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(二)测试学习JavaWeb之SpringMVC之拦截器

2019-02-26  本文已影响28人  Tomandy

前言

SpringMVC 中的Interceptor 拦截器主要用于拦截用户的请求并进行相应的处理,定义一个Interceptor主要有两种方式:

拦截器应用场景

以qq邮箱登录为例,登录成功后,会进入到个人邮箱页面。在短时间内,即使关闭了登录页面(不退出),再打开登录页,也会跳转到个人邮箱页面。如果退出,再打开个人邮箱页面链接,则会跳转到登录页面。以上登录状态的检查其实就是测试过程中常听说的session检查了,也就是说每一个 Controller 方法执行前(上图的preHandle)都需要进行 session 登录态的检查,如果存在登录态,则继续执行
Controller 的方法,如果不存在,则直接返回。


QQ邮箱登录

拦截器示例

参考《开发测试spring应用》书中提到的登录案例,对拦截器的应用做以下说明。


项目结构
pom依赖
<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.springDemo</groupId>
    <artifactId>springMVCDemo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>springMVCDemo Maven Webapp</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
        <spring.version>4.2.8.RELEASE</spring.version>
        <!-- 解决mvn编译乱码问题
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        -->
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
            <scope>provided</scope>
        </dependency>

        <!-- springframe start -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- springframe end -->

    </dependencies>

    <build>
        <finalName>springMVCDemo</finalName>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <plugin>
                    <artifactId>maven-clean-plugin</artifactId>
                    <version>3.1.0</version>
                </plugin>
                <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
                <plugin>
                    <artifactId>maven-resources-plugin</artifactId>
                    <version>3.0.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.0</version>
                </plugin>
                <plugin>
                    <artifactId>maven-surefire-plugin</artifactId>
                    <version>2.22.1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-war-plugin</artifactId>
                    <version>3.2.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-install-plugin</artifactId>
                    <version>2.5.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-deploy-plugin</artifactId>
                    <version>2.8.2</version>
                </plugin>

                <!--
                <plugin>
                  <groupId>org.apache.tomcat.maven</groupId>
                  <artifactId>tomcat7-maven-plugin</artifactId>
                  <version>2.2</version>
                </plugin>
                -->

            </plugins>
        </pluginManagement>
    </build>
</project>

新建jsp及controller

login.jsp:登录页面

<%--
  Created by IntelliJ IDEA.
  User: lenovo
  Date: 2019/2/25
  Time: 15:03
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>测试系统</title>
</head>
<body>
<form action="/login" method="get">
    <table>
        <tr>
            <td>用户名:</td>
            <td><input type="text" name="username"></td>
        </tr>
        <tr>
            <td>密码:</td>
            <td><input type="password" name="password"></td>
        </tr>
        <tr>
            <td colspan="2">
                <button type="submit">登录</button>
            </td>
        </tr>
    </table>
</form>

</body>
</html>

welcome.jsp:需注意,某些版本的isELIgnored默认为true,此时需要设置为isELIgnored="false",否则${username}变量无法传递到页面展现。

<%--
  Created by IntelliJ IDEA.
  User: lenovo
  Date: 2019/2/25
  Time: 15:20
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
    <title>测试系统</title>
</head>
<body>
<div>欢迎${username}登录测试系统啊!</div>
<div><a href="/logout">退出</a> </div>
</body>
</html>

LoginController.java:“redirect:+路径”表示重定向跳转。代码中用到的session,有效时间可以在web.xml中设置。

    <!--session有效时间为30分钟-->
    <session-config>
        <session-timeout>30</session-timeout>
    </session-config>
package example.controller;

import example.info.LoginInfo;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.http.HttpSession;
import java.util.Map;

@Controller
public class LoginController {
    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String login(Map<String, Object> map) {
        return "login";
    }

    @RequestMapping(value = "/login", method = RequestMethod.GET)
    public String login(LoginInfo loginInfo, HttpSession httpSession) { //此处的参数传递使用的是LoginInfo 实体对象
        System.out.println("username:"+loginInfo.getUsername());
        if (loginInfo.getUsername() != null){
            httpSession.setAttribute("username", loginInfo.getUsername()); 
            return "redirect:/welcome"; //点击登录按钮后,重定向跳转到 /welcome 路径
        }else
            return "redirect:/";  //如果直接访问/login路径,则跳转到登录页

    }

    @RequestMapping(value = "/welcome", method = RequestMethod.GET)
    public String welcome(Map<String, Object> map, HttpSession httpSession) {
        String username = "";
        if (httpSession.getAttribute("username") != null)
            username = httpSession.getAttribute("username").toString();
        map.put("username", username);  //传递变量给welcome.jsp的${username}
        return "welcome";
    }

