JavaSE 反射 Part1，javase反射part1

JavaSE 反射 Part1，javase反射part1

原作者:尚硅谷-佟刚

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package com.atweihai.reflection;

import java.lang.reflect.Method;

import org.junit.Test;

public class ReflectionTest {

    @Test
    public void testReflection() throws Exception{
        //测试子类私有方法
        String className="com.atweihai.reflection.Student";
        String methodName="method2";
        Class clazz=Class.forName(className);

        Method method=getMethod(clazz, methodName);
        invokeMethod(clazz, method);

        //测试父类私有Person 方法
        className="com.atweihai.reflection.Student";
        methodName="method1";
        Object[] args={"北京",24};

        clazz=Class.forName(className);
        Class[] parameterTypes=getParameterTypes(args);
        method=getMethod(clazz, methodName, parameterTypes);
        Object obj=invokeMethod(clazz, method, args);
        System.out.println(obj);




    }

    //执行方法
    public Object invokeMethod(Class clazz,Method method,Object ... args) throws Exception{
        //使私有方法变为可访问的
        method.setAccessible(true);
        return method.invoke(clazz.newInstance(), args);
    }

    //获取方法
    public Method  getMethod(Class clazz,String methodName,Class ... parameterTypes){
        Method method=null; 
        //循环向上转型
        for(;clazz!=Object.class;clazz=clazz.getSuperclass()){
              try {
                method=clazz.getDeclaredMethod(methodName, parameterTypes);
                return method;
            } catch (Exception e) {}
        }

        return method;
    }

    //获取参数类型的Class数组
    private Class[] getParameterTypes(Object[] args) {

        Class[] parameterTypes=new Class[args.length];
        for(int i=0;i<args.length;i++){
            parameterTypes[i]=args[i].getClass();
        }
        return parameterTypes;
    }
}