fastjson SerializerFeature详解

依赖

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

SerializerFeature属性

不推荐

示例

准备

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：

{"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"
}
}
}