【转】 Json转换利器Gson之实例五-注册TypeAdapter及处理Enum类型

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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 + 

"]"

;

}

}

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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<PackageState>,

JsonDeserializer<PackageState> {

// 对象转为Json时调用,实现JsonSerializer<PackageState>接口

@Override

public

JsonElement serialize(PackageState state, Type arg1,

JsonSerializationContext arg2) {

return

new

JsonPrimitive(state.ordinal());

}

// json转为对象时调用,实现JsonDeserializer<PackageState>接口

@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

;

}

}

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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);

// 这个 state是枚举值

String s = gson.toJson(item);

System.out.println(s);

System.out.println(

"--------------------------------"

);

PackageItem retItem = gson.fromJson(s, PackageItem.

class

);

System.out.println(retItem);

}

}

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{

"name"

:

"item_name"

,

"state"

:

2

,

"size"

:

"500M"

}

--------------------------------

PackageItem [name=item_name, size=500M, state=UPDATING]