网络编程技术

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1、查看本机的IP地址和网络相关概念

config查看本机的IP地址
ping命令测试网络是否通畅
网络是连接在一起共享数据和资源的计算机
按照覆盖范围可以分为：局域网、城域网、广域网
ping 127.0.0.1检查TCP/IP协议安装是否正确

2、基于TCP协议的网络编程

①建立连接
②打开socket关联的输入/输出流
③从流中读取信息
④关闭流和socket

注意点：
1、先写服务器，再写客户端
2、在客户端输出部分要加socket.shutdownOutput()（相当于告诉服务器我说的话说完了），若用字符流写，需要在socket.shutdownOutput()前面加上flash方法，清空缓存
3、本机localhost
4、端口号不低于1024

三、实例

1、客户端发送的请求为String字符串

package demo1;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;


/*
 * 服务器
 */
public class LoginServece {
	public static void main(String[] args) throws Exception {
		//建立连接
		ServerSocket serverSocket= new ServerSocket(8000);
		Socket socket =serverSocket.accept();
		//打开输入流
		
		InputStream is=socket.getInputStream();
		//读
		BufferedReader br = new BufferedReader(new InputStreamReader(is));
		String info=null;
		while((info=br.readLine())!=null) {
			System.out.println("我是服务器，客户端说："+info);
		}
		
		// 给回应
		
		String reply ="我是服务器，欢迎登陆";
		OutputStream os=socket.getOutputStream();
		os.write(reply.getBytes());
		
		//关闭资源
		os.close();
		br.close();
		is.close();
		socket.close();
	}
}

package demo1;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;

/*
 * 客户端
 */
public class LoginClient {
	public static void main(String[] args) throws Exception, IOException {
		Socket socket = new Socket("localhost", 8000);
		// 发送请求
		OutputStream os = socket.getOutputStream();
		String info = "姓名：jim  密码12345";
		os.write(info.getBytes());
		socket.shutdownOutput();

		// 读回应
		InputStream is = socket.getInputStream();
		BufferedReader br = new BufferedReader(new InputStreamReader(is));
		String replu = null;
		while ((replu = br.readLine()) != null) {
			System.out.println("我是客户端，服务器说：" + replu);
		}
		br.close();
		is.close();
		os.close();
		socket.close();
	}
}

2、客户端传出的是一个对象的情况
需要将对象序列化，注意要实现Serializable接口

package demo2;

import java.io.Serializable;

public class User implements Serializable{
	private String name;
	private String psd;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPsd() {
		return psd;
	}
	public void setPsd(String psd) {
		this.psd = psd;
	}
	public User() {
		super();
		// TODO Auto-generated constructor stub
	}
	public User(String name, String psd) {
		super();
		this.name = name;
		this.psd = psd;
	}
	@Override
	public String toString() {
		return "用户名："+this.getName()+"\t"+"密码："+this.getPsd();
	}
	
	
}

package demo2;

import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;


/*
 * 服务器
 */
public class LoginServece {
	public static void main(String[] args) throws Exception {
		//建立连接
		ServerSocket serverSocket= new ServerSocket(8000);
		Socket socket =serverSocket.accept();
		
		//打开输入流
		InputStream is=socket.getInputStream();
		
		//读
		ObjectInputStream ois = new ObjectInputStream(is);
		User user=(User) ois.readObject();
		System.out.println(user);
		
		// 给回应
		
		
		OutputStream os=socket.getOutputStream();
		String reply ="我是服务器，欢迎登陆";
		os.write(reply.getBytes());
		
		//关闭资源
		os.close();
		ois.close();
		is.close();
		socket.close();
	}
}

package demo2;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.net.Socket;

/*
 * 客户端
 */
public class LoginClient {
	public static void main(String[] args) throws Exception, IOException {
		Socket socket = new Socket("localhost", 8000);
		// 发送请求
		OutputStream os = socket.getOutputStream();
		ObjectOutputStream oos =new ObjectOutputStream(os);
		User user =new User("Jack", "123456");
		oos.writeObject(user);

		// 读回应
		InputStream is = socket.getInputStream();
		BufferedReader br = new BufferedReader(new InputStreamReader(is));
		String replu = null;
		while ((replu = br.readLine()) != null) {
			System.out.println("我是客户端，服务器说：" + replu);
		}
		
		os.close();
		oos.close();
		socket.close();
	}
}

3、利用多线程实现多个客户端发出请求情况
①创建服务器线程类，run（）方法实现对一个请求的响应处理
②死循环让服务器一直处于监听状态
③服务器每监听一个线程，创建一个线程对象并启动

package demo3;

import java.net.ServerSocket;
import java.net.Socket;


