拦截器
| SpringMVC中的拦截器用于拦截控制器方法的执行 |
| SpringMVC中的拦截器需要实现HandlerInterceptor |
| # 浏览器 -> filter -> DispatcherServlet -> controller |
| # preHandle方法则是在controller执行前执行 |
| |
| preHandle:控制器方法执行之前执行preHandle(),其boolean类型的返回值表示是否拦截或放行,返回true为放行,即调用控制器方法;返回false表示拦截,即不调用控制器方法 |
| postHandle:控制器方法执行之后执行postHandle() |
| afterComplation:处理完视图和模型数据,渲染视图完毕之后执行afterComplation() |
| |
| |
| |
| |
| if (!mappedHandler.applyPreHandle(processedRequest, response)) { |
| return; |
| } |
| |
| |
| |
| mv = ha.handle(processedRequest, response, mappedHandler.getHandler()); |
| |
| if (asyncManager.isConcurrentHandlingStarted()) { |
| return; |
| } |
| |
| |
| applyDefaultViewName(processedRequest, mv); |
| mappedHandler.applyPostHandle(processedRequest, response, mv); |
| } |
| catch (Exception ex) { |
| dispatchException = ex; |
| } |
| catch (Throwable err) { |
| |
| |
| dispatchException = new NestedServletException("Handler dispatch failed", err); |
| } |
| |
| |
| processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException); |
| |
| private void processDispatchResult(HttpServletRequest request, HttpServletResponse response, |
| @Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv, |
| @Nullable Exception exception) throws Exception { |
| |
| boolean errorView = false; |
| |
| if (exception != null) { |
| if (exception instanceof ModelAndViewDefiningException) { |
| logger.debug("ModelAndViewDefiningException encountered", exception); |
| mv = ((ModelAndViewDefiningException) exception).getModelAndView(); |
| } |
| else { |
| Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null); |
| mv = processHandlerException(request, response, handler, exception); |
| errorView = (mv != null); |
| } |
| } |
| |
| |
| if (mv != null && !mv.wasCleared()) { |
| render(mv, request, response); |
| if (errorView) { |
| WebUtils.clearErrorRequestAttributes(request); |
| } |
| } |
| else { |
| if (logger.isTraceEnabled()) { |
| logger.trace("No view rendering, null ModelAndView returned."); |
| } |
| } |
| |
| if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) { |
| |
| return; |
| } |
| |
| if (mappedHandler != null) { |
| |
| mappedHandler.triggerAfterCompletion(request, response, null); |
| } |
| } |
| # springmvc配置文件中配置视图控制器,用于跳转到index.html |
| <mvc:view-controller path="/" view-name="index"></mvc:view-controller> |
| |
| # springmvc配置文件中配置拦截器 |
| <mvc:interceptors> |
| <bean class="com.atguigu.mvc.interceptors.FirstInterceptor"></bean> |
| </mvc:interceptors> |
| |
| # 编写1个控制器,用于测试 |
| @Controller |
| public class TestController { |
| |
| @RequestMapping("/**/testInterceptor") |
| public String testInterceptor(){ |
| return "success"; |
| } |
| |
| } |
| |
| # 编写1个拦截器 |
| @Component |
| public class FirstInterceptor implements HandlerInterceptor { |
| |
| @Override |
| public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { |
| System.out.println("FirstInterceptor-->preHandle"); |
| |
| return true; |
| } |
| |
| @Override |
| public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { |
| System.out.println("FirstInterceptor-->postHandle"); |
| } |
| |
| @Override |
| public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { |
| System.out.println("FirstInterceptor-->afterCompletion"); |
| } |
| } |
| |
| # 测试 |
| http: |
| # 控制台打印 |
| FirstInterceptor-->preHandle |
| FirstInterceptor-->postHandle |
| FirstInterceptor-->afterCompletion |
| |
| # 如果将拦截器中的preHandle方法改为不放行 |
| @Override |
| public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { |
| System.out.println("FirstInterceptor-->preHandle"); |
| |
| return false; |
| } |
