cn.hutool.core.annotation.AnnotationProxy Maven / Gradle / Ivy
package cn.hutool.core.annotation;
import cn.hutool.core.util.ReflectUtil;
import cn.hutool.core.util.StrUtil;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
/**
* 注解代理
* 通过代理指定注解，可以自定义调用注解的方法逻辑，如支持{@link Alias} 注解
*
* @param 注解类型
* @since 5.7.23
*/
public class AnnotationProxy implements Annotation, InvocationHandler, Serializable {
private static final long serialVersionUID = 1L;
private final T annotation;
private final Class type;
private final Map attributes;
/**
* 构造
*
* @param annotation 注解
*/
public AnnotationProxy(T annotation) {
this.annotation = annotation;
//noinspection unchecked
this.type = (Class) annotation.annotationType();
this.attributes = initAttributes();
}
@Override
public Class annotationType() {
return type;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// 注解别名
Alias alias = method.getAnnotation(Alias.class);
if(null != alias){
final String name = alias.value();
if(StrUtil.isNotBlank(name)){
if(false == attributes.containsKey(name)){
throw new IllegalArgumentException(StrUtil.format("No method for alias: [{}]", name));
}
return attributes.get(name);
}
}
final Object value = attributes.get(method.getName());
if (value != null) {
return value;
}
return method.invoke(this, args);
}
/**
* 初始化注解的属性
* 此方法预先调用所有注解的方法，将注解方法值缓存于attributes中
*
* @return 属性（方法结果）映射
*/
private Map initAttributes() {
final Method[] methods = ReflectUtil.getMethods(this.type);
final Map attributes = new HashMap<>(methods.length, 1);
for (Method method : methods) {
// 跳过匿名内部类自动生成的方法
if (method.isSynthetic()) {
continue;
}
attributes.put(method.getName(), ReflectUtil.invoke(this.annotation, method));
}
return attributes;
}
}