JDBC连接访问SQL Server2012

package com.pkg1;

import java.sql.*;
import com.microsoft.sqlserver.jdbc.*;

public class JdbcDemo2 {
    Connection conn;
    PreparedStatement st;
    final static String connUrl = "jdbc:sqlserver://127.0.0.1:1433;databaseName=TestDB";
    final static String dbUserName = "sa";
    final static String dbPwd = "123456";
    
    public JdbcDemo2(){
        try{
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); 
            this.conn = DriverManager.getConnection(connUrl, dbUserName, dbPwd);
        }catch(Exception e){
            e.printStackTrace();
            this.close();
        }
    }
    
    public ResultSet runQuery(String sql){
        ResultSet rs = null;
        try{
            this.st = this.conn.prepareStatement(sql);
            rs = this.st.executeQuery();
        }catch(Exception e){
            this.close();
            return null;
        }
        
        return rs;
        
    }
    
    public void close(){
        try{
            if(this.st != null){
                this.st.close();
            }
            
            if(this.conn != null){
                this.conn.close();
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }
    
}