SpringMVC--拦截器实现用户登录权限验证案例

青旅半醒 2021-08-14 02:13 506阅读 0赞

#### Spring MVC拦截器实现用户登录权限验证案例 ####

**1）创建应用并导入相关JAR包**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]  
**2）创建 POJO 类**

package pers.zhang.pojo;
    
    public class User { 
        private String uname;
        private String upwd;
        
    	public String getUname() { 
    		return uname;
    	}
    	public void setUname(String uname) { 
    		this.uname = uname;
    	}
    	public String getUpwd() { 
    		return upwd;
    	}
    	public void setUpwd(String upwd) { 
    		this.upwd = upwd;
    	}
    
    }

**3）创建控制器类**

package pers.zhang.controller;
    
    import javax.servlet.http.HttpSession;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    import pers.zhang.pojo.User;
    
    @Controller
    public class UserController { 
        /** * 登录页面初始化 */
        @RequestMapping("/toLogin")
        public String initLogin() { 
            return "login";
        }
    
        /** * 处理登录功能 */
        @RequestMapping("/login")
        public String login(User user, Model model, HttpSession session) { 
            System.out.println(user.getUname());
            if ("zhangsan".equals(user.getUname())
                    && "123456".equals(user.getUpwd())) { 
                // 登录成功，将用户信息保存到session对象中
                session.setAttribute("user", user);
                // 重定向到主页面的跳转方法
                return "redirect:main";
            }
            model.addAttribute("msg", "用户名或密码错误，请重新登录！ ");
            return "login";
        }
    
        /** * 跳转到主页面 */
        @RequestMapping("/main")
        public String toMain() { 
            return "main";
        }
    
        /** * 退出登录 */
        @RequestMapping("/logout")
        public String logout(HttpSession session) { 
            // 清除 session
            session.invalidate();
            return "login";
        }
    }

**4）创建拦截器类**

import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    public class LoginInterceptor implements HandlerInterceptor { 
        @Override
        public boolean preHandle(HttpServletRequest request,
                HttpServletResponse response, Object handler) throws Exception { 
            // 获取请求的URL
            String url = request.getRequestURI();
            // login.jsp或登录请求放行，不拦截
            if (url.indexOf("/toLogin") >= 0 || url.indexOf("/login") >= 0) { 
                return true;
            }
            // 获取 session
            HttpSession session = request.getSession();
            Object obj = session.getAttribute("user");
            if (obj != null)
                return true;
            // 没有登录且不是登录页面，转发到登录页面，并给出提示错误信息
            request.setAttribute("msg", "还没登录，请先登录！");
            request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request,
                    response);
            return false;
        }
    
        @Override
        public void afterCompletion(HttpServletRequest arg0,
                HttpServletResponse arg1, Object arg2, Exception arg3)
                throws Exception { 
            // TODO Auto-generated method stub
        }
    
        @Override
        public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1,
                Object arg2, ModelAndView arg3) throws Exception { 
            // TODO Auto-generated method stub
        }
    }

**5）配置拦截器**  
在 WEB-INF 目录下创建配置文件 springmvc-servlet.xml 和 web.xml。  
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>SpringMVCFileDemo</display-name>
      
      
        <filter>
            <filter-name>encodingFilter</filter-name>
            <filter-class>
                 org.springframework.web.filter.CharacterEncodingFilter
            </filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
        </filter>
        <filter-mapping>
            <filter-name>encodingFilter</filter-name>
            <url-pattern>/*</url-pattern>
        </filter-mapping>
        
    	
        <servlet>
    	  	<servlet-name>springmvc</servlet-name>
    	  	<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    	  	
    	  	<init-param>
    	  		<param-name>contextConfigLocation</param-name>
    	  		<param-value>classpath:springmvc-servlet.xml</param-value>
    	  	</init-param>
      	</servlet>
      	<servlet-mapping>
      		<servlet-name>springmvc</servlet-name>
      		<url-pattern>/</url-pattern>
      	</servlet-mapping>
      	
      	
    </web-app>

springmvc-servlet

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
        
        <context:component-scan base-package="pers.zhang" />
        
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/jsp/" />
            <property name="suffix" value=".jsp" />
        </bean>
        
        <mvc:interceptors>
            <mvc:interceptor>
                
                <mvc:mapping path="/**" />
                <bean class="pers.zhang.interceptor.LoginInterceptor" />
            </mvc:interceptor>
        </mvc:interceptors>
    </beans>

**6）创建视图 JSP 页面**  
在 WEB-INF 目录下创建文件夹 jsp，并在该文件夹中创建 login.jsp 和 main.jsp。  
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">
    <title>Insert title here</title>
    </head>
    <body>
        ${msg }
        <form action="${pageContext.request.contextPath }/login" method="post">
            用户名：<input type="text" name="uname" /><br>
            密码：<input type="password" name="upwd" /><br>
            <input type="submit" value="登录" />
        </form>
    </body>
    </html>

main.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">
    <title>Insert title here</title>
    </head>
    <body>
        当前用户：${user.uname }<br />
        <a href="${pageContext.request.contextPath }/logout">退出</a>
    </body>
    </html>

**7）发布并测试应用**  
首先将 SpringMVCInterceptorDemo 应用发布到 Tomcat 服务器并启动 Tomcat 服务器，然后通过地址“http://localhost:8080/SpringMVCInterceptorDemo /main”测试应用，运行效果如下：  
![在这里插入图片描述][20191103135919729.png]  
从上图可以看出，当用户没有登录而直接访问系统主页面时请求将被登录拦截器拦截，返回到登录页面，并提示信息。如果用户在用户名框中输入“zhangsan”，在密码框中输入“123456”，单击“登录”按钮后浏览器的显示结果如图 2 所示。如果输入的用户名或密码错误，浏览器的显示结果如下图所示：  
![在这里插入图片描述][20191103140006478.png]

![在这里插入图片描述][20191103140044626.png]  
当单击“退出”链接后，系统将从主页面返回到登录页面。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]: /images/20210813/70b6b8247aa347eb8d8eb0a79706018e.png
[20191103135919729.png]: /images/20210813/d8ecb9561b4f4c0b9b8ec1935bc92444.png
[20191103140006478.png]: /images/20210813/c8fef5c921c14e48b0090476d26eb5c7.png
[20191103140044626.png]: /images/20210813/be2986953b634cbab7fac2d44a2de012.png