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*数据库：SQLServer设计、MySQL设计、Access设计
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课堂作业：绘制一个登陆界面实现数据库连接。
输入正确的用户密码：
错误的：
不输入：
package com.jaovo.msg.Util;
import java.sql.*;
public class DBUtil {
public static Connection getConnection() {
try {
//1 加载驱动
Class.forName("com.mysql.jdbc.Driver").newInstance();
} catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String user = "root";
String password = "root";
String url = "jdbc:mysql://localhost:3306/jaovo_msg";
Connection connection = null;
try {
//2 创建链接对象connection
connection = DriverManager.getConnection(url,user,password);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return connection;
}
//关闭资源的方法
public static void close(Connection connection ) {
try {
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void close(PreparedStatement preparedStatement ) {
try {
if (preparedStatement != null) {
preparedStatement.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void close(ResultSet resultSet ) {
try {
if (resultSet != null) {
resultSet.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
<%@ 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>
<title>用户登录界面</title>
</head>
<body>
<form action="add.jsp" method="get">
<%=request.getAttribute("a") %>
<table align="center" border="1" width="500">
<tr>
<td>用户名：</td>
<td>
<input type="text" name="username"/>
</td>
</tr>
<tr>
<td>输入密码：</td>
<td>
<input type="password" name="password"/>
</td>
</tr>
<tr align="center">
<td colspan="2">
<input type="submit" value="提交" />
<input type="reset" value="重置" />
</td>
</tr>
</table>
</form>>
</body>
</html>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import = "com.jaovo.msg.Util.DBUtil" %>
<%@ page import = "java.sql.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<%
//接受客户端传递过来的参数
String username = request.getParameter("username");
if(username==null||"".equals(username))
{
request.setAttribute("a", "请输入用户名!");
%>
<jsp:forward page="addInput.jsp"></jsp:forward>
<%
}
String password = request.getParameter("password");
String sql="select * from t_user1 where username=?";
Connection connection=DBUtil.getConnection();
PreparedStatement preparedStatement=connection.prepareStatement(sql);
preparedStatement.setString(1, username);
ResultSet resultset=preparedStatement.executeQuery();
boolean flag=false;
while(resultset.next())
{
flag=true;
if(resultset.getString("password").equals(password))
{
request.setAttribute("a", "登陆成功!");
%>
<%=request.getAttribute("a")%>
<%
}
else
{
request.setAttribute("a", "登录失败!");
%>
<jsp:forward page="addInput.jsp"></jsp:forward>
<%
}
}
if(!flag)
{
request.setAttribute("a","用户不存在!");
%>
<jsp:forward page="addInput.jsp"></jsp:forward>
<%
}
%>
<body>
</body>
</html>
我计划每天花费一小时在这个课程上。