Javassist annoations problem
- by Ali
I'm trying to generate my Entity class using javassist. Everything went well until I added the GeneratedValue annotation to the Id field. The @Id annotation works fine but when I add @GeneeratedValue I get an exception. This is my code:
ClassPool cp = ClassPool.getDefault();
CtClass ctClass = cp.makeClass("test.Snake");
ClassFile classFile = ctClass.getClassFile();
classFile.setVersionToJava5();
AnnotationsAttribute attribute = new AnnotationsAttribute(classFile.getConstPool(), AnnotationsAttribute.visibleTag);
Annotation idAnnotation = new Annotation(classFile.getConstPool(), ClassPool.getDefault().get("javax.persistence.Id"));
attribute.addAnnotation(idAnnotation);
Annotation gvAnnotation = new Annotation(classFile.getConstPool(), ClassPool.getDefault().get("javax.persistence.GeneratedValue"));
attribute.addAnnotation(gvAnnotation);
CtField idField = new CtField(ClassPool.getDefault().get("java.lang.Long"), "id", ctClass);
idField.getFieldInfo().addAttribute(attribute);
ctClass.addField(idField);
CtField nameField = new CtField(ClassPool.getDefault().get("java.lang.String"), "name", ctClass);
ctClass.addField(nameField);
AnnotationsAttribute attr = new AnnotationsAttribute(classFile.getConstPool(), AnnotationsAttribute.visibleTag);
Annotation annotation = new Annotation(classFile.getConstPool(), ClassPool.getDefault().get("javax.persistence.Entity"));
attr.addAnnotation(annotation);
classFile.addAttribute(attr);
snakeClass = ctClass.toClass();
newInstance = snakeClass.newInstance();
And this is the exception I get:
java.lang.NullPointerException
at javassist.bytecode.ConstPool.getUtf8Info(ConstPool.java:565)
at javassist.bytecode.annotation.EnumMemberValue.getValue(EnumMemberValue.java:98)
at javassist.bytecode.annotation.EnumMemberValue.write(EnumMemberValue.java:116)
at javassist.bytecode.annotation.Annotation.write(Annotation.java:316)
at javassist.bytecode.AnnotationsAttribute.setAnnotations(AnnotationsAttribute.java:246)
at javassist.bytecode.AnnotationsAttribute.addAnnotation(AnnotationsAttribute.java:211)
at ClassLoadingTest.javassitTest(ClassLoadingTest.java:56)
It seems to be a problem with @GeneratedValue. When I use it alone whithout id I get this exception either. When I use eclipse debugger to watch variable values, I get get this
com.sun.jdi.InvocationException occurred invoking method.
instead of the annotation value. but for Id annotation it shows a javassist annotation object.
I'm new to javassist. Can anyone help me?
