[英]JSON to HashMap with objects using Gson
在我的Android应用程序(用Kotlin编写)中,我需要将一些JSON转换为MainObject哈希映射的字符串。 JSON如下所示:
{
"a": {
"name": "A",
"some_int": "2",
"some_string": "string",
"some_bool": false,
"some_string_arr": [
"str1",
"str2"
],
"sub_obj_arr": [
{
"obj_name": "d",
"some_obj_string": "s"
}
]
},
"b": {
"name": "B",
"some_int": "4",
"some_string": "string",
"some_bool": false,
"some_string_arr": [
"str5",
"str6"
]
}
}
我创建了几个对象来帮助解决这个问题。
class MainObject {
@SerializedName("name")
val name: String? = null
@SerializedName("some_int")
val someInt: Int? = null
@SerializedName("some_string")
val someString: String? = null
@SerializedName("some_bool")
val someBool: Boolean = false
@SerializedName("some_string_arr")
val someStringArr: List<String>? = null
@SerializedName("sub_obj_arr")
val someObjArr: List<SubObject>? = null
}
class SubObject {
@SerializedName("obj_name")
val objName: String? = null
@SerializedName("some_obj_string")
val someObjString: String? = null
}
如何将其转换为HashMap<String, MainObject>
? 我尝试按此处所述使用TypeToken,但出现错误“期望的开始对象但为字符串”。
有任何想法吗?
UPDATE
错误记录
10-15 20:06:42.771 10328-10328/xxx E/AndroidRuntime: FATAL EXCEPTION: main
Process: xxx, PID: 10328
java.lang.RuntimeException: Unable to start activity ComponentInfo{xxx}: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1 path $
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1 path $
at com.google.gson.Gson.fromJson(Gson.java:900)
at com.google.gson.Gson.fromJson(Gson.java:853)
at com.google.gson.Gson.fromJson(Gson.java:802)
at xxx.onCreate(BottomNavigation.kt:48)
at android.app.Activity.performCreate(Activity.java:6975)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1 path $
at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:385)
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:183)
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:145)
at com.google.gson.Gson.fromJson(Gson.java:888)
at com.google.gson.Gson.fromJson(Gson.java:853)
at com.google.gson.Gson.fromJson(Gson.java:802)
at xxx.onCreate(BottomNavigation.kt:48)
at android.app.Activity.performCreate(Activity.java:6975)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
更新2
实际问题是我在本地JSON文件中读取的方式有问题。 我使用的代码是这样的:
val input = this.resources.openRawResource(R.raw.json)
val json = try {
val size = input.available()
val buffer = ByteArray(size)
input.read(buffer)
input.close()
String(buffer)
} catch (ex: IOException) {
ex.printStackTrace()
null
}
当我将json打印到控制台时,这给了我这些奇怪的字符:
10-15 23:55:11.911 3351-3351 / xxx I / System.out: {
10-15 23:55:11.911 3351-3351 / xxx I / System.out: : {
不知道为什么。
我不知道你为什么有任何错误。 我可以使用以下代码解析JSON。
val gson = GsonBuilder().create()
val type = object:TypeToken<Map<String, MainObject>>(){}.type
val result = gson.fromJson<Map<String, MainObject>>("{ \"a\": { \"name\": \"A\", \"some_int\": \"2\", \"some_string\": \"string\", \"some_bool\": false, \"some_string_arr\": [ \"str1\", \"str2\" ], \"sub_obj_arr\": [ { \"obj_name\": \"d\", \"some_obj_string\": \"s\" } ] }, \"b\": { \"name\": \"B\", \"some_int\": \"4\", \"some_string\": \"string\", \"some_bool\": false, \"some_string_arr\": [ \"str5\", \"str6\" ] } }", type)
好的,在其他人的帮助下,我发现问题出在Gson或JSON或其他方面。 这是我将其读入内存的方式。 我使用的代码是:
val input = this.resources.openRawResource(R.raw.json)
val json = try {
val size = input.available()
val buffer = ByteArray(size)
input.read(buffer)
input.close()
String(buffer)
} catch (ex: IOException) {
ex.printStackTrace()
null
}
但是, String(buffer)
默认使用UTF_8字符集。 为了使我的工作正常,我需要使用UTF_16字符集。 工作更改是使用String(buffer, Charsets.UTF_16)
。
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