【需求】支持按照成员变量声明顺序，做序列化字段排序 #3115

yl-yue · 2020-04-06T05:48:37Z

目前FastJson采用的是按字母排序，和@JSONField注解实现自定义排序，是否可以考虑支持一下同toString()方法一样采用成员变量声明顺序做序列化字段排序 @wenshao

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yl-yue · 2020-04-06T06:08:47Z

关联 Issues
#728 #1214 #1224 #1777 #1859 #1995 #2107 #2524 #2594 #2961 #3054
@wenshao 望添加一个这样的需求支持，感谢。

yl-yue · 2020-04-06T06:13:01Z

/**
 * @author	ylyue
 * @since	2020年4月5日
 */
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
	
	/**
	 * <p>使用FastJson优先于默认的Jackson做json解析
	 * <p>https://github.com/alibaba/fastjson/wiki/%E5%9C%A8-Spring-%E4%B8%AD%E9%9B%86%E6%88%90-Fastjson
	 */
	@Override
	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
		FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();
		FastJsonConfig config = new FastJsonConfig();
		config.setDateFormat(JSON.DEFFAULT_DATE_FORMAT);
//		config.setFeatures(Feature.OrderedField);
//		config.setFeatures(Feature.SortFeidFastMatch);
		config.setSerializerFeatures(
//				SerializerFeature.SortField,
//				SerializerFeature.MapSortField,
				SerializerFeature.PrettyFormat, 
				SerializerFeature.BrowserCompatible, 
				SerializerFeature.WriteMapNullValue, 
				SerializerFeature.WriteNullBooleanAsFalse,
				SerializerFeature.WriteNullListAsEmpty, 
				SerializerFeature.WriteNullNumberAsZero,
				SerializerFeature.WriteNullStringAsEmpty
		);
		converter.setFastJsonConfig(config);
		converters.add(0, converter);
	}
    
}

在测试FastJson优先于默认的Jackson做消息转换器时，发现不能实现按照成员变量声明顺序做序列化字段排序，所产生的需求。
Jackson的默认排序规则就是：按照成员变量声明顺序做序列化字段排序

wenshao · 2020-05-04T15:47:16Z

https://github.com/alibaba/fastjson/wiki/guid_to_migrating_from_jackson_to_fastjson_cn

xuqiming · 2020-08-17T17:18:23Z

把默认的SortField剔除可解决这个问题
JSON.DEFAULT_GENERATE_FEATURE = JSON.DEFAULT_GENERATE_FEATURE &~ SerializerFeature.SortField.getMask();

yl-yue · 2020-09-10T08:33:18Z

把默认的SortField剔除可解决这个问题
JSON.DEFAULT_GENERATE_FEATURE = JSON.DEFAULT_GENERATE_FEATURE &~ SerializerFeature.SortField.getMask();

感谢你提供的方法，但设置了之后，并非按照声明的成员变量顺序进行排序，好像会变成无规律可循了。

测试代码

声明成员变量如下：

public class FastJsonHttpMessageConverterDTO {

	int inta;
	Integer intb;
	long longa;
	Long longb;
	boolean booleana;
	Boolean booleanb;
	String str;
	Map<?, ?> map;
	Map<?, ?> map2;
	JSONObject jsonObject;
	JSONObject jsonObject2;
	String[] arrayStr;
	long[] arrayLong;
	List<?> list;
	List<?> list2;
	TestEnum testEnum;
	Date date;
	DateTime dateTime;
	LocalDate localDate;
	LocalTime localTime;
	LocalDateTime localDateTime;
	
}

jackson响应结果：

{
    "code": 200,
    "msg": "成功",
    "flag": true,
    "count": 0,
    "data": {
        "inta": 0,
        "intb": 0,
        "longa": 0,
        "longb": 0,
        "booleana": false,
        "booleanb": null,
        "str": "",
        "map": {},
        "map2": {},
        "jsonObject": {},
        "jsonObject2": {},
        "arrayStr": [],
        "arrayLong": [],
        "list": [],
        "list2": [
            null,
            null,
            "",
            null
        ],
        "testEnum": null,
        "date": null,
        "dateTime": null,
        "localDate": null,
        "localTime": null,
        "localDateTime": null
    }
}

fastjson响应结果

{
    "code": 200,
    "msg": "成功",
    "flag": true,
    "count": null,
    "data": {
        "arrayLong": [],
        "arrayStr": [],
        "booleana": false,
        "booleanb": null,
        "date": null,
        "dateTime": null,
        "inta": 0,
        "intb": null,
        "jsonObject": {},
        "jsonObject2": {},
        "list": [],
        "list2": [
            null,
            null,
            "",
            null
        ],
        "localDate": null,
        "localDateTime": null,
        "localTime": null,
        "longa": 0,
        "longb": null,
        "map": {},
        "map2": {},
        "str": "",
        "testEnum": null
    }
}

设置之后的响应结果：

{
    "code": 200,
    "msg": "成功",
    "flag": true,
    "count": null,
    "data": {
        "map": {},
        "date": null,
        "map2": {},
        "jsonObject2": {},
        "arrayLong": [],
        "list": [],
        "list2": [
            null,
            null,
            "",
            null
        ],
        "jsonObject": {},
        "arrayStr": [],
        "inta": 0,
        "intb": null,
        "booleana": false,
        "longa": 0,
        "longb": null,
        "booleanb": null,
        "localTime": null,
        "testEnum": null,
        "dateTime": null,
        "localDate": null,
        "localDateTime": null,
        "str": ""
    }
}

xuqiming · 2020-09-10T16:14:44Z

@yl-yue
很抱歉我的回答给你带来了困扰，我引用你的示例代码做了一下测试。

    public static void main(String[] args) {
        FastJsonHttpMessageConverterDTO converterDTO = new FastJsonHttpMessageConverterDTO();

        JSON.DEFAULT_GENERATE_FEATURE = JSON.DEFAULT_GENERATE_FEATURE &~ SerializerFeature.SortField.getMask();
        System.out.println(JSON.toJSONString(converterDTO, SerializerFeature.PrettyFormat,
                SerializerFeature.WriteMapNullValue));

    }

    public static class FastJsonHttpMessageConverterDTO {

        public int inta;
        public Integer intb;
        public long longa;
        public Long longb;
        public boolean booleana;
        public Boolean booleanb;
        public String str;
        public Map<?, ?> map;
        public Map<?, ?> map2;
        public JSONObject jsonObject;
        public JSONObject jsonObject2;
        public String[] arrayStr;
        public long[] arrayLong;
        public List<?> list;
        public List<?> list2;
        public Date date;
        public DateTime dateTime;
        public LocalDate localDate;
        public LocalTime localTime;
        public LocalDateTime localDateTime;

    }

运行的结果

{
	"inta":0,
	"intb":null,
	"longa":0,
	"longb":null,
	"booleana":false,
	"booleanb":null,
	"str":null,
	"map":null,
	"map2":null,
	"jsonObject":null,
	"jsonObject2":null,
	"arrayStr":null,
	"arrayLong":null,
	"list":null,
	"list2":null,
	"date":null,
	"dateTime":null,
	"localDate":null,
	"localTime":null,
	"localDateTime":null
}

是可以按顺序输出的，但里面有一个前提，就是必须加上SerializerFeature.PrettyFormat，具体为什么我还没有具体去研究。抱歉我的疏忽给你带来了困扰。

这样做虽然可以保持顺序，但是不确定会不会带来其他的问题，所以这并不是一个标准的解决方案。

yl-yue · 2020-09-14T07:58:12Z

@xuqiming 不太确定是否是版本原因，我本地是1.2.73。
我测试了不管是在HttpMessageConverter中或者之间JSON.toJSONString中，顺序都是我上面描述的那样。

需要按照成员变量声明顺序排序，主要还是因为想使用FastJsonHttpMessageConverter替换MappingJackson2HttpMessageConverter。这样返回给前端的参数顺序是可控的，方便文档抒写与查看。

实际操作使用json并不关心顺序

tidus5 · 2020-11-24T09:53:23Z

经过测试。结论如下：
在gson和jackson 默认都是按字段定义顺序来序列化
fastjson版本1.2.73
如果bean 没有getter/setter，禁用 SerializerFeature.SortField.getMask() 之后，序列化会按照定义顺序。
但如果 bean 有getter/setter，禁用 SerializerFeature.SortField.getMask() 之后，序列化随机乱序。

没有getter/setter 时，TypeUtils.computeGetters():1858 这里获取不到getter方法，然后到2168行获取fields数组。
这里获取fields数组，~~和字段定义顺序是一致的~~。所以序列化出来也会按照定义顺序。
订正：根据 https://stackoverflow.com/questions/1097807/java-reflection-is-the-order-of-class-fields-and-methods-standardized
clazz.getFields() 和clazz.getMethods() 都是无序的。。。所以这里field和定义顺序一致只是个偶然。

但如果有getter/setter ，代码走到上面这处，根据map遍历结果来决定字段序列化顺序，这导致禁用排序后，每次序列化出来的顺序就是LinkedHashMap的插入顺序。而这个map插入顺序，是按 clazz.getMethods() 返回来遍历的，而这个返回每次顺序不确定。

然后在 2173行 getFieldInfos()
走到在 com.alibaba.fastjson.util.TypeUtils 的 2197行。就会按照linkedHashMap遍历顺序，生成fieldInfoList.

