java 动态修改方法上的注解值

https://blog.csdn.net/jiangzeyin_/article/details/78421178

上篇博客提起，动态修改类上注解的值。有博友问题如果修改方法上注解值，其实二者是相通的。

代码如下：

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

/**
 * Created by jiangzeyin on 2018/4/15.
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface testA {
    String value();
}

import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Map;

/**
 * Created by jiangzeyin on 2018/4/15.
 */
public class test {

    @testA("a")
    public static void main(String[] args) throws Exception {
        Method method = test.class.getMethod("main", String[].class);
        testA testA = method.getAnnotation(testA.class);
        if (testA == null)
            throw new RuntimeException("please add testA");
        InvocationHandler invocationHandler = Proxy.getInvocationHandler(testA);
        Field value = invocationHandler.getClass().getDeclaredField("memberValues");
        value.setAccessible(true);
        Map<String, Object> memberValues = (Map<String, Object>) value.get(invocationHandler);
        String val = (String) memberValues.get("value");
        System.out.println("改变前：" + val);
        val = "b";
        memberValues.put("value", val);
        System.out.println("改变后：" + testA.value());

    }
}

运行结果：