Java 网络编程

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纸上得来终觉浅

网络编程涉及的内容很多，它和多线程，I/O是Java的核心，也是Java产生时就很擅长的部分。之前用C和libpcap库做网关上的一个抓包小程序累得要死，光是网卡的选择，绑定和连接就很费劲，实现一个C/S简单的通信连接都很麻烦，主要是可考虑的太多了，现在看到java还有更高级的接口，不需要关注很多东西（现在看来和那些东西死磕真的毫无意义），实现一个简单的通信模拟是在太简单方便了：

1.TCP方式：

Client传送一张图片给Server，Server保存并且返回Client端一条消息：

<pre name="code" class="java">package roadArchitectWeb.Test;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.channels.ServerSocketChannel;

import org.junit.Test;

import sun.print.resources.serviceui;
/*Tcp Socket网络编程*/
public class Test11 {
	@Test
	public void client(){
		FileInputStream fileInputStream = null;
		OutputStream outputStream = null;
		InputStream inputStream = null;
		Socket socket = null;
		try {
			fileInputStream = new FileInputStream(new File("hello1.jpg"));
			InetAddress inetAddress = InetAddress.getByName("127.0.0.1");
			socket = new Socket(inetAddress,8980);
			outputStream = socket.getOutputStream();
			inputStream = socket.getInputStream();
			byte[] b = new byte[1024];
			int length;
			while(fileInputStream.available()!=0 && (length=fileInputStream.read(b)) != -1){
				outputStream.write(new String(b, 0, length).getBytes());
			}
			if(fileInputStream != null)
				try {
					fileInputStream.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			System.out.println("Test11.client()write");
			
			while(inputStream.available()!=0 &&(length=inputStream.read(b))!=-1){
				System.out.println("Test11.client():"+new String(b,0,length));
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			if(outputStream != null)
				try {
					outputStream.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			if(inputStream != null)
				try {
					inputStream.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			if(socket!=null)
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
		}
	}
	
	@Test
	public void server(){
		FileOutputStream fileOutputStream = null;
		InputStream inputStream = null;
		OutputStream outputStream = null;
		Socket socket = null;
		ServerSocket serverSocket = null;
		try {
			serverSocket = new ServerSocket(8980);
			socket = serverSocket.accept();
			
			inputStream = socket.getInputStream();
			fileOutputStream = new FileOutputStream("hello2.jpg");
			byte[] b = new byte[1024];
			int length;
			while(inputStream.available()!=0 && (length = inputStream.read(b)) != -1){
			length = inputStream.read(b);
				fileOutputStream.write(b, 0, length);
			}
			if(fileOutputStream != null)
				try {
					fileOutputStream.close();
				} catch (IOException e) {
					e.printStackTrace();
			}
			System.out.println("收到图片");
			
			outputStream = socket.getOutputStream();
			outputStream.write("服务端返回客户端信息".getBytes());
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			if(outputStream != null)
				try {
					outputStream.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			if(inputStream != null)
				try {
					inputStream.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			if(socket!=null)
				try {
					socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			if(serverSocket!=null)
				try {
					serverSocket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
		}
	}
}

Client发送一个消息(返回消息一样，就不做了)：

package roadArchitectWeb.Test;

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

import org.junit.Test;

public class Test12 {
	@Test
	public void client(){
		DatagramSocket datagramSocket= null;
		
		try {
			byte[] buf = "客户端发送的".getBytes();
			DatagramPacket datagramPacket = new DatagramPacket(buf,0,buf.length,
					InetAddress.getByName("127.0.0.1"),9390);
			datagramSocket = new DatagramSocket();
			datagramSocket.send(datagramPacket);
			System.out.println("Test12.client():已经发送");
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			if (datagramSocket!=null) {
				datagramSocket.close();
			}
		}
	}
	
	@Test
	public void server(){
		DatagramSocket datagramSocket= null;
		
		try {
			byte[] buf = new byte[30];
			DatagramPacket datagramPacket = new DatagramPacket(buf, 0, buf.length);
			datagramSocket = new DatagramSocket(9390);
			datagramSocket.receive(datagramPacket);
			System.out.println("Test12.server():"+new String(datagramPacket.getData(),
					0,datagramPacket.getLength()));
		} catch (SocketException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			if(datagramSocket!=null)
				datagramSocket.close();
		}
	}
}

Java 网络编程

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原文地址：http://blog.csdn.net/jintao_ma/article/details/51347850