Detailed explanation of fastjson SerializerFeature

@see https://blog.csdn.net/u010246789/article/details/52539576

rely

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.7</version>
        </dependency>

SerializerFeature property

name	meaning	Remark
QuoteFieldNames	Whether to use double quotes when outputting the key, the default is true
UseSingleQuotes	use single quotes instead of double quotes, defaults to false
WriteMapNullValue	Whether to output a field whose value is null, the default is false
WriteEnumUsingToString	Enum outputs name() or original, default is false
UseISO8601DateFormat	Date is output in ISO8601 format, the default is false
WriteNullListAsEmpty	If the List field is null, the output is [] instead of null
WriteNullStringAsEmpty	If the character type field is null, the output is "" instead of null
WriteNullNumberAsZero	If the value field is null, the output is 0, not null
WriteNullBooleanAsFalse	If the Boolean field is null, the output is false, not null
SkipTransientField	If it is true, the Field corresponding to the Get method in the class is transient, which will be ignored during serialization. Defaults to true
SortField	Output sorted by field name. Default is false
WriteTabAsSpecial	Make \t escape output, the default is false	不推荐
PrettyFormat	Whether the result is formatted, the default is false
WriteClassName	Write type information when serializing, default is false. deserialization is required
DisableCircularReferenceDetect	Eliminates problems with circular references to the same object, defaults to false
WriteSlashAsSpecial	Escape the slash '/'
BrowserCompatible	The Chinese will be serialized into \uXXXX format, the number of bytes will be more, but it is compatible with IE 6, the default is false
WriteDateUseDateFormat	Globally modify the date format, the default is false. JSON.DEFFAULT_DATE_FORMAT = "yyyy-MM-dd";JSON.toJSONString(obj, SerializerFeature.WriteDateUseDateFormat);
DisableCheckSpecialChar	If there are special characters such as double quotes in the string property of an object, it will be converted to json with a backslash transfer character. If escaping is not required, this property can be used. Default is false
NotWriteRootClassName	meaning
BeanToArray	Convert object to array output
WriteNonStringKeyAsString	meaning
NotWriteDefaultValue	meaning
BrowserSecure	meaning
IgnoreNonFieldGetter	meaning
WriteEnumUsingName	meaning

Example

Prepare

• User, Word to simulate various data types.
• SerializerFeatureTest: Example method for JSON partial example.

User type: default get, set method

public class User {

    private int id;
    private String name;
    private String add;
    private String old;
    }

Word type: default get, set method

public class Word {

    private String d;
    private String e;
    private String f;
    private String a;
    private int b;
    private boolean c;
    private Date date;
    private Map<String , Object> map;
    private List<User> list;
    }

SerializerFeatureTest: Test class

public class SerializerFeatureTest {

    private static Word word;

    private static void init() {
        word = new Word();
        word.setA("a");
        word.setB(2);
        word.setC(true);
        word.setD("d");
        word.setE("");
        word.setF(null);
        word.setDate(new Date());

        List<User> list = new ArrayList<User>();
        User user1 = new User();
        user1.setId(1);
        user1.setOld("11");
        user1.setName("用户1");
        user1.setAdd("北京");
        User user2 = new User();
        user2.setId(2);
        user2.setOld("22");
        user2.setName("用户2");
        user2.setAdd("上海");
        User user3 = new User();
        user3.setId(3);
        user3.setOld("33");
        user3.setName("用户3");
        user3.setAdd("广州");

        list.add(user3);
        list.add(user2);
        list.add(null);
        list.add(user1);

        word.setList(list);

        Map<String , Object> map = new HashedMap();
        map.put("mapa", "mapa");
        map.put("mapo", "mapo");
        map.put("mapz", "mapz");
        map.put("user1", user1);
        map.put("user3", user3);
        map.put("user4", null);
        map.put("list", list);
        word.setMap(map);
    }

    public static void main(String[] args) {
        init();
//        useSingleQuotes();
//        writeMapNullValue();
//        useISO8601DateFormat();
//        writeNullListAsEmpty();
//        writeNullStringAsEmpty();
//        sortField();
//        prettyFormat();
//        writeDateUseDateFormat();
//        beanToArray();
        showJsonBySelf();
    }

    /**
     * 9:自定义
     * 格式化输出
     * 显示值为null的字段
     * 将为null的字段值显示为""
     * DisableCircularReferenceDetect:消除循环引用
     */
    private static void showJsonBySelf() {
        System.out.println(JSON.toJSONString(word));
        System.out.println(JSON.toJSONString(word, SerializerFeature.PrettyFormat,
                SerializerFeature.WriteMapNullValue, SerializerFeature.WriteNullStringAsEmpty,
                SerializerFeature.DisableCircularReferenceDetect,
                SerializerFeature.WriteNullListAsEmpty));
    }

    /**
     * 8:
     * 将对象转为array输出
     */
    private static void beanToArray() {
        word.setMap(null);
        word.setList(null);
        System.out.println(JSON.toJSONString(word));
        System.out.println(JSON.toJSONString(word, SerializerFeature.BeanToArray));
    }

    /**
     * 7:
     * WriteDateUseDateFormat:全局修改日期格式,默认为false。
     */
    private static void writeDateUseDateFormat() {
        word.setMap(null);
        word.setList(null);
        System.out.println(JSON.toJSONString(word));
        JSON.DEFFAULT_DATE_FORMAT = "yyyy-MM-dd";
        System.out.println(JSON.toJSONString(word, SerializerFeature.WriteDateUseDateFormat));
    }

    /**
     * 6:
     * PrettyFormat
     */
    private static void prettyFormat() {
        word.setMap(null);
        word.setList(null);
        System.out.println(JSON.toJSONString(word));
        System.out.println(JSON.toJSONString(word, SerializerFeature.PrettyFormat));
    }

