gson read number类型全部转换为double问题gson read number类型全部转换为double问题

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我是靠谱客的博主勤恳冬瓜，最近开发中收集的这篇文章主要介绍gson read number类型全部转换为double问题gson read number类型全部转换为double问题，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

gson read number类型全部转换为double问题

问题描述

gson反序列化数据时默认会将int long double等数值类型全部作为double来转换

问题效果

“result”:0

解析出来为 0.00 会影响逻辑判断

解决办法

原理

1.改源码ObjectTypeAdapter 解析NUMBER片段代码打包为maven私服jar共用

2.自定义MapTypeAdapter 代替 ObjectTypeAdapter 功能

代码片段

本文采用第二种方式解决

public final class MapTypeAdapter extends TypeAdapter<Object> {
    private Gson gson;

    private MapTypeAdapter(Gson gson) {
        this.gson = gson;
    }
    public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
        @Override
        public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
            if (typeToken.getRawType() == Object.class) {
                return (TypeAdapter<T>) new MapTypeAdapter(gson);
            }
            return null;
        }
    };

    @Override
    public void write(JsonWriter out, Object value) throws IOException {
        if (value == null) {
            out.nullValue();
            return;
        }
        TypeAdapter<Object> typeAdapter = (TypeAdapter<Object>) gson.getAdapter(value.getClass());
        if (typeAdapter instanceof ObjectTypeAdapter) {
            out.beginObject();
            out.endObject();
            return;
        }
        typeAdapter.write(out, value);
    }

    @Override
    public Object read(JsonReader in) throws IOException {
        JsonToken token = in.peek();
        //判断字符串的实际类型
        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:
                String numberStr = in.nextString();
                if (numberStr.contains(".") || numberStr.contains("e")
                        || numberStr.contains("E")) {
                    return Double.parseDouble(numberStr);
                }
                if (Long.parseLong(numberStr) <= Integer.MAX_VALUE) {
                    return Integer.parseInt(numberStr);
                }
                return Long.parseLong(numberStr);
            case BOOLEAN:
                return in.nextBoolean();
            case NULL:
                in.nextNull();
                return null;
            default:
                throw new IllegalStateException();
        }
    }
}

private final static Gson getGson() {
        Gson gson = new GsonBuilder().create();
        try {
            Field factories = Gson.class.getDeclaredField("factories");
            factories.setAccessible(true);
            Object o = factories.get(gson);
            Class<?>[] declaredClasses = Collections.class.getDeclaredClasses();
            for (Class c : declaredClasses) {
                if ("java.util.Collections$UnmodifiableList".equals(c.getName())) {
                    Field listField = c.getDeclaredField("list");
                    listField.setAccessible(true);
                    List<TypeAdapterFactory> list = (List<TypeAdapterFactory>) listField.get(o);
                    int i = list.indexOf(ObjectTypeAdapter.FACTORY);
                    list.set(i, MapTypeAdapter.FACTORY);
                    break;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return gson;
    }