Question

我希望通过java反射获得一个类（在jar文件中打包）注释参数。

我这样的注释

@Documented
@Retention(RUNTIME)
@Target(TYPE)    
public @interface TestPlugin {
    public String moduleName();
    public String plugVersion();
    public String minLeapVersion();    
}

我这样的课

@TestPlugin(moduleName="xxx", plugVersion="1.0.0", minLeapVersion="1.3.0")

public class Plugin {

  ......

}

我的访问代码如下

Class<?> clazz = this.loadClass(mainClassName);  // myself classloader

Annotation[] annos = clazz.getAnnotations();

for (Annotation anno : annos) {
    Class<? extends Annotation> annoClass = anno.annotationType();

    /* Question is here
    This code can get right annotationType: @TestPlugin. 
    Debug windows show anno is $Proxy33. 
    But I can't find any method to get annotation membervalues even though I can find them in debug windows.
    How can I get annotation's parameters?
    */
}

Debug windows info

Answer 1

由于某些技术原因，Java VM使用的“真实”注释类是动态代理。这不应该打扰你。他们仍然“实现”你的注释类。只需使用

TestPlugin plugin = clazz.getAnnotation(TestPlugin.class);

plugin.getClass() == TestPlugin.class; // false - is Dynamic proxy
TestPlugin.class.isAssignableFrom(plugin.getClass()); // true - Dynamic proxy implements TestPlugin interface

编辑：刚刚在another answer中找到，您也可以在循环中询问您的anno对象，但不要使用getClass()。使用.annotationType()。

如何从jar文件中的类中获取注释参数

1 个答案: