[BUG] jackson的注解和fastjson的注解有些冲突，并且不同顺序表现不一致

[yimik]

问题描述

有个类，同时增加了自定义序列化的注解如下

@JsonSerialize(using = MyJacksonSerializer.class)
@JSONType(serializer = MyFastjsonSerializer.class)

此顺序下，fastjson和jackson均可以正常序列化

改为如下

@JSONType(serializer = MyFastjsonSerializer.class)
@JsonSerialize(using = MyJacksonSerializer.class)

此顺序下，jackson序列化正常，json自定义序列化失效，貌似走了默认序列化

环境信息

请填写以下信息：

• OS信息： Win11
• JDK信息： OpenJDK 17
• 版本信息：Fastjson2 2.0.41

[wenshao]

能帮构造重现问题的testcase么？

[yimik]

能帮构造重现问题的testcase么？

写了个可以重现的demo

DemoBean

package com.example.json;

import com.alibaba.fastjson2.annotation.JSONType;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import lombok.Data;

import java.util.Map;

@Data
@JsonSerialize(using = DemoJacksonSerializer.class)
@JSONType(serializer = DemoFastJsonSerializer.class)
// 下方注释为调换顺序后，结果异常
// @JSONType(serializer = DemoFastJsonSerializer.class)
// @JsonSerialize(using = DemoJacksonSerializer.class)
public class DemoBean {

    private String type;

    private Map<String, Object> map;
}

JacksonSerializer

package com.example.json;


import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;

import java.io.IOException;
import java.util.Map;

public class DemoJacksonSerializer extends JsonSerializer<DemoBean> {
    @Override
    public void serialize(DemoBean demoBean, JsonGenerator gen, SerializerProvider serializers) throws IOException {
        gen.writeStartObject();
        for (Map.Entry<String, Object> entry : demoBean.getMap().entrySet()) {
            gen.writeFieldName(entry.getKey());
            gen.writeObject(entry.getValue());
        }
        gen.writeEndObject();
    }
}

FastJsonSerializer

package com.example.json;


import com.alibaba.fastjson2.JSONWriter;
import com.alibaba.fastjson2.writer.ObjectWriter;

import java.lang.reflect.Type;
import java.util.Map;


public class DemoFastJsonSerializer implements ObjectWriter<DemoBean> {
    @Override
    public void write(JSONWriter jsonWriter, Object object, Object fieldName, Type fieldType, long features) {
        jsonWriter.startObject();
        DemoBean demoBean = (DemoBean) object;
        for (Map.Entry<String, Object> entry : demoBean.getMap().entrySet()) {
            jsonWriter.writeName(entry.getKey());
            jsonWriter.writeColon();
            jsonWriter.writeAny(entry.getValue());
        }
        jsonWriter.endObject();
    }
}

测试类

package com.example.json;

import com.alibaba.fastjson.JSON;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.json.JsonMapper;
import org.junit.jupiter.api.Test;

import java.util.Map;


class JsonTest {


    @Test
    public void test() throws JsonProcessingException {
        DemoBean demoBean = new DemoBean();
        demoBean.setType("test");
        demoBean.setMap(Map.of("a", 1));

        // 期望结果：{"a":1}

        System.out.println(JSON.toJSONString(demoBean));

        JsonMapper mapper = new JsonMapper();

        System.out.println(mapper.writeValueAsString(demoBean));
    }
}

执行结果：

上述代码执行结尾如下
{"a":1}
{"a":1}

将DemoBean中注释放开（即调换注解顺序）执行结果如下：
{"map":{"a":1},"type":"test"}
{"a":1}

[wenshao]

https://oss.sonatype.org/content/repositories/snapshots/com/alibaba/fastjson/2.0.42-SNAPSHOT/
问题已修复，请帮忙用2.0.42-SNAPSHOT版本验证，正式版本预计今晚发布。

[wenshao]

https://github.com/alibaba/fastjson2/releases/tag/2.0.42
问题已修复，请用新版本

[wwulfric]

借着issue咨询一下，fastjson2能否兼容掉jackson的序列化反序列化注解JsonDeserialize JsonSerialize