SpringMVC拦截器
1 拦截器（interceptor）的作用
SpringMVC的拦截器类似于Servlet开发中的过滤器Filter，用于对处理器进行预处理和后处理
将拦截器按一定的顺序连接成链，这条链称为拦截器链（Interceptor chain）。在访问被拦截的方法或字段时，拦截器链中的拦截器就会按其之前定义的顺序被调用。拦截器也是AOP思想的具体实现
2 拦截器和过滤器的区别
3 自定义拦截器
（1）创建拦截器类实现HandlerInterceptor接口
（2）配置拦截器（spring-mvc.xml中配）
（3）测试拦截器的拦截效果
4 拦截器方法说明
案例：页面初始的情况
pom.xml
<?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.company</groupId> <artifactId>spring_interceptor</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>5.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.0.5.RELEASE</version> </dependency> </dependencies> </project>
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> <!--配置springmvc的前端控制器--> <servlet> <servlet-name>DispatcherServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:spring-mvc.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>DispatcherServlet</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> </web-app>
spring-mvc.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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 "> <!-- 1、mvc注解驱动--> <mvc:annotation-driven/> <!-- 2、配置视图解析器--> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/"/> <property name="suffix" value=".jsp"/> </bean> <!-- 3、静态资源权限开放--> <mvc:default-servlet-handler/> <!-- 4、组件扫描，扫描Controller--> <context:component-scan base-package="com.company.controller"/> </beans>
index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<p>ssssssdss!!!${name}</p>
</body>
</html>
TargetController.java
package com.company.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class TargetController {
@RequestMapping("/target")
public ModelAndView show() {
System.out.println("目标资源执行...");
ModelAndView modelAndView = new ModelAndView();
modelAndView.addObject("name", "company");
modelAndView.setViewName("index");
return modelAndView;
}
}
浏览器中
下面来看看加入拦截器的案例
MyInterceptor1.java
package com.company.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyInterceptor1 implements HandlerInterceptor {
// 在目标方法执行之前 执行
public boolean preHandle(javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response, Object handler) throws Exception {
System.out.println("preHandle....");
return true;
}
// 在目标方法执行之后 视图返回之前执行
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
System.out.println("postHandle....");
}
// 在整个流程都执行完毕后 执行
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
System.out.println("afterCompletion....");
}
}
在spring-mvc.xml中配置拦截器
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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 "> <!-- 1、mvc注解驱动--> <mvc:annotation-driven/> <!-- 2、配置视图解析器--> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/"/> <property name="suffix" value=".jsp"/> </bean> <!-- 3、静态资源权限开放--> <mvc:default-servlet-handler/> <!-- 4、组件扫描，扫描Controller--> <context:component-scan base-package="com.company.controller"/> <!-- 配置拦截器--> <mvc:interceptors> <mvc:interceptor> <!--对那些资源执行拦截操作，/** 代表对所有的资源执行拦截--> <mvc:mapping path="/**"/> <bean class="com.company.interceptor.MyInterceptor1"/> </mvc:interceptor> </mvc:interceptors> </beans>
pom.xml添加servlet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.company</groupId> <artifactId>spring_interceptor</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>5.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>5.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.0.5.RELEASE</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>javax.servlet.jsp-api</artifactId> <version>2.2.1</version> </dependency> </dependencies> </project>
在浏览器中输入
看控制台上打印
注意：
下面配置拦截后转发到另外一个页面上error.jsp
package com.company.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyInterceptor1 implements HandlerInterceptor {
// 在目标方法执行之前 执行
public boolean preHandle(HttpServletRequest request,
HttpServletResponse response, Object handler) throws Exception {
System.out.println("preHandle....");
String param = request.getParameter("param");
if ("yes".equals(param)) {
return true;
} else {
request.getRequestDispatcher("error").forward(request, response);
return false;
}
}
// 在目标方法执行之后 视图对象返回之前执行
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
modelAndView.addObject("name", "wwhhdhd");
System.out.println("postHandle....");
}
// 在整个流程都执行完毕后 执行
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
System.out.println("afterCompletion....");
}
}
