javaWeb作业之前后台交互小Demo

java后台代码：

package util;
/**
 * @author LYB
 * 实现获取连接数据库对象方法类
 */
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//获取连接数据库对象
public class DBUtil {
	static{
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}
	public static Connection getConnection(String url){
		Connection conn = null;
		Properties pro = null;
		InputStream in = null;
		try {
			pro = new Properties();
			in = new FileInputStream("e:"+File.separator+"info.properties");
			pro.load(in);
			conn = DriverManager.getConnection(url,pro);
		} catch (Exception e) {
			e.printStackTrace();
		}
		  return conn;
	}

}

package myservlet;
/**
 * @author LYB
 * java后台实现登录servlet代码
 */
import java.io.*;
import java.sql.*;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import util.DBUtil;

public class LoginServletDemo extends HttpServlet{
	boolean flag = true;
	@Override
	public void init() throws ServletException {
		System.out.println("LoginServlet初始化了...");
	}
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String name = req.getParameter("username");
		String pwd = req.getParameter("pwd");
		login(name,pwd);
		if(flag){
			//resp.sendRedirect("/WebTest/MyJsp/welcome.jsp");
			req.getRequestDispatcher("/MyJsp/welcome.jsp").forward(req, resp);
		}else{
			//resp.sendRedirect("/WebTest/MyHtml/fail.html");
			req.getRequestDispatcher("/MyHtml/fali.html").forward(req, resp);
		}	
	}
	//用户登录方法
	private void login(String name, String pwd) {
		Connection conn = DBUtil.getConnection("jdbc:mysql://localhost:3306/mydb");
		PreparedStatement ps = null;
		ResultSet rs = null;
		String sql = "select * from user where name=? and pwd=?";
		try {
			   ps = conn.prepareStatement(sql);
			   ps.setString(1, name);
			   ps.setString(2, pwd);
			   rs = ps.executeQuery();
			   if(rs.next()){
				  System.out.println("该用户存在..."); 
			   }else{
				  System.out.println("该用户没有注册我们的网站...");
				  flag = false;
			   }
		    } catch (SQLException e) {
		 	   e.printStackTrace();
		    }finally{
		    	try {
					rs.close();
					ps.close();
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
		    }
	   }
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		
	}

}

package myservlet;
/**
 * @author LYB
 * 实现注册Servlet代码
 */
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import util.DBUtil;

//用户登录servlet类
public class RegisterServletDemo extends HttpServlet {
    @Override
    public void init() throws ServletException {
    	System.out.println("RegisterServlet初始化了...");
    }
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String name = req.getParameter("username");
		String pwd = req.getParameter("pwd");
		register(name, pwd);
		req.getRequestDispatcher("/MyJsp/success.jsp").forward(req, resp);

	}

	// 用户注册方法
	private void register(String name,String pwd) {
		Connection conn = DBUtil.getConnection("jdbc:mysql://localhost:3306/mydb");
		PreparedStatement ps = null;
		String sql = "insert into user(name,pwd)values(?,?)";
		try {
			   ps = conn.prepareStatement(sql);
			   ps.setString(1, name);
			   ps.setString(2, pwd);
			   ps.executeUpdate();
              System.out.println("数据库更新成功...");
		    } catch (SQLException e) {
		 	   e.printStackTrace();
		    }finally{
		    	try {
					ps.close();
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
		    }
	 }
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {

	}
}

前台HTML代码：

    
欢迎光临
    

            用户名： 


            密码： 


               
            
   

   
欢迎光临
   

	    注册用户名： 
	     
 

	     注册密码：  
              

	          
 

	          
	          
	

<%@page import="java.net.URLDecoder"%>
<%@ page contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>







   <%String username=request.getParameter("username");%>
   
恭喜,<%=username%>注册成功!

<%@page import="java.net.URLDecoder"%>
<%@ page contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>







   <%
      String username=request.getParameter("username");   // 获取请求参数名为user的参数值
   %>
    	  
欢迎<%=username%>,你是我们的VIP用户！

    
用户名或密码错误，请重新登录！
   点击跳转

服务器配置部署符web.xml：

  WebTest
  
    index.html
    index.htm
    index.jsp
    default.html
    default.htm
    default.jsp
  
  
      firstServlet
      myservlet.LoginServletDemo
       0
  
  
      secondServlet
      myservlet.RegisterServletDemo
       1
  
  
      firstServlet
      /MyHtml/loginURL
  
  
      secondServlet
      /MyHtml/registerURL