":"+dp2.getPort(); 23 System.out.println(str2); 24 25 ds.close(); 26 } 27 }
1 package com.wsy.tcp; 2 import java.net.*; 3 import java.io.*; 4 5 public class TcpClient { 6 public static void main(String[] args) { 7 try { 8 Socket s = new Socket(InetAddress.getByName("127.0.0.1"), 8001); //需要服务端先开启 9 10 //同一个通道，服务端的输出流就是客户端的输入流；服务端的输入流就是客户端的输出流 11 InputStream ips = s.getInputStream(); //开启通道的输入流 12 BufferedReader brNet = new BufferedReader(new InputStreamReader(ips)); 13 14 OutputStream ops = s.getOutputStream(); //开启通道的输出流 15 DataOutputStream dos = new DataOutputStream(ops); 16 17 BufferedReader brKey = new BufferedReader(new InputStreamReader(System.in)); 18 while (true) 19 { 20 String strWord = brKey.readLine(); 21 if (strWord.equalsIgnoreCase("quit")) 22 { 23 break; 24 } 25 else 26 { 27 System.out.println("I want to send: " + strWord); 28 dos.writeBytes(strWord + System.getProperty("line.separator")); 29 30 System.out.println("Server said: " + brNet.readLine()); 31 } 32 33 } 34 35 dos.close(); 36 brNet.close(); 37 brKey.close(); 38 s.close(); 39 } catch (Exception e) { 40 e.printStackTrace(); 41 } 42 } 43 }
1 package com.wsy.tcp; 2 3 import java.net.*; 4 import java.io.*; 5 public class TcpServer 6 { 7 public static void main(String [] args) 8 { 9 try 10 { 11 ServerSocket ss=new ServerSocket(8001); //驻守在8001端口 12 Socket s=ss.accept(); //阻塞，等到有客户端连接上来 13 System.out.println("welcome to the java world"); 14 InputStream ips=s.getInputStream(); //有人连上来，打开输入流 15 OutputStream ops=s.getOutputStream(); //打开输出流 16 //同一个通道，服务端的输出流就是客户端的输入流；服务端的输入流就是客户端的输出流 17 18 ops.write("Hello, Client!".getBytes()); //输出一句话给客户端 19 20 21 BufferedReader br = new BufferedReader(new InputStreamReader(ips)); 22 //从客户端读取一句话 23 System.out.println("Client said: " + br.readLine()); 24 25 26 ips.close(); 27 ops.close(); 28 s.close(); 29 ss.close(); 30 } 31 catch(Exception e) 32 { 33 e.printStackTrace(); 34 } 35 } 36 }
1 package com.wsy.tcp; 2 import java.net.*; 3 import java.util.concurrent.Executors; 4 import java.util.concurrent.ThreadPoolExecutor; 5 public class TcpServer2 6 { 7 public static void main(String [] args) 8 { 9 try 10 { 11 ServerSocket ss=new ServerSocket(8001); 12 while(true) 13 { 14 Socket s=ss.accept(); 15 System.out.println("来了一个client"); 16 // new Thread(new Worker(s)).start(); 17 Worker work = new Worker(s); 18 ThreadPoolExecutor pool = (ThreadPoolExecutor) Executors.newFixedThreadPool(5); 19 //这里遇到了之前的多线程知识，卡壳了一下 现在还有个问题就是 我固定线程5个 但是TcpClient 可以执行超过5个 20 pool.execute(work); 21 } 22 //ss.close(); 23 } 24 catch(Exception e) 25 { 26 e.printStackTrace(); 27 } 28 } 29 }
1 package com.wsy.tcp; 2 3 import java.net.*; 4 import java.io.*; 5 6 class Worker implements Runnable { 7 Socket s; 8 9 public Worker(Socket s) { 10 this.s = s; 11 } 12 13 public void run() { 14 try { 15 System.out.println("服务人员已经启动"); 16 InputStream ips = s.getInputStream(); 17 OutputStream ops = s.getOutputStream(); 18 19 BufferedReader br = new BufferedReader(new InputStreamReader(ips)); 20 DataOutputStream dos = new DataOutputStream(ops); 21 while (true) { 22 String strWord = br.readLine(); 23 System.out.println("client said:" + strWord +":" + strWord.length()); 24 if (strWord.equalsIgnoreCase("quit")) 25 break; 26 String strEcho = strWord + " 666"; 27 // dos.writeBytes(strWord +"---->"+ strEcho +"\r\n"); 28 System.out.println("server said:" + strWord + "---->" + strEcho); 29 dos.writeBytes(strWord + "---->" + strEcho + System.getProperty("line.separator")); 30 } 31 br.close(); 32 // 关闭包装类，会自动关闭包装类中所包装的底层类。所以不用调用ips.close() 33 dos.close(); 34 s.close(); 35 } catch (Exception e) { 36 e.printStackTrace(); 37 } 38 } 39 }