Grails：将注释应用于属性访问器而不是字段

Question

In Grails, is it possible to apply annotations to properties' accessors instead of (or in addition to) its field, without explicitly defining the accessors?

If so, what version of Grails is required?

eg, I'd like something like the following (using a fake syntax that uses specific labels to determine what to apply annotations to):

class C {
    field:
    @A1
    getter:
    @A2
    getter:
    @A3
    accessors:
    @A4
    all:
    @A5
    String p
}

Answer 1

When you define a property in a POGO like a Grails domain class, the Groovy compiler rewrites it as a private field with a getter and a setter, but only if there's no scope modifier ( public / protected /etc.)

This is convenient because if you later want to add logic or calculations when setting and/or getting the value, you can add your own getter and/or setter method and the compiler will only generate methods that aren't already explicitly defined. Java classes will have been using the getters and setters already, so this doesn't affect existing clients or require recompiling.

You can see by decompiling your domain class that the Groovy compiler moves any annotations defined on properties to the fields, so for example with this domain class

class Thing {
   @Foo
   String name
}

you'll see code similar to this in the decompiled code:

@Foo
private String name;

public String getName() {
   return name;
}

public void setName(String name) {
   this.name = name
}

Many frameworks will access field annotations or accessor annotations, so often this works without any additional configuration, but it depends on the framework or code that's reading the annotations.