英文:
Gson custom serialization for fields with custom annotation
问题
<!-- language: java -->class Demo {private String name;private int total;...}
当我使用 gson 序列化一个 Demo 对象时，在正常情况下会得到类似这样的结果：
{"name": "hello world", "total": 100}
现在，我有一个注解 @Xyz，可以添加到任何类的任何属性上。（我可以将此注解应用于任何属性，但目前如果仅限于 String 类型就可以。）
<!-- language: java -->class Demo {@Xyzprivate String name;private int total;...}
当我在类属性上使用这个注解时，序列化的数据应该符合以下格式：
{"name": {"value": "hello world", "xyzEnabled": true}, "total": 100}
请注意，无论类的类型如何，此注解都可以应用于任何（String）字段。如果我能在自定义的序列化器的 serialize 方法中获取特定字段的已声明注解，那对我来说将是有效的。
请指导如何实现这一点。
英文:
<!-- language: java -->
class Demo {private String name;private int total;...}
When I'm serializing an object of demo with gson, I'll get something like this in the normal scenario:
{"name": "hello world", "total": 100}
Now, I have an annotation @Xyz which can be added to any attribute of any class. (The attribute to which I can apply this annotation can be anything, but for now it should be okay if it is just String type )
<!-- language: java -->
class Demo {@Xyzprivate String name;private int total;...}
When I've the annotation on the class attribute, the serialized data should be of the following format:
{"name": {"value": "hello world", "xyzEnabled": true}, "total": 100}
Please note that this annotation can be applied to any (String) field regardless of the type of the class. If I could somehow get the declared annotations for that specific field on the custom serialiser serialize method, that would work for me.
Please advice how to achieve this.
答案1
得分: 6
I think you meant to use annotation JsonAdapter with your custom behaviour
这是一个示例类 Xyz，它扩展了 JsonSerializer<String>、JsonDeserializer<String>。
import com.google.gson.*;import java.lang.reflect.Type;public class Xyz implements JsonSerializer<String>, JsonDeserializer<String> {@Overridepublic JsonElement serialize(String element, Type typeOfSrc, JsonSerializationContext context) {JsonObject object = new JsonObject();object.addProperty("value", element);object.addProperty("xyzEnabled", true);return object;}@Overridepublic String deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {return json.getAsString();}}
这是一个示例用法：
import com.google.gson.annotations.JsonAdapter;public class Demo {@JsonAdapter(Xyz.class)public String name;public int total;}
我写了一些额外的测试，也许它们会帮助你解决这个问题：
import com.google.gson.Gson;import org.junit.Test;import static org.junit.Assert.assertEquals;public class Custom {@Testpublic void serializeTest() {//givenDemo demo = new Demo();demo.total = 100;demo.name = "hello world";//whenString json = new Gson().toJson(demo);//thenassertEquals("{\"name\":{\"value\":\"hello world\",\"xyzEnabled\":true},\"total\":100}", json);}@Testpublic void deserializeTest() {//givenString json = "{\"name\":\"hello world\",\"total\":100}";//whenDemo demo = new Gson().fromJson(json, Demo.class);//thenassertEquals("hello world", demo.name);assertEquals(100, demo.total);}}
请注意，以上是你提供的代码的翻译部分，没有其他内容。
英文:
I think you meant to use annotation JsonAdapter with your custom behaviour
This is a sample class Xyz which extends JsonSerializer<String>, JsonDeserializer<String>
import com.google.gson.*;import java.lang.reflect.Type;public class Xyz implements JsonSerializer<String>, JsonDeserializer<String> {@Overridepublic JsonElement serialize(String element, Type typeOfSrc, JsonSerializationContext context) {JsonObject object = new JsonObject();object.addProperty("value", element);object.addProperty("xyzEnabled", true);return object;}@Overridepublic String deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {return json.getAsString();}}
this is a sample use
import com.google.gson.annotations.JsonAdapter;public class Demo {@JsonAdapter(Xyz.class)public String name;public int total;}
I've written some more tests maybe they'll help you to solve this problem more
import com.google.gson.Gson;import org.junit.Test;import static org.junit.Assert.assertEquals;public class Custom {@Testpublic void serializeTest() {//givenDemo demo = new Demo();demo.total = 100;demo.name = "hello world";//whenString json = new Gson().toJson(demo);//thenassertEquals("{\"name\":{\"value\":\"hello world\",\"xyzEnabled\":true},\"total\":100}", json);}@Testpublic void deserializeTest() {//givenString json = "{ \"name\": \"hello world\", \"total\": 100}";//whenDemo demo = new Gson().fromJson(json, Demo.class);//thenassertEquals("hello world", demo.name);assertEquals(100, demo.total);}}
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