SpringBoot异步任务获取HttpServletRequest springboot

前言在使用框架日常开发中需要在controller中进行一些异步操作减少请求时间，但是发现在使用@Anysc注解后会出现Request对象无法获取的情况，本文就此情况给出完整的解决方案
原因分析

@Anysc注解会开启一个新的线程，主线程的Request和子线程是不共享的，所以获取为null
在使用springboot的自定带的线程共享后，代码如下，Request不为null，但是偶发的其中body/head/urlparam内容出现获取不到的情况，是因为异步任务在未执行完毕的情况下，主线程已经返回，拷贝共享的Request对象数据被清空

ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); //设置子线程共享 RequestContextHolder.setRequestAttributes(servletRequestAttributes, true); HttpServletRequest request = servletRequestAttributes.getRequest();

解决方案前置条件

启动类添加@EnableAsync注解
标记@Async的异步方法不能和调用者在同一个class中

pom配置

com.alibaba transmittable-thread-local 2.11.0

requrest共享通过TransmittableThreadLocal对象进行线程对象共享

public class CommonUtil { public static TransmittableThreadLocal requestTransmittableThreadLocal = new TransmittableThreadLocal(); public static void shareRequest(HttpServletRequest request){ requestTransmittableThreadLocal.set(request); }public static HttpServletRequest getRequest(){ HttpServletRequest request = requestTransmittableThreadLocal.get(); if(request!=null){ return requestTransmittableThreadLocal.get(); }else{ ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); if(requestAttributes!=null){ returnrequestAttributes.getRequest(); }else{ returnnull; } } }public static void remove(){ requestTransmittableThreadLocal.remove(); } }

注：系统中所有Request获取需要统一从CommonUtil指定来源，例如token鉴权等
自定义request过滤器 【SpringBoot异步任务获取HttpServletRequest】通过自定义过滤器对Request的内容进行备份保存，主线程结束时Request清除结束不会影响到子线程的相应参数的获取，也适用于增加拦截器/过滤器后body参数无法重复获取的问题。需要注意的是对header参数处理时key要忽略大小写

public class HttpServletRequestReplacedFilter implements Filter, Ordered { @Override public void destroy() {}@Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { ServletRequest requestWrapper = null; if (request instanceof HttpServletRequest) { requestWrapper = new RequestWrapper((HttpServletRequest) request); } //获取请求中的流如何，将取出来的字符串，再次转换成流，然后把它放入到新request对象中。 // 在chain.doFiler方法中传递新的request对象 if (requestWrapper == null) { chain.doFilter(request, response); } else { chain.doFilter(requestWrapper, response); } }@Override public void init(FilterConfig arg0) throws ServletException {}@Override public int getOrder() { return 10; } }

public class RequestWrapper extends HttpServletRequestWrapper{private final byte[] body; private final HashMap headMap; private final HashMap requestParamMap; public RequestWrapper(HttpServletRequest request) throws IOException { super(request); body = CommonUtil.getBodyString(request).getBytes(Charset.forName("UTF-8")); headMap = new HashMap(); Enumeration headNameList = request.getHeaderNames(); while (headNameList.hasMoreElements()){ String key = headNameList.nextElement(); headMap.put(key.toLowerCase(),request.getHeader(key)); }requestParamMap = new HashMap<>(); Enumeration parameterNameList = request.getParameterNames(); while (parameterNameList.hasMoreElements()){ String key = parameterNameList.nextElement(); requestParamMap.put(key,request.getParameter(key)); } }@Override public BufferedReader getReader() throws IOException { return new BufferedReader(new InputStreamReader(getInputStream())); }@Override public ServletInputStream getInputStream() throws IOException {final ByteArrayInputStream bais = new ByteArrayInputStream(body); return new ServletInputStream() {@Override public int read() throws IOException { return bais.read(); }@Override public boolean isFinished() { return false; }@Override public boolean isReady() { return false; }@Override public void setReadListener(ReadListener readListener) {} }; }@Override public String getHeader(String name) { return headMap.get(name.toLowerCase()); }@Override public String getParameter(String name) { return requestParamMap.get(name); } }

自定义任务执行器用于拦截异步任务执行，在任务执前统一进行Request共享操作，且可以定义多个，不影响原有的异步任务代码

public class CustomTaskDecorator implements TaskDecorator { @Override public Runnable decorate(Runnable runnable) { ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); HttpServletRequest request = requestAttributes.getRequest(); System.out.println("异步任务共享request"); return () -> { try { CommonUtil.shareRequest(request); runnable.run(); } finally { CommonUtil.remove(); } }; } }

@Configuration public class TaskExecutorConfig {@Bean() public Executor taskExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setCorePoolSize(10); executor.setMaxPoolSize(20); executor.setQueueCapacity(200); executor.setKeepAliveSeconds(60); executor.setThreadNamePrefix("taskExecutor-"); executor.setAwaitTerminationSeconds(60); executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy()); executor.initialize(); return executor; }@Bean("shareTaskExecutor") public Executor hpTaskExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setCorePoolSize(10); executor.setMaxPoolSize(20); executor.setQueueCapacity(200); executor.setKeepAliveSeconds(60); executor.setThreadNamePrefix("shareTaskExecutor-"); executor.setWaitForTasksToCompleteOnShutdown(true); executor.setAwaitTerminationSeconds(60); // 增加 TaskDecorator 属性的配置 executor.setTaskDecorator(new CustomTaskDecorator()); executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy()); executor.initialize(); return executor; } }

调用示例给@Anysc注解指定进行共享拦截的任务执行器即可

@PostMapping("/testAsync") @ResponseBody public Object testAsync(@RequestBody Map params) throws Exception{ Result result = Result.okResult(); asyncUtil.executeAsync(); return result; }

@Component public class AsyncUtil { @Async("shareTaskExecutor") public void executeAsync () throws InterruptedException { System.out.println("开始执行executeAsync"); Thread.sleep(3000); System.out.println("结束执行executeAsync"); } }