    /**
     * SortField:按字段名称排序后输出。默认为false
     * 这里使用的是fastjson：为了更好使用sort field martch优化算法提升parser的性能，fastjson序列化的时候，
     * 缺省把SerializerFeature.SortField特性打开了。
     * 反序列化的时候也缺省把SortFeidFastMatch的选项打开了。
     * 这样，如果你用fastjson序列化的文本，输出的结果是按照fieldName排序输出的，parser时也能利用这个顺序进行优化读取。
     * 这种情况下，parser能够获得非常好的性能。
     */
    private static void sortField() {
        System.out.println(JSON.toJSONString(word));
        System.out.println(JSON.toJSONString(word, SerializerFeature.SortField));
    }

    /**
     *  5:
     *  WriteNullStringAsEmpty:字符类型字段如果为null,输出为"",而非null
     *  需要配合WriteMapNullValue使用，现将null输出
     */
    private static void writeNullStringAsEmpty() {
        word.setE(null);
        System.out.println(JSONObject.toJSONString(word));
        System.out.println("设置WriteMapNullValue后：");
        System.out.println(JSONObject.toJSONString(word, SerializerFeature.WriteMapNullValue));
        System.out.println("设置WriteMapNullValue、WriteNullStringAsEmpty后：");
        System.out.println(JSONObject.toJSONString(word, SerializerFeature.WriteMapNullValue, SerializerFeature.WriteNullStringAsEmpty));
    }


    /**
     * 4:
     * WriteNullListAsEmpty:List字段如果为null,输出为[],而非null
     * 需要配合WriteMapNullValue使用，现将null输出
     */
    private static void writeNullListAsEmpty() {
        word.setList(null);
        System.out.println(JSONObject.toJSONString(word));
        System.out.println("设置WriteNullListAsEmpty后：");
        System.out.println(JSONObject.toJSONString(word, SerializerFeature.WriteMapNullValue, SerializerFeature.WriteNullListAsEmpty));
    }

    /**
     * 3:
     * UseISO8601DateFormat:Date使用ISO8601格式输出，默认为false
     */
    private static void useISO8601DateFormat() {
        System.out.println(JSONObject.toJSONString(word));
        System.out.println("设置UseISO8601DateFormat后：");
        System.out.println(JSONObject.toJSONString(word, SerializerFeature.UseISO8601DateFormat));
    }

    /**
     * 2:
     * WriteMapNullValue:是否输出值为null的字段,默认为false
     */
    private static void writeMapNullValue() {
        System.out.println(JSONObject.toJSONString(word));
        System.out.println("设置WriteMapNullValue后：");
        System.out.println(JSONObject.toJSONString(word, SerializerFeature.WriteMapNullValue));
    }

    /**
     * 1:
     * UseSingleQuotes:使用单引号而不是双引号,默认为false
     */
    private static void useSingleQuotes() {
        System.out.println(JSONObject.toJSONString(word));
        System.out.println("设置useSingleQuotes后：");
        System.out.println(JSONObject.toJSONString(word, SerializerFeature.UseSingleQuotes));
    }
}

• 
  

The corresponding output results are as follows:

• 1、useSingleQuotes： 
  

• 2 、 writeMapNullValue ： 
  

• 3、useISO8601DateFormat： 
  

• 4、writeNullListAsEmpty： 
  

• 5、writeNullStringAsEmpty： 
  

• 6、prettyFormat： 
  

• 7、writeDateUseDateFormat： 
  

• 8、beanToArray： 
  

• 9. Custom combination: showJsonBySelf: 
  
  The complete output at this time is as follows:

{"a":"a","b":2,"c":true,"d":"d","date":1473839656840,"e":"","list":[{"add":"广州","id":3,"name":"用户3","old":"33"},{"add":"上海","id":2,"name":"用户2","old":"22"},null,{"add":"北京","id":1,"name":"用户1","old":"11"}],"map":{"list":[{"$ref":"$.list[0]"},{"$ref":"$.list[1]"},null,{"$ref":"$.list[3]"}],"user3":{"$ref":"$.list[0]"},"mapz":"mapz","mapo":"mapo","mapa":"mapa","user1":{"$ref":"$.list[3]"}}}
{
    "a":"a",
    "b":2,
    "c":true,
    "d":"d",
    "date":1473839656840,
    "e":"",
    "f":"",
    "list":[
        {
            "add":"广州",
            "id":3,
            "name":"用户3",
            "old":"33"
        },
        {
            "add":"上海",
            "id":2,
            "name":"用户2",
            "old":"22"
        },
        null,
        {
            "add":"北京",
            "id":1,
            "name":"用户1",
            "old":"11"
        }
    ],
    "map":{
        "list":[
            {
                "add":"广州",
                "id":3,
                "name":"用户3",
                "old":"33"
            },
            {
                "add":"上海",
                "id":2,
                "name":"用户2",
                "old":"22"
            },
            null,
            {
                "add":"北京",
                "id":1,
                "name":"用户1",
                "old":"11"
            }
        ],
        "user4":null,
        "user3":{
            "add":"广州",
            "id":3,
            "name":"用户3",
            "old":"33"
        },
        "mapz":"mapz",
        "mapo":"mapo",
        "mapa":"mapa",
        "user1":{
            "add":"北京",
            "id":1,
            "name":"用户1",
            "old":"11"
        }
    }
}

• 
  

Note: 
-  fastjson converts objects to json to avoid $ref

学习地址： 
- http://blog.csdn.net/glarystar/article/details/6654494 
- http://blog.csdn.net/u013163567/article/details/50736096

项目github地址： 
- https://github.com/gubaijin/buildmavenweb