首先用一个JavaBean封装数据库操作,即mvc中的模型

JdbcBean.java

package data;import java.sql.*;public class JdbcBean {	  private String DBDriver="com.mysql.jdbc.Driver";	  private String DBUrl="jdbc:mysql://localhost:3306/test";	  private String DBUser="root";	  private String DBPassword="686175";	  public Connection conn=null;	  public ResultSet rs=null;	  public ResultSet query(String sql)throws Exception{		  try{			  Class.forName(DBDriver);			  conn=DriverManager.getConnection(DBUrl,DBUser,DBPassword);			  Statement stmt=conn.createStatement();			  rs=stmt.executeQuery(sql);			  return rs;		  }		  catch(SQLException e){			  System.out.println(e.getMessage());		  }		  return null;	  }	  public void update(String sql)throws Exception{		  try{			  Class.forName(DBDriver);			  conn=DriverManager.getConnection(DBUrl,DBUser,DBPassword);			  Statement stmt=conn.createStatement();			  stmt.executeUpdate(sql);			  stmt.close();			  conn.close();		  }		  catch(SQLException e){			  System.out.println(e.getMessage());		  }	  }}

在src的data包中另一个控制器Servlet,用于处理连接数据库的操作，此次project用的数据库是MySQL

LoginServlet.java

package data;import java.io.IOException;import java.sql.ResultSet;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LoginServlet extends HttpServlet {	public void doPost(HttpServletRequest request,			           HttpServletResponse response)			throws ServletException, IOException {		String toJSP="";		request.setCharacterEncoding("gbk");		response.setContentType("text/html;charset=gbk");		String username=request.getParameter("username");		String password=request.getParameter("password");		String sql="select * from user where username='"+username+"'" +				   "&&password='"+password+"'";		JdbcBean jdbc=new JdbcBean();		try{			ResultSet rs=jdbc.query(sql);			if(rs.next()){				toJSP="success.jsp";			}			else{				toJSP="error.jsp";			}			rs.close();		}		catch(Exception e){			System.out.println("发生查询异常");		}		RequestDispatcher rd=request.getRequestDispatcher(toJSP);		rd.forward(request, response);	} 	public void doGet(HttpServletRequest request, 			          HttpServletResponse response)	  throws ServletException, IOException {            doPost(request,response);    }}

接下来就是用jsp写的视图，显示页面操作

登录页面login.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>                  
     
   
        
       
             
         
                  
username
                  
                  
username不能为空
              
              
                  
密码
                  
                  
密码不能为空
              
              
                  
                  
 
              
          
       
  
        
     
  

登录成功页面success.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>                  <%       out.println("登录成功!");     %>  

假设登录的username和password和存放在数据库的数据对不上，就显示登录错误页面error.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>                <%       out.println("username或password错误，登录失败!");     %>  

输入usernameming,passwordming

输入usernamelin,passwordli

完整代码包:http://download.csdn.net/detail/u011731233/8093745