SpringMVC拦截器之介绍和搭建环境
1.1 拦截器的作用
Spring MVC 的处理器拦截器类似于Servlet开发中的过滤器Filter,用于对处理器进行预处理和后处理。 用户可以自己定义一些拦截器来实现特定的功能。
谈到拦截器,还要向大家提一个词——拦截器链(Interceptor Chain)。拦截器链就是将拦截器按一定的顺序联结成一条链。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。
说到这里,可能大家脑海中有了一个疑问,这不是我们之前学的过滤器吗?是的它和过滤器是有几分相似,但是也有区别,接下来我们就来说说他们的区别:
过滤器是servlet规范中的一部分,任何java web工程都可以使用。
拦截器是SpringMVC框架自己的,只有使用了SpringMVC框架的工程才能用。
过滤器在url-pattern中配置了/*之后,可以对所有要访问的资源拦截。
拦截器它是只会拦截访问的控制器方法,如果访问的是jsp,html,css,image或者js是不会进行拦截的。
它也是AOP思想的具体应用。
我们要想自定义拦截器, 要求必须实现:HandlerInterceptor接口。如图所示:
1.2 搭建环境
1.打开IDEA如图所示,并点击Create New Project。
2.选择Maven工程和JDK的版本,并点击Next。如图所示:
3.填写项目名称和保存地址,点击Next。如图所示:
4.解决maven项目创建过慢的问题如图所示,输入变量名:archetypeCatalog和变量值:internal,并点击ok和Finish。如图所示:
5.导入相应的jar包的代码如下:
<?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.txw</groupId>
<artifactId>springmvc_day02_04_interceptor</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>springmvc_day02_04_interceptor 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>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<spring.version>5.0.2.RELEASE</spring.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${
spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${
spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${
spring.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<finalName>springmvc_day02_04_interceptor</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>
</plugins>
</pluginManagement>
</build>
</project>
- 如图所示:项目的目录结构没有下载。
7.在main目录下新建Java和resouces.并设置如图所示:
8.在web.xml写人如下代码:
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
<display-name>Archetype Created Web Application</display-name>
<!--配置前端控制器-->
<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:springmvc.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>
<!--配置解决中文乱码的过滤器-->
<filter>
<filter-name>characterEncodingFilter</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>
</filter>
<filter-mapping>
<filter-name>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
9.在resources新建springmvc.xml的代码如下:
<?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/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<!-- 开启注解扫描 -->
<context:component-scan base-package="com.txw"/>
<!-- 视图解析器对象 -->
<bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/pages/"/>
<property name="suffix" value=".jsp"/>
</bean>
<!--前端控制器,哪些静态资源不拦截-->
<mvc:resources location="/css/" mapping="/css/**"/>
<mvc:resources location="/images/" mapping="/images/**"/>
<mvc:resources location="/js/" mapping="/js/**"/>
<!-- 开启SpringMVC框架注解的支持 -->
<mvc:annotation-driven />
</beans>
10.在index.jsp的代码如下:
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2020/7/7 0007
Time: 15:43
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>首页</title>
</head>
<body>
<h3>拦截器</h3>
<a href="user/testInterceptor">拦截器</a>
</body>
</html>
11.在webapp/WEB-INF下创建pages目录并success.jsp如图所示:
success.jsp的代码如下:
<%--
Created by IntelliJ IDEA.
User: adair
Date: 2020/7/7 0007
Time: 15:54
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>成功页面</title>
</head>
<body>
<h3>执行成功!!!!</h3>
</body>
</html>
12.创建拦截器处理类的代码如下:
package com.txw.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
/**
* 创建拦截器处理类
* @author Adair
*/
@Controller
@RequestMapping(path = "/user")
@SuppressWarnings("all") // 注解警告信息
public class UserController {
@RequestMapping("/testInterceptor")
public String testInterceptor(){
System.out.println("testInterceptor执行了...");
return "success";
}
}
13.配置Tomcat服务如图所示:
14.使用Tomcat服务运行结果如图所示:
15.通过浏览器访问http://localhost:8080/如图所示:
16.点击拦截器,会跳转到如图所示的界面:
17.控制台打印结果如图所示: