Java 网络编程

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();
}
}
}
}

2.UDP方式：

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();
}
}
}

这只是高级接口，更多网络编程后面再总结