切入点匹配的方法与参数注解 [英] Pointcut matching methods with annotated parameters
问题描述
我需要创建匹配方法切入点的一个方面，如果：
I need to create an aspect with a pointcut matching a method if:
- 这是annoted与MyAnnotationForMethod
- 它的一个参数（可以有多个）都标注有@MyAnnotationForParam（但可以有其他的注释也一样）。
纵横类看起来像这样
@Pointcut("execution(@MyAnnotationForMethod * *(..,@aspects.MyAnnotationForParam Object, ..)) && args(obj)")
void myPointcut(JoinPoint thisJoinPoint, Object obj) {
}
@Before("myPointcut(thisJoinPoint , obj)")
public void doStuffOnParam(JoinPoint thisJoinPoint, Object obj) {
LOGGER.info("doStuffOnParam :"+obj);
}
该annoted方法
The annoted method
@MyAnnotationForMethod
public string theMethod(String a, @MyAnnotationForParam @OtherAnnotation Object obj, Object b){
LOGGER.info(a+obj+b);
}
在Eclipse - >警告：在poincut：
With eclipse -> warnings : On the poincut :
Multiple markers at this line
- no match for this type name: MyAnnotationForMethod [Xlint:invalidAbsoluteTypeName]
- no match for this type name: aspects.MyAnnotationForParam On the before : advice defined in xxx.xxx.xxx.xxx.MyAspect has not been applied [Xlint:adviceDidNotMatch]
从<一个使用上次的AspectJ插件href=\"http://download.eclipse.org/tools/ajdt/35/update\">http://download.eclipse.org/tools/ajdt/35/update
通过使用AspectJ 1.6.9的Maven命令行
With maven command line using aspectj 1.6.9
[WARNING] no match for this type name: MyAnnotationForMethod [Xlint:invalidAbsoluteTypeName]
[WARNING] no match for this type name: aspects.MyAnnotationForParam [Xlint:invalidAbsoluteTypeName]
[WARNING] advice defined in xxx.xxx.xxx.xxx.MyAspect has not been applied [Xlint:adviceDidNotMatch]
注解：
package com.xxx.xxx.annotation;
// standard imports stripped
@Documented
@Target( { FIELD, CONSTRUCTOR, PARAMETER })
@Retention(RUNTIME)
public @interface @MyAnnotationForParam {}
和
package com.xxx.xxx.annotation;
// standard imports stripped
@Target(METHOD)
@Retention(RUNTIME)
@Documented
public @interface MyAnnotationForMethod {}
当然，它不正常工作。
And of course it doesn' work properly.
你能告诉我什么是错？
THX。
推荐答案
更新：
OK，我能找到的最好的参考就是这个页面上：<一href=\"http://www.eclipse.org/aspectj/doc/released/adk15notebook/annotations-pointcuts-and-advice.html#package-and-parameter-annotations\">Annotations,切入点和通知。
OK, the best reference I could find is on this page: Annotations, Pointcuts and Advice.
您可以匹配的方法，但是你将无法赶上参数（只是方法和注释）。所以，你必须做的是切入点的匹配和反射的组合。事情是这样的：
You can match the method, however you won't be able to catch the parameter (just the method and the annotation). So what you will have to do is a combination of pointcut matching and reflection. Something like this:
@Pointcut(
"execution(@com.xxx.xxx.annotation.MyAnnotationForMethod * *(.., @com.xxx.xxx.annotation.MyAnnotationForParam (*), ..))")
public void annotatedMethod(){}
@Before("annotatedMethod()")
public void doStuffOnParam(final JoinPoint jp){
final Signature signature = jp.getSignature();
if(signature instanceof MethodSignature){
final MethodSignature ms = (MethodSignature) signature;
final Method method = ms.getMethod();
final String[] parameterNames = ms.getParameterNames();
final Class<?>[] parameterTypes = ms.getParameterTypes();
final Annotation[][] parameterAnnotations =
method.getParameterAnnotations();
for(int i = 0; i < parameterAnnotations.length; i++){
final Annotation[] annotations = parameterAnnotations[i];
final MyAnnotationForParam paramAnnotation =
getAnnotationByType(annotations, MyAnnotationForParam.class);
if(paramAnnotation != null){
this.processParameter(ms.toShortString(),
parameterNames[i],
parameterTypes[i],
paramAnnotation);
}
}
}
}
/**
* In an array of annotations, find the annotation of the specified type, if any.
* @return the annotation if available, or null
*/
@SuppressWarnings("unchecked")
private static <T extends Annotation> T getAnnotationByType(final Annotation[] annotations,
final Class<T> clazz){
T result = null;
for(final Annotation annotation : annotations){
if(clazz.isAssignableFrom(annotation.getClass())){
result = (T) annotation;
break;
}
}
return result;
}
/**
* Do some processing based on what we found.
* @param signature method signature
* @param paramName parameter name
* @param paramType parameter type
* @param paramAnnotation annotation we found
*/
private void processParameter(final String signature,
final String paramName,
final Class<?> paramType,
final MyAnnotationForParam paramAnnotation){
System.out.println(MessageFormat.format(
"Found parameter ''{0}'' \n of type ''{1}'' \n with annotation ''{2}'' \n in method ''{3}''",
paramName,
paramType,
paramAnnotation,
signature));
}
下面是我的测试类的上述方面：
Here is my test class for the above aspect:
public class TestClass{
@MyAnnotationForMethod
public void simpleTestMethod(@MyAnnotationForParam final String param1){
System.out.println("Method body (simple)");
};
@MyAnnotationForMethod
public void complexTestMethod(final String param1,
@MyAnnotationForParam final Float param2,
@MyAnnotationForParam final Boolean param3){
System.out.println("Method body (complex)");
};
public static void main(final String[] args){
System.out.println("Starting up");
final TestClass testObject = new TestClass();
testObject.simpleTestMethod("Hey");
testObject.complexTestMethod("Hey", 123.4f, false);
System.out.println("Finished");
}
}
和这里是输出：
Starting up
Found parameter 'param1'
of type 'class java.lang.String'
with annotation '@com.xxx.xxx.annotation.MyAnnotationForParam()'
in method 'TestClass.simpleTestMethod(..)'
Method body (simple)
Found parameter 'param2'
of type 'class java.lang.Float'
with annotation '@com.xxx.xxx.annotation.MyAnnotationForParam()'
in method 'TestClass.complexTestMethod(..)'
Found parameter 'param3'
of type 'class java.lang.Boolean'
with annotation '@com.xxx.xxx.annotation.MyAnnotationForParam()'
in method 'TestClass.complexTestMethod(..)'
Method body (complex)
Finished
提示
您可能会想缓存很多这一点，就没有必要解析每个标注的各项参数在每次执行。保持一个地图，其中的参数的方法进行注释和处理仅是那些参数。
Hint
You will probably want to cache a lot of this, there is no need to parse every parameter of every annotation in every execution. Keep a map of which parameter of which method carries the annotation and process only those parameters.
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