如何通过反射在Java中调用setter方法

Question

how to invoke Bean private setter method by reflection in java

I can't Understand how to invoke private setter Method in My User Bean. I all ready used PropertyDescriptor and many way but i am not access private setter method by the Reflection.

public class GetterAndSetter
 {
     public static void main(String[] args)
     {
         GetterAndSetter gs = new GetterAndSetter();
         User user = new User();

          try {
            gs.callSetter(user,"name","Sanket");
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IntrospectionException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

     }

     private void callSetter(Object obj,String fieldName, Object value) throws IntrospectionException, InvocationTargetException, IllegalAccessException , IllegalArgumentException
     {
         PropertyDescriptor pd;

         pd = new PropertyDescriptor(fieldName,obj.getClass());
         pd.getWriteMethod().invoke(obj,value);
     }

 }

This Code I would only access the filed and set the value in filed,But I can't access the setter Field directly to the Reflection

Answer 1

This how you can call a private method in the User class:

try {
    User user = new User();
    Method method = User.class.getDeclaredMethod("setName", String.class);
    method.setAccessible(true);
    method.invoke(user, "Some name");
    System.out.println("user.getName() = " + user.getName());
} catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
    e.printStackTrace();
}

Note the call to method.setAccessible(true);