详解Java泛型中类型擦除问题的解决方法

/** Test. */
@Data
@NoArgsConstructor
@AllArgsConstructor
public static class Foo {
    public String name;
}
 
/** Test. */
@Data
@NoArgsConstructor
@AllArgsConstructor
public static class Dummy {
    public String name;
}

@NoArgsConstructor
@AllArgsConstructor
@Data
public static class Spec<T> {
 
    public String spec;
 
    public T deserializeTo() throws JsonProcessingException {
        var mapper = new ObjectMapper();
        return (T) mapper.readValue(spec, Foo.class);
    }
}

 @Test
    public void test() throws JsonProcessingException {
        var foo = new Foo("foo");
        var spec = new Spec<Foo>(mapper.writeValueAsString(foo));
        var deserialized = spec.deserializeTo();
        Assertions.assertTrue(deserialized instanceof Foo);
    }
 
    @NoArgsConstructor
    @AllArgsConstructor
    @Data
    public static class Spec<T> {
 
        public String spec;
 
        private Class<T> getSpecClass() {
            return (Class<T>)
                    ((ParameterizedType) getClass().getGenericSuperclass())
                            .getActualTypeArguments()[0];
        }
 
        public T deserializeTo() throws JsonProcessingException {
            var mapper = new ObjectMapper();
            System.out.println(spec);
            return (T) mapper.readValue(spec, getSpecClass());
        }
    }

@Data
public abstract static class AbstractSpec<T> {
 
    public String spec;
 
    public AbstractSpec(String spec) {
        this.spec = spec;
    }
 
    private Class<T> getSpecClass() {
        return (Class<T>)
                ((ParameterizedType) getClass().getGenericSuperclass())
                        .getActualTypeArguments()[0];
    }
 
    public T deserializeTo() throws JsonProcessingException {
        var mapper = new ObjectMapper();
        System.out.println(spec);
        return (T) mapper.readValue(spec, getSpecClass());
    }
}
 
public static class Spec extends AbstractSpec<Foo> {
    public Spec(String spec) {
        super(spec);
    }
}
 
@Test
public void test() throws JsonProcessingException {
    var foo = new Foo("foo");
    var spec = new Spec(mapper.writeValueAsString(foo));
    var deserialized = spec.deserializeTo();
    Assertions.assertTrue(deserialized instanceof Foo);
}

$ javap -verbose ./org/apache/flink/kubernetes/operator/controller/GenericTest\$Spec.class | grep Signature
  #15 = Utf8               Signature
        Start  Length  Slot  Name   Signature
Signature: #19                          // Lorg/apache/flink/kubernetes/operator/controller/GenericTest$AbstractSpec<Lorg/apache/flink/kubernetes/operator/controller/GenericTest$Foo;>;