Byte Buddy可以在运行时创建字段和方法注释吗? [英] Can Byte Buddy create fields and method annotations at runtime?

问题描述

我想实现此第三方注释，以将班级的字段/属性映射到我的数据库表列.我可以在编译时轻松实现注释(如下面的示例代码所示)，但是我找不到在运行时执行此操作的方法. (我正在使用反射在运行时加载库.)

I would like to implement this 3rd-party annotation to map my class's fields/properties to my database table columns. I can easily implement the annotations at compile time (as shown in the example code below) but I can't find a way to do this at runtime. (I am loading the library at runtime using reflection.)

我的问题是在运行时加载库时如何实现相同的映射注释? Byte Buddy可以为Android处理吗?

My question is how can I implement the same mapping annotation when loading a library at run time? Can Byte Buddy handle this for Android?

//3rd party annotation code
package weborb.service;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
public @interface MapToProperty {
    String property();
}

///////////////////////////////////////////////////////

/////////////////////////////////////////////////////

//Here is the implementation using non-reflection
import weborb.service;
    Class Person
    {
        @MapToProperty(property="Person_Name")
        String name;

        @MapToProperty(property="Person_Age")
        int age;

        @MaptoProperty(property="Person_Name")
        public String getName()
        {
            return this.name;
        }

        @MaptoProperty(property="Person_Name")
        public void setName(String name)
        {
            this.name = name;
        }

        @MaptoProperty(property="Person_Age")
        public int getAge()
        {
             return this.age;
        }

        @MaptoProperty(property="Person_Age")
        public void setAge(int age)
        {
            this.age = age;
        }
    }

推荐答案

是的，请参考 注释文档中的部分.

Yes, please refer to the Annotations section of the documentation for details.

您可以使用AnnotationDescription.Builder通过以下方式构建注释:

You can build an annotation using an AnnotationDescription.Builder by:

AnnotationDescription.Builder.ofType(MapToProperty.class)
                             .define("property", "<value>")
                             .build();

生成的AnnotationDescription可以作为参数提供给动态类型生成器:

The resulting AnnotationDescription can be supplied to a dynamic type builder as an argument:

new ByteBuddy()
  .subclass(Object.class)
  .defineField("foo", Void.class)
  .annotateField(annotationDescription)
  .make();

类似地，它适用于方法.

Similarly, it works for methods.

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