1.IP 地址
IP地址：InetAddress
import java.net.InetAddress;
import java.net.UnknownHostException;//测试IP
public class TestInetAddress {public static void main(String[] args) {try {//获取本机地址InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");System.out.println(inetAddress1);InetAddress inetAddress3 = InetAddress.getByName("localhost");System.out.println(inetAddress3);InetAddress inetAddress4 = InetAddress.getLocalHost();System.out.println(inetAddress4);//查询网站 IP 地址InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");System.out.println(inetAddress2);//常用方法//System.out.println(inetAddress2.getAddress());System.out.println(inetAddress2.getCanonicalHostName());//规范的名字System.out.println(inetAddress2.getHostAddress());//IPSystem.out.println(inetAddress2.getHostName());//域名，或自己电脑的名字} catch (UnknownHostException e) {throw new RuntimeException(e);}}
}
2.端口
import java.net.InetSocketAddress;public class TestSocketAddress {public static void main(String[] args) {InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);System.out.println(socketAddress);System.out.println(socketAddress.getAddress());System.out.println(socketAddress.getHostName());System.out.println(socketAddress.getPort());}
}
3.通信协议
4.TCP
客户端
- 连接服务器 Socket
- 发送消息
服务器
- 建立服务器的端口 ServerSocket
- 等待用户的连接 accept
- 接收用户的消息
例子：
客户端
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;//客户端
public class TcpClientDemo01 {public static void main(String[] args) throws Exception {//1.创建一个 socket 连接Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);//2.创建一个输出流OutputStream os = socket.getOutputStream();//3.读取文件FileInputStream fis = new FileInputStream(new File("1.jpg"));//4.写出文件byte[] buffer = new byte[1024];int len;while ((len = fis.read(buffer)) != -1){os.write(buffer, 0, len);}//通知服务器，我已经结束了socket.shutdownOutput();//我已经传输完了//确定服务器接收完毕，才能断开连接InputStream inputStream = socket.getInputStream();ByteArrayOutputStream baos = new ByteArrayOutputStream();byte[] buffer2 = new byte[1024];int len2;while ((len2 = inputStream.read(buffer2)) != -1){baos.write(buffer2, 0, len2);}//5.关闭连接baos.close();inputStream.close();fis.close();os.close();socket.close();}
}
服务器端
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;//服务端
public class TcpServerDemo01 {public static void main(String[] args) throws Exception {//1.创建服务ServerSocket serverSocket = new ServerSocket(9000);//2.监听客户端的连接Socket socket = serverSocket.accept();//阻塞式监听，会一直等待客户端连接//3.获取输入流InputStream is = socket.getInputStream();//4.文件输出FileOutputStream fos = new FileOutputStream(new File("receive.jpg"));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("我接收完毕了，你可以断开了".getBytes());//5.关闭资源fos.close();is.close();socket.close();serverSocket.close();}
}
5.UDP
不用连接，但需要直到对方的地址：Datagram
例1：消息发送
发送端
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;//不需要连接服务器
public class UdpClientDemo01 {public static void main(String[] args) throws Exception {//1.建立一个 socketDatagramSocket socket = new DatagramSocket();//2.建个包String msg = "你好，服务器";//发送给谁InetAddress localhost = InetAddress.getByName("localhost");int port = 9090;//数据，数据的长度起始，要发送给谁DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);//3.发送包socket.send(packet);//4.关闭流socket.close();}
}
接收端
import java.net.DatagramPacket;
import java.net.DatagramSocket;
//还是要等待客户端的连接
public class UdpServerDemo02 {public static void main(String[] args) throws Exception {//开放端口DatagramSocket socket = new DatagramSocket(9090);//接收数据包byte[] buffer = new byte[1024];DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);socket.receive(packet);//阻塞接收System.out.println(packet.getAddress().getHostAddress());System.out.println(new String(packet.getData(), 0, packet.getLength()));//关闭连接socket.close();}
}
例2：聊天实现
发送端
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;public class UdpSenderDemo01 {public static void main(String[] args) throws IOException {DatagramSocket socket = new DatagramSocket(8888);//准备数据：控制台读取 System.inBufferedReader reader = new BufferedReader(new InputStreamReader(System.in));while (true){String data = reader.readLine();byte[] datas = data.getBytes();DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress("localhost", 6666));socket.send(packet);if (data.equals("bye")) break;}socket.close();}
}
接收端
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;public class UdpReceiveDemo02 {public static void main(String[] args) throws IOException {DatagramSocket socket = new DatagramSocket(6666);while (true){//准备接收包裹byte[] container = new byte[1024];DatagramPacket packet = new DatagramPacket(container, 0, container.length);socket.receive(packet);//阻塞式接收包裹//断开连接 byebyte[] data = packet.getData();String receiveData = new String(data, 0, data.length);System.out.println(receiveData);if (receiveData.equals("bye")) break;}socket.close();}
}
例3：UDP 多线程在线咨询
发送端
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;public class TalkSend implements Runnable {DatagramSocket socket = null;BufferedReader reader = null;private int fromPort;private String toIP;private int toPort;public TalkSend(int fromPort, String toIP, int toPort) {this.fromPort = fromPort;this.toIP = toIP;this.toPort = toPort;try {socket = new DatagramSocket(fromPort);reader = new BufferedReader(new InputStreamReader(System.in));} catch (SocketException e) {throw new RuntimeException(e);}}public TalkSend(DatagramSocket socket) {this.socket = socket;}@Overridepublic void run() {while (true){try {String data = reader.readLine();byte[] datas = data.getBytes();DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, this.toPort));socket.send(packet);if (data.equals("bye")) break;}catch (Exception e){e.printStackTrace();}}socket.close();}
}
接收端
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;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 {socket = new DatagramSocket(port);} catch (SocketException e) {throw new RuntimeException(e);}}@Overridepublic void run() {while (true){try {//准备接收包裹byte[] container = new byte[1024];DatagramPacket packet = new DatagramPacket(container, 0, container.length);socket.receive(packet);//阻塞式接收包裹//断开连接 byebyte[] data = packet.getData();String receiveData = new String(data, 0, data.length);System.out.println(msgFrom + "：" + receiveData);if (receiveData.equals("bye")) break;} catch (IOException e) {throw new RuntimeException(e);}}socket.close();}
}
学生端：
public class TalkStudent {public static void main(String[] args) {//开启两个线程new Thread(new TalkSend(777, "localhost", 9999)).start();new Thread(new TalkReceive(8888, "老师")).start();}
}
老师端：
public class TalkTeacher {public static void main(String[] args) {new Thread(new TalkSend(5555, "localhost", 8888)).start();new Thread(new TalkReceive(9999, "学生")).start();}
}
6.URL 下载网络资源
url 使用：
import java.net.MalformedURLException;
import java.net.URL;public class URLDemo {public static void main(String[] args) throws MalformedURLException {URL url = new URL("http://localhost:8080/helloworld/index.jsp?user=test&password=123");System.out.println(url.getProtocol());//协议System.out.println(url.getHost());//主机IPSystem.out.println(url.getPort());//端口System.out.println(url.getPath());//文件System.out.println(url.getFile());//全路径System.out.println(url.getQuery());//参数}
}
下载网络资源：
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;public class URLDown {public static void main(String[] args) throws IOException {//1.下载地址URL url = new URL("https://t7.baidu.com/it/u=1951548898,3927145&fm=193&f=GIF");//2.连接到这个资源 HTTPHttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();InputStream inputStream = urlConnection.getInputStream();FileOutputStream fos = new FileOutputStream("1.jpg");byte[] buffer = new byte[1024];int len;while ((len = inputStream.read(buffer)) != -1) fos.write(buffer, 0, len);//写出这个数据fos.close();inputStream.close();urlConnection.disconnect();//断开连接}
}
