【轉】 Json轉換利器Gson之實例五-註冊TypeAdapter及處理Enum類型

時間 2019-11-12

標籤 json 轉換利器 gson 實例註冊 typeadapter 處理 enum 類型欄目 JavaScript 简体版

原文原文鏈接

枚舉類型給咱們的程序帶來了好處,如何用Gson來實現與Json的互轉呢?請看本文.html

本文重點掌握如何本身寫一個TypeAdapter及註冊TypeAdapter和處理Enum類型.java

實體類:json

1ide

2測試

3ui

public enum PackageState {this

PLAY, UPDATE, UPDATING, DOWNLOAD, DOWNLOADING,google

}spa

1.net

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 + "]";

}

　本身寫一個轉換器實現JsonSerializer<T>接口和jsonDeserializer<T>接口:

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> {

// 對象轉爲Json時調用,實現JsonSerializer<PackageState>接口

@Override

public JsonElement serialize(PackageState state, Type arg1,

JsonSerializationContext arg2) {

return new JsonPrimitive(state.ordinal());

}

// json轉爲對象時調用,實現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;

}

　測試類:

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);// 這個 state是枚舉值

String s = gson.toJson(item);

System.out.println(s);

System.out.println("--------------------------------");

PackageItem retItem = gson.fromJson(s, PackageItem.class);

System.out.println(retItem);

}

　輸出結果(結果中已經將state的對應枚舉類型轉爲了int類型):

{"name":"item_name","state":2,"size":"500M"}

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

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

分類: JSP

標籤: Enum, Gson, json, TypeAdapter, 實例

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