java ParameterizedType使用

短命女 2022-08-20 09:16 178阅读 0赞

package com.tencent.weread.dict;
    
    import java.lang.reflect.ParameterizedType;
    import java.lang.reflect.Type;
    
    public class Main {
    	public static void main(String[] args) throws NoSuchMethodException {
    		new Sub();
    	}
    }
    
    class Parent {
    
    }
    
    class Child extends Parent {
    
    }
    
    class UpperGeneric {
    	static class Generic<T, R> {
    		T t;
    		R r;
    
    		protected Generic(T t, R r) {
    			this.t = t;
    			this.r = r;
    		}
    
    		void foo() {
    			System.err.println(t + " " + r);
    		}
    	}
    }
    
    class Sub extends UpperGeneric.Generic<Child, Integer> {
    
    	protected Sub() {
    		super(new Child(), 1);
    		Class clazz = getClass().getSuperclass();
    		System.err.println("super clazz:" + clazz);
    
    		Type type = getClass().getGenericSuperclass();
    		System.err.println("generic super class type:" + type);
    
    		Type trueType = ((ParameterizedType) type).getActualTypeArguments()[0];
    		System.err.println("generic super class type:" + trueType);
    		trueType = ((ParameterizedType) type).getActualTypeArguments()[1];
    		System.err.println("type:" + trueType);
    
    		trueType = ((ParameterizedType) type).getRawType();
    		System.err.println("raw type:" + trueType);
    
    		trueType = ((ParameterizedType) type).getOwnerType();
    		System.err.println("owner type:" + trueType);
    	}
    }
    
    getOwnerType：获取一个type的包装类。如果type不是任何类的内部类，返回null，否则返回外部类的Type

getActualTypeArguments：获取泛型类的参数类型