Java中获取泛型类型信息的方法

public class MyTest extends TestClass<String> implements TestInterface1<Integer>,TestInterface2<Long> {

    private List<Integer> list;

    private Map<Integer, String> map;

    public List<String> aa() {
        return null;
    }

    public void bb(List<Long> list) {

    }

    public static void main(String[] args) throws Exception {
        System.out.println("======================================= 泛型类声明的泛型类型 =======================================");
        ParameterizedType parameterizedType = (ParameterizedType)MyTest.class.getGenericSuperclass();
        System.out.println(parameterizedType.getTypeName() + "--------->" + parameterizedType.getActualTypeArguments()[0].getTypeName());

        Type[] types = MyTest.class.getGenericInterfaces();
        for (Type type : types) {
            ParameterizedType typ = (ParameterizedType)type;
            System.out.println(typ.getTypeName() + "--------->" + typ.getActualTypeArguments()[0].getTypeName());
        }

        System.out.println("======================================= 成员变量中的泛型类型 =======================================");
        ParameterizedType parameterizedType1 = (ParameterizedType)MyTest.class.getDeclaredField("list").getGenericType();
        System.out.println(parameterizedType1.getTypeName() + "--------->" + parameterizedType1.getActualTypeArguments()[0].getTypeName());

        ParameterizedType parameterizedType2 = (ParameterizedType)MyTest.class.getDeclaredField("map").getGenericType();
        System.out.println(parameterizedType2.getTypeName() + "--------->" + parameterizedType2.getActualTypeArguments()[0].getTypeName()+","+parameterizedType2.getActualTypeArguments()[1].getTypeName());

        System.out.println("======================================= 方法参数中的泛型类型 =======================================");
        ParameterizedType parameterizedType3 = (ParameterizedType)MyTest.class.getMethod("aa").getGenericReturnType();
        System.out.println(parameterizedType3.getTypeName() + "--------->" + parameterizedType3.getActualTypeArguments()[0].getTypeName());

        System.out.println("======================================= 方法返回值中的泛型类型 =======================================");
        Type[] types1 = MyTest.class.getMethod("bb", List.class).getGenericParameterTypes();
        for (Type type : types1) {
            ParameterizedType typ = (ParameterizedType)type;
            System.out.println(typ.getTypeName() + "--------->" + typ.getActualTypeArguments()[0].getTypeName());
        }
    }
}

class TestClass<T> {

}

interface TestInterface1<T> {

}

interface TestInterface2<T> {

}

public abstract class TestClass2<T> {

    private final Type type;

    public TestClass2() {
        Type superClass = getClass().getGenericSuperclass();
        if (!(superClass instanceof ParameterizedType)) {
            throw new IllegalArgumentException("无泛型类型信息");
        }
        type = ((ParameterizedType) superClass).getActualTypeArguments()[0];
    }

    public Type getType() {
        return type;
    }
}

public class Test {

    public static  <T> T get(TestClass2<T> tTestClass2) throws IllegalAccessException, InstantiationException {
        Type type = tTestClass2.getType();
        Class clazz = (Class) type;
        return (T)clazz.newInstance();
    }

    public static void main(String[] args) throws InstantiationException, IllegalAccessException {
        String str = get(new TestClass2<String>() {});
        Date date = get(new TestClass2<Date>() {});
    }
}