我在使用 GsonBuilder 注册多个 typeAdapter 时遇到问题。似乎只有一个会开火，而从不考虑第二个。如果我一个人做每一个，它似乎工作得很好。但我需要他们与两者一起工作，似乎我做错了什么。另外我目前正在使用 GSON v2.2.4。
Zip Object 简单形式：
public class Zip {
private String zipCode;
private String city;
private String state;
public Zip(){}
}
ZipSerializer：
public class ZipSerializer implements JsonSerializer<Zip>{
@Override
public JsonElement serialize(Zip obj, Type type, JsonSerializationContext jsc) {
Gson gson = new Gson();
JsonObject jObj = (JsonObject)gson.toJsonTree(obj);
jObj.remove("state");
return jObj;
}
}
JsonResponse 对象简单形式：
public class JsonResponse {
private String jsonrpc = "2.0";
private Object result = null;
private String id = null;
public JsonResponse(){}
}
JsonResponseSerializer：
public class JsonResponseSerializer implements JsonSerializer<JsonResponse> {
@Override
public JsonElement serialize(JsonResponse obj, Type type, JsonSerializationContext jsc) {
Gson gson = new Gson();
JsonObject jObj = (JsonObject)gson.toJsonTree(obj);
jObj.remove("id");
return jObj;
}
}
测试示例：
public class Test {
public static void main(String[] args) {
Zip zip = new Zip();
zip.setCity("testcity");
zip.setState("OH");
zip.setZipCode("12345");
JsonResponse resp = new JsonResponse();
resp.setId("1");
resp.setResult(zip);
resp.setJsonrpc("2.0");
Gson gson1 = new GsonBuilder()
.registerTypeAdapter(JsonResponse.class, new JsonResponseSerializer())
.registerTypeAdapter(Zip.class, new ZipSerializer())
.setPrettyPrinting()
.create();
String json = gson1.toJson(resp);
System.out.println(json);
}
}
输出：
{
"jsonrpc": "2.0",
"result": {
"zipCode": "12345",
"city": "testcity",
"state": "OH"
}
}
预期输出：（注意 ZipSerializer 没有启动）
{
"jsonrpc": "2.0",
"result": {
"zipCode": "12345",
"city": "testcity"
}
}
我为此简化了测试用例。我知道我可以在这个例子中使用 excludeStrategy 来获得结果，但真正的问题要复杂得多，这是我描述和复制我的问题的最佳方式。
谢谢
<---------------------------- 解决方案-------- ------------>
我设法使用 TypeAdapter 为对象中的一个（多个）变量读取 Gson 自定义序列化程序，它对我有很大帮助。
我创建了一个基本的 customTypeAdapterFactory，然后为每个需要特殊序列化的类扩展它。
CustomizedTypeAdapterFactory
public abstract class CustomizedTypeAdapterFactory<C> implements TypeAdapterFactory {
private final Class<C> customizedClass;
public CustomizedTypeAdapterFactory(Class<C> customizedClass) {
this.customizedClass = customizedClass;
}
@SuppressWarnings("unchecked") // we use a runtime check to guarantee that 'C' and 'T' are equal
public final <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
return type.getRawType() == customizedClass
? (TypeAdapter<T>) customizeMyClassAdapter(gson, (TypeToken<C>) type)
: null;
}
private TypeAdapter<C> customizeMyClassAdapter(Gson gson, TypeToken<C> type) {
final TypeAdapter<C> delegate = gson.getDelegateAdapter(this, type);
final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
return new TypeAdapter<C>() {
@Override public void write(JsonWriter out, C value) throws IOException {
JsonElement tree = delegate.toJsonTree(value);
beforeWrite(value, tree);
elementAdapter.write(out, tree);
}
@Override public C read(JsonReader in) throws IOException {
JsonElement tree = elementAdapter.read(in);
afterRead(tree);
return delegate.fromJsonTree(tree);
}
};
}
/**
* Override this to muck with {@code toSerialize} before it is written to
* the outgoing JSON stream.
*/
protected void beforeWrite(C source, JsonElement toSerialize) {
}
/**
* Override this to muck with {@code deserialized} before it parsed into
* the application type.
*/
protected void afterRead(JsonElement deserialized) {
}
}
ZipTypeAdapterFactory（使用 JsonResponseTypeAdapterFactory 做到这一点）
public class ZipTypeAdapterFactory extends CustomizedTypeAdapterFactory<Zip> {
ZipTypeAdapterFactory() {
super(Zip.class);
}
@Override
protected void beforeWrite(Zip source, JsonElement toSerialize) {
JsonObject obj = (JsonObject) toSerialize;
obj.remove("state");
}
}
测试代码：
Gson gson1 = new GsonBuilder()
.registerTypeAdapterFactory(new JsonResponseTypeAdapterFactory())
.registerTypeAdapterFactory(new ZipTypeAdapterFactory())
.setPrettyPrinting()
.create();
String json = gson1.toJson(resp);
System.out.println(json);
谢谢大家的帮助。