SpringBoot+拦截器(Interceptor)

记录一下SpringBoot的拦截器(Interceptor)使用

拦截器(Interceptor)是AOP面向切面编程的思想来实现的，对于只写代码的来说，具体如何实现不需要多关心，只需要关心如何去使用，会用在那些地方。

当http请求进入Springboot应用程序后，会去调用 Controller 层，在进入Controller处理应用业务之前，这个请求是需要通过经过拦截器(Interceptor)的，可能是一个也可能是多个，根据需求来，在Controller处理完业务逻辑之后，也要经过拦截器(Interceptor)，最终将结果返回给请求着，即使不返回，也会经过的。

在拦截器(Interceptor)中，最常的应用有几个方面

1.校验token(最常用):根据请求token拦截校验是否允许访问特定资源比如用户列表，开放的请求地址url需要额外的拦截器配置比如登录
2.记录日志: 记录请求信息的日志数据
3.数据统计: 统计请求某一资源的次数，统计请求进入到响应的处理时间等
4.其他一些实际需求的功能

目前使用的是SpringBoot2.0.5版本

<parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.0.5.RELEASE</version><relativePath/> <!-- lookup parent from repository -->
</parent>

自定义 Interceptor一般是实现 org.springframework.web.servlet.HandlerInterceptor接口
myw
源码是这样的

/** Copyright 2002-2017 the original author or authors.** Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at**      http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/package org.springframework.web.servlet;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.springframework.lang.Nullable;
import org.springframework.web.method.HandlerMethod;/*** Workflow interface that allows for customized handler execution chains.* Applications can register any number of existing or custom interceptors* for certain groups of handlers, to add common preprocessing behavior* without needing to modify each handler implementation.** <p>A HandlerInterceptor gets called before the appropriate HandlerAdapter* triggers the execution of the handler itself. This mechanism can be used* for a large field of preprocessing aspects, e.g. for authorization checks,* or common handler behavior like locale or theme changes. Its main purpose* is to allow for factoring out repetitive handler code.** <p>In an asynchronous processing scenario, the handler may be executed in a* separate thread while the main thread exits without rendering or invoking the* {@code postHandle} and {@code afterCompletion} callbacks. When concurrent* handler execution completes, the request is dispatched back in order to* proceed with rendering the model and all methods of this contract are invoked* again. For further options and details see* {@code org.springframework.web.servlet.AsyncHandlerInterceptor}** <p>Typically an interceptor chain is defined per HandlerMapping bean,* sharing its granularity. To be able to apply a certain interceptor chain* to a group of handlers, one needs to map the desired handlers via one* HandlerMapping bean. The interceptors themselves are defined as beans* in the application context, referenced by the mapping bean definition* via its "interceptors" property (in XML: a &lt;list&gt; of &lt;ref&gt;).** <p>HandlerInterceptor is basically similar to a Servlet Filter, but in* contrast to the latter it just allows custom pre-processing with the option* of prohibiting the execution of the handler itself, and custom post-processing.* Filters are more powerful, for example they allow for exchanging the request* and response objects that are handed down the chain. Note that a filter* gets configured in web.xml, a HandlerInterceptor in the application context.** <p>As a basic guideline, fine-grained handler-related preprocessing tasks are* candidates for HandlerInterceptor implementations, especially factored-out* common handler code and authorization checks. On the other hand, a Filter* is well-suited for request content and view content handling, like multipart* forms and GZIP compression. This typically shows when one needs to map the* filter to certain content types (e.g. images), or to all requests.** @author Juergen Hoeller* @since 20.06.2003* @see HandlerExecutionChain#getInterceptors* @see org.springframework.web.servlet.handler.HandlerInterceptorAdapter* @see org.springframework.web.servlet.handler.AbstractHandlerMapping#setInterceptors* @see org.springframework.web.servlet.handler.UserRoleAuthorizationInterceptor* @see org.springframework.web.servlet.i18n.LocaleChangeInterceptor* @see org.springframework.web.servlet.theme.ThemeChangeInterceptor* @see javax.servlet.Filter*/
public interface HandlerInterceptor {/*** Intercept the execution of a handler. Called after HandlerMapping determined* an appropriate handler object, but before HandlerAdapter invokes the handler.* <p>DispatcherServlet processes a handler in an execution chain, consisting* of any number of interceptors, with the handler itself at the end.* With this method, each interceptor can decide to abort the execution chain,* typically sending a HTTP error or writing a custom response.* <p><strong>Note:</strong> special considerations apply for asynchronous* request processing. For more details see* {@link org.springframework.web.servlet.AsyncHandlerInterceptor}.* <p>The default implementation returns {@code true}.* @param request current HTTP request* @param response current HTTP response* @param handler chosen handler to execute, for type and/or instance evaluation* @return {@code true} if the execution chain should proceed with the* next interceptor or the handler itself. Else, DispatcherServlet assumes* that this interceptor has already dealt with the response itself.* @throws Exception in case of errors*/default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)throws Exception {return true;}/*** Intercept the execution of a handler. Called after HandlerAdapter actually* invoked the handler, but before the DispatcherServlet renders the view.* Can expose additional model objects to the view via the given ModelAndView.* <p>DispatcherServlet processes a handler in an execution chain, consisting* of any number of interceptors, with the handler itself at the end.* With this method, each interceptor can post-process an execution,* getting applied in inverse order of the execution chain.* <p><strong>Note:</strong> special considerations apply for asynchronous* request processing. For more details see* {@link org.springframework.web.servlet.AsyncHandlerInterceptor}.* <p>The default implementation is empty.* @param request current HTTP request* @param response current HTTP response* @param handler handler (or {@link HandlerMethod}) that started asynchronous* execution, for type and/or instance examination* @param modelAndView the {@code ModelAndView} that the handler returned* (can also be {@code null})* @throws Exception in case of errors*/default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,@Nullable ModelAndView modelAndView) throws Exception {}/*** Callback after completion of request processing, that is, after rendering* the view. Will be called on any outcome of handler execution, thus allows* for proper resource cleanup.* <p>Note: Will only be called if this interceptor's {@code preHandle}* method has successfully completed and returned {@code true}!* <p>As with the {@code postHandle} method, the method will be invoked on each* interceptor in the chain in reverse order, so the first interceptor will be* the last to be invoked.* <p><strong>Note:</strong> special considerations apply for asynchronous* request processing. For more details see* {@link org.springframework.web.servlet.AsyncHandlerInterceptor}.* <p>The default implementation is empty.* @param request current HTTP request* @param response current HTTP response* @param handler handler (or {@link HandlerMethod}) that started asynchronous* execution, for type and/or instance examination* @param ex exception thrown on handler execution, if any* @throws Exception in case of errors*/default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,@Nullable Exception ex) throws Exception {}}

