Warum bekomme ich "Duplicate local variable error" hier?

Question

Ich habe diesen Code, wo ich versuche, eine E-Mail mit JAVA Mail API zu senden. Wenn ich diesen Code in Eclipse ausführe, erhalte ich den Fehler "Mehrere Anmerkungen gefunden in dieser Zeile: Duplicate local variable session". Ich habe die Sitzungsvariable nur einmal deklariert, warum bekomme ich diesen Fehler?

try{ 
    String host="smtp.gmail.com"; 
    String to="abc@gmail.com"; 
    final String user="xyz@gmail.com"; 
    final String password="*********"; 
    Properties properties = System.getProperties(); 
    properties.setProperty("mail.smtp.host",host); 
    properties.put("mail.smtp.auth", "true"); 

    Session session = Session.getDefaultInstance(properties, 
    new javax.mail.Authenticator() { 
    protected PasswordAuthentication getPasswordAuthentication() { 
    return new PasswordAuthentication(user,password); 
    } 
    }); 
    MimeMessage message = new MimeMessage(session); 
    message.setFrom(new InternetAddress(user)); 
    message.addRecipient(Message.RecipientType.TO, 
          new InternetAddress(to)); 

    message.setSubject("Thank you subscriber"); 
    message.setContent("<table><tr><td>Name</td><td>+name+</td></tr><tr><td>Address</td><td>+Addr+</td></tr><tr><td>Age</td><td>+age+</td></tr><tr><td>Qualification</td><td>+Qual+</td></tr><tr><td>Percentage</td><td>+Persent+</td></tr><tr><td>Passout</td><td>+Year+</td></tr></table>","text/html"); 

    Transport.send(message); 
    System.out.println("message sent...."); 
} 
catch (MessagingException ex) {ex.printStackTrace();} 
finally {} 

Dies ist mein Servlet, das ich benutze.

package com.registration; 

import java.io.IOException; 
import java.io.PrintWriter; 

import javax.servlet.RequestDispatcher; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

/** 
* Servlet implementation class RegistrationController 
*/ 
public class RegistrationController extends HttpServlet { 
    private static final long serialVersionUID = 1L; 

    /** 
    * @see HttpServlet#HttpServlet() 
    */ 
    public RegistrationController() { 
     super(); 
     // TODO Auto-generated constructor stub 
    } 

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

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

     response.setContentType("text/html"); 
     PrintWriter out = response.getWriter(); 
     String name = request.getParameter("fullname"); 
     String Addr = request.getParameter("address"); 
     String age = request.getParameter("age"); 
     String Qual = request.getParameter("qual"); 
     String Persent = request.getParameter("percent"); 
     String Year = request.getParameter("yop"); 
     if(name.isEmpty()||Addr.isEmpty()||age.isEmpty()||Qual.isEmpty()||Persent.isEmpty()||Year.isEmpty()) 
     { 
      RequestDispatcher rd = request.getRequestDispatcher("registration.jsp"); 
      out.println("<font color=red>OOPS!! YOU MISSED OUT SOME FIELDS. FILL THEM AGAIN</font>"); 
      rd.include(request, response); 
     } 
     else 
     { 
      RequestDispatcher rd = request.getRequestDispatcher("home.jsp"); 
      rd.forward(request, response); 
     } 
    } 


} 

Answer 1

jsp hat eine integrierte Sitzungsvariable, die Sie tatsächlich verwenden können. Also, da Sie es wiederverwenden, erhalten Sie den doppelten Fehler.

Dies entspricht der Ausführung von Session session = request.getSession() in einem Servlet;