fastjson SerializerFeature详解

依赖

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

SerializerFeature属性

名称	含义	备注
QuoteFieldNames	输出key时是否使用双引号,默认为true
UseSingleQuotes	使用单引号而不是双引号,默认为false
WriteMapNullValue	是否输出值为null的字段,默认为false
WriteEnumUsingToString	Enum输出name()或者original,默认为false
UseISO8601DateFormat	Date使用ISO8601格式输出，默认为false
WriteNullListAsEmpty	List字段如果为null,输出为[],而非null
WriteNullStringAsEmpty	字符类型字段如果为null,输出为”“,而非null
WriteNullNumberAsZero	数值字段如果为null,输出为0,而非null
WriteNullBooleanAsFalse	Boolean字段如果为null,输出为false,而非null
SkipTransientField	如果是true，类中的Get方法对应的Field是transient，序列化时将会被忽略。默认为true
SortField	按字段名称排序后输出。默认为false
WriteTabAsSpecial	把\t做转义输出，默认为false	不推荐
PrettyFormat	结果是否格式化,默认为false
WriteClassName	序列化时写入类型信息，默认为false。反序列化是需用到
DisableCircularReferenceDetect	消除对同一对象循环引用的问题，默认为false
WriteSlashAsSpecial	对斜杠’/’进行转义
BrowserCompatible	将中文都会序列化为\uXXXX格式，字节数会多一些，但是能兼容IE 6，默认为false
WriteDateUseDateFormat	全局修改日期格式,默认为false。JSON.DEFFAULT_DATE_FORMAT = “yyyy-MM-dd”;JSON.toJSONString(obj, SerializerFeature.WriteDateUseDateFormat);
DisableCheckSpecialChar	一个对象的字符串属性中如果有特殊字符如双引号，将会在转成json时带有反斜杠转移符。如果不需要转义，可以使用这个属性。默认为false
NotWriteRootClassName	含义
BeanToArray	将对象转为array输出
WriteNonStringKeyAsString	含义
NotWriteDefaultValue	含义
BrowserSecure	含义
IgnoreNonFieldGetter	含义
WriteEnumUsingName	含义

示例

准备

• User、Word来模拟各种数据类型。
• SerializerFeatureTest：JSON部分示例的示例方法。

User类型：缺省get、set方法

public class User { private int id; private String name; private String add; private String old; } 

Word类型：缺省get、set方法

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:测试类

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)); } }

对应输出结果如下：

• 1、useSingleQuotes：
  

• 2、writeMapNullValue：
  

• 3、useISO8601DateFormat：
  

• 4、writeNullListAsEmpty：
  

• 5、writeNullStringAsEmpty：
  

• 6、prettyFormat：
  

• 7、writeDateUseDateFormat：
  

• 8、beanToArray：
  

• 9、自定义组合：showJsonBySelf：
  
  此时完整的输出如下：

{"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" } } }