| # 再次测试,控制台打印如下 |
| FirstInterceptor-->preHandle |
| # 这是因为访问testInterceptor接口时,被拦截了,后面的postHandle方法和afterCompletion方法就不会执行了 |
| # springmvc配置文件中配置拦截器,如下方式,会拦截所有请求 |
| <mvc:interceptors> |
| <bean class="com.atguigu.mvc.interceptors.FirstInterceptor"></bean> |
| </mvc:interceptors> |
| |
| # 编写1个控制器,用于测试 |
| @Controller |
| public class TestController { |
| |
| @RequestMapping("/**/testInterceptor") |
| public String testInterceptor(){ |
| return "success"; |
| } |
| |
| } |
| |
| # 编写1个拦截器 |
| @Component |
| public class FirstInterceptor implements HandlerInterceptor { |
| |
| @Override |
| public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { |
| System.out.println("FirstInterceptor-->preHandle"); |
| |
| return true; |
| } |
| |
| @Override |
| public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { |
| System.out.println("FirstInterceptor-->postHandle"); |
| } |
| |
| @Override |
| public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { |
| System.out.println("FirstInterceptor-->afterCompletion"); |
| } |
| } |
| |
| # 测试 |
| http: |
| # 控制台打印 |
| FirstInterceptor-->preHandle |
| FirstInterceptor-->postHandle |
| FirstInterceptor-->afterCompletion |
| # 拦截器FirstInterceptor添加注解@Component,将其注册为1个bean |
| |
| # springmvc配置文件中开启组件扫描,确保拦截器能够被扫描到 |
| <context:component-scan base-package="com.atguigu.mvc"></context:component-scan> |
| |
| # springmvc配置文件中配置拦截器,如下方式,会拦截所有请求 |
| <mvc:interceptors> |
| <ref bean="firstInterceptor"></ref> |
| </mvc:interceptors> |
| |
| # 编写1个控制器,用于测试 |
| @Controller |
| public class TestController { |
| |
| @RequestMapping("/**/testInterceptor") |
| public String testInterceptor(){ |
| return "success"; |
| } |
| |
| } |
| |
| # 编写1个拦截器 |
| @Component |
| public class FirstInterceptor implements HandlerInterceptor { |
| |
| @Override |
| public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { |
| System.out.println("FirstInterceptor-->preHandle"); |
| |
| return true; |
| } |
| |
| @Override |
| public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { |
| System.out.println("FirstInterceptor-->postHandle"); |
| } |
| |
| @Override |
| public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { |
| System.out.println("FirstInterceptor-->afterCompletion"); |
| } |
| } |
| |
| # 测试 |
| http: |
| # 控制台打印 |
| FirstInterceptor-->preHandle |
| FirstInterceptor-->postHandle |
| FirstInterceptor-->afterCompletion |
| # 拦截器FirstInterceptor添加注解@Component,将其注册为1个bean |
| |
| # springmvc配置文件中开启组件扫描,确保拦截器能够被扫描到 |
| <context:component-scan base-package="com.atguigu.mvc"></context:component-scan> |
| |
| # springmvc配置文件中配置拦截器,如下方式,会拦截指定请求 |
| <mvc:interceptors> |
| <mvc:interceptor> |
| <!-- 表示拦截一级目录的所有请求 --> |
| <mvc:mapping path="/*"/> |
| <!-- 表示放行该请求 --> |
| <mvc:exclude-mapping path="/"/> |
| <ref bean="firstInterceptor"></ref> |
| </mvc:interceptor> |
| </mvc:interceptors> |
| |
| # 编写1个控制器,用于测试 |
| @Controller |
| public class TestController { |
| |
| @RequestMapping("/**/testInterceptor") |
| public String testInterceptor(){ |
| return "success"; |
| } |
| |
| } |
| |
| # 编写1个拦截器 |
| @Component |
| public class FirstInterceptor implements HandlerInterceptor { |
| |
| @Override |
| public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { |
| System.out.println("FirstInterceptor-->preHandle"); |
| |
| return true; |
| } |
| |
| @Override |
| public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { |
| System.out.println("FirstInterceptor-->postHandle"); |
| } |
| |
| @Override |
| public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { |
| System.out.println("FirstInterceptor-->afterCompletion"); |
