server.java

j2me中udp传输的功能实验室试过感觉不错！！！！

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import java.io.IOException;
import javax.microedition.io.Connector;
import javax.microedition.io.Datagram;
import javax.microedition.io.UDPDatagramConnection;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

/**
 * @author Administrator
 */
public class Server extends MIDlet implements CommandListener{
    private Display ds;
    private Form fm=new Form("Server");
    private TextField tf= new TextField("输入内容","",255,TextField.ANY);
    private Command cmdSend= new Command("Send",Command.SCREEN,1);
    
    private Datagram dg;
    private UDPDatagramConnection udc;
    private final int MAX =255 ;//定义一个空间给接受的数据报最大字节数
   private String adress;//保存客户端地址
    public void startApp() {
        ds= Display.getDisplay(this);
        ds.setCurrent(fm);
        fm.append(tf);
       fm.addCommand(cmdSend);
       fm.setCommandListener(this);
        try {
            udc = 
                (UDPDatagramConnection) Connector.open("datagram://:9999");
     
            new ReceiveThread().start();
 
        } catch (IOException ex) {
            ex.printStackTrace();
        }
   
    }
    
       public void commandAction(Command c,Displayable d){
        if(c==cmdSend){
            String str=tf.getString();  //发送数据报
    try {
                dg = udc.newDatagram(str.getBytes(), str.getBytes().length);
              dg.setAddress(adress);
                udc.send(dg);//送给服务器端
                 
    } catch (IOException ex) {
                ex.printStackTrace();
            }
 
        }
    }
       class ReceiveThread extends Thread{
        public void run(){
            while(true){
                         //接受数据报
      try{
                dg= udc.newDatagram(MAX);
        udc.receive(dg);
    adress=dg.getAddress();
        byte[] data=dg.getData();
        String str=new String(data,0,dg.getLength());
        fm.append(str+'\n'); 
      }catch(Exception e){
          e.printStackTrace();
      }
            }
        }
    }

    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional) {
    }
}