Is there a way to find anonymous classes by some annotation with some java reflection library like (Reflections)?
I have this code:
it use declare a inner class (extends Object) and annotated it with @DemoAnnotation
public class DemoUsageService {
public void doSomething() {
this.test(new @DemoAnnotation(value="Test") Object() {
String content = "myContent";
});
}
}
@Retention(RUNTIME)
@Target({ElementType.TYPE_USE})
public @interface DemoAnnotation {
String value();
}
Now I want to find all (anonymous) classes in my project that are annotated with @DemoAnnotation.
I tried the Reflections Library: but it seams not to find anonymous classes (inner static classes are found).
@Test
public void testFindAnnotatedClasses() throws Exception {
Reflections reflections = new Reflections(
new ConfigurationBuilder()
.setUrls(ClasspathHelper.forPackage(DemoUsageService.class.getPackageName()))
.setScanners(
new SubTypesScanner(false),
new TypeAnnotationsScanner()));
Set<Class<?>> result = reflections.getTypesAnnotatedWith(DemoAnnotation.class);
assertEquals(1, result.size()); //fails, because result.size == 0
//...
}
<dependency>
<groupId>org.reflections</groupId>
<artifactId>reflections</artifactId>
<version>0.9.12</version>
</dependency>
@chrylis -cautiouslyoptimistic: The javap decompiler output for DemoUsageService$1 looks like the annotation in there.
Classfile /C:/Users/engelmann/git/experiment-anonymousclass-annotationscanning/target/classes/DemoUsageService$1.class
Last modified 21.09.2020; size 1016 bytes
MD5 checksum 2dcb03fe361641b6e04fbb62bbb6c971
Compiled from "DemoUsageService.java"
class DemoUsageService$1
minor version: 0
major version: 55
flags: (0x0020) ACC_SUPER
this_class: #5 // DemoUsageService$1
super_class: #6 // java/lang/Object
interfaces: 0, fields: 2, methods: 1, attributes: 5
Constant pool:
#1 = Fieldref #5.#30 // DemoUsageService$1.this$0:LDemoUsageService;
#2 = Methodref #6.#31 // java/lang/Object."<init>":()V
#3 = String #32 // myContent
#4 = Fieldref #6.#33 // java/lang/Object.content:Ljava/lang/String;
#5 = Class #34 // DemoUsageService$1
#6 = Class #35 // java/lang/Object
#7 = Utf8 content
#8 = Utf8 Ljava/lang/String;
#9 = Utf8 this$0
#10 = Utf8 LDemoUsageService;
#11 = Utf8 <init>
#12 = Utf8 (LDemoUsageService;)V
#13 = Utf8 Code
#14 = Utf8 LineNumberTable
#15 = Utf8 LocalVariableTable
#16 = Utf8 this
#17 = Utf8 InnerClasses
#18 = Utf8 LDemoUsageService$1;
#19 = Utf8 MethodParameters
#20 = Utf8 SourceFile
#21 = Utf8 DemoUsageService.java
#22 = Utf8 RuntimeVisibleTypeAnnotations
#23 = Utf8 LDemoAnnotation;
#24 = Utf8 value
#25 = Utf8 Test
#26 = Utf8 EnclosingMethod
#27 = Class #36 // DemoUsageService
#28 = NameAndType #37:#38 // doSomething:()V
#29 = Utf8 NestHost
#30 = NameAndType #9:#10 // this$0:LDemoUsageService;
#31 = NameAndType #11:#38 // "<init>":()V
#32 = Utf8 myContent
#33 = NameAndType #7:#8 // content:Ljava/lang/String;
#34 = Utf8 DemoUsageService$1
#35 = Utf8 java/lang/Object
#36 = Utf8 DemoUsageService
#37 = Utf8 doSomething
#38 = Utf8 ()V
{
java.lang.String content;
descriptor: Ljava/lang/String;
flags: (0x0000)
final DemoUsageService this$0;
descriptor: LDemoUsageService;
flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC
DemoUsageService$1(DemoUsageService);
descriptor: (LDemoUsageService;)V
flags: (0x0000)
Code:
stack=2, locals=2, args_size=2
0: aload_0
1: aload_1
2: putfield #1 // Field this$0:LDemoUsageService;
5: aload_0
6: invokespecial #2 // Method java/lang/Object."<init>":()V
9: aload_0
10: ldc #3 // String myContent
12: putfield #4 // Field java/lang/Object.content:Ljava/lang/String;
15: return
LineNumberTable:
line 7: 0
line 8: 9
LocalVariableTable:
Start Length Slot Name Signature
0 16 0 this LDemoUsageService$1;
0 16 1 this$0 LDemoUsageService;
MethodParameters:
Name Flags
this$0 final mandated
}
SourceFile: "DemoUsageService.java"
RuntimeVisibleTypeAnnotations:
0: #23(#24=s#25): CLASS_EXTENDS, type_index=65535
DemoAnnotation(
value="Test"
)
EnclosingMethod: #27.#28 // DemoUsageService.doSomething
NestHost: class DemoUsageService
InnerClasses:
#5; // class DemoUsageService$1
I never used this library before, but some poking here and there in the source code and it seems I can make it work (it is written in a nice fashion - so I was lucky, pretty much). I have no idea if there are better ways, but here you go:
static class TestScanner extends AbstractScanner {
@Override
public void scan(Object cls, Store store) {
String className = getMetadataAdapter().getClassName(cls);
try {
Class<?> c = Class.forName(className);
if (c.isAnonymousClass()) {
for (Annotation ann : c.getAnnotatedSuperclass().getAnnotations()) {
store.put(Utils.index(TypeAnnotationsScanner.class), ann.annotationType().getName(), className);
}
}
} catch (ClassNotFoundException e) {
throw new RuntimeException(e);
}
}
}
And usage like:
Reflections reflections = new Reflections(
new ConfigurationBuilder().setUrls(ClasspathHelper.forPackage(DemoUsageService.class.getPackageName()))
.setScanners(new TestScanner(), new SubTypesScanner(false), new TypeAnnotationsScanner()));
Set<Class<?>> result = reflections.getTypesAnnotatedWith(DemoAnnotation.class);
result.forEach(x -> System.out.println(x.getName()));