一、套接字 Socket
网络驱动程序提供给应用程序编程的接口和一种机制，可以比喻成一个港口码头 应用程序只要把货放在这,就算完成了货物的运送。它在应用程序中创建,通过一种绑定机制与驱动程序建立关系,告诉自已对应的IP 和 Port。
Socket是 java 中网络编程的类 , 位于java.net包中。
---- DatagramSocket //用于UDP通迅
---- ServerSocket //用于TCP通讯,用于服务端
---- Socket //用于Tcp通讯的服务端和客户端
二、UDP 网络程序
InetAddress 类 表示互联协议(IP)地址
//static InetAddress getLocalHost() throws UnknownHostException 返回本地主机
//static InetAddress getByName(String host) 在给定主机名的情况下确定主机的 IP 地址。 主机名可以是机器名
//（如 "java.sun.com"），也可以是其 IP 地址的文本表示形式
//static InetAddress[] getAllByName(String host) 根据主机名返回其 IP 地址所组成的数组。
static void ipDemo() throws UnknownHostException{
InetAddress netAddr=InetAddress.getLocalHost(); //取得本地电脑的一些信息System.out.println(netAddr.toString());
System.out.println(netAddr.getHostAddress());
System.out.println(netAddr.getHostName()); //取得其他电脑的信息InetAddress netAddr2=InetAddress.getByName("DELL-PC"); //这里也可以传IP地址System.out.println(netAddr2.getHostAddress()); //169.254.170.71System.out.println(netAddr2.getHostName()); //DELL-PC //取得百度的地址InetAddress [] ipList=InetAddress.getAllByName("www.baidu.com");for(InetAddress addr:ipList){
System.out.println(addr.toString());
}
}三、UDP发送和接收 DatagramSocket , DatagramPacket
//例一 最简的发送和接收
发送端==要导java.net包
通过UDP的方式把数据发出去：
1) 建立UDPSocket服务
2) 提供数据,将数据封装到数据包中 DatagramPacket (byte[] buf, int length, InetAddress address, int port) //构造函数有多个
3) 通过Socket服务,发送数据
4) 关闭资源
import java.net.*;class Sender4{//DatagramPacket (byte[] buf, int length, InetAddress address, int port) public static void main(String [] args) throws Exception
{ byte [] buff="hello cat".getBytes();
DatagramSocket socket=new DatagramSocket();
DatagramPacket packet=new DatagramPacket(buff,buff.length,InetAddress.getByName("192.168.0.103"),8888);
socket.send(packet);
socket.close();
System.out.println("ok");
}
}--接收端
1) 创建Socket服务,指定在某个端口上监听
2) 创建一个用于接收数据的 DatagramPacket
3) 从包中取出数据
4) 关闭资源
import java.net.*;class Receive4
{public static void main(String [] args) throws Exception
{
DatagramSocket socket=new DatagramSocket(8888); //别忘了端口号byte[] buff=new byte[1024] ;
DatagramPacket packet=new DatagramPacket(buff,buff.length);
socket.receive(packet);
String senderIp=packet.getAddress().getHostAddress();
String senderData=new String(packet.getData(),0,packet.getLength());int senderPort=packet.getPort();
System.out.println(senderIp+"---"+senderData+"---"+senderPort);
socket.close();
}
}
//例二,循环的发送和接收
import java.net.*;import java.io.*;class NewSender{public static void main(String [] args) throws Exception
{
System.out.println("发送端启动了");
DatagramSocket socket=new DatagramSocket();
BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); //包装键盘输入流String str=null;while((str=br.readLine())!=null){byte [] buff=str.getBytes();
DatagramPacket packet=new DatagramPacket(buff,buff.length,InetAddress.getByName("127.0.0.1"),9000);
socket.send(packet);
}
br.close();
socket.close();
}
}import java.net.*;class NewReceiver{public static void main(String [] args) throws Exception
{
DatagramSocket socket=new DatagramSocket(9000);
System.out.println("接收端启动了"); while(true){
byte [] buff=new byte[1024] ;
DatagramPacket packet=new DatagramPacket(buff,buff.length);
socket.receive(packet);
String senderIp=packet.getAddress().getHostAddress(); int sendPort=packet.getPort();
String msg= new String(packet.getData(),0,packet.getLength());
System.out.println(senderIp+":"+sendPort+":"+msg);
}
}
}
例三：多线程聊天室程序
class Chat
{public static void main(String [] args)
{new Thread(new SendThread()).start(); new Thread(new ReceiveThread()).start();
}
}//发送端import java.io.*;import java.net.*;class SendThread implements Runnable
{ private DatagramSocket socket;public void run()
{try{
socket=new DatagramSocket();
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String msg=null;while((msg=br.readLine())!=null){byte[] buff=msg.getBytes();
DatagramPacket packet=new DatagramPacket(buff,buff.length,InetAddress.getByName("127.0.0.1"),10000);
socket.send(packet);
}
socket.close();
br.close();
}catch(Exception ex){
ex.printStackTrace();
}
}
}//接收端import java.net.*;class ReceiveThread implements Runnable{ private DatagramSocket socket; public void run(){try{
socket=new DatagramSocket(10000);while(true){byte [] buff=new byte[1024];
DatagramPacket packet=new DatagramPacket(buff,buff.length);
socket.receive(packet);
String senderIp=packet.getAddress().getHostAddress();int senderPort=packet.getPort();
String msg=new String(packet.getData(),0,packet.getLength());
System.out.println(senderIp+":"+senderPort+":"+msg);
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
}
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