    @RequestMapping(value = "/logout", method = RequestMethod.GET)
    public String logout(HttpSession httpSession) {
        httpSession.setAttribute("username", null);
        return "redirect:/";
    }
}

新建实体类LoginInfo

需注意的是,LoginInfo 定义的变量必须与login.jsp标签里的 name 属性对应,并且要有getter/setter 方法,这样才能在表单提交时自动赋值。


login.jsp标签属性
package example.info;

public class LoginInfo {
    private String username;
    private String password;

    public String getUsername() {
        return this.username;
    }

    public String getPassword() {
        return this.password;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPassword(String password) {
        this.password = password;
    }

}

回看LoginController类的login方法,除了通过实体类LoginInfo来传递参数,

@RequestMapping(value = "/login", method = RequestMethod.GET)
    public String login(LoginInfo loginInfo, HttpSession httpSession) {
        System.out.println("username:"+loginInfo.getUsername());
        if (loginInfo.getUsername() != null){
            httpSession.setAttribute("username", loginInfo.getUsername());
            return "redirect:/welcome"; //重定向跳转到 /welcome 路径
        }else
            return "redirect:/";  //如果直接访问/login路径,则跳转到登录页

    }

还可以通过以下两种方式来实现同样的效果。
方式一:变量名依旧和login.jsp标签的name属性名一致。

    @RequestMapping(value = "/login", method = RequestMethod.GET)
    public String login(String username,String password, HttpSession httpSession) {
        
        if (username != null){
            httpSession.setAttribute("username", username);
            return "redirect:/welcome"; //重定向跳转到 /welcome 路径
        }else
            return "redirect:/";  //如果直接访问/login路径,则跳转到登录页

    }

方式二:通过@RequestParam注解来实现,此方式不要求变量名与login.jsp标签属性一致。

    @RequestMapping(value = "/login", method = RequestMethod.GET)
    public String login(@RequestParam("username")String name, HttpSession httpSession) {

        if (name != null){
            httpSession.setAttribute("username", name);
            return "redirect:/welcome"; //重定向跳转到 /welcome 路径
        }else
            return "redirect:/";  //如果直接访问/login路径,则跳转到登录页

    }
新建拦截类DemoInterceptor

前文提到每一个Controller方法执行前都需要进行session登录态的检查,此时便需要用到拦截器了,接下来以实现HandlerInterceptor 接口为例说明。

package example.interceptor;

import org.springframework.util.StringUtils;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

public class DemoInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        String username = (String) httpServletRequest.getSession().getAttribute("username");
        System.out.println("name:"+username);
        if (StringUtils.isEmpty(username)) {
            httpServletResponse.sendRedirect(httpServletRequest.getContextPath());
            return false;
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {

    }
}

配置拦截器

配置dispatcher-servlet.xml,增加拦截器interceptor配置。

<?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:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       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="example.controller"/>

    <mvc:default-servlet-handler/>

    <!--启用spring的一些annotation -->
    <context:annotation-config/>

    <!-- 配置注解驱动 可以将request参数与绑定到controller参数上 -->
    <mvc:annotation-driven/>

    <!--静态资源映射-->
    <!--本项目把静态资源放在了webapp的statics目录下,资源映射如下-->
    <!--statics目录下所有文件不会被DispatcherServlet拦截,直接访问,当做静态资源交给Servlet处理-->
    <mvc:resources mapping="/statics/**" location="/WEB-INF/statics/"/>
    <!--mvc:resources mapping="/js/**" location="/WEB-INF/statics/js/"/-->
    <!--mvc:resources mapping="/image/**" location="/WEB-INF/statics/image/"/-->

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/view/"/><!--设置JSP文件的目录位置-->
        <property name="suffix" value=".jsp"/>
        <property name="exposeContextBeansAsAttributes" value="true"/>
    </bean>

    <!--mvc:mapping 表示要拦截的请求路径,”/**”表示拦截所有的路径-->
    <!--mvc:exclude-mapping 表示要排除拦截的路径,即不拦截的路径-->
    <!--bean 表示拦截后要做的事,都写在了 DemoInterceptor 这个类里-->
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <mvc:exclude-mapping path="/"/>
            <mvc:exclude-mapping path="/login"/>
            <mvc:exclude-mapping path="/view/**"/>
            <bean class="example.interceptor.DemoInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

</beans>

增加拦截器后,未登录前,打开 http://localhost:8082/welcome会跳转到登录页面。如果不增加拦截器,未登录前打开 http://localhost:8082/welcome 则会跳转到欢迎页面。

页面验证

做完以上处理后,一个登录页面基本完成了,启动Tomcat服务。
输入http://locathost:8082,展现登录页面如下:

登录页面

点击登录按钮,进入welcome页面。


欢迎页面

点击退出按钮,回到登录页面。


退出后页面

参考资料

《开发测试的spring应用》

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