UDP / IP Echo Server在向服务器传输数据时遇到问题

Question

因此，我已经使用UDP / IP协议套件创建了服务器和客户端应用程序进行通信。我可以将数据获取到服务器，但是当它到达时，我尝试将字符串解析为整数，我得到NumberFormatException，但是当我在格式之前打印字符串时，我得到的应该是“ 8”。我在下面发布了我的代码：

服务器

package udp_ip;


import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.io.*;

public class UDPServer {

static private int destport = 9999;
static private int bufsize = 1024;

private DatagramSocket serverSocket;
private InetAddress local_addr;

private UDPServer()
{
    try
    {
        serverSocket = new DatagramSocket(destport);
    }
    catch(IOException ioe)
    {
        System.err.println("Client SOcket could not be created");
    }
    try
    {
        local_addr = InetAddress.getLocalHost();
    }
    catch(Exception uhe)
    {
        System.err.println("Uknown Host:\tLocalHost");
    }
}

private InetAddress getLocalAddress()
{
    return this.local_addr;
}

private DatagramSocket getSocket()
{
    return serverSocket;
}

public static void main(String args[]) throws Exception
{
    UDPServer server = new UDPServer();
    DatagramSocket serverSocket = server.getSocket();
    byte[] acceptData = new byte[bufsize];
    InetAddress local_addr = server.getLocalAddress();

    DatagramPacket receiveTestData = new DatagramPacket (acceptData, 
 acceptData.length);
    serverSocket.receive(receiveTestData);
    String str = new String(receiveTestData.getData());
    System.out.println(str);
    int num = Integer.parseInt(str);
    int result = num*num;

    byte[] testData = (result+"").getBytes();
    DatagramPacket sendPacket = new DatagramPacket(testData, 
 testData.length, local_addr, receiveTestData.getPort());
    serverSocket.send(sendPacket);

     }
   }

Client
package udp_ip;
import java.io.IOException;
import java.net.DatagramPacket;
 import java.net.DatagramSocket;
 import java.net.InetAddress;



public class UDPClient {


static private int destport = 9999;
static private int bufsize = 1024;

private DatagramSocket clientSocket;
private InetAddress local_addr;

private UDPClient()
{
    try
    {
        clientSocket = new DatagramSocket();
    }
    catch(IOException ioe)
    {
        System.err.println("Client Socket could not be created");
    }
    try
    {
        local_addr = InetAddress.getLocalHost();
    }
    catch(Exception uhe)
    {
        System.err.println("Uknown Host:\tLocalHost");
    }
}

private InetAddress getLocalAddress()
{
    return this.local_addr;
}

private DatagramSocket getSocket()
{
    return clientSocket;
}

public static void main(String args[]) throws Exception
{
    UDPClient client = new UDPClient();

    byte[] targetData = new byte[bufsize];
    InetAddress local_addr = client.getLocalAddress();
    int testSend = 8;
    byte[] testTargetData = String.valueOf(testSend).getBytes();

    DatagramPacket testSendPacket = new DatagramPacket(testTargetData, 
    testTargetData.length, local_addr, destport);
    DatagramSocket clientSocket = client.getSocket();
    clientSocket.send(testSendPacket);

    DatagramPacket acceptTargetData = new DatagramPacket(targetData, 
  targetData.length);
    clientSocket.receive(acceptTargetData);

    String str = new String(acceptTargetData.getData());
    System.out.println("Server Sent" + str);
   }
    }

NumberFormatExceptionError