Netbeans上的MYSQL连接丢失了

Question

我正在做一些功课，我需要将 mysql 与 netbeans 相关联，以便保存一些certian数据。 我失去了联系，我不知道为什么和在哪里。

这是我的代码：

  public void runThread(int  taban , int tavan) {
    int primNum=0;
       try
    {
        Class.forName("com.mysql.jdbc.Driver");
    }
    catch (ClassNotFoundException e) {
        System.out.println("MySQL JDBC Driver not found !!");
        return;
    }



   try{
       Connection con  = DriverManager.getConnection("jdbc:mysql://localhost/primenumbers" , "root" , "password123");
       System.out.println("SQL Connection to database established!");
       Statement stmt = (Statement) con.createStatement();
       int i=taban;

       while(i<tavan){

        boolean tf = TredAsal.isPrime(i);
        if(tf==true) {
        primNum++;

        if(i>15){ 
        String insert = "INSERT INTO primenumbers VALUES (" + i + ")";
        stmt.execute(insert);
        stmt.cancel();
        }
        Thread.sleep(500);
                       }
       i+=2;
       }                          
       con.close();
   }

   catch(Exception e){
    System.out.println("Connection Failed! Check output console1");
   }
  }

我正在调用runThread的代码：

    StringBuilder sb = new StringBuilder();
    StringBuilder sb2 = new StringBuilder();
    sb.append("");
    sb.append(clicks);
    String strI = sb.toString();
    jTextField1.setText(strI);
    int tavan;
    tavan=(int) sqrt(clicks);
    int tredsayisi=0;
    int Brojgrupe;


            TredAsal ta= new TredAsal();
            int x = ta.run(tavan);
            sb2.append("");
            sb2.append(x);
            String strP=sb2.toString();

            if(x<100){

            tredsayisi = 2 ; 
            }
            else {
            tredsayisi=(int) (x/100)+1;
            }
            Brojgrupe = tavan / tredsayisi;
            if(tredsayisi==2 ){
                StringBuilder sb3 = new StringBuilder();
                StringBuilder sb4 = new StringBuilder();
                sb3.append("");
                sb3.append(Brojgrupe);
                sb4.append("");
                sb4.append(tavan);
                String strBit2 = sb3.toString();
                String strBit3 = sb4.toString(); // pravim text za bas i bitis noktasi
                   TredAsal t1 = new TredAsal();
                   TredAsal t2 = new TredAsal();
                   t1.runThread(3, Brojgrupe); //Thread.sleep(1000);
                   t2.runLastThread(tavan, Brojgrupe);// Thread.sleep(1000);
                   jTextField2.setText("2");
                   jTextField9.setText(strBit2);
                   jTextField3.setText(strBit2);
                   jTextField10.setText(strBit3);


     }

每当我调用此函数时，SQL连接都会建立，但在某些时候会被某些我看不到的东西打断。