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拦截器1. 拦截器概念2. 拦截器入门案例2.1 环境准备2.2 拦截器开发步骤1: 创建拦截器类步骤2: 配置拦截器类步骤3: SpringMVC添加SpringMvcSupport包扫描和interceptor包扫描步骤4: 简化SpringMvcSupport的编写5 测试3. 拦截器参数解析了解3.1 前置处理方法3.2 后置处理方法3.3 完成处理方法4. 拦截器链配置1. 拦截器概念 (1) 浏览器发送一个请求会先到Tomcat的web服务器
(2) Tomcat服务器接收到请求以后会去判断请求的是静态资源还是动态资源
(3) 如果是静态资源会直接到Tomcat的项目部署目录下去直接访问
(4) 如果是动态资源就需要交给项目的后台代码进行处理
(5) 在找到具体的方法之前我们可以去配置过滤器(可以配置多个Filter)按照顺序进行执行
(6) 然后进入到到中央处理器(SpringMVC中的内容)SpringMVC会根据配置的规则进行拦截
(7) 如果满足规则则进行处理找到其对应的controller类中的方法进行执行,完成后返回结果
(8) 如果不满足规则则不进行处理
拦截器要做的事情
拦截器Interceptor是一种动态拦截方法调用的机制在SpringMVC中动态拦截控制器方法的执行作用: 在指定的方法调用前后执行预先设定的代码阻止原始方法的执行拦截器就是用来做增强
注意区分过滤器和拦截器
归属不同Filter属于Servlet技术Interceptor属于SpringMVC技术拦截内容不同Filter对所有访问进行增强Interceptor仅针对SpringMVC的访问进行增强
2. 拦截器入门案例
2.1 环境准备
步骤1创建一个Web的Maven项目 步骤2在pom.xml中添加所需的jar包
?xml version1.0 encodingUTF-8?
project xmlnshttp://maven.apache.org/POM/4.0.0xmlns:xsihttp://www.w3.org/2001/XMLSchema-instancexsi:schemaLocationhttp://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsdmodelVersion4.0.0/modelVersiongroupIdorg.example/groupIdartifactIdspringMVC_12_interceptor/artifactIdversion1.0-SNAPSHOT/versionpackagingwar/packagingpropertiesmaven.compiler.source8/maven.compiler.sourcemaven.compiler.target8/maven.compiler.target/propertiesdependenciesdependencygroupIdjavax.servlet/groupIdartifactIdjavax.servlet-api/artifactIdversion3.1.0/versionscopeprovided/scope/dependencydependencygroupIdorg.springframework/groupIdartifactIdspring-webmvc/artifactIdversion5.2.10.RELEASE/version/dependencydependencygroupIdcom.fasterxml.jackson.core/groupIdartifactIdjackson-databind/artifactIdversion2.9.0/version/dependency/dependenciesbuildpluginsplugingroupIdorg.apache.tomcat.maven/groupIdartifactIdtomcat7-maven-plugin/artifactIdversion2.1/versionconfigurationport8080/portpath//path/configuration/plugin/plugins/build
/project步骤3编写Controller
package com.itheima.controller;import com.itheima.domain.Book;
import org.springframework.web.bind.annotation.*;/*** Author Mr.Lu* Date 2023/2/11 15:16* ClassName BookController* Version 1.0*/
RestController
RequestMapping(/books)
public class BookController {PostMappingpublic String save(RequestBody Book book){System.out.println(book save ... book);return {module:book save};}DeleteMapping(/{id})public String delete(PathVariable Integer id){System.out.println(book delete... id);return {module:book delete};}PutMappingpublic String update(RequestBody Book book){System.out.println(book update ... book);return {module:book update};}GetMapping(/{id})public String getById(PathVariable Integer id){System.out.println(book getById ... id);return {module:book getById};}GetMappingpublic String getAll(){System.out.println(book getAll...);return {module:book getAll};}
}
步骤4创建模型类Book
package com.itheima.domain;/*** Author Mr.Lu* Date 2023/2/11 15:12* ClassName Book* Version 1.0*/
public class Book {private String name;private double price;public Book() {}public Book(String name, double proce) {this.name name;this.price proce;}public String getName() {return name;}public void setName(String name) {this.name name;}public double getProce() {return price;}public void setProce(double proce) {this.price proce;}Overridepublic String toString() {return Book{ name name \ , proce price };}
}
步骤5创建对应的配置类
Configuration
ComponentScan({com.itheima.controller})
EnableWebMvc
public class SpringMvcConfig {
