详解Spring Controller autowired Request变量
详解SpringControllerautowiredRequest变量
spring的DI大家比较熟悉了，对于依赖注入的实现也无须赘述。
那么spring的bean的默认scope为singleton，对于controller来说每次方法中均可以获得request还是比较有意思的。
对于方法参数上的request通过构建方法的参数可以获得最新的request
publicfinalObjectinvokeForRequest(NativeWebRequestrequest,ModelAndViewContainermavContainer,
Object...providedArgs)throwsException{
Object[]args=getMethodArgumentValues(request,mavContainer,providedArgs);
if(logger.isTraceEnabled()){
StringBuildersb=newStringBuilder("Invoking[");
sb.append(getBeanType().getSimpleName()).append(".");
sb.append(getMethod().getName()).append("]methodwitharguments");
sb.append(Arrays.asList(args));
logger.trace(sb.toString());
}
ObjectreturnValue=invoke(args);
if(logger.isTraceEnabled()){
logger.trace("Method["+getMethod().getName()+"]returned["+returnValue+"]");
}
returnreturnValue;
}
2.对于controller等单实例变量来说如何动态注入变量呢？spring使用了很聪明的办法
- 首先request和用户请求相关
- 不同的用户同时访问时是在不同的线程中
- 保存了用户的请求在threadlocal中
- 用户获取该请求需要手动调用threadlocal来获取
- 为了帮助用户减少重复代码，spring可以让用户‘动态'注入request
- 当controller在实例化时，动态注册一个proxy到当前request变量中
- 此proxy当被使用是可以将所有方法动态路由到threadlocal中该request变量上执行
/**
*Registerweb-specificscopes("request","session","globalSession","application")
*withthegivenBeanFactory,asusedbytheWebApplicationContext.
*@parambeanFactorytheBeanFactorytoconfigure
*@paramsctheServletContextthatwe'rerunningwithin
*/
publicstaticvoidregisterWebApplicationScopes(ConfigurableListableBeanFactorybeanFactory,ServletContextsc){
beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST,newRequestScope());
beanFactory.registerScope(WebApplicationContext.SCOPE_SESSION,newSessionScope(false));
beanFactory.registerScope(WebApplicationContext.SCOPE_GLOBAL_SESSION,newSessionScope(true));
if(sc!=null){
ServletContextScopeappScope=newServletContextScope(sc);
beanFactory.registerScope(WebApplicationContext.SCOPE_APPLICATION,appScope);
//RegisterasServletContextattribute,forContextCleanupListenertodetectit.
sc.setAttribute(ServletContextScope.class.getName(),appScope);
}
beanFactory.registerResolvableDependency(ServletRequest.class,newRequestObjectFactory());
beanFactory.registerResolvableDependency(HttpSession.class,newSessionObjectFactory());
beanFactory.registerResolvableDependency(WebRequest.class,newWebRequestObjectFactory());
if(jsfPresent){
FacesDependencyRegistrar.registerFacesDependencies(beanFactory);
}
}
/**
*Factorythatexposesthecurrentrequestobjectondemand.
*/
@SuppressWarnings("serial")
privatestaticclassRequestObjectFactoryimplementsObjectFactory,Serializable{
publicServletRequestgetObject(){
returncurrentRequestAttributes().getRequest();
}
@Override
publicStringtoString(){
return"CurrentHttpServletRequest";
}
}
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