preHandler(HttpServletRequest request, HttpServletResponse response, Object handler) 方法

这个方法是在http请求进来之后处理之前被调用的返回是 Boolean 类型，返回 false 时，表示直接掐断请求，直接结束了，那么也就不会进入Controller；返回 true 时，会继续进入下一个拦截器同样的方法（preHandler）直到所有的preHandler方法都通过才进入Controller。

postHandler(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) 方法
http请求处理好业务后，从Controller控制器返回后调用，视图解析器之前，也就是在渲染数据返回数据之前被调用。

afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handle, Exception ex) 方法
当对应的拦截器preHandle返回值是 true 时才会在整个请求结束之后执行，视图解析器之后，也可以理解为postHandler后

自定义CustomHandlerInterceptor.java

package boot.example.interceptor.config;import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class CustomHandlerInterceptor implements HandlerInterceptor{/*** Controller逻辑执行之前进行拦截*/@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("preHandle:");String uri = request.getRequestURI();System.out.println("拦截的uri:"+uri);if (handler instanceof HandlerMethod) {HandlerMethod handlerMethod = (HandlerMethod) handler;System.out.println("拦截 Controller："+ handlerMethod.getBean().getClass().getName());System.out.println("拦截方法："+handlerMethod.getMethod().getName());}//拦截token，没有token的不允许继续往下执行String token = request.getHeader("token");if(token == null){return false;}long startTime = System.currentTimeMillis();System.out.println("start-time: " + startTime);request.setAttribute("startTime", startTime);return true;}/*** Controller逻辑执行完毕但是视图解析器还为进行解析之前进行拦截*/@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("postHandle:");long endTime = System.currentTimeMillis();long startTime = (Long) request.getAttribute("startTime");System.out.println("post-end-time: " + endTime);System.out.println("post-差值ms:" + (endTime - startTime));HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);}/*** Controller逻辑和视图解析器执行完毕进行拦截*/@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("afterCompletion:");long startTime = (Long) request.getAttribute("startTime");long endTime = System.currentTimeMillis();System.out.println("after-end-time: " + endTime);System.out.println("after-差值ms:" + (endTime - startTime));HandlerInterceptor.super.afterCompletion(request, response, handler, ex);}
}

配置拦截器
bean方式（不推荐）

package boot.example.interceptor.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;/*** 使用bean的方式**/
@Configuration
public class InterceptorConfig {@Beanpublic CustomHandlerInterceptor customHandlerInterceptor(){return new CustomHandlerInterceptor();}@Beanpublic WebMvcConfigurer webMvcConfigurer(){return new WebMvcConfigurer() {@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(customHandlerInterceptor()).addPathPatterns("/**")//.excludePathPatterns("/").excludePathPatterns("/index/**");}};}}

重写方式来配置（推荐)

package boot.example.interceptor.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;/*** 重写方式来配置，推荐**/
@Configuration
public class InterceptorConfig implements WebMvcConfigurer {@Beanpublic CustomHandlerInterceptor customHandlerInterceptor(){return new CustomHandlerInterceptor();}@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(customHandlerInterceptor()).addPathPatterns("/**")//.excludePathPatterns("/").excludePathPatterns("/index/**");}}

