学习了很久的Java网络编程，因为没有实际操作过，所以很久没有总结，但网络编程毕竟是Java系统学习中很重要的一部分，所以今天还是要来总结一下。
Java网络编程是什么
网络编程是指编写运行在多个设备（计算机）的程序，这些设备都通过网络连接起来。java.net包中J2SE的API包含有类和接口，它们提供低层次的通信细节。java.net包中提供了两种常见的网络协议的支持：
TCP
TCP是传输控制协议的缩写，它保障了两个应用程序之间的可靠通信。通常用于互联网协议，被称TCP/IP。
Server
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| public class Server {
public static void main(String[] args) throws IOException {
ServerSocket server = new ServerSocket(8888);
while(true) {
Socket socket = server.accept();
System.out.println("客户端建立连接");
String msg = "欢迎使用";
DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
dos.writeUTF(msg);
dos.flush();
}
}
}
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Client
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| public class Client {
public static void main(String[] args) throws UnknownHostException, IOException {
Socket client = new Socket("localhost",8888);
DataInputStream dis = new DataInputStream(client.getInputStream());
String echo = dis.readUTF();
System.out.println(echo);
}
}
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UDP
UDP是用户数据报协议的缩写，一个无连接的协议。提供了应用程序之间要发送的数据的数据包。
Server
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| public class Server {
public static void main(String[] args) throws IOException {
DatagramSocket server = new DatagramSocket(8888);
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, container.length);
server.receive(packet);
byte[] data = packet.getData();
int len = packet.getLength();
System.out.println(new String(data,0,len));
server.close();
}
}
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Client
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| public class Client {
public static void main(String[] args) throws IOException {
DatagramSocket client = new DatagramSocket(6666);
String msg = "udp编程";
byte[] data = msg.getBytes();
DatagramPacket packet = new DatagramPacket(data, data.length,new InetSocketAddress("localhost",8888));
client.send(packet);
client.close();
}
}
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手写网络编程服务器实例
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| public class Server2 {
private ServerSocket server;
public static void main(String[] args) {
Server2 server = new Server2();
server.start();
}
public void start() {
try {
server = new ServerSocket(8888);
this.receive();
} catch (IOException e) {
e.printStackTrace();
}
}
private void receive() {
try {
Socket client = server.accept();
String msg = null;
byte[] data = new byte[20480];
int len = client.getInputStream().read(data);
String requestInfo = new String(data, 0, len).trim();
System.out.println(requestInfo);
} catch (IOException e) {
}
}
public void stop() {
}
}
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在浏览器地址栏输入localhost:8888，访问我们手写的网络服务器，在控制台会输出我们的访问请求信息。
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| GET / HTTP/1.1
Host: localhost:8888
Connection: keep-alive
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*
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