1、目的
- 传播交流信息
- TCP：打电话
- UDP：发短信
2、通信协议：
- http
- TCP/IP簇：三次握手（aba），四次挥手(abba)
- https
3、IP与端口
1.IP地址类：InetAddress、InetSocketAddress
InetAddress inetAddress1 = InetAddress.getLocalHost();
InetAddress inetAddress2 = InetAddress.getByName("");
inetAddress1.getHostName(); //计算机名
inetAddress2.getHostAddress(); //IP地址
2.端口
-
单个协议下，端口号不能冲突
-
公有端口0-1023
- HTTP：80
- HTTPS：443
- FTP：21
- Telent:23
-
程序注册端口：1024-49151
- MySQL：3306
- ORACLE：1521
-
端口查看的dos命令：
netstat -ano #查看所有端口 netstat -ano |findstr 1521 #查看1521这个端口
4、UDP编程实例
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
//使用UDP通信实现接收多条消息，并可以同时接收多个客户端的消息
public class ReceiveDemo02 {public static void main(String[] args) throws IOException {System.out.println("----服务端启动----");//创建接收端的Socket对象,并配置监听端口，端口10000与发送端dp里配置的端口相同DatagramSocket socket = new DatagramSocket(10000);//创建数据包对象，配置接收数组、数组大小DatagramPacket dp = new DatagramPacket(new byte[1024], 1024);while (true) {//receive会进行线程阻塞socket.receive(dp);//打印接收的数据,对dp.getData()进行一个实际数据大小的截位System.out.println("收到来自" + dp.getAddress().getHostAddress() + "的消息：" + new String(dp.getData(), 0, dp.getLength()));}//释放资源//socket.close();}
}
import java.io.IOException;
import java.net.*;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;
//使用UDP通信实现发多条消息
public class SendDemo02 {public static void main(String[] args) throws IOException {System.out.println("----客户端启动----");Scanner scanner = new Scanner(System.in);//创建发送端的Socket对象，系统会随机分配一个端口号DatagramSocket socket = new DatagramSocket();while (true){System.out.println("请输入要发送的内容：");String next = scanner.next();if(next.equals("exit")){//释放资源socket.close();return;}else {//定义存放数据的数组byte[] bytes = next.getBytes(StandardCharsets.UTF_8);//创建数据包对象，配置发送数据、数据长度、对方IP、对方端口DatagramPacket dp = new DatagramPacket(bytes, bytes.length, InetAddress.getByName("127.0.0.1"), 10000);//发送数据socket.send(dp);}}}
}
5、TCP编程实例
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;
//客户端多发消息
public class ClientDemo04 {public static void main(String[] args) throws IOException {Scanner scanner = new Scanner(System.in);//创建Socket，配置服务端IP与端口Socket socket = new Socket("127.0.0.1", 10012);//调用socket.getOutputStream()获取输出流，并用DataOutputStream进行包装DataOutputStream dos = new DataOutputStream(socket.getOutputStream());while (true){System.out.println("请输入要发送的数据：");String next = scanner.next();if(next.equals("exit")){//关闭流dos.close();socket.close();return;}else {//发送数据dos.writeUTF(next);}}}
}
import java.io.DataInputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
//目标：掌握利用线程池优化tcp服务端的方式
public class ServerDemo04 {public static void main(String[] args) throws IOException {//创建ServerSocket对象，配置监听端口ServerSocket serverSocket = new ServerSocket(10012);//创建线程池final ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(3, 5, 60, TimeUnit.SECONDS,new LinkedBlockingQueue<>(10), Executors.defaultThreadFactory(), new ThreadPoolExecutor.AbortPolicy());System.out.println("服务端启动成功");while (true) {//调用serverSocket.accept();，阻塞线程，等待客户端连接Socket socket = serverSocket.accept();System.out.println(socket.getInetAddress().getHostAddress() + ":" + socket.getPort() + "连接成功");//新建线程处理消息接收Thread thread = new Thread(() -> {//获取socket的流数据，并用DataInputStream进行封装try (DataInputStream dis = new DataInputStream(socket.getInputStream())) {while (true) {//打印信息，dis.readUTF()阻塞线程，等待客户端发送消息System.out.println("收到来自" + socket.getInetAddress().getHostAddress() + ":" + socket.getPort() + "的数据： " + dis.readUTF());}} catch (Exception e) {//当客户端意外断开时，会出现异常，在此进行手动处理System.out.println(socket.getInetAddress().getHostAddress() + ":" + socket.getPort() + " 断开连接");}}, socket.getInetAddress().getHostName());//将线程添加到线程池,线程池会自己启动线程，不需要单独调用start()poolExecutor.execute(thread);/*//关闭流dis.close();socket.close();serverSocket.close();*/}}
}