}package com.itheima.config;import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.servlet.support.AbstractDispatcherServletInitializer;import javax.servlet.Filter;public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {/*** 加载springmvc配置类** return*/Overrideprotected WebApplicationContext createServletApplicationContext() {AnnotationConfigWebApplicationContext ctx new AnnotationConfigWebApplicationContext();ctx.register(SpringMvcConfig.class);return ctx;}/*** 设置由springmvc控制器处理的请求映射路径** return*/Overrideprotected String[] getServletMappings() {return new String[]{/};}/*** 加载spring配置类** return*/Overrideprotected WebApplicationContext createRootApplicationContext() {
// AnnotationConfigWebApplicationContext ctx new AnnotationConfigWebApplicationContext();
// ctx.register(SpringConfig.class);
// return ctx;return null;}// 乱码处理Overrideprotected Filter[] getServletFilters() {CharacterEncodingFilter filter new CharacterEncodingFilter();filter.setEncoding(UTF-8);return new Filter[]{filter};}
}
2.2 拦截器开发
步骤1: 创建拦截器类
在com.itheima目录下面建一个interceptor包在interceptor包下面建一个实现HandlerIntercepror接口的类并重写里面的额三个方法。
注意 拦截器中的preHandler方法如果返回true,则代表放行会执行原始Controller类中要请求的方法如果返回false则代表拦截后面的就不会再执行了。 当有拦截器后请求会先进入preHandle方法 如果方法返回true则放行继续执行后面的handle[controller的方法]和后面的方法 如果返回false则直接跳过后面方法的执行。
package com.itheima.interceptor;import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;// 定义拦截器类实现HandlerInterceptor接口
// 注意当前类必须受Spring容器控制
Component
public class ProjectInterceptor implements HandlerInterceptor {Override// 原始方法调用前执行的内容public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println(preHandle...);return true;}Override// 原始方法调用后执行的内容public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println(postHandle...);}Override// 原始方法调用完成后执行的内容public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println(afterCompletion...);}
}
步骤2: 配置拦截器类
在config目录下创建一个类来配置拦截器类
package com.itheima.config;import com.itheima.interceptor.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;/*** Author Mr.Lu* Date 2023/2/12 15:13* ClassName SpringMvcSupport* Version 1.0*/
Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {Autowired(required false)private ProjectInterceptor projectInterceptor;// Override
// protected void addResourceHandlers(ResourceHandlerRegistry registry) {
// registry.addResourceHandler(/pages/**).addResourceLocations(/pages/);
// }Overrideprotected void addInterceptors(InterceptorRegistry registry) {// 配置拦截器registry.addInterceptor(projectInterceptor).addPathPatterns(/books, /books/*); // 为可变参数可以写几种路径}
}
步骤3: SpringMVC添加SpringMvcSupport包扫描和interceptor包扫描
Configuration
ComponentScan({com.itheima.controller, com.itheima.interceptor, com.itheima.config})
EnableWebMvc
public class SpringMvcConfig {
}步骤4: 简化SpringMvcSupport的编写
让SpringMvcConfig类实现WebMvcConfigurer接口。
Configuration
ComponentScan({com.itheima.controller})
EnableWebMvc
// 实现WebMvcConfigurer接口可以简化开发但具有一定的侵入性
public class SpringMvcConfig implements WebMvcConfigurer {Autowiredprivate ProjectInterceptor projectInterceptor;Overridepublic void addInterceptors(InterceptorRegistry registry) {//配置多拦截器registry.addInterceptor(projectInterceptor).addPathPatterns(/books,/books/*);}
}5 测试
访问http://localhost:8080/books 访问http://localhost:8080/books/666 3. 拦截器参数解析了解
3.1 前置处理方法
原始方法之前运行preHandle
public boolean preHandle(HttpServletRequest request,HttpServletResponse response,Object handler) throws Exception {System.out.println(preHandle);return true;
}request:请求对象response:响应对象handler:被调用的处理器对象本质上是一个方法对象对反射中的Method对象进行了再包装
