springboot實現攔截器的3種方式及異步執行的思考
實際項目中,我們經常需要輸出請求參數,響應結果,方法耗時,統一的權限校驗等。
本文首先為大家介紹 HTTP 請求中三種常見的攔截實現,并且比較一下其中的差異。(1)基于 Aspect 的攔截器(2)基于 HandlerInterceptor 的攔截器(3)基于 ResponseBodyAdvice 的攔截器
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統一日志框架: https://github.com/houbb/auto-log
為了便于大家學習,我們首先從最基本的 springboot 例子講起。
maven 引入引入必須的 jar 包。
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version></parent><dependencies> <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency><groupId>org.aspectj</groupId><artifactId>aspectjrt</artifactId><version>1.8.10</version> </dependency> <dependency><groupId>org.aspectj</groupId><artifactId>aspectjweaver</artifactId><version>1.8.10</version> </dependency></dependencies><!-- Package as an executable jar --><build> <plugins><plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId></plugin> </plugins></build>啟動類
實現最簡單的啟動類。
@SpringBootApplicationpublic class Application { public static void main(String[] args) {SpringApplication.run(Application.class, args); }}定義 Controller
為了演示方便,我們首先實現一個簡單的 controller。
@RestControllerpublic class IndexController { @RequestMapping('/index') public AsyncResp index() {AsyncResp asyncResp = new AsyncResp();asyncResp.setResult('ok');asyncResp.setRespCode('00');asyncResp.setRespDesc('成功');System.out.println('IndexController#index:' + asyncResp);return asyncResp; }}
其中 AsyncResp 的定義如下:
public class AsyncResp { private String respCode; private String respDesc; private String result; // getter & setter & toString()}攔截器定義基于 Aspect
import org.aspectj.lang.ProceedingJoinPoint;import org.aspectj.lang.annotation.Around;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Pointcut;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.context.annotation.EnableAspectJAutoProxy;import org.springframework.stereotype.Component;import java.util.Arrays;/** * * @author binbin.hou * @since 1.0.0 */@Aspect@Component@EnableAspectJAutoProxypublic class AspectLogInterceptor { /** * 日志實例 * @since 1.0.0 */ private static final Logger LOG = LoggerFactory.getLogger(AspectLogInterceptor.class); /** * 攔截 controller 下所有的 public方法 */ @Pointcut('execution(public * com.github.houbb.springboot.learn.aspect.controller..*(..))') public void pointCut() {// } /** * 攔截處理 * * @param point point 信息 * @return result * @throws Throwable if any */ @Around('pointCut()') public Object around(ProceedingJoinPoint point) throws Throwable {try { //1. 設置 MDC // 獲取當前攔截的方法簽名 String signatureShortStr = point.getSignature().toShortString(); //2. 打印入參信息 Object[] args = point.getArgs(); LOG.info('{} 參數: {}', signatureShortStr, Arrays.toString(args)); //3. 打印結果 Object result = point.proceed(); LOG.info('{} 結果: {}', signatureShortStr, result); return result;} finally { // 移除 mdc} }}
這種實現的優點是比較通用,可以結合注解實現更加靈活強大的功能。
是個人非常喜歡的一種方式。主要用途:(1)日志的出參/入參(2)統一設置 TraceId(3)方法的調用耗時統計
基于 HandlerInterceptorimport org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.stereotype.Component;import org.springframework.web.servlet.HandlerInterceptor;import org.springframework.web.servlet.ModelAndView;import javax.servlet.DispatcherType;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * @author binbin.hou * @since 1.0.0 */@Componentpublic class LogHandlerInterceptor implements HandlerInterceptor { private Logger logger = LoggerFactory.getLogger(LogHandlerInterceptor.class); @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {// 統一的權限校驗、路由等logger.info('LogHandlerInterceptor#preHandle 請求地址:{}', request.getRequestURI());if (request.getDispatcherType().equals(DispatcherType.ASYNC)) { return true;}return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {logger.info('LogHandlerInterceptor#postHandle 調用'); } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { }}
