/*练习题：
* 在Mysql数据库中创建一个person数据表，添加三个字段，id，user，password，并录入几条记录 * *练习题：定义一个login.html，里面定义了两个请求字段：user，password，发送请求到loginServlet。 *再创建一个，LoginServlet（需要继承自HttpServlet,并重写doPost方法） *在其中获取请求的user，password * *利用jdbc从person表中查询有没有和页面输入的user，password对应的记录 * *若有则相应Hello：XXX,若没有，相应sorry：XXX XXX 为user * */------------------------------------------------------------------------------------------------------------------
首先在mysql中建立一个表名我person的表，然后再将连接数据库的开源包导进去
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在lib下面的web.xml文件配置为：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> <!-- loginServlet的配置和映射 --> <servlet> <servlet-name>loginServlet</servlet-name> <servlet-class>com.lanqiao.javatest.LoginServlet1</servlet-class> </servlet> <servlet-mapping> <servlet-name>loginServlet</servlet-name> <!-- /loginServlet是login.html中表单的提交方法 --> <url-pattern>/loginServlet</url-pattern> </servlet-mapping> </web-app>-------------------------------------------------------------------------------------------
在WebContent下面建立的表单login.html，使类,配置文件，表单建立起来了连接
<!DOCTYPE html>
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>表单的提交方法</title></head><body> <form action="loginServlet" method="post"> <p> username:<input type="text" name="username"/> password:<input type="password" name="password"/> <br><br> <input type="submit" value="Submit"/> </p> </form></body></html>-------------------------------------------------------------------------------------
LoginServlet1类：
public class LoginServlet1 extends HttpServlet{
//HttpServlet: 是一个 Servlet, 继承自 GenericServlet. 针对于 HTTP 协议所定制. @Override //重写doPost方法 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { PrintWriter out=resp.getWriter(); String username1=req.getParameter("username"); String password1=req.getParameter("password"); String sql="select count(id) from person where " + "username=? and password=?"; Connection connection=null; PreparedStatement preparedStatement=null; ResultSet resultSet=null; try { //获取连接数据库的文件 Class.forName("com.mysql.jdbc.Driver"); String url="jdbc:mysql:///test"; String username2="root"; String password2="lxn123"; connection=DriverManager.getConnection(url, username2, password2); preparedStatement=connection.prepareStatement(sql); preparedStatement.setString(1, username1); preparedStatement.setString(2, password1); resultSet=preparedStatement.executeQuery(); if(resultSet.next()){ int count=resultSet.getInt(1); if (count>0) { out.println("Hello:"+username1); } else{ out.println("Sorry:"+username1); } } } catch (Exception e) { e.printStackTrace(); } finally { if (resultSet!=null) { try { resultSet.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (preparedStatement!=null) { try { preparedStatement.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (connection!=null) { try { connection.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }}