JavaWeb之过滤器实现自动登录案例

01-数据库

create database day_autologin;
use day_autologin;
create table user(
id int primary key auto_increment,
username varchar(20),
password varchar(20)
);
insert into user values(null,'tom','123');

02-JavaBean: User.java

package com.hngy.domain;

import java.io.Serializable;

public class User implements Serializable {
private static final long serialVersionUID = 1L;

private int id;
private String username;
private String password;

// setter和getter方法...

}

03-工具类：DataSourceUtils.java

package com.hngy.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 ComboPooledDataSource ds=new ComboPooledDataSource();
private static ThreadLocal<Connection> tl=new ThreadLocal<>();

/**
* 获取数据源
* @return 连接池
*/
public static DataSource getDataSource(){
return ds;
}

/**
* 从当前线程上获取连接
* @return 连接
* @throws SQLException
*/
public static Connection getConnection() throws SQLException{
Connection conn = tl.get();
if(conn==null){
//第一次获取 创建一个连接 和当前的线程绑定
conn=ds.getConnection();

//绑定
tl.set(conn);
}
return conn;
}

/**
* 释放资源
*
* @param conn
*            连接
* @param st
*            语句执行者
* @param rs
*            结果集
*/
public static void closeResource(Connection conn, Statement st, ResultSet rs) {
closeResource(st, rs);
closeConn(conn);
}

public static void closeResource(Statement st, ResultSet rs) {
closeResultSet(rs);
closeStatement(st);
}

/**
* 释放连接
*
* @param conn
*            连接
*/
public static void closeConn(Connection conn) {
if (conn != null) {
try {
conn.close();
//和当前的线程解绑
tl.remove();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}

}

/**
* 释放语句执行者
*
* @param st
*            语句执行者
*/
public static void closeStatement(Statement st) {
if (st != null) {
try {
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
st = null;
}

}

/**
* 释放结果集
*
* @param rs
*            结果集
*/
public static void closeResultSet(ResultSet rs) {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
rs = null;
}

}

/**
* 开启事务
* @throws SQLException
*/
public static void startTransaction() throws SQLException{
//获取连接//开启事务
getConnection().setAutoCommit(false);;
}

/**
* 事务提交
*/
public static void commitAndClose(){
try {
//获取连接
Connection conn = getConnection();
//提交事务
conn.commit();
//释放资源
conn.close();
//解除绑定
tl.remove();
} catch (SQLException e) {
e.printStackTrace();
}
}

/**
* 事务回滚
*/
public static void rollbackAndClose(){
try {
//获取连接
Connection conn = getConnection();
//事务回滚
conn.rollback();
//释放资源
conn.close();
//解除绑定
tl.remove();
} catch (SQLException e) {
e.printStackTrace();
}
}
}

04-工具类：CookieUtils.java

package com.hngy.utils;

import javax.servlet.http.Cookie;

public class CookieUtils {
/**
* 通过名称在cookie数组获取指定的cookie
* @param name cookie名称
* @param cookies  cookie数组
* @return
*/
public static Cookie getCookieByName(String name, Cookie[] cookies) {
if(cookies!=null){
for (Cookie c : cookies) {
//通过名称获取
if(name.equals(c.getName())){
//返回
return c;
}
}
}
return null;
}
}

05-编写C3P0配置文件：c3p0-config.xml

<c3p0-config>
<!-- 默认配置，如果没有指定则使用这个配置 -->
<default-config>
<!-- 基本配置 -->
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/day_autologin</property>
<property name="user">root</property>
<property name="password">root</property>

<!--扩展配置-->
<property name="checkoutTimeout">30000</property>
<property name="idleConnectionTestPeriod">30</property>
<property name="initialPoolSize">10</property>
<property name="maxIdleTime">30</property>
<property name="maxPoolSize">100</property>
<property name="minPoolSize">10</property>
<property name="maxStatements">200</property>
</default-config>

<!-- 命名的配置 -->
<named-config name="itcast">
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/xxxx</property>
<property name="user">root</property>
<property name="password">1234</property>

<!-- 如果池中数据连接不够时一次增长多少个 -->
<property name="acquireIncrement">5</property>
<property name="initialPoolSize">20</property>
<property name="minPoolSize">10</property>
<property name="maxPoolSize">40</property>
<property name="maxStatements">20</property>
<property name="maxStatementsPerConnection">5</property>
</named-config>
</c3p0-config>

06-常量类：Constant.java

package com.hngy.constant;

public interface Constant {

// 勾选了自动登录
String IS_AUTO_LOGIN = "ok";
}

07-编写登录页：login.jsp

<%@ 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">
</head>
<body>
<center>
<form action="${pageContext.request.contextPath }/login" method="post">
用户名： <input type="text" name="username" /><br/>
密码：<input type="password" name="password" /><br/>
记住用户名：<input type="checkbox" name="auto_login" value="ok" /><br/>
<input type="submit" value="登录" />
</form>
</center>
</body>
</html>

08-编写LoginServlet.java

package com.hngy.web.servlet;

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

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.hngy.constant.Constant;
import com.hngy.domain.User;
import com.hngy.service.UserService;
import com.hngy.service.impl.UserServiceImpl;

/**
* 用户登录
*/
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");

// 01-接收数据
String username = request.getParameter("username");
String password = request.getParameter("password");

// 02-调用service完成操作
UserService service = new UserServiceImpl();
User user = null;
try {
user = service.login(username, password);
} catch (SQLException e) {
e.printStackTrace();
}

// 03-判断数据是否为空
if (user == null) {
request.setAttribute("msg", "用户名与密码不匹配！");
request.getRequestDispatcher("/login.jsp").forward(request, response);
return;
} else {
// 不为空, 把user放入session中
request.getSession().setAttribute("user", user);

// 判断是否勾选了自动登录
if (Constant.IS_AUTO_LOGIN.equals(request.getParameter("auto_login"))) {
// 勾选了，使用cookie，把信息写回浏览器
Cookie cookie = new Cookie("autologin", username+"-"+password);
cookie.setMaxAge(3600);
cookie.setPath(request.getContextPath()+"/");
response.addCookie(cookie);
}

// 04-页面重定向
response.sendRedirect(request.getContextPath()+"/success.jsp");
}

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
doGet(request, response);
}

}

09-编写UserService.java

package com.hngy.service;

import java.sql.SQLException;

import com.hngy.domain.User;

public interface UserService {

User login(String username, String password) throws SQLException;

}

10-编写UserServiceImpl.java

package com.hngy.service.impl;

import java.sql.SQLException;

import com.hngy.dao.UserDao;
import com.hngy.dao.impl.UserDaoImpl;
import com.hngy.domain.User;
import com.hngy.service.UserService;

public class UserServiceImpl implements UserService {

@Override
public User login(String username, String password) throws SQLException {
UserDao dao = new UserDaoImpl();
return dao.login(username, password);
}

}

11-编写UserDao.java

package com.hngy.dao;

import java.sql.SQLException;

import com.hngy.domain.User;

public interface UserDao {

User login(String username, String password) throws SQLException;

}

12-编写UserDaoImpl.java

package com.hngy.dao.impl;

import java.sql.SQLException;

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

import com.hngy.dao.UserDao;
import com.hngy.domain.User;
import com.hngy.utils.DataSourceUtils;

public class UserDaoImpl implements UserDao {

/**
* 用户登录
*/
@Override
public User login(String username, String password) throws SQLException {
QueryRunner qr = new QueryRunner(DataSourceUtils.getDataSource());
String sql = "select * from user where username=? and password=? limit 1";
Object[] params = {username,password};
return qr.query(sql, new BeanHandler<>(User.class), params);
}

}

13-编写success.jsp

<%@ 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">
</head>
<body>
${user.username }, 欢迎登录
</body>
</html>

14-编写AutoLoginFilter.java

package com.hngy.web.filter;

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

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.hngy.domain.User;
import com.hngy.service.UserService;
import com.hngy.service.impl.UserServiceImpl;
import com.hngy.utils.CookieUtils;

/**
* 自动登录的过滤器
* 		自动登录只需要登录一次:当session中没有用户的时候
* 		访问有些资源是不需要自动登录的(和登录还有注册相关的资源)
* @author Administrator
* @date 2017年12月16日
* @version v1.0
*/
public class AutoLoginFilter implements Filter {

@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)
throws IOException, ServletException {
// 00.强转
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;

// 01-获取指定的session
User user = (User) request.getSession().getAttribute("user");

// 02-判断session中是否有用户
if (user == null) {
// 03-session中，没有用户，需要用户自动登录

// 04-判断访问的资源是否与注册登录相关
String path = request.getRequestURI();
if (!path.contains("/login")) {
// 05-不相关, 自动登录

// 获取指定的cookie
Cookie c = CookieUtils.getCookieByName("autologin", request.getCookies());

// 判断cookie是否为空
if (c != null) {
// cookie不为空，则获取里面的值(username, password)
String username = c.getValue().split("-")[0];
String password = c.getValue().split("-")[1];

//调用service, 完成登录操作
UserService service = new UserServiceImpl();
// user = null;
try {
user = service.login(username, password);
} catch (SQLException e) {
e.printStackTrace();
}

// 判断user是否为空
if (user != null) {
// 把user放入session中
request.getSession().setAttribute("user", user);
}
}
}

}

// 放行
chain.doFilter(request, response);
}

}

15-注册Filter

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<display-name>day20-filter</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>login.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>

<filter>
<filter-name>AutoLoginFilter</filter-name>
<filter-class>com.hngy.web.filter.AutoLoginFilter</filter-class>
</filter>

<filter-mapping>
<filter-name>AutoLoginFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>