How to write a TypeAdapter and register TypeAdapter and handle Enum types yourself.
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Enumerated types bring benefits to our program, how to use Gson to achieve interconversion with Json? Please read this article.
How to write a TypeAdapter and register TypeAdapter and handle Enum types yourself.
Entity class:
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Public enum PackageState {
PLAY, UPDATE, UPDATING, DOWNLOAD, DOWNLOADING
}
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Public class PackageItem {
Private String name
Private PackageState state
Private String size
Public String getName () {
Return name
}
Public void setName (String name) {
This.name = name
}
Public PackageState getState () {
Return state
}
Public void setState (PackageState state) {
This.state = state
}
Public String getSize () {
Return size
}
Public void setSize (String size) {
This.size = size
}
@ Override
Public String toString () {
Return "PackageItem [name=" + name + ", size=" + size + ", state="
+ state + "]"
}
}
Write a converter to implement JsonSerializer interface and jsonDeserializer interface:
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Mport java.lang.reflect.Type
Import com.google.gson.JsonDeserializationContext
Import com.google.gson.JsonDeserializer
Import com.google.gson.JsonElement
Import com.google.gson.JsonParseException
Import com.google.gson.JsonPrimitive
Import com.google.gson.JsonSerializationContext
Import com.google.gson.JsonSerializer
Public class EnumSerializer implements JsonSerializer
JsonDeserializer {
/ / it is called when the object is converted to Json to implement the JsonSerializer interface
@ Override
Public JsonElement serialize (PackageState state, Type arg1
JsonSerializationContext arg2) {
Return new JsonPrimitive (state.ordinal ())
}
/ / json is called when it is converted to an object to implement the JsonDeserializer interface
@ Override
Public PackageState deserialize (JsonElement json, Type typeOfT
JsonDeserializationContext context) throws JsonParseException {
If (json.getAsInt () < PackageState.values () .length)
Return PackageState.values () [json.getAsInt ()]
Return null
}
}
Test class:
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Import com.google.gson.Gson
Import com.google.gson.GsonBuilder
Public class GsonTest6 {
Public static void main (String [] args) {
GsonBuilder gsonBuilder = new GsonBuilder ()
GsonBuilder.registerTypeAdapter (PackageState.class
New EnumSerializer ()
Gson gson = gsonBuilder.create ()
PackageItem item = new PackageItem ()
Item.setName ("item_name")
Item.setSize ("500m")
Item.setState (PackageState.UPDATING); / / this state is an enumerated value
String s = gson.toJson (item)
System.out.println (s)
System.out.println ("-")
PackageItem retItem = gson.fromJson (s, PackageItem.class)
System.out.println (retItem)
}
}
Output result (the corresponding enumeration type of state has been changed to int type in the result):
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{"name": "item_name", "state": 2, "size": "500m"}
-
PackageItem [name=item_name, size=500M, state=UPDATING]
Classification: JSP
Tags: Enum, Gson, json, TypeAdapter, instance
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