[jboss-user] [Javassist] - javassist not injecting annotation on an existing field

[Ankur Gupta]

Ankur Gupta [https://community.jboss.org/people/geekerebos] created the discussion

"javassist not injecting annotation on an existing field"

To view the discussion, visit: https://community.jboss.org/message/801815#801815

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|  0 down vote  favorite (http://stackoverflow.com/questions/15332399/javassist-not-injecting-annotation-at-existing-field#) | 
I'm trying to inject JAXB annotation at runtime using Javassist. I have written following code:
public class AssistAnnotationInjector { public static void addAnnotationRunTime(String className, String fieldName) throws NotFoundException, CannotCompileException, IOException, ClassNotFoundException{  CtClass ctClass = ClassPool.getDefault().get(className); ClassFile ccFile = ctClass.getClassFile(); ConstPool constPool = ccFile.getConstPool(); AnnotationsAttribute attr = new AnnotationsAttribute(constPool, AnnotationsAttribute.visibleTag); Annotation annot = new Annotation("javax.xml.bind.annotation.XmlTransient",constPool); attr.addAnnotation(annot); CtField field = ctClass.getDeclaredField(fieldName); field.getFieldInfo().addAttribute(attr); System.out.println(field.getAnnotation(XmlTransient.class)); ccFile.setVersionToJava5(); ctClass.writeFile(); }  public static void main (String args[]) throws CannotCompileException, NotFoundException, IOException, SecurityException, NoSuchMethodException, ClassNotFoundException, JAXBException, NoSuchFieldException{ Person<Student> p = new Person<Student>(); p.setName("XYZ"); Student s = new Student(); s.setName("ABC"); s.setId("239423"); p.setPayload(s);  addAnnotationRunTime("RuntimeAnnotation.Person", "name");  Field f = p.getClass().getDeclaredField("name"); System.out.println(f.getAnnotation(XmlTransient.class));  JAXBContext context = JAXBContext.newInstance(p.getClass());  Marshaller mr = context.createMarshaller(); mr.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);  mr.marshal(p, System.out); } } 
And Person.java class is:
@XmlRootElement(name="Person") @XmlAccessorType(XmlAccessType.FIELD) @XmlSeeAlso({Student.class}) public class Person <T>{  private T payload;  private String name;  public void setPayload(T payload){ this.payload = payload; }  public T getPayload(){ return payload; }  public void setName(String name){ this.name = name; }  public String getName(){ return name; } } 
In AssistAnnotationInjector.java, I am trying to add XmlTransient annotation to 'name' field. But the name field is still coming in marshalling output. Why is it so?
PS: marshal output is :
@javax.xml.bind.annotation.XmlTransient null <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Person> <payload xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="student"> <name>ABC</name> <id>239423</id> </payload> **<name>XYZ</name>** </Person> 
name tag was not expected to present in output.. |
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