login.java

简单实现的一个登录模块

//login.java

//import required classes
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;

//class login
public class login extends HttpServlet
{
	public void doGet(HttpServletRequest req,HttpServletResponse res)
	throws IOException,ServletException
	{
		String username = req.getParameter("username");
		String password = req.getParameter("password");
		if(this.checklogin(username,password))
		{
			Cookie mylogin = new Cookie("username",username);
			mylogin.setVersion(1);
			mylogin.setPath("/");
			mylogin.setComment("Your login username");
			res.addCookie(mylogin);
		}
		//Cookie[] myCookies = req.getCookies();
		//String nameValue = this.getCookieValue(myCookies,"username","not found");
		//PrintWriter out = res.getWriter();
		//out.println("username" + ":" + nameValue);
		//out.println("Test Cookie Success!");
		res.sendRedirect("/index.jsp");
	}

	public void doPost(HttpServletRequest req,HttpServletResponse res)
	throws IOException,ServletException
	{
		doGet(req,res);
	}

	public static String getCookieValue(Cookie[] cookies,String cookieName,String defaultValue)
	{
		for(int i=0;i<cookies.length;i++) {
			Cookie cookie = cookies[i];
			if (cookieName.equals(cookie.getName()))
			return(cookie.getValue());
		}
		return(defaultValue);
	}



	public boolean checklogin(String username,String password)
	{
		try{
			DBConn loginConn = new DBConn();
			loginConn.executeQuery("select * from tbl_user where name='" + username + "'");
			if(loginConn.rs_next())
			{
				System.out.println("Connection created!");
				if(loginConn.rs_getString("pwd").trim().equals(password))
				{
					System.out.println(loginConn.rs_getString("name"));
					return true;
				}
				else
				{
					return false;
				}
			}
			System.out.println("Test Login Success!");
			return false;
			}catch(Exception e){
				System.out.println(e.toString());
				return false;
			}
		}

		public static void main(String args[])
		{
			login mylogin = new login();
			System.out.println(mylogin.checklogin("shandong","shandong"));
		}

	}