测试-BootIndexController.java

package boot.example.interceptor.controller;import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;@Controller
public class BootIndexController {@RequestMapping("/")@ResponseBodypublic String index() {return "index";}@RequestMapping("/index/hello")@ResponseBodypublic String indexHello() {return "hello world";}@RequestMapping("/inter/hello")@ResponseBodypublic String interHello(){return "inter world";}@RequestMapping("/inter/sleep")@ResponseBodypublic String sleepHello() throws InterruptedException {// 假装处理2sThread.sleep(2000);return "inter world";}}

表示拦截所有的url请求

.addPathPatterns(“/**”)

表示放开拦截的url请求

.excludePathPatterns(“/”)
.excludePathPatterns(“/index/**”)

请求无拦截的情况，直接返回数据，不会经过拦截器
myw

请求有拦截的情况，没有token是访问不到资源的
myw
查看控制台
myw
随意写个token
myw
可以看到拦截通过了执行了对应的三个方法在这里有测试的故意延迟
myw
一个应用可能有多个拦截器，有的时候拦截器需要执行的先后顺序，默认的情况下是按照注册的先后顺序
拦截器ONE
CustomOrderOneHandlerInterceptor.java

package boot.example.interceptor.config;import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class CustomOrderOneHandlerInterceptor implements HandlerInterceptor{/*** Controller逻辑执行之前进行拦截*/@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("CustomOrderOneHandlerInterceptor: preHandle");return true;}/*** Controller逻辑执行完毕但是视图解析器还为进行解析之前进行拦截*/@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("CustomOrderOneHandlerInterceptor: postHandle");}/*** Controller逻辑和视图解析器执行完毕进行拦截*/@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("CustomOrderOneHandlerInterceptor: afterCompletion");}
}

拦截器TWO
CustomOrderTwoHandlerInterceptor.java

package boot.example.interceptor.config;import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class CustomOrderTwoHandlerInterceptor implements HandlerInterceptor{/*** Controller逻辑执行之前进行拦截*/@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("CustomOrderTwoHandlerInterceptor: preHandle");return true;}/*** Controller逻辑执行完毕但是视图解析器还为进行解析之前进行拦截*/@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("CustomOrderTwoHandlerInterceptor: postHandle");}/*** Controller逻辑和视图解析器执行完毕进行拦截*/@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("CustomOrderTwoHandlerInterceptor: afterCompletion");}
}

拦截器配置
OderInterceptorConfig.java

package boot.example.interceptor.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;/*** 重写方式来配置，推荐**/
@Configuration
public class OderInterceptorConfig implements WebMvcConfigurer {@Beanpublic CustomOrderOneHandlerInterceptor customOrderOneHandlerInterceptor(){return new CustomOrderOneHandlerInterceptor();}@Beanpublic CustomOrderTwoHandlerInterceptor customOrderTwoHandlerInterceptor(){return new CustomOrderTwoHandlerInterceptor();}@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(customOrderOneHandlerInterceptor()).addPathPatterns("/**").excludePathPatterns("/index/**");registry.addInterceptor(customOrderTwoHandlerInterceptor()).addPathPatterns("/**").excludePathPatterns("/index/**");}}

可以看到customOrderOneHandlerInterceptor()在customOrderTwoHandlerInterceptor()之前，启动程序打开访问打开控制台查看打印日志确认
myw
交换顺序可以看到TWO在ONE之前执行
myw
使用order自定义顺序可以看到值小的比值大的先执行
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使用拦截器重定向
当访问

http://localhost:8080

重定向

http://localhost:8080/home

CustomRedirectOneHandlerInterceptor.java

package boot.example.interceptor.config;import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class CustomRedirectOneHandlerInterceptor implements HandlerInterceptor{/*** Controller逻辑执行之前进行拦截*/@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("CustomRedirectOneHandlerInterceptor: preHandle");System.out.println("CustomRedirectOneHandlerInterceptor Request url: " + request.getRequestURL());response.sendRedirect(request.getContextPath()+ "/home");return false;}/*** Controller逻辑执行完毕但是视图解析器还为进行解析之前进行拦截*/@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("CustomRedirectOneHandlerInterceptor: postHandle");}/*** Controller逻辑和视图解析器执行完毕进行拦截*/@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("CustomRedirectOneHandlerInterceptor: afterCompletion");}
}

CustomRedirectTwoHandlerInterceptor.java


package boot.example.interceptor.config;import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class CustomRedirectTwoHandlerInterceptor implements HandlerInterceptor{/*** Controller逻辑执行之前进行拦截*/@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("CustomRedirectTwoHandlerInterceptor: preHandle");System.out.println("CustomRedirectTwoHandlerInterceptor Request url: " + request.getRequestURL());return true;}/*** Controller逻辑执行完毕但是视图解析器还为进行解析之前进行拦截*/@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("CustomRedirectTwoHandlerInterceptor: postHandle");}/*** Controller逻辑和视图解析器执行完毕进行拦截*/@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("CustomRedirectTwoHandlerInterceptor: afterCompletion");}
}

BootIndexController.java

package boot.example.interceptor.controller;import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;@Controller
public class BootIndexController {@RequestMapping("/")@ResponseBodypublic String index() {return "/";}@RequestMapping("/home")@ResponseBodypublic String indexHello() {return "/home";}}