servlet没有运行thearraylist

Question

我的代码在Servlet中没有工作，但是当从另一个类进行相同的调用时工作正常。

  

index.java它的servlet

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import java.util.*;
import java.util.ListIterator;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class Index extends HttpServlet {

private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    PrintWriter pri=response.getWriter();
    JdbcConnection jdbc=new JdbcConnection();
    try {
        ArrayList<String> rs = jdbc.getData();
        ListIterator<String> itr=rs.listIterator();
        while(itr.hasNext()){
            pri.print(itr.next());
        }
    } catch (SQLException e) {
    e.printStackTrace();
    }
    pri.close();
    }
    }

  

JdbcConnection.java

import java.sql.*;
import java.util.ArrayList;
public class JdbcConnection {

static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost:3309/shopping";
   static final String USER = "root";
   static final String PASS = "sukh";

public ArrayList<String> getData() throws SQLException{
    Connection conn = null;
       Statement stmt = null;
       try {
        Class.forName("com.mysql.jdbc.Driver");
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
       conn = DriverManager.getConnection(DB_URL,USER,PASS);
       stmt = conn.createStatement();
       ArrayList<String> list=new ArrayList<String>();
          String sql;
          sql = "select * from users";
          ResultSet rs = stmt.executeQuery(sql);
          while(rs.next()){
              String s=rs.getString("name");
              list.add(s);
          }
         return list;

    }
   }