ParameterizedType的作用

public interface ParameterizedType  extends Type

subParam.Java

package com.example.test;

public class subParam extends param<myclass, myinvoke> {
    public static void main(String[] args) throws Exception{
        subParam  s = new subParam();
    }
}

param.java

package com.example.test;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

public class param<T1, T2> {
    class A {}
    class B extends A {}

    private Class<T1> entityClass;
    protected param (){
        Type type = getClass().getGenericSuperclass();
        System.out.println("getClass()==" + getClass());
        System.out.println("type = " + type);
        Type trueType = ((ParameterizedType)type).getActualTypeArguments()[0];
        System.out.println("trueType1 = " + trueType);
        trueType = ((ParameterizedType)type).getActualTypeArguments()[1];
        System.out.println("trueType2 = " + trueType);
        this.entityClass = (Class<T1>)trueType;


        B t = new B();
        type = t.getClass().getGenericSuperclass();

        System.out.println("B is A's super class :" + ((ParameterizedType)type).getActualTypeArguments().length);
    }

}

===================== output =======================

getClass()==class com.example.test.subParam

type = com.example.test.param<com.example.test.myclass, com.example.test.myinvoke>

trueType1 = class com.example.test.myclass

trueType2 = class com.example.test.myinvoke

B is A's super class :0

总结

((ParameterizedType)type).getActualTypeArguments()

是用来的到类的模板参数的类型的？ 入T1, T2  etc...

返回表示此类型实际类型参数的 Type 对象的数组。