3.2 后置处理方法
原始方法运行后运行如果原始方法被拦截前置方法返回false则不执行
public void postHandle(HttpServletRequest request,HttpServletResponse response,Object handler,ModelAndView modelAndView) throws Exception {System.out.println(postHandle);
}modelAndView:如果处理器执行完成具有返回结果可以读取到对应数据与页面信息并进行调整
3.3 完成处理方法
拦截器最后执行的方法无论原始方法是否执行只要前置方法返回true,那么完成处理方法就一定执行
public void afterCompletion(HttpServletRequest request,HttpServletResponse response,Object handler,Exception ex) throws Exception {System.out.println(afterCompletion);
}4. 拦截器链配置
步骤1:创建拦截器类实现接口并重写接口中的方法
拦截器2 ProjectInterceptor2
package com.itheima.interceptor;import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;/*** Author Mr.Lu* Date 2023/2/12 15:09* ClassName ProjectInterceptor* Version 1.0*/// 定义拦截器类实现HandlerInterceptor接口
// 注意当前类必须受Spring容器控制
Component
public class ProjectInterceptor2 implements HandlerInterceptor {Override// 原始方法调用前执行的内容public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println(preHandle...222);return true;}Override// 原始方法调用后执行的内容public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println(postHandle...222);}Override// 原始方法调用完成后执行的内容public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println(afterCompletion...222);}
}
拦截器3ProjectInterceptor3
package com.itheima.interceptor;import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;/*** Author Mr.Lu* Date 2023/2/12 15:09* ClassName ProjectInterceptor* Version 1.0*/// 定义拦截器类实现HandlerInterceptor接口
// 注意当前类必须受Spring容器控制
Component
public class ProjectInterceptor3 implements HandlerInterceptor {Override// 原始方法调用前执行的内容public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println(preHandle...333);return true;}Override// 原始方法调用后执行的内容public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println(postHandle...333);}Override// 原始方法调用完成后执行的内容public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println(afterCompletion...333);}
}
步骤2:配置拦截器类
package com.itheima.config;import com.itheima.interceptor.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;/*** Author Mr.Lu* Date 2023/2/12 15:13* ClassName SpringMvcSupport* Version 1.0*/
Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {Autowired(required false)private ProjectInterceptor projectInterceptor;Autowired(required false)private ProjectInterceptor2 projectInterceptor2;Autowired(required false)private ProjectInterceptor3 projectInterceptor3;// Override
// protected void addResourceHandlers(ResourceHandlerRegistry registry) {
// registry.addResourceHandler(/pages/**).addResourceLocations(/pages/);
// }Overrideprotected void addInterceptors(InterceptorRegistry registry) {// 配置拦截器registry.addInterceptor(projectInterceptor).addPathPatterns(/books, /books/*);registry.addInterceptor(projectInterceptor2).addPathPatterns(/books, /books/*);registry.addInterceptor(projectInterceptor3).addPathPatterns(/books, /books/*);}
}
步骤3:运行程序观察顺序 拦截器执行的顺序是和配置顺序有关先进后出。
当配置多个拦截器时形成拦截器链拦截器链的运行顺序参照拦截器添加顺序为准当拦截器中出现对原始处理器的拦截后面的拦截器均终止运行当拦截器运行中断仅运行配置在前面的拦截器的afterCompletion操作
注 当ProjectInterceptorProjectInterceptor2ProjectInterceptor3中的preHandle方法都返回true时拦截器链执行顺序为pre1, pre2, pre3, Controller, post3, post2, post1, after3, after2, after1. 当ProjectInterceptorProjectInterceptor2中的preHandle方法返回trueProjectInterceptor3中的preHandle方法返回false时拦截器链执行顺序为pre1, pre2, pre3, after2, after1. 当ProjectInterceptor中的preHandle方法返回trueProjectInterceptor2中的preHandle方法返回false时拦截器链执行顺序为pre1, pre2, after1. 当ProjectInterceptor中的preHandle方法返回false时拦截器链执行顺序为pre1
