震惊！fastjson SerializerFeature详解竟然是这个样子

蔚落 2022-10-10 12:51 246阅读 0赞

# ![1aa247a7909d007322b32a5b173483ac.gif][] #

# 依赖 #

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

# SerializerFeature属性 #

<table> 
 <thead> 
  <tr> 
   <th>名称</th> 
   <th>含义</th> 
   <th>备注</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>QuoteFieldNames</td> 
   <td>输出key时是否使用双引号,默认为true</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>UseSingleQuotes</td> 
   <td>使用单引号而不是双引号,默认为false</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteMapNullValue</td> 
   <td>是否输出值为null的字段,默认为false</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteEnumUsingToString</td> 
   <td>Enum输出name()或者original,默认为false</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>UseISO8601DateFormat</td> 
   <td>Date使用ISO8601格式输出，默认为false</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteNullListAsEmpty</td> 
   <td>List字段如果为null,输出为[],而非null</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteNullStringAsEmpty</td> 
   <td>字符类型字段如果为null,输出为”“,而非null</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteNullNumberAsZero</td> 
   <td>数值字段如果为null,输出为0,而非null</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteNullBooleanAsFalse</td> 
   <td>Boolean字段如果为null,输出为false,而非null</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>SkipTransientField</td> 
   <td>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</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>SortField</td> 
   <td>按字段名称排序后输出。默认为false</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteTabAsSpecial</td> 
   <td>把\t做转义输出，默认为false</td> 
   <td><code>不推荐</code></td> 
  </tr> 
  <tr> 
   <td>PrettyFormat</td> 
   <td>结果是否格式化,默认为false</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteClassName</td> 
   <td>序列化时写入类型信息，默认为false。反序列化是需用到</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>DisableCircularReferenceDetect</td> 
   <td>消除对同一对象循环引用的问题，默认为false</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteSlashAsSpecial</td> 
   <td>对斜杠’/’进行转义</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>BrowserCompatible</td> 
   <td>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</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteDateUseDateFormat</td> 
   <td>全局修改日期格式,默认为false。JSON.DEFFAULT_DATE_FORMAT = “yyyy-MM-dd”;JSON.toJSONString(obj, SerializerFeature.WriteDateUseDateFormat);</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>DisableCheckSpecialChar</td> 
   <td>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</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>NotWriteRootClassName</td> 
   <td>含义</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>BeanToArray</td> 
   <td>将对象转为array输出</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteNonStringKeyAsString</td> 
   <td>含义</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>NotWriteDefaultValue</td> 
   <td>含义</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>BrowserSecure</td> 
   <td>含义</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>IgnoreNonFieldGetter</td> 
   <td>含义</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>WriteEnumUsingName</td> 
   <td>含义</td> 
   <td></td> 
  </tr> 
 </tbody> 
</table>

# 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：  
![这里写图片描述][20160914162745717]

2、writeMapNullValue：  
![这里写图片描述][20160914162804474]

3、useISO8601DateFormat：  
![这里写图片描述][20160914162819850]

4、writeNullListAsEmpty：  
![这里写图片描述][20160914162835389]

5、writeNullStringAsEmpty：  
![这里写图片描述][20160914162849530]

6、prettyFormat：  
![这里写图片描述][20160914162904593]

7、writeDateUseDateFormat：  
![这里写图片描述][20160914162919077]

8、beanToArray：  
![这里写图片描述][20160914162933874]

9、自定义组合：showJsonBySelf：  
![这里写图片描述][20160914162947258]  
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"
            }
        }
    }

注意：  
\- fastjson把对象转化成json避免$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

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