带有反射的 IllegalArgumentException

Question

这是一个小测试代码，用于将背景设置为 itext 块对象。我打算做的是使用反射在块对象上执行以下方法 块块 = 新块（）； BaseColor baseColor = new BaseColor(45,90,135); chunk.setBackground(baseColor);

package com.blubench.test;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import com.itextpdf.text.Chunk;

public class BaseColorReflection {

    static final String methodName = "setBackground";
    static final String className = "com.itextpdf.text.Chunk";
    static final String param = "com.itextpdf.text.BaseColor";


    public static void main(String[] args) throws ClassNotFoundException, SecurityException, NoSuchMethodException, IllegalArgumentException, InstantiationException, IllegalAccessException, InvocationTargetException {

        //**********Target Class**************
        Class<?> chunkClass = Class.forName(className);
        Chunk chunk = (Chunk) chunkClass.newInstance();

        //*********Parameter to Target Method*********
        Class<?> baseColorClass = Class.forName(param);     
        Class<?>[] argTypes = {int.class,int.class,int.class};
        Constructor<?> baseColorCtor = baseColorClass.getDeclaredConstructor(argTypes);     
        Object[] argValues = {45,90,135};
        Object baseColorObject = baseColorCtor.newInstance(argValues);

        //*********Target Method****************
        Method method = chunkClass.getDeclaredMethod(methodName,baseColorObject.getClass());

        try {

            //***********Invoke Target Method on Target Class with Parameter**********
            method.invoke(chunk, baseColorObject.getClass());

        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }   

}

这就是我得到的

java.lang.IllegalArgumentException：参数类型不匹配 sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 在 sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke（未知来源）在 java.lang.reflect.Method.invoke（未知来源）在 com.blubench.test.BaseColorReflection.main(BaseColorReflection.java:33)

这是一个非常常见的问题，但我无法确定是什么原因造成的？

Answer 1

传递参数实例，而不是参数的类：

改变

method.invoke(chunk, baseColorObject.getClass());

到

method.invoke(chunk, baseColorObject);