使用Servlet进行用户登录（六）_用户输入登录信息提交给servlet进行接收,servlet接收到请求内容后,对其合法性进行-优快云博客

本文介绍了一个简单的用户登录系统的实现过程，包括数据库设计、前端页面构建、后端Servlet处理逻辑及数据库连接配置等内容。

我们通过servlet来实现一次用户登录的功能。

一、数据库

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL,
  `username` varchar(50) DEFAULT NULL,
  `password` varchar(50) DEFAULT NULL,
  `email` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', 'tom', '123', 'tom@163.com');
INSERT INTO `user` VALUES ('2', 'lucy', '123', 'lucy@163.com');

二、前端页面

<%@ page language="java" contentType="text/html; charset=UTF-16"
    pageEncoding="UTF-16"%>
<!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-16">
<title>Insert title here</title>
</head>
<body>

	<form action="/servlet_first/login" method="post">
		用户名：<input type="text" name="username"><br/>
		密码：<input type="password" name="password"><br/>
		<input type="submit" name="登录"><br/>
	</form>

</body>
</html>

三、Servlet

package com.ken.login;

import java.io.IOException;
import java.sql.SQLException;

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

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;

import com.ken.domain.User;
import com.ken.utils.DataSourceUtils;

public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		// 1.获得用户名和密码
		String username = request.getParameter("username");
		String password = request.getParameter("password");

		// 2.从数据库中验证该用户名和密码是否正确
		QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());

		String sql = " select * from user where username = ? and password = ? ";
		User user = null;
		try {
			user = runner.query(sql, new BeanHandler<User>(User.class), username, password);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		// 3.根据返回结果给用户不同的显示信息
		if (user != null) {
			// 用户登录成功
			response.getWriter().write(user.toString());
		} else {
			// 用户登录失败
			response.getWriter().write("sorry your username or password is wrong");
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
}

四、连接数据库

4.1 工具类DataSourceUtils

package com.ken.utils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DataSourceUtils {

	private static DataSource dataSource = new ComboPooledDataSource();

	private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();

	// 直接可以获取一个连接池
	public static DataSource getDataSource() {
		return dataSource;
	}

	// 获取连接对象
	public static Connection getConnection() throws SQLException {

		Connection con = tl.get();
		if (con == null) {
			con = dataSource.getConnection();
			tl.set(con);
		}
		return con;
	}

	// 开启事务
	public static void startTransaction() throws SQLException {
		Connection con = getConnection();
		if (con != null) {
			con.setAutoCommit(false);
		}
	}

	// 事务回滚
	public static void rollback() throws SQLException {
		Connection con = getConnection();
		if (con != null) {
			con.rollback();
		}
	}

	// 提交并且 关闭资源及从ThreadLocall中释放
	public static void commitAndRelease() throws SQLException {
		Connection con = getConnection();
		if (con != null) {
			con.commit(); // 事务提交
			con.close();// 关闭资源
			tl.remove();// 从线程绑定中移除
		}
	}

	// 关闭资源方法
	public static void closeConnection() throws SQLException {
		Connection con = getConnection();
		if (con != null) {
			con.close();
		}
	}

	public static void closeStatement(Statement st) throws SQLException {
		if (st != null) {
			st.close();
		}
	}

	public static void closeResultSet(ResultSet rs) throws SQLException {
		if (rs != null) {
			rs.close();
		}
	}

}

4.2 c3p0-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
	<default-config>
		<property name="user">root</property>
		<property name="password">123456</property>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql:///servlet_first</property>
	</default-config> 
</c3p0-config>

五、web.xml

<?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">
	<display-name>servlet_first</display-name>
	<servlet>
		<servlet-name>abc</servlet-name>
		<servlet-class>com.ken.servlet.QuickStartServlet</servlet-class>
		<init-param>
			<param-name>url</param-name>
			<param-value>jdbc:mysql:///mydb</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>abc</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
	<servlet>
		<servlet-name>QuickStartServlet2</servlet-name>
		<servlet-class>com.ken.servlet.QuickStartServlet2</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>QuickStartServlet2</servlet-name>
		<url-pattern>/quickStartServlet2</url-pattern>
	</servlet-mapping>
	<servlet>
		<description></description>
		<display-name>LoginServlet</display-name>
		<servlet-name>LoginServlet</servlet-name>
		<servlet-class>com.ken.login.LoginServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>LoginServlet</servlet-name>
		<url-pattern>/login</url-pattern>
	</servlet-mapping>
</web-app>