网络编程三要素
IP地址常用命令:
ipconfig:查看本机IP地址
ping IP地址:检查网络是否连通
特殊IP地址:127.0.0.1,是回送地址,可以代表本机地址,一般用来测试使用
InetAddress的使用
-
这个类代表一个互联网协议(IP)地址。
package com._01; import java.net.InetAddress; import java.net.UnknownHostException; public class InetAddressDemo { public static void main(String[] args) throws UnknownHostException { InetAddress inetAddress = InetAddress.getByName("DESKTOP-19TGGLI"); String hostName = inetAddress.getHostName(); System.out.println(hostName); String hostAddress = inetAddress.getHostAddress(); System.out.println(hostAddress); } }
- 结果:
DESKTOP-19TGGLI
192.168.0.188
端口
端口:设备上应用程序的唯一标识
端口号:用两个字节表示的整数,他的取值范围是0-65535.其中,0-1023之间的端口号用于一些知名的网络服务和应用,普通的应用程序需要使用1024以上的端口号。如果端口号被另一个服务或应用所占用,会导致当前程序启动失败。
协议
UDP通信程序
UDP发送数据
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import java.io.IOException; import java.net.*; /* UDP发送数据的步骤 1:创建发送端的Socket对象(DatagramSocket) DatagramSocket() 2:创建数据,并把数据打包 DatagramPacket(byte[] buf,int length,InetAddress,int port) 3:调用DatagramSocket对象的方法发送数据 void send(DatagramPacket p ) 4:关闭发送端 void close() */ public class SendDemo { public static void main(String[] args) throws IOException { //创建发送端的Socket对象(DatagramSocket) // DatagramSocket() 构造数据报套接字并将其绑定到本地主机上的任何可用端口 DatagramSocket ds = new DatagramSocket(); //创建数据,并把数据打包 //DatagramPacket(byte[] buf, int length, InetAddress address, int port) //构造一个数据包,发送长度为 length的数据包到指定主机上的指定端口号。 byte[] bys = "hello,udp,我来了".getBytes(); // int length = bys.length; // InetAddress address = InetAddress.getByName("192.168.1.66"); // int port = 10086; // DatagramPacket dp = new DatagramPacket(bys,length,address,port); DatagramPacket dp = new DatagramPacket(bys,bys.length,InetAddress.getByName("192.168.1.66"),10086); //调用DatagramSocket对象的方法发送数据 //void send(DatagramPacket p) 从此套接字发送数据报包 ds.send(dp); //关闭发送端 //void close() 关闭此数据报套接字 ds.close(); } }
UDP接收数据
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import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.SocketException; /* UDP接收数据的步骤 1:创建接收端的Socket对象(DatagramSocket) DatagramSocket(int port) 2:创建一个数据包,用于接收数据 DatagramPacket(byte[] buf,int length) 3:调用DatagramSocket对象的方法接收数据 void receive(DatagramPacket p) 4:解析数据包,并把数据在控制台显示 byte[] getData() 5:关闭接收端 close() */ public class ReceiveDemo { public static void main(String[] args) throws IOException { //创建接收端的Socket对象(DatagramSocket) //DatagramSocket(int port) 构造数据报套接字并将其绑定到本地主机上的指定端口 DatagramSocket ds = new DatagramSocket(10086); //创建一个数据包,用于接收数据 //DatagramPacket(byte[] buf, int length) 构造一个 DatagramPacket用于接收长度为 length数据包 byte[] bys = new byte[1024]; DatagramPacket dp = new DatagramPacket(bys,bys.length); //调用DatagramSocket对象的方法接收数据 ds.receive(dp); //解析数据包,并把数据在控制台显示 //byte[] getData() 返回数据缓冲区 // byte[] datas = dp.getData(); //int getLength() 返回要发送的数据的长度或接收到的数据的长度 // int len = dp.getLength(); // String dataString = new String(datas,0,len); // System.out.println("数据是:" + dataString); System.out.println("数据是:" + new String(dp.getData(),0,dp.getLength())); //关闭接收端 ds.close(); } }
简单的UDP程序练习:模拟简单的聊天室
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import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.SocketException; /* UDP接收数据: 因为接收端不知道发送端什么时候停止发送,故采用死循环接收 */ public class ReceiveDemo { public static void main(String[] args) throws IOException { //创建接收端的Socket对象(DatagramSocket) DatagramSocket ds = new DatagramSocket(12345); while (true) { //创建一个数据包,用于接收数据 byte[] bys = new byte[1024]; DatagramPacket dp = new DatagramPacket(bys, bys.length); //调用DatagramSocket对象的方法接收数据 ds.receive(dp); //解析数据包,并把数据在控制台显示 System.out.println("数据是:" + new String(dp.getData(), 0, dp.getLength())); } //关闭接收端 // ds.close(); } }
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import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; /* UDP发送数据: 数据来自于键盘录入,直到输入的数据是886,发送数据结束 */ public class SendDemo { public static void main(String[] args) throws IOException { //创建发送端的Socket对象(DatagramSocket) DatagramSocket ds = new DatagramSocket(); //自己封装键盘录入数据 BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String line; while ((line = br.readLine()) != null) { //输入的数据是886,发送数据结束 if ("886".equals(line)) { break; } //创建数据,并把数据打包 byte[] bys = line.getBytes(); DatagramPacket dp = new DatagramPacket(bys, bys.length, InetAddress.getByName("192.168.1.66"), 12345); //调用DatagramSocket对象的方法发送数据 ds.send(dp); } //关闭发送端 ds.close(); } }
TCP通信程序
TCP客户端发送数据
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import java.io.IOException; import java.io.OutputStream; import java.net.InetAddress; import java.net.Socket; import java.net.UnknownHostException; /* TCP发送数据的步骤 1:创建客户端的Socket对象(Socket) Socket(String host,int port) 2:获取输出流,写数据 OutputStream getOutputStream() 3:释放资源 void close() */ public class ClientDemo { public static void main(String[] args) throws IOException { //创建客户端的Socket对象(Socket) //Socket(InetAddress address, int port) 创建流套接字并将其连接到指定IP地址的指定端口号 // Socket s = new Socket(InetAddress.getByName("192.168.1.66"),10000); //Socket(String host, int port) 创建流套接字并将其连接到指定主机上的指定端口号 Socket s = new Socket("192.168.1.66",10000); //获取输出流,写数据 //OutputStream getOutputStream() 返回此套接字的输出流 OutputStream os = s.getOutputStream(); os.write("hello,tcp,我来了".getBytes()); //释放资源 s.close(); } }
