java 确定字段是否使用给定的注释进行注释
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Determine whether field is annotated with a given annotations
提问by Dave
I don't know if you managed to figure out what i am trying to do just from the title so I'll try to explain with example
我不知道你是否设法从标题中弄清楚我想要做什么，所以我会尝试用例子来解释
Lets suppose I have created my own annotation @VerifySomething
假设我已经创建了自己的注释 @VerifySomething
And I have created test class for that annotation to make sure it works.
我已经为该注释创建了测试类以确保它有效。
Now lets suppose that I have class SomeClasswith field somethinganoted with annotation @VerifySomething
现在让我们假设我有一个带有注释的SomeClass字段的类something@VerifySomething
class SomeClass {
@VerifySomething
String something;
}
So far so good, but now I want to create test classfor my SomeClasshowever I don't see any point in verifying all the test cases of something as I have already checked that @VerifySomethingworks as it should in class which tests that annotation, however I need to make sure that field something actually has @VerifySomethingannotation without copy pasting all these test cases.
到目前为止一切顺利，但现在我想test class为我创建，SomeClass但是我认为验证某些东西的所有测试用例没有任何意义，因为我已经检查@VerifySomething过它在测试该注释的课堂上应该正常工作，但是我需要确保该字段实际上具有@VerifySomething注释，而无需复制粘贴所有这些测试用例。
So my question is, is there a way to check if some field has one or more required annotation without writing test cases I have already written in annotation test class to make sure it works as it should.
所以我的问题是，有没有一种方法可以检查某个字段是否有一个或多个必需的注释，而无需编写我已经在注释测试类中编写的测试用例，以确保它按预期工作。
回答by Pavla Nováková
You can use getAnnotationto determine if there is a specific Annotation on the field, which takes the annotation class as a parameter:
可以getAnnotation用来判断字段上是否有特定的Annotation，以注解类为参数：
field.getAnnotation( SomeAnnotation.class );
Here is a method you can use to verify that a class has a field annotated by given annotation:
下面是一种方法，可用于验证类是否具有由给定注释注释的字段：
import java.lang.reflect.Field;
import javax.validation.constraints.NotNull;
import org.junit.Test;
import org.springframework.util.Assert;
public class TestHasAnnotatedField {
@Test
public void testHasFieldsWithAnnotation() throws SecurityException, NoSuchFieldException {
Class<?>[] classesToVerify = new Class[] {MyClass1.class, MyClass2.class};
for (Class<?> clazz : classesToVerify) {
Field field = clazz.getDeclaredField("something");
Assert.notNull(field.getAnnotation(NotNull.class));
}
}
static class MyClass1 { @NotNull String something; }
static class MyClass2 { @NotNull String something; }
}
回答by Hardy
I am not sure I am following, but in case you want to verify whether a class and or its properties have a given Bean Validation constraint, you can use the meta data api. The entry point is Validator#getConstraintsForClass(SomeClass.class). You get a BeanDescriptor. From there you can do _beanDescriptor#getConstraintsForProperty("something") which gives you a PropertyDescriptor. Via propertyDescriptor#getConstraintDescriptors()you get then a set of ConstraintDescriptorswhich you can iterate to verify that a given constraint annotation was used.
我不确定我是否在关注，但如果您想验证类及其属性是否具有给定的 Bean 验证约束，您可以使用元数据 api。入口点是Validator#getConstraintsForClass(SomeClass.class)。你得到一个BeanDescriptor。从那里你可以做 _beanDescriptor#getConstraintsForProperty("something") 这给你一个PropertyDescriptor。通过propertyDescriptor#getConstraintDescriptors()，您将获得一组ConstraintDescriptors，您可以对其进行迭代以验证是否使用了给定的约束注释。
Note, this is a Bean Validation specific solution compared to generic reflection as in the answer above, but it depends what you are really after. To be honest I don't quite understand your use case yet.
请注意，与上面的答案中的通用反射相比，这是一个 Bean 验证特定的解决方案，但这取决于您真正想要的是什么。老实说，我还不太了解您的用例。
