如何在Java中將值從java類返回到Servlet

Question

我有java類LoginValidation和Servlet登錄，我從servlet傳遞值到java類，但沒有獲取返回值..從servlet到java類...

//正常的Java類LoginValidation

public class LoginValidation { 

    String userid=""; 
    String password=""; 
    String que=""; 
    Connection dbConnection = null; 
    PreparedStatement pst=null; 
    ResultSet rs=null; 
    String userid1=""; 
    String password1=""; 
    int pan1=0; 

    public long valiDate(String userid ,String password){ 


     long flag = 0l; 
     this.password=password; 
     this.userid=userid; 

     dbConnection = JDBCConnection.getDBConnection(); 
     que="select * from shivu"; 
     try { 
      pst = dbConnection.prepareStatement(que); 
      rs=pst.executeQuery(); 

      while(rs.next()){ 
      userid1=rs.getString(3); 
      password1=rs.getString(2); 
      pan1=rs.getInt(8); 

      if ((userid.equals(userid1)) && (password.equals(password1))){ 
        flag = pan1;  

      }else{ 
       flag = 0; 

      } 
      } 

     } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 

     return flag; 
    } 
} 

// Servlet的登錄

public class Login extends HttpServlet { 
    private static final long serialVersionUID = 1L; 

    /** 
    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) 
    */ 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
     // TODO Auto-generated method stub 



     String userid=request.getParameter("userid"); 

     String password=request.getParameter("password"); 

     LoginValidation lv=new LoginValidation(); 

     System.out.println("control flow"); 

     long i=lv.valiDate(userid,password); 

     System.out.println(i); 

     if(i>=1){  

      System.out.println("control flow inside method call"); 

      HttpSession session = request.getSession(); 

      if (session != null) 
       session.setAttribute("pan", i); 

      response.sendRedirect("welcome.jsp"); 
     } 
     else 
     { 

      System.out.println("Username or Password incorrect"); 
      response.sendRedirect("login1.jsp"); 
     } 




    } 

} 

Answer 1

可以打印，看看validate方法裏面的值。

 while(rs.next()){ 
     userid1=rs.getString(3); 
     password1=rs.getString(2); 
     pan1=rs.getInt(8); 

     // print userid, userid1, password, password1, pan1 

     if ((userid.equals(userid1)) && (password.equals(password1))){ 
       flag = pan1;  

     }else{ 
      flag = 0; 

     } 
     }