Java 使用gson反序列化接口数据不返回值？

我在下面做一个简单的实验测试

public class MyTest {

    @Test
    public void testing() {
        GsonBuilder builder = new GsonBuilder();
        builder.registerTypeAdapter(SubData.class, new SubDataImplInstanceCreator());
        Gson gson = builder.create();

        Dataclass data = new Dataclass();
        data.key1 = "abc";
        SubDataImpl subData = new SubDataImpl();
        subData.hello = "ttt";
        data.sub = subData;
        String jsonValue = gson.toJson(data);
        System.out.println(jsonValue);

        Dataclass data2 = gson.fromJson(jsonValue, Dataclass.class);
        System.out.println(gson.toJson(data2));

    }

    class Dataclass implements Serializable {
        String key1;
        SubData sub;
    }

    interface SubData {
        String getHello();
    }

    class SubDataImpl implements SubData, Serializable {

        String hello;

        @Override
        public String getHello() {
            return hello;
        }
    }


    public class SubDataImplInstanceCreator implements InstanceCreator<SubDataImpl> {
        @Override
        public SubDataImpl createInstance(Type type) {
            return new SubDataImpl();
        }
    }
}

因为它们本质上是被序列化和反序列化的相同数据

然而，当我运行它时，我得到了

{"key1":"abc","sub":{"hello":"ttt"}}
{"key1":"abc","sub":{}}

---

为什么在反序列化Json字符串之后，我会丢失我的

子数据

值？我的代码中遗漏了什么吗？

您似乎已经找到了这个问题，建议的解决方案是在接口中使用TypeAdapter

快速而肮脏的实现（使用它代替SubDataImplInstanceTypeAdapter）

public类subdataimpleInstanceTypeAdapter实现JsonDeserializer、JsonSerializer{
@凌驾
public SubDataImpl反序列化（JsonElement json，类型typeOfT，JsonDeserializationContext）引发JsonParseException{
SubDataImpl impl=新的SubDataImpl（）；
JsonObject object=json.getAsJsonObject（）；
impl.setHello（object.get（“hello”）.getAsString（）；
返回impl；
}
@凌驾
公共JsonElement序列化（SubDataImpl src，类型typeOfSrc，JsonSerializationContext）{
返回context.serialize（src）；
}
}

我正在使用下面的

public class MyTest {
    @Test
    public void testing() {
        GsonBuilder builder = new GsonBuilder();
        builder.registerTypeAdapter(SubData.class, new SubDataTypeAdapter());
        Gson gson = builder.create();

        Dataclass data = new Dataclass();
        data.key1 = "abc";
        SubDataImpl subData = new SubDataImpl();
        subData.hello = "ttt";
        data.sub = subData;
        String jsonValue = gson.toJson(data);
        System.out.println(jsonValue);

        Dataclass data2 = gson.fromJson(jsonValue, Dataclass.class);
        System.out.println(gson.toJson(data2));
    }

    class SubDataTypeAdapter extends TypeAdapter<SubDataImpl> {

        @Override
        public void write(JsonWriter out, final SubDataImpl subData) throws IOException {
            out.beginObject();
            out.name("hello").value(subData.getHello());
            out.endObject();
        }

        @Override
        public SubDataImpl read(JsonReader in) throws IOException {
            final SubDataImpl subData = new SubDataImpl();

            in.beginObject();
            while (in.hasNext()) {
                switch (in.nextName()) {
                    case "hello":
                        subData.hello = in.nextString();
                        break;
                }
            }
            in.endObject();

            return subData;
        }
    }

    class Dataclass implements Serializable {
        String key1;
        SubData sub;
    }

    abstract class SubData {
        abstract String getHello();
    }

    class SubDataImpl extends SubData implements Serializable {

        String hello;

        @Override
        public String getHello() {
            return hello;
        }
    }
}

公共类MyTest{
@试验
公开无效测试（）{
GsonBuilder=新的GsonBuilder（）；
registerTypeAdapter（SubData.class，新的SubDataTypeAdapter（））；
Gson Gson=builder.create（）；
Dataclass数据=新的Dataclass（）；
data.key1=“abc”；
SubDataImpl subData=新的SubDataImpl（）；
subData.hello=“ttt”；
data.sub=子数据；
字符串jsonValue=gson.toJson（数据）；
System.out.println（jsonValue）；
Dataclass data2=gson.fromJson（jsonValue，Dataclass.class）；
System.out.println（gson.toJson（data2））；
}
类SubDataTypeAdapter扩展了TypeAdapter{
@凌驾
public void write（JsonWriter out，final SubDataImpl subData）抛出IOException{
out.beginObject（）；
out.name（“hello”）.value（subData.getHello（））；
out.endObject（）；
}
@凌驾
public SubDataImpl read（JsonReader in）引发IOException{
final SubDataImpl subData=new SubDataImpl（）；
in.beginObject（）；
while（在.hasNext（）中）{
开关（在.nextName（）中）{
案例“你好”：
subData.hello=in.nextString（）；
打破
}
}
in.endObject（）；
返回子数据；
}
}
类Dataclass实现可序列化{
字符串键1；
子数据子；
}
抽象类子数据{
抽象字符串getHello（）；
}
类SubDataImpl扩展子数据实现可序列化{
串你好；
@凌驾
公共字符串getHello（）{
回复你好；
}
}
}

很酷。你的工作。我还使用下面的方法实现了它。

 public class SubDataImplInstanceTypeAdapter implements JsonDeserializer<SubDataImpl>, JsonSerializer<SubDataImpl> {


    @Override
    public SubDataImpl deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
        SubDataImpl impl = new SubDataImpl();
        JsonObject object = json.getAsJsonObject();
        impl.setHello(object.get("hello").getAsString());
        return impl;

    }

    @Override
    public JsonElement serialize(SubDataImpl src, Type typeOfSrc, JsonSerializationContext context) {
        return context.serialize(src);
    }
}

public class MyTest {
    @Test
    public void testing() {
        GsonBuilder builder = new GsonBuilder();
        builder.registerTypeAdapter(SubData.class, new SubDataTypeAdapter());
        Gson gson = builder.create();

        Dataclass data = new Dataclass();
        data.key1 = "abc";
        SubDataImpl subData = new SubDataImpl();
        subData.hello = "ttt";
        data.sub = subData;
        String jsonValue = gson.toJson(data);
        System.out.println(jsonValue);

        Dataclass data2 = gson.fromJson(jsonValue, Dataclass.class);
        System.out.println(gson.toJson(data2));
    }

    class SubDataTypeAdapter extends TypeAdapter<SubDataImpl> {

        @Override
        public void write(JsonWriter out, final SubDataImpl subData) throws IOException {
            out.beginObject();
            out.name("hello").value(subData.getHello());
            out.endObject();
        }

        @Override
        public SubDataImpl read(JsonReader in) throws IOException {
            final SubDataImpl subData = new SubDataImpl();

            in.beginObject();
            while (in.hasNext()) {
                switch (in.nextName()) {
                    case "hello":
                        subData.hello = in.nextString();
                        break;
                }
            }
            in.endObject();

            return subData;
        }
    }

    class Dataclass implements Serializable {
        String key1;
        SubData sub;
    }

    abstract class SubData {
        abstract String getHello();
    }

    class SubDataImpl extends SubData implements Serializable {

        String hello;

        @Override
        public String getHello() {
            return hello;
        }
    }
}