fastJosn是阿里爸爸推出一款高性能序列化工具，號稱最快的json序列化工具。不過好像也就那樣，在量比較大的時候優勢才會明顯。單次序列化時間還是會達到幾十毫秒的級別。
Fastjson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Fastjson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of.
Fastjson Goals
- Provide?best performance?in server side and android client.
- Provide simple toJSONString() and parseObject() methods to convert Java objects to JSON and vice-versa.
- Allow pre-existing unmodifiable objects to be converted to and from JSON.
- Extensive support of Java Generics.
- Allow custom representations for objects.
- Support arbitrarily complex objects (with deep inheritance hierarchies and extensive use of generic types).?
toJSONString:
使用toJSONString時有兩個點需要注意：
（1）默認情況下屬性值為null的字段不會打印，若需要展示需使用SerializerFeature.WRITE_MAP_NULL_FEATURES
SerializerFeature屬性：
| 名稱 | 含義 |
| QuoteFieldNames | 輸出key時是否使用雙引號,默認為true |
| UseSingleQuotes | 使用單引號而不是雙引號,默認為false |
| WriteMapNullValue | 是否輸出值為null的字段,默認為false |
| WriteEnumUsingToString | Enum輸出name()或者original,默認為false |
| SortField | 按字段名稱排序后輸出。默認為false |
| WriteTabAsSpecial | 把\t做轉義輸出，默認為false |
| PrettyForma | 結果是否格式化,默認為false |
| WriteClassName | 序列化時寫入類型信息，默認為false。反序列化是需用到 |
（2）只會打印正常類型的屬性信息，自定義類無法展示。
/*** This method serializes the specified object into its equivalent Json representation. Note that this method works fine if the any of the object fields are of generic type,* just the object itself should not be of a generic type. If you want to write out the object to a* {@link Writer}, use {@link #writeJSONString(Writer, Object, SerializerFeature[])} instead.** @param object the object for which json representation is to be created setting for fastjson* @return Json representation of {@code object}.*/public static String toJSONString(Object object) {return toJSONString(object, emptyFilters);}?
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