/*
 * 服务器
 */
public class LoginServece {
	public static void main(String[] args) throws Exception {
		//建立连接
		ServerSocket serverSocket= new ServerSocket(8000);
		Socket socket;
		while(true) {
			socket=serverSocket.accept();
			MyThread thread =new MyThread(socket);
			thread.start();
		}
	}
}

package demo3;

import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.OutputStream;
import java.net.Socket;

public class MyThread extends Thread{
	private Socket socket;
	
	public MyThread(Socket socket) {
		this.socket = socket;
	}
	@Override
	public void run() {
		//打开输入流
				InputStream is=null;
				ObjectInputStream ois=null;
				OutputStream os=null;
				try {
					is = socket.getInputStream();
					//读
					ois = new ObjectInputStream(is);
					User user=(User) ois.readObject();
					System.out.println(user);
					
					// 给回应
					
					
					os=socket.getOutputStream();
					String reply ="我是服务器，欢迎登陆";
					os.write(reply.getBytes());
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				} catch (ClassNotFoundException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}finally {

					//关闭资源
					try {
						os.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					try {
						ois.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					try {
						is.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					try {
						socket.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
				
				
				
	}
	
}

package demo3;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;

/*
 * 客户端
 */
public class LoginClient22 {
	public static void main(String[] args) throws Exception, IOException {
		Socket socket = new Socket("localhost", 8000);
		// 发送请求
		OutputStream os = socket.getOutputStream();
		ObjectOutputStream oos =new ObjectOutputStream(os);
		User user =new User("good", "111111");
		oos.writeObject(user);

		// 读回应
		InputStream is = socket.getInputStream();
		BufferedReader br = new BufferedReader(new InputStreamReader(is));
		String replu = null;
		while ((replu = br.readLine()) != null) {
			System.out.println("我是客户端，服务器说：" + replu);
		}
		
		os.close();
		oos.close();
		socket.close();
	}
}

四、InetAddress类

位于java.net包中，常用于封装IP地址和DNS
静态方法
InetAddress.getByName(String hostName)
返回指定主机名的InetAddress对象

五、基于UDP协议的socket编程

四个步骤
1、DatagramPacket对象封装数据包
2、DatagramSocket发送数据包
3、DatagramSocket接收数据包
4、DatagramPacket处理数据包
TCP和UDP协议的异同

实现实例：

package socket4;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

/*
 * 基于UDP协议的网络编程
 */
public class LoginnServerce {
	public static void main(String[] args) {
		DatagramSocket socket=null;
		
		try {
			//接收客户端发过来的请求
			//1、建立一个空包用来收
			byte[] b =new byte[1024];
			DatagramPacket dp = new DatagramPacket(b, b.length);
			//2、创建DatagramSocket，（快递点）
			socket =new DatagramSocket(8000);
			//3、收数据
			socket.receive(dp);
			//读取数据
			String info = new String(dp.getData(),0,dp.getData().length);
			System.out.println("客户端说："+info);
			
			
			//给客户端一个响应
			String reply = "我是服务器，你好，客户端！";
			DatagramPacket dp1=new DatagramPacket(reply.getBytes(), reply.getBytes().length, InetAddress.getByName("localhost"), 8000);
			//不用再创建socket
			socket.send(dp1);
		} catch (SocketException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			if(null!=socket) {
				socket.close();
			}
		}
	}
}

package socket4;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.Inet4Address;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

/*
 * 客户端
 */
public class LoginClient {
	public static void main(String[] args) {
		String info="你好啊，服务器！";
		byte[] infos=info.getBytes();
		//获得一个InetAddress
		InetAddress address;
		DatagramSocket socket=null;
		try {
			address = Inet4Address.getByName("localhost");
			//建立一个包裹封装数据
			DatagramPacket dp =new DatagramPacket(infos,infos.length,address,8000);
			//建立快递点
			socket =new DatagramSocket();
			//通过快递点发送数据
			socket.send(dp);
			
			//接收服务器发来的信息
			//创建一个空包接收
			byte[] b = new byte[1024];
			DatagramPacket dp1 =new DatagramPacket(b, b.length);
			socket.receive(dp1);
			// 读取信息
			String reply = new String(dp1.getData(), 0, dp1.getData().length);
			System.out.println(reply);
		} catch (UnknownHostException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SocketException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			socket.close();
		}
		
	}
}