| } |
| } |
| |
| # 测试 |
| http: |
| # 控制台打印没有打印,说明指定的根路径被放行了 |
| |
| # 测试 |
| http: |
| # 控制台打印 |
| FirstInterceptor-->preHandle |
| FirstInterceptor-->postHandle |
| FirstInterceptor-->afterCompletion |
| |
| # 测试二级目录 |
| http: |
| # 控制台打印没有打印说明没有拦截 |
| # 拦截器FirstInterceptor添加注解@Component,将其注册为1个bean |
| |
| # springmvc配置文件中开启组件扫描,确保拦截器能够被扫描到 |
| <context:component-scan base-package="com.atguigu.mvc"></context:component-scan> |
| |
| # springmvc配置文件中配置拦截器,如下方式,会拦截指定请求 |
| <mvc:interceptors> |
| <mvc:interceptor> |
| <!-- 表示拦截所有请求 --> |
| <mvc:mapping path="/**"/> |
| <!-- 表示放行该请求 --> |
| <mvc:exclude-mapping path="/"/> |
| <ref bean="firstInterceptor"></ref> |
| </mvc:interceptor> |
| </mvc:interceptors> |
| |
| # 编写1个控制器,用于测试 |
| @Controller |
| public class TestController { |
| |
| @RequestMapping("/**/testInterceptor") |
| public String testInterceptor(){ |
| return "success"; |
| } |
| |
| } |
| |
| # 编写1个拦截器 |
| @Component |
| public class FirstInterceptor implements HandlerInterceptor { |
| |
| @Override |
| public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { |
| System.out.println("FirstInterceptor-->preHandle"); |
| |
| return true; |
| } |
| |
| @Override |
| public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { |
| System.out.println("FirstInterceptor-->postHandle"); |
| } |
| |
| @Override |
| public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { |
| System.out.println("FirstInterceptor-->afterCompletion"); |
| } |
| } |
| |
| # 测试 |
| http: |
| # 控制台打印没有打印,说明指定的根路径被放行了 |
| |
| # 测试 |
| http: |
| # 控制台打印 |
| FirstInterceptor-->preHandle |
| FirstInterceptor-->postHandle |
| FirstInterceptor-->afterCompletion |
| |
| # 测试二级目录 |
| http: |
| # 控制台打印 |
| FirstInterceptor-->preHandle |
| FirstInterceptor-->postHandle |
| FirstInterceptor-->afterCompletion |
| # 在拦截器上添加注解@Component,将其注册为bean |
| |
| # springmvc配置文件中开启组件扫描,确保拦截器能够被扫描到 |
| <context:component-scan base-package="com.atguigu.mvc"></context:component-scan> |
| |
| # springmvc配置文件中配置拦截器,如下方式,会拦截指定请求 |
| <mvc:interceptors> |
| <ref bean="firstInterceptor"></ref> |
| <ref bean="secondInterceptor"></ref> |
| </mvc:interceptors> |
| |
| # 编写1个控制器,用于测试 |
| @Controller |
| public class TestController { |
| |
| @RequestMapping("/**/testInterceptor") |
| public String testInterceptor(){ |
| return "success"; |
| } |
| |
| } |
| |
| # 编写1个拦截器 |
| @Component |
| public class FirstInterceptor implements HandlerInterceptor { |
| |
| @Override |
| public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { |
| System.out.println("FirstInterceptor-->preHandle"); |
| |
| return true; |
| } |
| |
| @Override |
| public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { |
| System.out.println("FirstInterceptor-->postHandle"); |
| } |
| |
| @Override |
| public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { |
| System.out.println("FirstInterceptor-->afterCompletion"); |
| } |
| } |
| |
| # 编写第2个拦截器 |
| @Component |
| public class SecondInterceptor implements HandlerInterceptor { |
| |
| @Override |
| public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { |
| System.out.println("SecondInterceptor-->preHandle"); |
| return true; |
| } |
| |
| @Override |
| public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { |
| System.out.println("SecondInterceptor-->postHandle"); |
| } |
| |
| @Override |
| public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { |
| System.out.println("SecondInterceptor-->afterCompletion"); |
| } |
| } |
| |
| # 测试1:将2个拦截器改为true |
| http: |
| # 控制台打印 |
| FirstInterceptor-->preHandle |
