如何用Gson解析不同对象的Json数组？

Question

Json字符串:

  [  
       //Object 1

       {  
          TypeName:"CheckSpecificDday",
          SpecificDay:"20160413",
          Lunar:1
       },

       {  
          TypeName:"CheckSpecificDday",
          SpecificDay:"20160414",
          Lunar:1
       },

       //Object 2

       {  
          TypeName:"CheckEveryDayDday",
          StartDate:"20160413",
          EndDate:"20260417",
          Interval:1,
          StartOption:"D",
          HolidayCondition:1
       },

       //Object 3

       {  
          TypeName:"CheckEveryDdayOfWeek",
          StartDate:"20160413",
          EndDate:"",
          Interval:1,
          SpecificDayOfWeek:"3",
          HolidayCondition:1
       },

       //Object 4

       {  
          TypeName:"CheckEveryMonthSpecificDday",
          StartDate:"20160413",
          EndDate:"",
          Interval:1,
          SpecificDD:"13,14",
          HolidayCondition:1
       },

       //Object 5

       {  
          TypeName:"CheckEveryYearWeek",
          StartDate:"20160413",
          EndDate:"",
          Interval:1,
          SpecificMMnthWeek:"0433",
          HolidayCondition:1
       }

    ]

我有一个像上面这样的Json数组.我想要的是用Gson将它解析为不同的对象类型(正如我评论的那样让它更清晰),但我不知道该怎么做.请帮我.先感谢您!

Answer 1

我认为SO上有很多类似的问题.一,二

解析这个问题的一种方法是使用简单的方法

Object[] result = new Gson().fromJson(json, Object[].class);

但这会给你对象LinkedTreeMap<Integer, LinkedTreeMap<String, String>>或类似的东西.你可以使用它,但它有点困难,你也会遇到整数作为双打的问题.

另一种方法是在TypeName需要时使用字段创建自定义接口或抽象类:

private interface CheckInterface{}

并使用您拥有的每个POJO类对象类型实现它:

private static class CheckEveryDayBase implements CheckInterface{
    private String StartDate;
    private String EndDate;
    private int Interval;
    private int HolidayCondition;
}

private static class CheckSpecificDday implements CheckInterface{
    private String SpecificDay;
    private int Lunar;
}

private static class CheckEveryDayDday extends CheckEveryDayBase{
    private String StartOption;
}

private static class CheckEveryDdayOfWeek extends CheckEveryDayBase{
    private String SpecificDayOfWeek;
}

private static class CheckEveryMonthSpecificDday extends CheckEveryDayBase{
    private String SpecificDD;
}

private static class CheckEveryYearWeek extends CheckEveryDayBase{
    private String SpecificMMnthWeek;
}

然后为您的CheckInterface:创建自定义解析器:

public static class CheckInterfaceDeserializer implements JsonDeserializer<CheckInterface>{

    @Override
    public CheckInterface deserialize(JsonElement json, Type typeOfT,
                       JsonDeserializationContext context) throws JsonParseException {
        JsonObject jObject = (JsonObject) json;
        JsonElement typeObj = jObject.get("TypeName");

        if(typeObj!= null ){
            String typeVal = typeObj.getAsString();

            switch (typeVal){
                case "CheckSpecificDday":
                   return context.deserialize(json, CheckSpecificDday.class);
                case "CheckEveryDayDday":
                    return context.deserialize(json, CheckEveryDayDday.class);
                case "CheckEveryDdayOfWeek":
                    return context.deserialize(json, CheckEveryDdayOfWeek.class);
                case "CheckEveryMonthSpecificDday":
                    return context.deserialize(json, CheckEveryMonthSpecificDday.class);
                case "CheckEveryYearWeek":
                    return context.deserialize(json, CheckEveryYearWeek.class);
            }
        }

        return null;
    }
}

以下是如何使用它:

GsonBuilder builder = new GsonBuilder();

// Register custom deserializer for CheckInterface.class
builder.registerTypeAdapter(CheckInterface.class, new CheckInterfaceDeserializer());
Gson gson = builder.create();

CheckInterface[] result2 = gson.fromJson(json, CheckInterface[].class);