Java 每个字段有多个 GSON @SerializedName？
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Multiple GSON @SerializedName per field?
提问by Gus
Is there any way in Gson to map multiple JSON fields to a single Java object member variable?
Gson 有没有办法将多个 JSON 字段映射到单个 Java 对象成员变量？
Let's say I have a Java class...
假设我有一个 Java 类...
public class MyClass {
String id;
String name;
}
I want to use this single class with two different services. However, these two services differ in how they return their data...
我想将这个单一的类与两种不同的服务一起使用。但是，这两种服务在返回数据的方式上有所不同......
{ "id": 2341, "person": "Bob" }
... and ...
... 和 ...
{ "id": 5382, "user": "Mary" }
... respectively.
... 分别。
Is there any way to map both the "person"and "user"fields in the JSON string to the namefield in the Java object?
有没有办法将 JSON 字符串中的"person"和"user"字段映射到nameJava 对象中的字段？
(Note: I only ever need to convert from JSON string to Java object - never the other way around.)
（注意：我只需要从 JSON 字符串转换为 Java 对象 - 从不反过来。）
回答by Devrim
It is not supported to define multiple @SerializedNameannotations to a field at Gson.
@SerializedNameGson不支持为一个字段定义多个注释。
Reason:By default Deserialization is managed with a LinkedHashMap and the keys are defined by incoming json's field names (not the custom class's field names or the serializedNames) and there is a one to one mapping. You can see the implementation(how deserialization works) at ReflectiveTypeAdapterFactoryclass's inner class Adapter<T>'s read(JsonReader in)method.
原因：默认情况下，反序列化由 LinkedHashMap 管理，键由传入的 json 字段名称（不是自定义类的字段名称或序列化名称）定义，并且存在一对一映射。您可以在ReflectiveTypeAdapterFactory类的内部类Adapter<T>的read(JsonReader in)方法中看到实现（反序列化是如何工作的）。
Solution:You can write a custom TypeAdapterwhich handles name, personand userjson tags and maps them to name field of your custom class MyClass:
解决办法：你可以写一个自定义的TypeAdapter负责处理name，person而userJSON标签，并将它们映射到您的自定义类的名称字段MyClass：
class MyClassTypeAdapter extends TypeAdapter<MyClass> {
@Override
public MyClass read(final JsonReader in) throws IOException {
final MyClass myClassInstance = new MyClass();
in.beginObject();
while (in.hasNext()) {
String jsonTag = in.nextName();
if ("id".equals(jsonTag)) {
myClassInstance.id = in.nextInt();
} else if ("name".equals(jsonTag)
|| "person".equals(jsonTag)
|| "user".equals(jsonTag)) {
myClassInstance.name = in.nextString();
}
}
in.endObject();
return myClassInstance;
}
@Override
public void write(final JsonWriter out, final MyClass myClassInstance)
throws IOException {
out.beginObject();
out.name("id").value(myClassInstance.id);
out.name("name").value(myClassInstance.name);
out.endObject();
}
}
Test case:
测试用例：
String jsonVal0 = "{\"id\": 5382, \"user\": \"Mary\" }";
String jsonVal1 = "{\"id\": 2341, \"person\": \"Bob\"}";
final GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(MyClass.class, new MyClassTypeAdapter());
final Gson gson = gsonBuilder.create();
MyClass myClassInstance0 = gson.fromJson(jsonVal0, MyClass.class);
MyClass myClassInstance1 = gson.fromJson(jsonVal1, MyClass.class);
System.out.println("jsonVal0 :" + gson.toJson(myClassInstance0));
// output: jsonVal0 :{"id":5382,"name":"Mary"}
System.out.println("jsonVal1 :" + gson.toJson(myClassInstance1));
// output: jsonVal1 :{"id":2341,"name":"Bob"}
Edit 2016.04.06 :As @Mathieu Castets has written at his answer, it is supported now. (That is the correct answer for this question.)
编辑 2016.04.06 ：正如@Mathieu Castets 在他的回答中所写的那样，现在支持它。（这是这个问题的正确答案。）
public abstract String[] alternate
Returns: the alternative names of the field when it is deserialized
Default: {}
public abstract String[] 替代
返回：字段反序列化时的替代名称
默认值：{}
回答by Mathieu Castets
In October 2015, Gson version 2.4(changelog) added the ability to use alternate/multiple names for @SerializedNamewhen deserializing. No more custom TypeAdapter needed!
2015 年 10 月，Gson 2.4 版( changelog) 添加了@SerializedName在反序列化时使用备用/多个名称的功能。不再需要自定义 TypeAdapter！
Usage:
用法：
@SerializedName(value="name", alternate={"person", "user"})
回答by Mostafa Anter
for Kotlinfans
对于Kotlin粉丝
@SerializedName(value="name", alternate= ["person", "user"])
回答by android
For KOTLIN i used below but doesn't work
对于我在下面使用的 KOTLIN 但不起作用
@SerializedName(value="name", alternate= ["person", "user"])
so i edited it and here it works fine!!
所以我编辑了它，在这里它工作正常！！
@SerializedName(value="name", alternate= arrayOf("person", "user"))