TCP服务器端接受数据
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import java.io.IOException; import java.io.InputStream; import java.net.ServerSocket; import java.net.Socket; /* TCP接收数据的步骤 1:创建服务器端的Socket对象(ServerSocket) ServerSocket(int port) 2.监听客户端连接,获得一个Socket对象 Scoket accept() 2:获取输入流,读数据,并把数据显示在控制台 InputStream getInputStream() 3:释放资源 void close() */ public class ServerDemo { public static void main(String[] args) throws IOException { //创建服务器端的Socket对象(ServerSocket) //ServerSocket(int port) 创建绑定到指定端口的服务器套接字 ServerSocket ss = new ServerSocket(10000); //Socket accept() 侦听要连接到此套接字并接受它 Socket s = ss.accept(); //获取输入流,读数据,并把数据显示在控制台 InputStream is = s.getInputStream(); byte[] bys = new byte[1024]; int len = is.read(bys); String data = new String(bys,0,len); System.out.println("数据是:" + data); //释放资源 s.close(); ss.close(); } }
TCP程序练习:客户端给出反馈
注意:客户端是先写数据再读数据,服务器端先读数据再写数据
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package com.itheima_05; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.Socket; /* 客户端:发送数据,接收服务器反馈 */ public class ClientDemo { public static void main(String[] args) throws IOException { //创建客户端的Socket对象(Socket) Socket s = new Socket("192.168.1.66", 10000); //获取输出流,写数据 OutputStream os = s.getOutputStream(); os.write("hello,tcp,我来了".getBytes()); //接收服务器反馈 InputStream is = s.getInputStream(); byte[] bys = new byte[1024]; int len = is.read(bys); String data = new String(bys, 0, len); System.out.println("客户端:" + data); //释放资源 // is.close(); // os.close(); s.close(); } }
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import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.ServerSocket; import java.net.Socket; /* 服务器:接收数据,给出反馈 */ public class ServerDemo { public static void main(String[] args) throws IOException { //创建服务器端的Socket对象(ServerSocket) ServerSocket ss = new ServerSocket(10000); //监听客户端连接,返回一个Socket对象 Socket s = ss.accept(); //获取输入流,读数据,并把数据显示在控制台 InputStream is = s.getInputStream(); byte[] bys = new byte[1024]; int len = is.read(bys); String data = new String(bys, 0, len); System.out.println("服务器:" + data); //给出反馈 OutputStream os = s.getOutputStream(); os.write("数据已经收到".getBytes()); //释放资源 // s.close(); ss.close(); } }
TCP通讯程序多线程实现文件上传
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import java.io.*; import java.net.Socket; public class ServerThread implements Runnable { private Socket s; public ServerThread(Socket s) { this.s = s; } @Override public void run() { try { //接收数据写到文本文件 BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream())); // BufferedWriter bw = new BufferedWriter(new FileWriter("myNet\\Copy.java")); //解决名称冲突问题 int count = 0; File file = new File("myNet\\Copy["+count+"].java"); while (file.exists()) { count++; file = new File("myNet\\Copy["+count+"].java"); } BufferedWriter bw = new BufferedWriter(new FileWriter(file)); String line; while ((line=br.readLine())!=null) { bw.write(line); bw.newLine(); bw.flush(); } //给出反馈 BufferedWriter bwServer = new BufferedWriter(new OutputStreamWriter(s.getOutputStream())); bwServer.write("文件上传成功"); bwServer.newLine(); bwServer.flush(); //释放资源 s.close(); } catch (IOException e) { e.printStackTrace(); } } }
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import java.io.*; import java.net.Socket; /* 客户端:数据来自于文本文件,接收服务器反馈 */ public class ClientDemo { public static void main(String[] args) throws IOException { //创建客户端Socket对象 Socket s = new Socket("192.168.1.66",10000); //封装文本文件的数据 BufferedReader br = new BufferedReader(new FileReader("myNet\\InetAddressDemo.java")); //封装输出流写数据 BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream())); String line; while ((line=br.readLine())!=null) { bw.write(line); bw.newLine(); bw.flush(); } s.shutdownOutput(); //接收反馈 BufferedReader brClient = new BufferedReader(new InputStreamReader(s.getInputStream())); String data = brClient.readLine(); //等待读取数据 System.out.println("服务器的反馈:" + data); //释放资源 br.close(); s.close(); } }
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import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; /* 服务器:接收到的数据写入文本文件,给出反馈,代码用线程进行封装,为每一个客户端开启一个线程 */ public class ServerDemo { public static void main(String[] args) throws IOException { //创建服务器Socket对象 ServerSocket ss = new ServerSocket(10000); while (true) { //监听客户端连接,返回一个对应的Socket对象 Socket s = ss.accept(); //为每一个客户端开启一个线程 new Thread(new ServerThread(s)).start(); } // ss.close(); } }