fastjson Request passing context information to plugins

lsmd5eda 于 5个月前发布在其他

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For the following code:

public class Record {

    @JSONField(format = "yyyy-MMM-dd")
    public Date date1 = new Date();

    @JSONField(format = "yyyyMMdd")
    public Date date2 = date1;

    @JSONField(format = "yyyy_MM_dd hh:mm")
    public DateTime dateTime = DateTime.now();
}
``

and I use FastJSON to serialize the `Record` instance as:

```java
System.out.println(JSON.toJSONString(new Record()));

I will get something like:

{
	"date1":"2018-Jan-06",
	"date2":"20180106",
	"dateTime":{
		"afterNow":false,
		"beforeNow":true,
		"centuryOfEra":20,
		"chronology":{
			"zone":{
				"fixed":false,
				"iD":"Australia/Sydney",
                ...
			}
		},
        ...
		"zone":{"$ref":"$.null.chronology.zone"}
	}
}

Obviously fastjson doesn't support serialization of joda DateTime type. thus I want to create my own ObjecSerializer to implement that, here is something I can write:

public class JodaDateTimeSerializer implements ObjectSerializer {
    @Override
    public void write(
        JSONSerializer serializer, 
        Object object, 
        Object fieldName, 
        Type fieldType, 
        int features
    ) throws IOException {
        SerializeWriter out = serializer.getWriter();
        if (object == null) {
            out.writeNull();
        } else {
            Class cls = object.getClass();
            if (cls == DateTime.class) {
                // question? where can I get the JSONView annotation and the format string?
                out.writeString(object.toString());
            } else {
                out.writeString(object.toString());
            }
        }
    }
}

As it shown above my problem here is I lost the context of the serialization, the interface doesn't pass me the field context, say the @JSONView annotation and the format.

The request is to extend the ObjectSerializer and ObjectDeserializer interface so we can get the field class in order to get the context information, specifically all annotations put on that field.

fastjson

来源：https://github.com/alibaba/fastjson/issues/1691

9条答案

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44u64gxh1#

Note, when I won't be able to get fieldType and fieldName information:

As the caller method passed null for those fields:

If I go further upper level caller the writeWithFormat I can see there is the format string, but it's not get passed into the next call:

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fd3cxomn2#

DateTime is not a builtin class in JDK，
If you created it, so you could registry a Serializer for it.

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unftdfkk3#

@kimmking that's all what I mean, I have created the serializer, however I need to access the field context in the serializer, e.g. I need to know if there is a @JSONView annotation with format parameter set to something like "yyyy_MM_dd hh:mm" , so that I can serialize the DateTime data property:

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cnjp1d6j4#

fastjson dont know the type DateTime is a date type.

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6ovsh4lw5#

SerializeConfig.getGlobalInstance().put(DateTime .class, new DateCodec ());

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7vhp5slm6#

@kimmking I said I have the codec for DateTime if you read my issue report carefully:

I know exactly what SerializeConfig.getGlobalInstance() does, and I use it in my app already: https://github.com/actframework/actframework/blob/master/src/main/java/act/util/JsonUtilConfig.java

My question is how can I access the field context @JSONField(format="yyyy-MM-dd hh:mm") from within the codec.

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vaj7vani7#

I consider this as a bug.
The build-in support for JDK8 java.time package is also not effected by format field.

see getPropertyValue() in fastjson/src/main/java/com/alibaba/fastjson/serializer/FieldSerializer.java

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xtfmy6hx8#

@wenshao what do you think about this one?

Now I have a concrete use case from our real project.

// the tooth care kit 
public class Kit {
    public int id;
    public String description;
    ...
}

// the order info encapsulate kit and quantity
public class OrderInfo {
    @DbBind @NotNull
    public Kit kit;
    public int qty;
}

// The request handler
@PostAction("orders")
public void placeKitOrders(List<OrderInfo> orders) {
    ....
}

// the JSON body for order request

{
    "orders": [
        {"kit": 1, "qty": 3}, {"kit": 2, "qty": 5}
    ]
}

Here one important thing is I need to use the kit id (in the above sample data, 1 and 2 ) to look up Kit table and fetch the corresponding record to construct a Kit instance and inject into the OrderInfo instance. Thus I need FastJSON to provide the mechanism for me to inject logic sense the annotation DbBind and get the job done.

Any idea if this could be doable(planned) in FastJSON ?

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h4cxqtbf9#

This issue is been solved as(using kimmking‘s solution’) :

FastJsonJodaDateCodec jodaDateCodec = new FastJsonJodaDateCodec(app);
        app.registerSingleton(FastJsonJodaDateCodec.class, jodaDateCodec);

        FastJsonValueObjectSerializer valueObjectSerializer = new FastJsonValueObjectSerializer();
        app.registerSingleton(FastJsonValueObjectSerializer.class, valueObjectSerializer);
        FastJsonKeywordCodec keywordCodec = new FastJsonKeywordCodec();
        FastJsonSObjectCodec sObjectCodec = new FastJsonSObjectCodec();

        config.put(DateTime.class, jodaDateCodec);

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fastjson Request passing context information to plugins

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