自己写了一个关于java UDP传输文件的代码，运行不了，没有错误，不知道哪里出问题了，求助！

Question

发送端：

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.Inet4Address;
import java.net.SocketException;
import java.util.Date;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class LoginJiemian {
public static void main(String[] args) throws FileNotFoundException {
new FileSend().FileSen();
}
}

class FileSend{
JFrame jFrame;

JPanel InputPanel;
JLabel PortNumberLabel;
JButton buttonChooseFile,buttonTransportFile;
JTextField textPortNumber;
File file;
byte[] buffer,bufferPacketNum,bufferPacketContent,receiveByte;
DatagramPacket packet,packet1;
DatagramSocket socket;
DataInputStream fis;
int read;
long a;
int Num;
String str;

FileSend() throws FileNotFoundException{
    try {
        socket = new DatagramSocket(9);
        String filePath = "e:\\mysql.rar";
        fis = new DataInputStream(new BufferedInputStream(
                new FileInputStream(filePath)));                    
    } catch (SocketException e) {
        e.printStackTrace();
    }
    FileSen();
}

public void FileSen(){
    jFrame = new JFrame("UDP文件传输");
    jFrame.setBounds(400, 200,400, 400);        
    jFrame.setLayout(null);
    jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    InputPanel=new JPanel();
    InputPanel.setBounds(0,0,400, 400);
    InputPanel.setLayout(null);
//两个功能按钮    
    buttonChooseFile=new JButton("选择文件");
    buttonChooseFile.setBounds(20, 10, 100, 28);
    buttonTransportFile=new JButton("发送");
    buttonTransportFile.setBounds(20, 50, 100, 28);
//文本输入框   输入端口号
    textPortNumber=new JTextField();
    textPortNumber.setBounds(200, 10, 130, 20);
//标签  提示输入端口号 
    PortNumberLabel=new JLabel("端口号");
    PortNumberLabel.setBounds(200, 50, 130, 20);

    InputPanel.add(buttonChooseFile);
    InputPanel.add(buttonTransportFile);
    InputPanel.add(textPortNumber);
    InputPanel.add(PortNumberLabel);

    jFrame.add(InputPanel); 
    jFrame.setVisible(true);

    buttonChooseFile.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {                        
        }
    });

    buttonTransportFile.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            try {   
                receiveByte = new byte[20];
                bufferPacketNum=new byte[20];
                bufferPacketContent=new byte[1024]; 
                buffer=new byte[1080];
                Num=1;
                a = new Date().getTime();
                read = 0;
                if (fis != null) {  
                    try {
                        read = fis.read(bufferPacketContent);
                        buffer=byteMerger(intToByteArray(Num),bufferPacketContent);
                        packet = new DatagramPacket(buffer,0,buffer.length,
                                (Inet4Address) Inet4Address.getByName("localhost"), 8);
                        packet1=packet;//备份重传
                        socket.send(packet);
                    } catch (IOException e1) {
                        e1.printStackTrace();
                    }
                }
                if (read == -1) {
                    System.out.print("用时：");
                    System.out.println(new Date().getTime() - a);
                    return;
                }



                while (true) {
                    packet = new DatagramPacket(receiveByte, receiveByte.length);
                    socket.receive(packet);

                    if (fis != null) {  
                        str = new String(packet.getData(),0,packet.getLength());
                        System.out.println(str);
                        if(str.equals(new String().valueOf(Num))){
                            Num++;
                            read = fis.read(bufferPacketContent);
                            buffer=byteMerger(intToByteArray(Num),bufferPacketContent);
                            packet = new DatagramPacket(buffer,buffer.length,
                                    (Inet4Address) Inet4Address.getByName("localhost"), 8);
                            packet1=packet;//备份重传
                            socket.send(packet);                            
                        }else{
                            socket.send(packet1);
                        }   
                    }

                    if (read == -1) {
                        System.out.print("用时：");
                        System.out.println(new Date().getTime() - a);
                        break;
                    }           
                }                                                                                                       
            } catch (FileNotFoundException e1) {
                e1.printStackTrace();
            } catch (SocketException e1) {
                e1.printStackTrace();
            } catch (IOException e1) {
                e1.printStackTrace();
            }           
        }
    }); 
}

public static byte[] intToByteArray(int i) {   
    byte[] result = new byte[4];   
    //由高位到低位
    result[0] = (byte)((i >> 24) & 0xFF);
    result[1] = (byte)((i >> 16) & 0xFF);
    result[2] = (byte)((i >> 8) & 0xFF); 
    result[3] = (byte)(i & 0xFF);
    return result;
}

public static byte[] byteMerger(byte[] byte_1, byte[] byte_2){  
    byte[] byte_3 = new byte[byte_1.length+byte_2.length];  
    System.arraycopy(byte_1, 0, byte_3, 0, byte_1.length);  
    System.arraycopy(byte_2, 0, byte_3, byte_1.length, byte_2.length);  
    return byte_3; 
}

}

接收端：

import java.io.BufferedOutputStream;
import java.io.DataOutputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.Inet4Address;
import java.net.SocketException;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class UdpReceive {
public static void main(String[] args) throws IOException {
new FileRece().Udprecev();;
}
}

class FileRece{
JFrame jFrame;

JPanel InputPanel;
JLabel PortNumberLabel;
JButton buttonSaveFile;
JTextField textPortNumber;

DatagramSocket dataSocket;
final int PORT = 8;
byte[] receiveByte,receiveByte1,sendByte;
DatagramPacket dataPacket;
String FileName,str;
DataOutputStream fileOut;
int j,len;

public FileRece() throws SocketException, FileNotFoundException {

    dataSocket = new DatagramSocket(PORT);
    fileOut = new DataOutputStream(
            new BufferedOutputStream(new FileOutputStream(
                    "D:\\mysql.rar")));
    receiveByte = new byte[1080];
    sendByte=new byte[20];
}

public void Udprecev() throws IOException{
    j=0;
    while(true){
        dataPacket = new DatagramPacket(receiveByte, receiveByte.length);
        dataSocket.receive(dataPacket);

        String s=""+j; //把数字转成字符串
        len=s.length(); 

        str = new String(dataPacket.getData(),0,len);
        System.out.println(str);

        if(str.equals(new String().valueOf(j+1))){                          
            // 指定接收到数据的长度，可使接收数据正常显示，开始时很容易忽略这一点
            fileOut.write(receiveByte, len, dataPacket.getLength());
            fileOut.flush();    
            j++;
            sendByte=intToByteArray(j);
            dataPacket = new DatagramPacket(sendByte,sendByte.length,
                    (Inet4Address) Inet4Address.getByName("localhost"), 9);
            dataSocket.send(dataPacket);
        }       
    }
}   

public static byte[] intToByteArray(int i) {   
    byte[] result = new byte[4];   
    //由高位到低位
    result[0] = (byte)((i >> 24) & 0xFF);
    result[1] = (byte)((i >> 16) & 0xFF);
    result[2] = (byte)((i >> 8) & 0xFF); 
    result[3] = (byte)(i & 0xFF);
    return result;
}

}

Answer 1

测试了，可以运行的。先运行UdpReceive类，这类似服务器；然后启动LoginJieMain类，发送文件。
你的选择文件按钮的响应代码为空，所以不能选择文件，点击发送时可以输出这个操作的用时。
最终的结果就是可以看到你的mysql.rar文件从E盘复制了一份存储到D盘了。页面上直接看到到执行效果的，你到D盘看到刚刚生成的mysql.rar文件就说明程序正确了。