            for(FieldInfo fieldInfo : fieldInfoMap.values()){
                fieldInfoList.add(fieldInfo);
            }
            if(sorted){
                Collections.sort(fieldInfoList);
            }

tidus5 · 2020-11-24T10:58:45Z

再补充一下，gson和jackson为什么实现会和字段的定义顺序一致。
基本都是使用了 getDeclaredFields 来作为字段序列化的顺序的

Gson 2.8.6   com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields():152
Field[] fields = raw.getDeclaredFields();

jackson-databind-2.11.3   com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector.collectAll():322
- POJOPropertiesCollector._addFields():393
...
- com.fasterxml.jackson.databind.introspect.AnnotatedFieldCollector.collect():48
- com.fasterxml.jackson.databind.introspect.AnnotatedFieldCollector._findFields():73
cls.getDeclaredFields()

rilyu · 2021-01-27T11:16:49Z

在网上搜了很久都无法解决，最终通过单步跟踪分析代码找到了解决办法，我这里是正确的:

JSON.DEFAULT_GENERATE_FEATURE &= ~SerializerFeature.SortField.getMask();
SerializeConfig serializeConfig = new SerializeConfig(true);
System.out.println(JSON.toJSONString(javaObject, serializeConfig));

yl-yue · 2021-01-29T10:20:08Z

@rilyu 感谢提供有效示例，已测试通过。改天对排序与不排序的性能进行测试下

panmaze · 2022-07-06T08:55:32Z

@rilyu 感谢,找了好久

yumo1g · 2022-08-18T03:33:55Z

**rilyu ** commented on 27 Jan 2021

100w次测试，性能呈千倍级下降啊

ArronYR · 2024-10-22T13:20:50Z

在网上搜了很久都无法解决，最终通过单步跟踪分析代码找到了解决办法，我这里是正确的:
JSON.DEFAULT_GENERATE_FEATURE &= ~SerializerFeature.SortField.getMask();
SerializeConfig serializeConfig = new SerializeConfig(true);
System.out.println(JSON.toJSONString(javaObject, serializeConfig));

<dependency>
	<groupId>com.alibaba</groupId>
	<artifactId>fastjson</artifactId>
	<version>2.0.21</version>
</dependency>

2.0.21 按照这个方法也不行

public class Test {

    public static void main(String[] args) {
        B b = new B();
        b.setStart("1");
        b.setEnd("2");
        b.setName("3");

        ArrayList<B> list = new ArrayList<>();
        list.add(b);

        A a = new A();
        a.setList(list);

        JSON.DEFAULT_GENERATE_FEATURE &= ~SerializerFeature.SortField.getMask();
        SerializeConfig serializeConfig = new SerializeConfig(true);
        System.out.println(JSON.toJSONString(a, serializeConfig));
    }

    @Data
    static class B {
        private String start;
        private String end;
        private String name;
    }

    @Data
    static class A {
        private List<B> list;
    }
}

得到的还是

{"list":[{"end":"2","name":"3","start":"1"}]}

cloudlessa mentioned this issue Sep 11, 2024

fastjson tojsonString 序列化对象顺序被打乱 alibaba/fastjson2#1202

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【需求】支持按照成员变量声明顺序，做序列化字段排序 #3115

【需求】支持按照成员变量声明顺序，做序列化字段排序 #3115

yl-yue commented Apr 6, 2020

yl-yue commented Apr 6, 2020

yl-yue commented Apr 6, 2020

wenshao commented May 4, 2020

xuqiming commented Aug 17, 2020

yl-yue commented Sep 10, 2020 •

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xuqiming commented Sep 10, 2020 •

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yl-yue commented Sep 14, 2020

tidus5 commented Nov 24, 2020 •

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tidus5 commented Nov 24, 2020 •

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rilyu commented Jan 27, 2021

yl-yue commented Jan 29, 2021

panmaze commented Jul 6, 2022

yumo1g commented Aug 18, 2022

ArronYR commented Oct 22, 2024

【需求】支持按照成员变量声明顺序，做序列化字段排序 #3115

【需求】支持按照成员变量声明顺序，做序列化字段排序 #3115

Comments

yl-yue commented Apr 6, 2020

yl-yue commented Apr 6, 2020

yl-yue commented Apr 6, 2020

wenshao commented May 4, 2020

xuqiming commented Aug 17, 2020

yl-yue commented Sep 10, 2020 • edited Loading

测试代码

xuqiming commented Sep 10, 2020 • edited Loading

yl-yue commented Sep 14, 2020

tidus5 commented Nov 24, 2020 • edited Loading

tidus5 commented Nov 24, 2020 • edited Loading

rilyu commented Jan 27, 2021

yl-yue commented Jan 29, 2021

panmaze commented Jul 6, 2022

yumo1g commented Aug 18, 2022

ArronYR commented Oct 22, 2024

yl-yue commented Sep 10, 2020 •

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xuqiming commented Sep 10, 2020 •

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tidus5 commented Nov 24, 2020 •

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