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简介
在使用Gson进行数据的序列化和反序列化时，会出现将Int类型转为Double类型的现象，但我们需要区分Int和double，本文将介绍如何修改
序列化和反序列化修改
我们可以通过定时序列化和反序列化的相关实现类，重新编写类型
下面两个是针对Object和Map的，代码如下：
private static class DataTypeAdapter extends TypeAdapter<Object> {
private final TypeAdapter<Object> delegate = new Gson().getAdapter(Object.class);
@Override
public Object read(JsonReader in) throws IOException {
JsonToken token = in.peek();
switch (token) {
case BEGIN_ARRAY:
List<Object> list = new ArrayList<>();
in.beginArray();
while (in.hasNext()) {
list.add(read(in));
}
in.endArray();
return list;
case BEGIN_OBJECT:
Map<String, Object> map = new LinkedTreeMap<>();
in.beginObject();
while (in.hasNext()) {
map.put(in.nextName(), read(in));
}
in.endObject();
return map;
case STRING:
return in.nextString();
case NUMBER:
/**
* 改写数字的处理逻辑，将数字值分为整型与浮点型。
*/
double dbNum = in.nextDouble();
// 数字超过long的最大值，返回浮点类型
if (dbNum > Long.MAX_VALUE) {
return dbNum;
}
// 判断数字是否为整数值
long lngNum = (long) dbNum;
if (dbNum == lngNum) {
try {
return (int) lngNum;
} catch (Exception e) {
return lngNum;
}
} else {
return dbNum;
}
case BOOLEAN:
return in.nextBoolean();
case NULL:
in.nextNull();
return null;
default:
throw new IllegalStateException();
}
}
@Override
public void write(JsonWriter out, Object value) throws IOException {
delegate.write(out, value);
}
}
public static class MapDeserializerDoubleAsIntFix implements JsonDeserializer<Map<String, Object>>{
@Override @SuppressWarnings("unchecked")
public Map<String, Object> deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
return (Map<String, Object>) read(json);
}
public Object read(JsonElement in) {
if(in.isJsonArray()){
List<Object> list = new ArrayList<>();
JsonArray arr = in.getAsJsonArray();
for (JsonElement anArr : arr) {
list.add(read(anArr));
}
return list;
}else if(in.isJsonObject()){
Map<String, Object> map = new LinkedTreeMap<>();
JsonObject obj = in.getAsJsonObject();
Set<Map.Entry<String, JsonElement>> entitySet = obj.entrySet();
for(Map.Entry<String, JsonElement> entry: entitySet){
map.put(entry.getKey(), read(entry.getValue()));
}
return map;
}else if( in.isJsonPrimitive()){
JsonPrimitive prim = in.getAsJsonPrimitive();
if(prim.isBoolean()){
return prim.getAsBoolean();
}else if(prim.isString()){
return prim.getAsString();
}else if(prim.isNumber()){
Number num = prim.getAsNumber();
// here you can handle double int/long values
// and return any type you want
// this solution will transform 3.0 float to long values
if(Math.ceil(num.doubleValue()) == num.longValue())
return num.longValue();
else{
return num.doubleValue();
}
}
}
return null;
}
}
然后在Gson初始化进行设置即可：
private static final Gson GSON = new GsonBuilder()
.registerTypeAdapter(String.class, new StringTypeAdapter())
.registerTypeHierarchyAdapter(Pair.class, new PairTypeAdapter())
.registerTypeAdapter(new TypeToken<Map<String, Object>>() {}.getType(), new DataTypeAdapter())
.registerTypeAdapter(Map.class, new MapDeserializerDoubleAsIntFix())
.create();
总结
上面是对 TypeToken<Map<String, Object>>、Map的相关操作，如果还有其他情况，可以参考进行操作
