为计算机网络中进行数据交换而建立的规则、标准或约定的集合。
UDP
面向无连接,数据不安全,速度快。不区分客户端与服务端。
TCP
面向连接(三次握手),数据安全,速度略低。分为客户端和服务端。
三次握手: 客户端先向服务端发起请求, 服务端响应请求, 传输数据
四.Socket
通信的两端都有Socket。
网络通信其实就是Socket间的通信。
数据在两个Socket间通过IO流传输。
Socket在应用程序中创建,通过一种绑定机制与驱动程序建立关系,告诉自己所对应的IP和port。
五.UDP传输
1.发送
创建DatagramSocket, 随机端口号
创建DatagramPacket, 指定数据, 长度, 地址, 端口
使用DatagramSocket发送DatagramPacket
关闭DatagramSocket
2.接收
创建DatagramSocket, 指定端口号
创建DatagramPacket, 指定数组, 长度
使用DatagramSocket接收DatagramPacket
关闭DatagramSocket
从DatagramPacket中获取数据
3.接收方获取ip和端口号
String ip =packet.getAddress().getHostAddress();
int port = packet.getPort();
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import java.io.IOException;
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import java.net.DatagramPacket;
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import java.net.DatagramSocket;
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import java.net.InetAddress;
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import java.net.SocketException;
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import java.util.Scanner;
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public class Demo2_Send {
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public static void main(String[] args) throws IOException {
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DatagramSocket socket = new DatagramSocket();
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Scanner sc = new Scanner(System.in);
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while (true) {
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String line = sc.nextLine();
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if("quit".equals(line))
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break;
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DatagramPacket packet =
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new DatagramPacket(line.getBytes(), line.getBytes().length,InetAddress.getByName("127.0.0.1"), 6666);
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socket.send(packet);
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}
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socket.close();
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}
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}
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import java.io.IOException;
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import java.net.DatagramPacket;
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import java.net.DatagramSocket;
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import java.net.SocketException;
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public class Demo2_Receive {
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public static void main(String[] args) throws IOException {
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DatagramSocket socket = new DatagramSocket(6666);
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DatagramPacket packet = new DatagramPacket(new byte[1024], 1024);
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while(true) {
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socket.receive(packet);
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byte[] arr = packet.getData();
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int len = packet.getLength();
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String ip = packet.getAddress().getHostAddress();
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System.out.println(ip + ":" + new String(arr,0,len));
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}
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}
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}
多线程
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import java.io.IOException;
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import java.net.DatagramPacket;
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import java.net.DatagramSocket;
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import java.net.InetAddress;
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import java.net.SocketException;
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import java.net.UnknownHostException;
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import java.util.Scanner;
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public class Demo3_MoreThread {
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public static void main(String[] args) {
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new Receive().start();
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new Send().start();
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}
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}
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class Receive extends Thread {
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public void run() {
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try {
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DatagramSocket socket = new DatagramSocket(6666);
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DatagramPacket packet = new DatagramPacket(new byte[1024], 1024);
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while(true) {
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socket.receive(packet);
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byte[] arr = packet.getData();
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int len = packet.getLength();
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String ip = packet.getAddress().getHostAddress();
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System.out.println(ip + ":" + new String(arr,0,len));
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}
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}
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class Send extends Thread {
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public void run() {
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try {
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DatagramSocket socket = new DatagramSocket();
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Scanner sc = new Scanner(System.in);
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while (true) {
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String line = sc.nextLine();
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if("quit".equals(line))
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break;
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DatagramPacket packet =
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new DatagramPacket(line.getBytes(), line.getBytes().length,InetAddress.getByName("192.168.33.186"), 6666);
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socket.send(packet);
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}
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socket.close();
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}
六.TCP传输
1.客户端
创建Socket连接服务端(指定ip地址,端口号)通过ip地址找对应的服务器
调用Socket的getInputStream()和getOutputStream()方法获取和服务端相连的IO流
输入流可以读取服务端输出流写出的数据
输出流可以写出数据到服务端的输入流
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import java.io.BufferedReader;
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import java.io.BufferedWriter;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.OutputStream;
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import java.io.OutputStreamWriter;
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import java.io.PrintStream;
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import java.net.Socket;
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import java.net.UnknownHostException;
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public class Demo2_Client {
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public static void main(String[] args) throws Exception {
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Socket socket = new Socket("127.0.0.1", 12345);
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BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
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PrintStream ps = new PrintStream(socket.getOutputStream());
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System.out.println(br.readLine());
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ps.println("我要报名就业班");
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System.out.println(br.readLine())
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ps.println("不学了");
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socket.close();
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}
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}
2.服务端
创建ServerSocket(需要指定端口号)
调用ServerSocket的accept()方法接收一个客户端请求,得到一个Socket
调用Socket的getInputStream()和getOutputStream()方法获取和客户端相连的IO流
输入流可以读取客户端输出流写出的数据
输出流可以写出数据到客户端的输入流
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import java.io.BufferedReader;
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import java.io.BufferedWriter;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.OutputStream;
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import java.io.OutputStreamWriter;
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import java.io.PrintStream;
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import java.net.ServerSocket;
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import java.net.Socket;
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public class Demo2_Server {
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public static void main(String[] args) throws Exception {
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ServerSocket server = new ServerSocket(54321);
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Socket socket = server.accept();
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BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
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PrintStream ps = new PrintStream(socket.getOutputStream());
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ps.println("欢迎咨询传智播客");
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System.out.println(br.readLine());
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ps.println("报满了,等下一期吧");
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System.out.println(br.readLine());
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server.close();
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socket.close();
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}
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}
创建多线程的服务端,可以不断的向服务端访问
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import java.io.PrintStream;
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import java.net.ServerSocket;
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import java.net.Socket;
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public class Demo3_MoreThread {
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public static void main(String[] args) throws IOException {
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ServerSocket server = new ServerSocket(12345);
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while(true) {
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final Socket socket = server.accept();
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new Thread() {
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public void run() {
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try {
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BufferedReader br =
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new BufferedReader(new InputStreamReader(socket.getInputStream()));
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PrintStream ps = new PrintStream(socket.getOutputStream());
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ps.println("欢迎咨询黑马程序员");
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System.out.println(br.readLine());
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ps.println("不一万就业不给一分钱");
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System.out.println(br.readLine());
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ps.println("不学拉到");
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socket.close();
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}.start();
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}
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}
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}