练习JavaWeb连接数据库

1.添加jar包。

建立动态java项目，在Web-INF文件夹下的lib文件夹里添加jar包。

区别：java中添加的jar包需要添加构建路径，而javaWeb中添加的jar不需要构建路径，自动添加。

2.创建请求页面

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

<form action="Check.jsp" method="post">

卡号：<input type="text" name="cardid"><br>

密码：<input type="password" name="password"><br>

按钮：<input type="submit" value="登录">

</form>

</body>

</html>

3.创建接收页面

<%@page import="java.sql.ResultSet"%>

<%@page import="java.sql.PreparedStatement"%>

<%@page import="java.sql.Connection"%>

<%@page import="java.sql.DriverManager"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

<%

//接收验证

    String cardid = request.getParameter("cardid");

    String password = request.getParameter("password");

    //数据验证

    if(cardid.equals("")||password.equals(""))

    {

        out.write("请正确登录系统");

    }

    else if(cardid==null||password==null)

    {

        out.write("请正确登录系统");

    }

    else

    {

        out.write(cardid);

        out.write(password);

    //连接数据库

    Class.forName("oracle.jdbc.driver.OracleDriver");

    Connection conn =DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "test0816", "laoer123");

    PreparedStatement ps = conn.prepareStatement("select * from t_balance where card_id=? and password=?  ");

    ps.setString(1, cardid);

    ps.setString(2,password);

    ResultSet rs =ps.executeQuery();

//数据验证

    if(rs.next())

    {

        out.write("用户名和密码正确");

    }

    else

    {

        out.write("用户名或密码错误");

    }

    rs.close();

    ps.close();

    conn.close();

}

%>

</body>

</html>

4.通过连接池连接数据库

（1）添加jar包，同上。

（2）在JavaResources - src- 创建java包 -创建类，并将配置文件放在src下

package com.hanqi.web;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import com.mchange.v2.c3p0.ComboPooledDataSource;

//单例模式

public class CardDAO {

    //构建连接池对象并配置

    private  ComboPooledDataSource cpds =new ComboPooledDataSource("helloc3p0");

    public boolean checklogin(String cardid,String password)

    {

        boolean rtn =false;

        try {

                Connection conn = cpds.getConnection();

                PreparedStatement ps = conn.prepareStatement("select * from t_balance where card_id=? and password=?  ");

                ps.setString(1, cardid);

                ps.setString(2,password);

                ResultSet rs =ps.executeQuery();

                rtn=rs.next();

                rs.close();

                ps.close();

                conn.close();

            } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

        return rtn;

    }

}

请求信息页面

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

<form action="Check2.jsp" method="post">

卡号：<input type="text" name="cardid"><br>

密码：<input type="password" name="password"><br>

按钮：<input type="submit" value="登录">

</form>

</body>

</html>

接收信息的页面

<%@page import="com.hanqi.web.CardDAO"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

<%

    //    设置不缓存页面

    response.setHeader("Cache-Control", "no-cache");

    //定时跳转

    //response.setHeader("refresh", "2;URL=http://www.baidu.com");

    //

String cardid = request.getParameter("cardid");

String password =request.getParameter("password");

if(cardid==null||password==null||

cardid.equals("")||password.equals(""))

{

    out.write("请正确登录");

}

else

{

    //检查登录信息

    CardDAO cd = new CardDAO();

    if(cd.checklogin(cardid, password))

    {

        //out.write("登录成功！");

        response.getWriter().write("验证成功！");

        //页面跳转

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

        response.sendRedirect("http://www.baidu.com");

    }

    else

    {

        out.write("登录失败！");

        //跳回登录页面

        response.setHeader("refresh", "2;URL=loginin.jsp");

    }

}

%>

</body>

</html>

附原本的图，不是以上程序

练习JavaWeb连接数据库

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练习JavaWeb连接数据库

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