| SecondInterceptor-->preHandle |
| SecondInterceptor-->postHandle |
| FirstInterceptor-->postHandle |
| SecondInterceptor-->afterCompletion |
| FirstInterceptor-->afterCompletion |
| |
| # 测试2:将2个拦截器改为false |
| 13:43:49.883 [http-nio-8081-exec-1] DEBUG org.springframework.web.servlet.DispatcherServlet - GET "/mvc/", parameters={} |
| 13:43:49.890 [http-nio-8081-exec-1] DEBUG org.springframework.web.servlet.handler.SimpleUrlHandlerMapping - Mapped to ParameterizableViewController [view="index"] |
| FirstInterceptor-->preHandle |
| 13:43:49.893 [http-nio-8081-exec-1] DEBUG org.springframework.web.servlet.DispatcherServlet - Completed 200 OK |
| 13:43:50.150 [http-nio-8081-exec-3] DEBUG org.springframework.web.servlet.DispatcherServlet - GET "/mvc/", parameters={} |
| 13:43:50.150 [http-nio-8081-exec-3] DEBUG org.springframework.web.servlet.handler.SimpleUrlHandlerMapping - Mapped to ParameterizableViewController [view="index"] |
| FirstInterceptor-->preHandle |
| |
| # 结论: |
| a>若每个拦截器的preHandle()都返回true |
| 此时多个拦截器的执行顺序和拦截器在SpringMVC的配置文件的配置顺序有关: |
| preHandle()会按照配置的顺序执行,而postHandle()和afterComplation()会按照配置的反序执行 |
| b>若某个拦截器的preHandle()返回了false |
| preHandle()返回false和它之前的拦截器的preHandle()都会执行,postHandle()都不执行,返回false的拦截器之前的拦截器的afterComplation()会执行 |
| |
| # 打开DispatcherServlet.java 1061行 |
| |
| # 首先进入如下代码,该执行链中放的是3个拦截器(1个是springmvc自己创建的,2个是我们自己创建的),执行链包括2个部分(控制器方法、处理控制器方法的拦截器) |
| if (!mappedHandler.applyPreHandle(processedRequest, response)) { |
| return; |
| } |
| |
| # 当以上的方法,返回false时执行 |
| |
| # 进入applyPreHandle方法,遍历执行链中的拦截器,所以preHandle方法是按顺序执行 |
| boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception { |
| for (int i = 0; i < this.interceptorList.size(); i++) { |
| HandlerInterceptor interceptor = this.interceptorList.get(i); |
| if (!interceptor.preHandle(request, response, this.handler)) { |
| triggerAfterCompletion(request, response, null); |
| return false; |
| } |
| this.interceptorIndex = i; |
| } |
| return true; |
| } |
| |
| # 之后执行postHandle方法 |
| applyDefaultViewName(processedRequest, mv); |
| mappedHandler.applyPostHandle(processedRequest, response, mv); |
| |
| # 进入postHandle方法,所以postHandle是反序执行 |
| void applyPostHandle(HttpServletRequest request, HttpServletResponse response, @Nullable ModelAndView mv) |
| throws Exception { |
| |
| for (int i = this.interceptorList.size() - 1; i >= 0; i--) { |
| HandlerInterceptor interceptor = this.interceptorList.get(i); |
| interceptor.postHandle(request, response, this.handler, mv); |
| } |
| } |
| |
| # 最后执行afterComplation方法 |
| finally { |
| if (asyncManager.isConcurrentHandlingStarted()) { |
| |
| if (mappedHandler != null) { |
| mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response); |
| } |
| } |
| else { |
| |
| if (multipartRequestParsed) { |
| cleanupMultipart(processedRequest); |
| } |
| } |
| } |
| |
| # 进入applyAfterConcurrentHandlingStarted,所以afterComplation是反序执行的 |
| void applyAfterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response) { |
| for (int i = this.interceptorList.size() - 1; i >= 0; i--) { |
| HandlerInterceptor interceptor = this.interceptorList.get(i); |
| if (interceptor instanceof AsyncHandlerInterceptor) { |
| try { |
| AsyncHandlerInterceptor asyncInterceptor = (AsyncHandlerInterceptor) interceptor; |
| asyncInterceptor.afterConcurrentHandlingStarted(request, response, this.handler); |
| } |
| catch (Throwable ex) { |
| if (logger.isErrorEnabled()) { |
| logger.error("Interceptor [" + interceptor + "] failed in afterConcurrentHandlingStarted", ex); |
| } |
| } |
| } |
| } |
| } |
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