ParameterizedType的作用

原創

2020-02-21 10:41

CSDN日报0711——《离开校园，入职阿里，开启新的程序人生》 征文 | 你会为 AI 转型么？ 专家问答 | 资深Java工程师带你解读MyBatis

ParameterizedType的作用

标签： Gradle

2015-01-09 18:55 16259人阅读评论(0)收藏举报

分类：

我的学习历程（44）

作者同类文章X

public interface ParameterizedType extends Type

subParam.Java

[java] view plain copy

print?

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

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

[java] view plain copy

print?

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);
}
}

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。