然后需要指定對應的 url 和攔截器之間的關系才會生效:
import com.github.houbb.springboot.learn.aspect.aspect.LogHandlerInterceptor;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.WebMvcConfigurerAdapter;/** * spring mvc 配置 * @since 1.0.0 */@Configurationpublic class SpringMvcConfig extends WebMvcConfigurerAdapter { @Autowired private LogHandlerInterceptor logHandlerInterceptor; @Override public void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(logHandlerInterceptor).addPathPatterns('/**').excludePathPatterns('/version');super.addInterceptors(registry); }}
這種方式的優點就是可以根據 url 靈活指定不同的攔截器。缺點是主要用于 Controller 層。
基于 ResponseBodyAdvice此接口有beforeBodyWrite方法,參數body是響應對象response中的響應體,那么我們就可以用此方法來對響應體做一些統一的操作。
比如加密,簽名等。
import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.core.MethodParameter;import org.springframework.http.MediaType;import org.springframework.http.converter.HttpMessageConverter;import org.springframework.http.server.ServerHttpRequest;import org.springframework.http.server.ServerHttpResponse;import org.springframework.http.server.ServletServerHttpRequest;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;import javax.servlet.http.HttpServletRequest;/** * @author binbin.hou * @since 1.0.0 */@ControllerAdvicepublic class MyResponseBodyAdvice implements ResponseBodyAdvice<Object> { /** * 日志實例 * @since 1.0.0 */ private static final Logger LOG = LoggerFactory.getLogger(MyResponseBodyAdvice.class); @Override public boolean supports(MethodParameter methodParameter, Class aClass) {//這個地方如果返回false, 不會執行 beforeBodyWrite 方法return true; } @Override public Object beforeBodyWrite(Object resp, MethodParameter methodParameter, MediaType mediaType, Class<? extends HttpMessageConverter<?>> aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {String uri = serverHttpRequest.getURI().getPath();LOG.info('MyResponseBodyAdvice#beforeBodyWrite 請求地址:{}', uri);ServletServerHttpRequest servletServerHttpRequest = (ServletServerHttpRequest) serverHttpRequest;HttpServletRequest servletRequest = servletServerHttpRequest.getServletRequest();// 可以做統一的攔截器處理// 可以對結果做動態修改等LOG.info('MyResponseBodyAdvice#beforeBodyWrite 響應結果:{}', resp);return resp; }}測試
我們啟動應用,頁面訪問:http://localhost:18080/index頁面響應:{'respCode':'00','respDesc':'成功','result':'ok'}
后端日志:
c.g.h.s.l.a.a.LogHandlerInterceptor : LogHandlerInterceptor#preHandle 請求地址:/indexc.g.h.s.l.a.aspect.AspectLogInterceptor : IndexController.index() 參數: []IndexController#index:AsyncResp{respCode=’00’, respDesc=’成功’, result=’ok’}c.g.h.s.l.a.aspect.AspectLogInterceptor : IndexController.index() 結果: AsyncResp{respCode=’00’, respDesc=’成功’, result=’ok’}c.g.h.s.l.a.aspect.MyResponseBodyAdvice : MyResponseBodyAdvice#beforeBodyWrite 請求地址:/indexc.g.h.s.l.a.aspect.MyResponseBodyAdvice : MyResponseBodyAdvice#beforeBodyWrite 響應結果:AsyncResp{respCode=’00’, respDesc=’成功’, result=’ok’}c.g.h.s.l.a.a.LogHandlerInterceptor : LogHandlerInterceptor#postHandle 調用
