login.java

使用servlet写的简单网上书店

package c;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.sql.DataSource;

import utils.UsersUtil;

public class Login extends HttpServlet {

	private DataSource ds;

	public void init(ServletConfig config) throws ServletException {
		super.init(config);
		ServletContext context=config.getServletContext();
		ds=(DataSource) context.getAttribute("DataSource");
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		Connection con = null;
		try {
			con = ds.getConnection();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		    if(this.isValidUser(con,request)){

		        HttpSession session = request.getSession(true);
		    	session.setAttribute("login","success");	
		    	
		    	response.sendRedirect("BookList");
		    }else {
		    	response.sendRedirect("../login.html");
		    }
	}
	private synchronized boolean isValidUser(Connection con,HttpServletRequest request){
		 boolean isValid=false;
		 UsersUtil userUtil=new UsersUtil(con);
		 String username = request.getParameter("username"); //obtain user name value
	     String password = request.getParameter("password"); //obtain password value
		 isValid=userUtil.findUser(username, password);
		 if(con!=null){
		 try {
			con.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}}
		return  isValid;
	}
	
	public void destroy() {		
		ds=null;
		super.destroy();
	}
}