package sime.login.servlet;

import java.sql.Statement;
import java.io.IOException;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet implements Servlet
{
public LoginServlet ()
{
// TODO Auto-generated constructor stub

}
/*
* (non-Javadoc)
*
* @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest,
* javax.servlet.http.HttpServletResponse)
*/
@Override
protected void doGet ( HttpServletRequest arg0, HttpServletResponse arg1 )
   throws ServletException, IOException
{
}
/*
* (non-Javadoc)
*
* @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
* javax.servlet.http.HttpServletResponse)
*/
@Override
public void doPost ( HttpServletRequest request, HttpServletResponse response )
   throws ServletException, IOException
{
response.setContentType ( "text/html" );
String result = "";
// 获取用户名

String sUserName = request.getParameter ( "txtUserName" );
if ( sUserName == "" || sUserName == null || sUserName.length ( ) > 20 )
{
   try
   {
    result = "请输入用户名（不超过20字符）！";
    request.setAttribute ( "ErrorUserName", result );
    response.sendRedirect ( "login.html" );
   } catch ( Exception e )
   {
   }
}
// 获取密码

String sPasswd = request.getParameter ( "txtPassword" );
if ( sPasswd == "" || sPasswd == null || sPasswd.length ( ) > 20 )
{
   try
   {
    result = "请输入密码（不超过20字符）！";
    request.setAttribute ( "ErrorPassword", result );
    response.sendRedirect ( "login.html" );
   } catch ( Exception e )
   {
   }
}
// 登记JDBC驱动程序

try
{
   Class.forName ( "org.gjt.mm.mysql.Driver" ).newInstance ( );
} catch ( InstantiationException e )
{
   // TODO Auto-generated catch block

   e.printStackTrace ( );
   System.out.println ("InstantiationException");
} catch ( IllegalAccessException e )
{
   // TODO Auto-generated catch block

   e.printStackTrace ( );
   System.out.println ("IllegalAccessException");
} catch ( ClassNotFoundException e )
{
   // TODO Auto-generated catch block

   e.printStackTrace ( );
   System.out.println ("ClassNotFoundException");
}
// 连接参数与Access不同

String url = "jdbc:mysql://localhost/learnJSP";
// 建立连接

java.sql.Connection connection = null;
Statement stmt = null;
ResultSet rs = null;
try
{
   connection = DriverManager.getConnection ( url, "root", "woshipis" );
   stmt = connection.createStatement ( );
   // SQL语句

   String sql = "select * from logintest where Username='" + sUserName
     + "' and Userpwd = '" + sPasswd + "'";
   rs = stmt.executeQuery ( sql );// 返回查询结果

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

   e.printStackTrace ( );
}
try
{
   if (rs.next())// 如果记录集非空，表明有匹配的用户名和密码，登陆成功

   {
    // 登录成功后将sUserName设置为session变量的UserName

    // 这样在后面就可以通过 session.getAttribute("UserName") 来获取用户名，

    // 同时这样还可以作为用户登录与否的判断依据

    request.getSession ( ).setAttribute ( "UserName", sUserName );
    response.sendRedirect ( "login_success.jsp" );
   } else
   {
    // 否则登录失败

    //response.sendRedirect ( "MyJsp.jsp" );

    response.sendRedirect ( "login_failure.jsp" );
   }
} catch ( SQLException e )
{
   // TODO Auto-generated catch block

   e.printStackTrace ( );
}
try
{
   if ( null!=rs )
   {
    rs.close ( );
   }
   if ( null!=stmt )
   {
    stmt.close ( );
   }
   if ( null!=connection )
   {
    connection.close ( );
   }
} catch ( SQLException e )
{
   // TODO Auto-generated catch block

   e.printStackTrace ( );
}
}
/**
*
*/
private static final long serialVersionUID = 1L;
}