這里執行的先后順序也比較明確,此處不再贅述。
異步執行當然,如果只是上面這些內容,并不是本篇文章的重點。接下來,我們一起來看下,如果引入了異步執行會怎么樣。
定義異步線程池springboot 中定義異步線程池,非常簡單。
import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.core.task.AsyncTaskExecutor;import org.springframework.scheduling.annotation.EnableAsync;import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;/** * 請求異步處理配置 * * @author binbin.hou */@Configuration@EnableAsyncpublic class SpringAsyncConfig { @Bean(name = 'asyncPoolTaskExecutor') public AsyncTaskExecutor taskExecutor() {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();executor.setMaxPoolSize(10);executor.setQueueCapacity(10);executor.setCorePoolSize(10);executor.setWaitForTasksToCompleteOnShutdown(true);return executor; }}異步執行的 Controller
@RestControllerpublic class MyAsyncController extends BaseAsyncController<String> { @Override protected String process(HttpServletRequest request) {return 'ok'; } @RequestMapping('/async') public AsyncResp hello(HttpServletRequest request) {AsyncResp resp = super.execute(request);System.out.println('Controller#async 結果:' + resp);return resp; }}
其中 BaseAsyncController 的實現如下:
@RestControllerpublic abstract class BaseAsyncController<T> { protected abstract T process(HttpServletRequest request); @Autowired private AsyncTaskExecutor taskExecutor; protected AsyncResp execute(HttpServletRequest request) {// 異步響應結果AsyncResp resp = new AsyncResp();try { taskExecutor.execute(new Runnable() {@Overridepublic void run() { try {T result = process(request);resp.setRespCode('00');resp.setRespDesc('成功');resp.setResult(result.toString()); } catch (Exception exception) {resp.setRespCode('98');resp.setRespDesc('任務異常'); }} });} catch (TaskRejectedException e) { resp.setRespCode('99'); resp.setRespDesc('任務拒絕');}return resp; }}
execute 的實現也比較簡單:(1)主線程創建一個 AsyncResp,用于返回。(2)線程池異步執行具體的子類方法,并且設置對應的值。
思考接下來,問大家一個問題。如果我們請求 http://localhost:18080/async,那么:(1)頁面得到的返回值是什么?(2)Aspect 日志輸出的返回值是?(3)ResponseBodyAdvice 日志輸出的返回值是什么?你可以在這里稍微停一下,記錄下你的答案。
測試我們頁面請求 http://localhost:18080/async。
頁面響應如下:
{'respCode':'00','respDesc':'成功','result':'ok'}
后端的日志:
c.g.h.s.l.a.a.LogHandlerInterceptor : LogHandlerInterceptor#preHandle 請求地址:/asyncc.g.h.s.l.a.aspect.AspectLogInterceptor : MyAsyncController.hello(..) 參數: [org.apache.catalina.connector.RequestFacade@7e931750]Controller#async 結果:AsyncResp{respCode=’null’, respDesc=’null’, result=’null’}c.g.h.s.l.a.aspect.AspectLogInterceptor : MyAsyncController.hello(..) 結果: AsyncResp{respCode=’null’, respDesc=’null’, result=’null’}c.g.h.s.l.a.aspect.MyResponseBodyAdvice : MyResponseBodyAdvice#beforeBodyWrite 請求地址:/asyncc.g.h.s.l.a.aspect.MyResponseBodyAdvice : MyResponseBodyAdvice#beforeBodyWrite 響應結果:AsyncResp{respCode=’00’, respDesc=’成功’, result=’ok’}c.g.h.s.l.a.a.LogHandlerInterceptor : LogHandlerInterceptor#postHandle 調用
對比一下,可以發現我們上面問題的答案:(1)頁面得到的返回值是什么?
{'respCode':'00','respDesc':'成功','result':'ok'}
可以獲取到異步執行完成的結果。(2)Aspect 日志輸出的返回值是?
AsyncResp{respCode=’null’, respDesc=’null’, result=’null’}
無法獲取異步結果。(3)ResponseBodyAdvice 日志輸出的返回值是什么?
AsyncResp{respCode=’00’, respDesc=’成功’, result=’ok’}
可以獲取到異步執行完成的結果。
反思可以發現,spring 對于頁面的響應也許和我們想的有些不一樣,并不是直接獲取同步結果。寫到這里,發現自己對于 mvc 的理解一直只是停留在表面,沒有真正理解整個流程。Aspect 的形式在很多框架中都會使用,不過這里會發現無法獲取異步的執行結果,存在一定問題。
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