Java - 反射 - 如何使用反射获取@RequestHeader值

Question

以下是我的方法:

@PreAuthorize("isAuthenticated() and hasPermission(#request, 'CREATE_REQUISITION')")
    @RequestMapping(method = RequestMethod.POST, value = "/trade/createrequisition")
    public @ResponseBody
    void createRequisition(@RequestBody CreateRequisitionRO[] request,
            @RequestHeader("validateOnly") boolean validateOnly) {
        logger.debug("Starting createRequisition()...");
        for (int i = 0; i < request.length; i++) {
            CreateRequisitionRO requisitionRequest = request[i];

            // FIXME this has to be removed/moved
            requisitionRequest.setFundManager(requisitionRequest.getUserId());
            // FIXME might have to search using param level as well
            SystemDefault sysDefault = dbFuncs.references.systemDefault
                    .findByCompanyAndDivisionAndPortfolio(
                            userContext.getCompany(),
                            userContext.getDivision(),
                            requisitionRequest.getPortfolio());
            requisitionRequest.setCustodianN(sysDefault.getCustodianN());

            gateKeeper.route(requisitionRequest);
        }
    }

其中我可以获得以下详细信息

1. @RequestMapping(method = RequestMethod.POST, value = "/trade/createrequisition")
2. void createRequisition(@RequestBody CreateRequisitionRO[] request,
                @RequestHeader("validateOnly") boolean validateOnly)
 (in thesecond one i am able to get the argument type like boolean etc)

我得到的上述详细信息如下:

Class cls;
cls = Class.forName(obj.getName());
Method[] method = cls.getDeclaredMethods();
for (Method method2 : method) {
     RequestMapping requestMappingAnnotation =   method2.getAnnotation(RequestMapping.class);       // gets the method which is maped with   RequestMapping Annotation
     requestMappingValues = requestMappingAnnotation.value(); // to get the url value
      RequestMethod[] methods = requestMappingAnnotation.method(); // to get the request   method type
      requestingMethod = methods[0].name();
}

以同样的方式，当我尝试获取如下所示的 @RequestHeader 时，我得到 java.lang.NullPointerException

下面是我使用的代码片段

RequestHeader requestHeader = method2.getAnnotation(RequestHeader.class);
System.out.println("requestHeader : "+requestHeader.value());

我想要获取的是@RequestHeader("validateOnly")此注释包含的值。

编辑:

感谢@NilsH，他始终支持所有提出的澄清，即使这需要花费时间:

这就是我解决它的方法但是如果程序处于 Debug模式，该信息将可用

我使用 spring 来做到这一点:

LocalVariableTableParameterNameDiscoverer lcl = new LocalVariableTableParameterNameDiscoverer();
                                parametersDefinedForMethod = lcl.getParameterNames(method2);
                                for (String params : parametersDefinedForMethod) {
                                    System.out.println("Params : "+params);
                                }

请帮我完成这件事。

谢谢

Answer 1

@RequestHeader 在本例中是参数级别注释。尝试使用Method.getParameterAnnotations()得到它。

编辑

一个例子:

public class MyClass {
    public void someMethodWithParamAnnotations(String s, @MyAnnotation String s2) {

    }
}

然后到其他地方

Method m = MyClass.class.getMethod("someMethodWithParamAnnotations", String.class, String.class);
Annotation[][] paramAnnotations = m.getParameterAnnotations();
Annotation[] firstParamAnnotation = paramAnnotations[0]; 
// Above is empty array, since first parameter has no annotation

Annotation[] secondParamAnnotation = paramAnnotations[1]; 
// Above contains an array with the `@MyAnnotation` annotation