通過Class類上的 getGenericSuperclass() 或者 getGenericInterfaces() 獲取父類或者介面的型別,然後通過ParameterizedType.getActualTypeArguments()

可以得到定義在類或者介面上的泛型型別,具體參考如下程式碼:

 /*
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 */

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

public class GenericTypeTest {
    static class Test1 extends T<Person, Animal> {

    }

    static class Test2 implements I<Person, Animal>, I2<Fruit> {
    }

    public static void main(String[] args) {
        //獲取類定義上的泛型型別
        Test1 test1 = new Test1();
        Type types = test1.getClass().getGenericSuperclass();

        Type[] genericType = ((ParameterizedType) types).getActualTypeArguments();
        for (Type t : genericType) {
            System.out.println(t.getTypeName());
        }
        System.out.println("===============================================");

        //獲取介面定義上的泛型型別
        Test2 test2 = new Test2();
        //一個類可能實現多個介面,每個介面上定義的泛型型別都可取到
        Type[] interfacesTypes = test2.getClass().getGenericInterfaces();
        for (Type t : interfacesTypes) {
            Type[] genericType2 = ((ParameterizedType) t).getActualTypeArguments();
            for (Type t2 : genericType2) {
                System.out.println(t2.getTypeName());
            }
        }


    }
}

class T<T1, T2> {
    public void printT(T1 t1, T2 t2) {
        System.out.println(t1.getClass());
        System.out.println(t2.getClass());
    }
}

interface I<T1, T2> {
}

interface I2<K> {

}

class Person {
    @Override
    public String toString() {
        return "Person Type";
    }
}

class Animal {
    @Override
    public String toString() {
        return "Animal Type";
    }
}

class Fruit {
    @Override
    public String toString() {
        return "Fruit Type";
    }
}