[英]How to do custom serialization/deserialization using JACKSON?
我試圖將以下gson序列化轉換為JACKSON序列化。 請讓我知道我需要更改什么才能讓它適用於JACKSON
public class AbstractElementAdapter
implements JsonSerializer<AbstractElement>, JsonDeserializer<AbstractElement>
{
@Override
public JsonElement serialize(AbstractElement src, Type typeOfSrc, JsonSerializationContext context) {
JsonObject result = new JsonObject();
JsonObject properties = context.serialize(src, src.getClass()).getAsJsonObject();
if (src instanceof TruncatedElement) {
result.add("type", new JsonPrimitive(((TruncatedElement) src).getClassName()));
properties.remove("className");
} else {
result.add("type", new JsonPrimitive(src.getClass().getSimpleName()));
}
result.add("properties", properties);
return result;
}
@Override
public AbstractElement deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
JsonObject jsonObject = json.getAsJsonObject();
String type = jsonObject.get("type").getAsString();
JsonElement element = jsonObject.get("properties");
try {
return context.deserialize(element, Class.forName("com.zreflect.emyed.whiteboard.model.element." + type));
} catch (ClassNotFoundException cnfe) {
throw new JsonParseException("Unknown element type: " + type, cnfe);
}
}
}
您可以創建自定義序列化程序,如下所示:
public class ItemSerializer extends JsonSerializer<AbstractElement> {
@Override
public void serialize(AbstractElement src, JsonGenerator jgen, SerializerProvider provider)
throws IOException, JsonProcessingException {
jgen.writeStartObject();
if (src instanceof TruncatedElement) {
jgen.writeStringField("type",((TruncatedElement) src).getClassName());
jgen.writeObjectFieldStart("properties");
//use jgen.writeStringField();
//jgen.writeNumberField();
//etc to every one of the values,
//but skipping className
jgen.writeEndObject();
} else {
jgen.writeStringField("type", src.getClass().getSimpleName() );
//write everythin
jgen.writeObjectField("properties", src);
}
jgen.writeEndObject();
}
}
並使用ObjectMapper注冊它,然后進行序列化:
ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.addSerializer(yourObject.class, new ItemSerializer());
mapper.registerModule(module);
String serialized = mapper.writeValueAsString(yourObject);
對於跳過className
的技巧,您可能還想使用自定義字段過濾器,這里有一個很好的例子: http : //www.baeldung.com/jackson-ignore-properties-on-serialization
Jackson允許您通過注釋指定序列化程序。 例如,請參閱下面的簡單示例:
@JsonSerialize(using FooToStringSerializer)
public class Foo implements Serializable {
private String bar;
public Foo(String bar) {
this.bar = bar;
}
然后,如果所有我想要查看對象序列化的時間是bar
,我會像這樣創建序列化器:
public class FooToStringSerializer extends JsonSerializer<Foo> {
@Override
public void serialize(final Foo value, final JsonGenerator jgen,
final SerializerProvider provider) throws IOException
{
jgen.writeObject(value.getBar());
}
對於反序列化,您可以創建反序列化器並將其與將要執行反序列化的ObjectMapper
一起注冊。
要使用對象映射器注冊反序列化器,請執行以下操作:
ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.addDeserializer(Item.class, new FooDeserializer());
mapper.registerModule(module);
有關自定義反序列化的簡單示例,請參閱以下鏈接: http : //www.baeldung.com/jackson-deserialization
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