loginaction.java

对初学者非常有用的,学习学习吧,简单的Java编程

package com.city.oa.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;


import javax.servlet.*;
import javax.servlet.http.*;


public class LoginAction extends HttpServlet {

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException
	{
         String id=request.getParameter("id");
         ServletContext ctx=this.getServletContext();
         
         
         
         String password=request.getParameter("password");
         String sql="select * from EMP where EMPID=? and password=?";
         
         String driver=ctx.getInitParameter("driver");
         String dburl=ctx.getInitParameter("url");
         
         
         
         try
         {
        	 Class.forName(driver);
        	 Connection cn=DriverManager.getConnection(dburl);
        	 PreparedStatement ps=cn.prepareStatement(sql);
        	 ps.setString(1, id);
        	 ps.setString(2, password);
        	 
        	 ResultSet rs=ps.executeQuery();
        	 String url="";
        	 if(rs.next())
        	 {
        		 
        		 Integer num=(Integer)ctx.getAttribute("num");
        		 if(num==null)
        		 {
        			 num=1;
        		 }
        		 else
        		 {
        			 num++;
        		 }
        		 ctx.setAttribute("num", num);
        		 
        		 HttpSession session=request.getSession();
        		 session.setAttribute("id", id);
        		 url="main";
        	 }
        	 else
        	 {
        		 url="login.jsp";
        	 }
        	 rs.close();
        	 ps.close();
        	 cn.close();
        	 
        	 RequestDispatcher rd=request.getRequestDispatcher(url);
        	 rd.forward(request, response);
        	 
         }
         catch(Exception e)
         {
        	 System.out.println("Error:"+e.getMessage());
         }
         
		
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request,response);
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occure
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}