英文:
Make Gson to use Enum string value instead of constant name
问题
以下是您提供的内容的翻译部分:
有没有办法告诉 Gson 使用字符串值本身,而不是其 Java 常量名称?
理想情况下在 Gson 配置中进行全局设置,这样它会对所有枚举类型执行此操作。
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
public class Main {
public static class Dress {
public Color color;
}
public static enum Color {
RED("red"),
BLUE("blue");
private final String type;
Color(final String type) { this.type = type; }
public String toString() { return type; }
}
public static void main(String[] args) throws InterruptedException {
Dress dress = new Dress();
dress.color = Color.RED;
GsonBuilder builder = new GsonBuilder();
builder.setPrettyPrinting();
Gson gson = builder.create();
System.out.println(gson.toJson(dress));
// ==> { "color": "RED" }
}
}
它输出的是 { "color": "RED" }
而不是 { "color": "red" }
。
英文:
Is there a way to tell Gson to use the string value itself, not its Java constant name?
Ideally globally in Gson config, so it would do that for all enums.
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
public class Main {
public static class Dress {
public Color color;
}
public static enum Color {
RED("red"),
BLUE("blue");
private final String type;
Color(final String type) { this.type = type; }
public String toString() { return type; }
}
public static void main(String[] args) throws InterruptedException {
Dress dress = new Dress();
dress.color = Color.RED;
GsonBuilder builder = new GsonBuilder();
builder.setPrettyPrinting();
Gson gson = builder.create();
System.out.println(gson.toJson(dress));
// ==> { "color": "RED" }
}
}
It prints { "color": "RED" }
instead of { "color": "red" }
.
答案1
得分: 5
使用@SerializedName
设置序列化值
import com.google.gson.annotations.SerializedName;
public static enum Color {
@SerializedName("red")
RED("red"),
@SerializedName("blue")
BLUE("blue");
...
}
另一种方法是使用自定义序列化器
class ColorSerializer implements JsonSerializer {
@Override
public JsonElement serialize(Color src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive(src.toString());
}
}
并在构建器中注册自定义序列化器
builder.registerTypeAdapter(Color.class, new ColorSerializer());
英文:
Use @SerializedName
with serialization value
import com.google.gson.annotations.SerializedName;
public static enum Color {
@SerializedName("red")
RED("red"),
@SerializedName("blue")
BLUE("blue");
...
}
Another way is using a custom serializer
class ColorSerializer implements JsonSerializer {
@Override
public JsonElement serialize(Color src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive(src.toString());
}
}
And register custom serializer in builder
builder.registerTypeAdapter(Color.class, new ColorSerializer());
答案2
得分: 2
创建一个自定义的序列化器,例如:
public class EnumSerializer<T extends Enum<T>> implements JsonSerializer<T> {
@Override
public JsonElement serialize(T src, Type typeOfSrc, JsonSerializationContext context) {
return new JsonPrimitive(src.toString());
}
}
像这样进行注册:
builder.registerTypeAdapter(Color.class, new EnumSerializer<>());
// 这里使用泛型的原因是可以轻松地将其注册到其他枚举类型,例如:
// builder.registerTypeAdapter(SomeEnum.class, new EnumSerializer<>());
如果你需要将它应用于多个枚举类型或所有枚举类型,且不希望为每个枚举类型单独注册,你可以使用 TypeAdapterFactory(稍微复杂一些)。首先,你需要创建 TypeAdapter:
public class EnumTypeAdapter<T extends Enum<T>> extends TypeAdapter<T> {
@Override
public void write(JsonWriter out, T value) throws IOException {
out.jsonValue(value.toString());
}
@Override
public T read(JsonReader in) throws IOException {
return null;
}
}
然后是工厂类:
public static class EnumTypeAdapterFactory implements TypeAdapterFactory {
@Override
// 实际上将 EnumTypeAdapter 设为非泛型可能会更简单
// 但另一方面,在其他上下文和其他方式中使用时可能会更好。因此这些抑制警告
@SuppressWarnings({"rawtypes", "unchecked"})
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
// 这个条件适用于所有枚举类型。如果不需要,可以进行更改。
if (Enum.class.isAssignableFrom(type.getRawType())) {
return new EnumTypeAdapter();
} else {
return null;
}
}
}
然后进行注册:
builder.registerTypeAdapterFactory(new EnumTypeAdapterFactory());
英文:
Create a custom serializer like:
public class EnumSerializer<T extends Enum<T>>
implements JsonSerializer<T> {
@Override
public JsonElement serialize(T src, Type typeOfSrc,
JsonSerializationContext context) {
return new JsonPrimitive(src.toString());
}
}
Register it like:
builder.registerTypeAdapter(Color.class, new EnumSerializer<>());
// there is a reason for generics: that way you can easily register it to
// other Enum types also, for example:
// builder.registerTypeAdapter(SomeEnum.class, new EnumSerializer<>());
If you need to apply it to a more than one or all Enum and you do not wish to register it separately to each one you can use TypeAdapterFactory (bit more complicated). First you need the TypeAdapter:
public class EnumTypeAdapter<T extends Enum<T>> extends TypeAdapter<T> {
@Override
public void write(JsonWriter out, T value) throws IOException {
out.jsonValue(value.toString());
}
@Override
public T read(JsonReader in) throws IOException {
return null;
}
}
Then the factory:
public static class EnumTypeAdapterFactory implements TypeAdapterFactory {
@Override
// Actually it might be easier to just make EnumTypeAdapter non-generic
// but on the other hand it might be better if used in some other contexts
// and in some other ways. Thus these suppressions
@SuppressWarnings({"rawtypes", "unchecked"})
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
// This if applies to all Enums. Change if not wanted.
if(Enum.class.isAssignableFrom(type.getRawType())) {
return new EnumTypeAdapter();
} else {
return null;
}
}
}
and register it:
builder.registerTypeAdapterFactory(new EnumTypeAdapterFactory());
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