詳解Spring Controller autowired Request變量
spring的DI大家比較熟悉了,對(duì)于依賴注入的實(shí)現(xiàn)也無(wú)須贅述。
那么spring的bean的默認(rèn)scope為singleton,對(duì)于controller來(lái)說(shuō)每次方法中均可以獲得request還是比較有意思的。
對(duì)于方法參數(shù)上的request通過(guò)構(gòu)建方法的參數(shù)可以獲得最新的request
public final Object invokeForRequest(NativeWebRequest request, ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception { Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs); if (logger.isTraceEnabled()) { StringBuilder sb = new StringBuilder("Invoking ["); sb.append(getBeanType().getSimpleName()).append("."); sb.append(getMethod().getName()).append("] method with arguments "); sb.append(Arrays.asList(args)); logger.trace(sb.toString()); } Object returnValue = invoke(args); if (logger.isTraceEnabled()) { logger.trace("Method [" + getMethod().getName() + "] returned [" + returnValue + "]"); } return returnValue;}
2. 對(duì)于controller等單實(shí)例變量來(lái)說(shuō)如何動(dòng)態(tài)注入變量呢?spring使用了很聰明的辦法
/** * Register web-specific scopes ("request", "session", "globalSession", "application") * with the given BeanFactory, as used by the WebApplicationContext. * @param beanFactory the BeanFactory to configure * @param sc the ServletContext that we're running within */public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory, ServletContext sc) { beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST, new RequestScope()); beanFactory.registerScope(WebApplicationContext.SCOPE_SESSION, new SessionScope(false)); beanFactory.registerScope(WebApplicationContext.SCOPE_GLOBAL_SESSION, new SessionScope(true)); if (sc != null) { ServletContextScope appScope = new ServletContextScope(sc); beanFactory.registerScope(WebApplicationContext.SCOPE_APPLICATION, appScope); // Register as ServletContext attribute, for ContextCleanupListener to detect it. sc.setAttribute(ServletContextScope.class.getName(), appScope); } beanFactory.registerResolvableDependency(ServletRequest.class, new RequestObjectFactory()); beanFactory.registerResolvableDependency(HttpSession.class, new SessionObjectFactory()); beanFactory.registerResolvableDependency(WebRequest.class, new WebRequestObjectFactory()); if (jsfPresent) { FacesDependencyRegistrar.registerFacesDependencies(beanFactory); }}
/** * Factory that exposes the current request object on demand. */ @SuppressWarnings("serial") private static class RequestObjectFactory implements ObjectFactory<ServletRequest>, Serializable { public ServletRequest getObject() { return currentRequestAttributes().getRequest(); } @Override public String toString() { return "Current HttpServletRequest"; } }
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