我正在使用 GSON 反序列化一些 JSON 文件。这是我编写的反序列化方法，我读取了 JSON 文件并将整个内容存储为我传递给该方法的字符串。此方法成功地适用于与该项目相关的 5 个 JSON 文件中的 4 个。
protected ArrayList<Entry> deserialize(String json) throws Exception
{
ArrayList<Entry> list = new ArrayList<Entry>( );
JsonParser parser = new JsonParser();
JsonArray jarray = (JsonArray) parser.parse(json);
for (int i = 0; i < jarray.size(); i++)
{
// Parse out the brand
JsonObject jentry = (JsonObject) jarray.get(i);
JsonPrimitive jbrand = jentry.getAsJsonPrimitive("brand");
String className = jbrand.getAsString();
Entry entry = (Entry) gson.fromJson(jentry, Class.forName(className));
list.add(entry);
}
return list;
}
这是我解析并放入字符串的 JSON 文件，有几个对象绑定到“jentry”，但我只包含一个。如果它看起来很奇怪，可能是因为我一直在使用 firefox 插件来查看 JSON 文件，并且我从该插件中复制/粘贴。
[
*
-
{
o pattern: "3 5 * * 1-5"
o starts: 1288249260913
o ends: 1291125660913
o skipHolidays: false
o lastFired: 1289988180395
o
-
template: {
+ location: ""
+ damageCause: ""
+ signed: false
+ signedBy: ""
+ approvedBy: "Ralph"
+ requestedBy: "Ralph"
+ estHours: 0
+ actHours: 0
+ chargeTo: ""
+ priority: "ROUTINE"
+ reason: ""
+ materials: ""
+ serviceId: 1
+ descr: "HELP WITH LEAVES,BLOW LEAVES IN YOUR AREA NEAR DRAINS Check for garbage. [sp] Mow and weedeat where needed in your area. [sp] Work on leaves where needed. [wi]"
+ comments: [ ]
+ futureId: 3
+ inventoryId: -1
+
-
trail: [
#
-
{
* stamp: 1288026816857
* status: "OPEN"
* byId: 2
}
#
-
{
* stamp: 1288026889374
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1288194095170
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1288287964481
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1288785076532
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1288797119525
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1289307416921
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1289308339165
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1289834523635
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1289847660913
* status: "DISPATCHED"
* byId: 2
}
]
+ requestDate: 1289329260913
+ assignedDate: 1288029660912
+ supplies: [ ]
+ id: 3
+ updateDate: 1289847660913
+ createUserId: 2
+ updateUserId: 2
+ createDate: 1288026816857
+ brand: "org.workplicity.marist.grounds.GroundsRequest"
}
o workSlateId: 16
o serviceId: 1
o enabled: false
o id: 3
o updateDate: 1291235385719
o createUserId: 2
o updateUserId: 2
o createDate: 1288026889373
o brand: "org.workplicity.entry.event.Weekdays"
}
问题是当 GSON 转回 JSON（序列化？）时，它缺少一些字段。这是输出，相关的缺失行是“模板：”下方和“服务ID：”上方的所有内容，我将继续并再次包含整个对象。
[
*
-
{
o pattern: "3 5 * * 1-5"
o starts: 1288249260913
o ends: 1291125660913
o skipHolidays: false
o lastFired: 1289988180395
o
-
template: {
+ serviceId: 1
+ descr: "HELP WITH LEAVES,BLOW LEAVES IN YOUR AREA NEAR DRAINS Check for garbage. [sp] Mow and weedeat where needed in your area. [sp] Work on leaves where needed. [wi]"
+ comments: [ ]
+ futureId: 3
+ inventoryId: -1
+
-
trail: [
#
-
{
* stamp: 1288026816857
* status: "OPEN"
* byId: 2
}
#
-
{
* stamp: 1288026889374
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1288194095170
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1288287964481
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1288785076532
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1288797119525
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1289307416921
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1289308339165
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1289834523635
* status: "DISPATCHED"
* byId: 2
}
#
-
{
* stamp: 1289847660913
* status: "DISPATCHED"
* byId: 2
}
]
+ requestDate: 1289329260913
+ assignedDate: 1288029660912
+ supplies: [ ]
+ id: 3
+ updateDate: 1289847660913
+ createUserId: 2
+ updateUserId: 2
+ createDate: 1288026816857
+ brand: "org.workplicity.marist.grounds.GroundsRequest"
}
o workSlateId: 16
o serviceId: 1
o enabled: false
o id: 3
o updateDate: 1299694066807
o createUserId: 2
o updateUserId: 2
o createDate: 1288026889373
o brand: "org.workplicity.entry.event.Weekdays"
}
JSON 文件中的每个对象都会发生这种情况。NetBeans 中的调试显示 JsonObject 'jentry' 有一个哈希表，其中包含 JSON 字符串中每个数据成员的对应键值对；并且“模板”作为哈希表存储在这个哈希表中，这可能是也可能不是我真的无法找出的问题。
现在，当我最初在问题 JSON 文件上运行此方法时，我在这一行遇到了异常：
Entry entry = (Entry) gson.fromJson(jentry, Class.forName(className));
问题是与此特定 JSON 文件相关的特定类没有无参数构造函数，因此我必须向 GSON 构建器注册一些 InstanceCreators，如下所示：
gsonBuilder.registerTypeAdapter(Weekdays.class, new WeekdaysInstanceCreator());
gsonBuilder.registerTypeAdapter(Once.class, new OnceInstanceCreator());
在我这样做之后，异常停止被抛出并且一切似乎都工作了，当然减去了丢失的字段。
所以这就是我所在的地方，我真的不知道出了什么问题。非常感谢任何帮助。