【daily】Java枚举 - fastjson对enum的处理

目的

  1、枚举值转换成完全的json；

  2、对象中的枚举成员完全转换成json；

  3、枚举类的全部值转换成json；

 

枚举定义

public enum SongsEnum {
     SAFE_AND_SOUND(1,"Taylor Swift","Safe&Sound","2011-12-26")
    ,SHAKE_IT_OFF(2,"Taylor Swift","Shake It Off","2014-08-19")
    ,STYLE(3,"Taylor Swift","Style","2015-02-09")
    ,SOUND_OF_SILENCE(4,"Simon & Garfunkel","The Sound Of Silence","1966-01-17")
    ,BETTER_MAN(5,"Little Big Town","Better Man","2016-10-20")
    ,YESTERDAY_ONCE_MORE(6,"Carpenters","Yesterday Once More","1973-05-16")
    ;

    public final int index;
    public final String singer;
    public final String name;
    public final String date;

    private SongsEnum(int seq, String singer, String name, String date) {
        this.index = seq;
        this.singer = singer;
        this.name = name;
        this.date = date;
    }

    public int getIndex() { return index; }

    public String getSinger() { return singer; }

    public String getName() { return name; }

    public String getDate() { return date; }
}

 

一、枚举值转换json

期望结果：SongsEnum.SAFE_AND_SOUND -> {"date":"2011-12-26","index":1,"name":"Safe&Sound","singer":"Taylor Swift"}

## 默认调用结果

JSON.toJSONString(SongsEnum.SAFE_AND_SOUND) -> "SAFE_AND_SOUND"

JSON.toJSONString(SongsEnum.BETTER_MAN,SerializerFeature.WriteEnumUsingName) -> "BETTER_MAN"

JSON.toJSONString(SongsEnum.STYLE,SerializerFeature.WriteEnumUsingToString) -> "STYLE"

默认的使用fastjson转换enum,那么得到的enum json可能不是想要的.

(1) 重写enum的toString()

@Override
public String toString() {
  return "{'name':"+this.name+",'singer':"+this.singer+"}";
}

JSON.toJSONString(SongsEnum.STYLE,SerializerFeature.WriteEnumUsingToString) -> "{'name':Style,'singer':Taylor Swift}"

  虽然可以这样得到想要的结果,但相对来说太麻烦,每个enum类都要从写toString().

  (此种方式并没有研究，所以以上重写toString()的代码可能存在问题)

(2) fastjson的config设置

  fastjson提供的JSON.toJSONString(...)有很多重载的方法，例如：

    public static String toJSONString(Object object, SerializeConfig config, SerializerFeature... features)

  所以，fastjson可以通过设置SerializeConfig来配置enum的序列化。

public static void main(String[] args) {
    SerializeConfig config = new SerializeConfig();
    config.configEnumAsJavaBean(SongsEnum.class);
    String s = JSON.toJSONString(SongsEnum.SOUND_OF_SILENCE, config);
    System.out.println(s);
    // {"date":"1966-01-17","index":4,"name":"The Sound Of Silence","singer":"Simon & Garfunkel"}
}

二、对象中的枚举成员完全转换成json

public enum StatusEnum {
    STATUS_A(0,"状态A"),
    STATUS_B(1,"状态B"),
    STATUS_C(2,"状态C");

    public final int index;
    public final String status;

    StatusEnum(int i, String status) {
        this.index = i;
        this.status = status;
    }

    public int getIndex() { return index; }

    public String getStatus() { return status; }
}

class JavaBean{
    private String name;

    private SongsEnum song;

    private StatusEnum status;

    public JavaBean(String name,SongsEnum song,StatusEnum status){
        this.name = name;
        this.song = song;
        this.status = status;
    }

    //省略setter/getter
}

期望: {"name":"vegilyn","song":{"date":"2014-08-19","index":2,"name":"Shake It Off","singer":"Taylor Swift"},"status":{"index":1,"status":"状态B"}}

默认结果:

JSON.toJSONString(new JavaBean("vegilyn",SongsEnum.SHAKE_IT_OFF,StatusEnum.STATUS_B)) -> {"name":"vegilyn","song":"SHAKE_IT_OFF","status":"STATUS_B"}

可以看出此结果和目的1中的结果一样的，所以通过目的1的方式也可以解决。

SerializeConfig config = new SerializeConfig();

config.configEnumAsJavaBean(SongsEnum.class); // 配置enum转换
String s = JSON.toJSONString(new JavaBean("vegilyn",SongsEnum.SHAKE_IT_OFF,StatusEnum.STATUS_B),config);
System.out.println(s);
// {"name":"vegilyn","song":{"date":"2014-08-19","index":2,"name":"Shake It Off","singer":"Taylor Swift"},"status":"STATUS_B"}

SerializeConfig config = new SerializeConfig();
config.configEnumAsJavaBean(SongsEnum.class,StatusEnum.class); // 配置enum转换 
String s = JSON.toJSONString(new JavaBean("vegilyn",SongsEnum.SHAKE_IT_OFF,StatusEnum.STATUS_B),config);
System.out.println(s);
// {"name":"vegilyn","song":{"date":"2014-08-19","index":2,"name":"Shake It Off","singer":"Taylor Swift"},"status":{"index":1,"status":"状态B"}}

特别枚举数组转换的json：(注意重复值的json值)

public static void main(String[] args) {
    SongsEnum[] songsEnums = {SongsEnum.BETTER_MAN, SongsEnum.SAFE_AND_SOUND, SongsEnum.BETTER_MAN};
    SerializeConfig config = new SerializeConfig();
    config.configEnumAsJavaBean(SongsEnum.class);

    System.out.println(JSON.toJSONString(songsEnums,config));

}

// [{"date":"2016-10-20","index":5,"name":"Better Man","singer":"Little Big Town"},{"date":"2011-12-26","index":1,"name":"Safe&Sound","singer":"Taylor Swift"},{"$ref":"$[0]"}]

 

三、枚举类的全部值转换成json

期望结果：

[
    {"index": 1, "singer": "Taylor Swift", "name": "Safe&Sound", "date": "2011-12-26"},
    {"index": 2, "singer": "Taylor Swift", "name": "Shake It Off", "date": "2014-08-19"},
    {"index": 3, "singer": "Taylor Swift", "name": "Style", "date": "2015-02-09"},
    {"index": 4, "singer": "Simon & Garfunkel", "name": "The Sound Of Silence", "date": "1966-01-17"},
    {"index": 5, "singer": "Little Big Town", "name": "Better Man", "date": "2016-10-20"},
    {"index": 6, "singer": "Carpenters", "name": "Yesterday Once More", "date": "1973-05-16"}
]

实现代码：

 public static void main(String[] args) {
        SongsEnum[] values = SongsEnum.values();
        List songsEnums = new ArrayList();
        for (SongsEnum value : values) {
            songsEnums.add(value);
        }

        SerializeConfig config = new SerializeConfig();
        config.configEnumAsJavaBean(SongsEnum.class);

        System.out.println(JSON.toJSONString(songsEnums, config));
    }

以上能达到想要的效果，但是，每个enum类都要重复写以上代码。所以，利用反射来写一个公共的方法。

 public static String toJson(Classextends Enum> enumClass) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        Method methodValues = enumClass.getMethod("values");
        Object invoke = methodValues.invoke(null);
        int length = java.lang.reflect.Array.getLength(invoke);
        List