使用Gson转json字符串序列化问题_gson unsupportedoperationexception: expecting para-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_39364289/article/details/108995790

本文介绍使用Gson进行JSON字符串序列化时遇到的问题及其解决办法，详细展示了如何通过自定义日期类型适配器来避免UnsupportedOperationException异常。

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使用Gson转json字符串序列化问题
gson序列化会遇到问题：
java.lang.UnsupportedOperationException: Expecting parameterized type, got class

Are you missing the use of TypeToken idiom?

See http://sites.google.com/site/gson/gson-user-guide#TOC-Serializing-and-Deserializing-Gener

at com.google.gson.TypeInfoFactory.getActualType(TypeInfoFactory.java:105)

at com.google.gson.TypeInfoFactory.getTypeInfoForField(TypeInfoFactory.java:54)

at com.google.gson.ObjectNavigator.navigateClassFields(ObjectNavigator.java:156)

at com.google.gson.ObjectNavigator.accept(ObjectNavigator.java:131)

at com.google.gson.JsonSerializationContextDefault.serialize(JsonSerializationContextDefault.java:56)

at com.google.gson.Gson.toJsonTree(Gson.java:233)

at com.google.gson.Gson.toJson(Gson.java:273)

at com.google.gson.Gson.toJson(Gson.java:253)

解决办法如下：
private static Gson gsonUtils = null;

public synchronized static Gson getGsonUtils(){
    if(gsonUtils == null) {
        GsonBuilder builder = new GsonBuilder()
            .registerTypeAdapter(Date.class, new JsonSerializer<Date>() {
                @Override
                public JsonElement serialize(Date src, Type typeOfSrc, JsonSerializationContext context) {
                    return new JsonPrimitive(src.getTime());
                }
            }).registerTypeAdapter(Date.class, new JsonDeserializer<Date>() {
                @Override
                public Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
                    return new Date(json.getAsJsonPrimitive().getAsLong());
                }
            }).setDateFormat(DateFormat.LONG);
        gsonUtils = builder.create();
    }
    return gsonUtils;
}