使用Gson解析json数据
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使用Gson解析复杂的JSON数据
使用Gson解析json数据
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搞定Gson泛型封装
简单新闻客户端
1. json
Json 全称 JavaScript Object Natation ，用来描述数据结构，它是基于纯文本的数据格式，是一种轻量级的数据交换格式。广泛应用于服务端与客户端的数据交互。
2. 格式
- Json 以key－value的形式存储数据
- Key的取值为String类型
- Value的取值为String，boolean，Number，数组，Object，null
- Json串以{ 开始，以 } 结尾
- Json 串中数组是以 [ 开始，以 ] 结尾
- Json串中Object是以 { 开始，以 } 结尾
3. 原生解析
JSONObject root = new JSONObject(response);
JSONArray jsonArray = root.getJSONArray("appinfo");
JSONObject jsonObject = jsonArray.getJSONObject(0);
String des = jsonObject.getString("des");
jsonObject.optString()[
{
"infos": [
{
"name1": "休闲",
"name2": "棋牌",
"name3": "益智",
"url1": "image/category_game_0.jpg",
"url2": "image/category_game_1.jpg",
"url3": "image/category_game_2.jpg"
},
{
"name1": "射击",
"name2": "体育",
"name3": "儿童",
"url1": "image/category_game_3.jpg",
"url2": "image/category_game_4.jpg",
"url3": "image/category_game_5.jpg"
},
{
"name1": "网游",
"name2": "角色",
"name3": "策略",
"url1": "image/category_game_6.jpg",
"url2": "image/category_game_7.jpg",
"url3": "image/category_game_8.jpg"
},
{
"name1": "经营",
"name2": "竞速",
"name3": "",
"url1": "image/category_game_9.jpg",
"url2": "image/category_game_10.jpg",
"url3": ""
}
],
"title": "游戏"
},
{
"infos": [
{
"name1": "浏览器",
"name2": "输入法",
"name3": "健康",
"url1": "image/category_app_0.jpg",
"url2": "image/category_app_1.jpg",
"url3": "image/category_app_2.jpg"
},
{
"name1": "效率",
"name2": "教育",
"name3": "理财",
"url1": "image/category_app_3.jpg",
"url2": "image/category_app_4.jpg",
"url3": "image/category_app_5.jpg"
},
{
"name1": "阅读",
"name2": "个性化",
"name3": "购物",
"url1": "image/category_app_6.jpg",
"url2": "image/category_app_7.jpg",
"url3": "image/category_app_8.jpg"
},
{
"name1": "资讯",
"name2": "生活",
"name3": "工具",
"url1": "image/category_app_9.jpg",
"url2": "image/category_app_10.jpg",
"url3": "image/category_app_11.jpg"
},
{
"name1": "出行",
"name2": "通讯",
"name3": "拍照",
"url1": "image/category_app_12.jpg",
"url2": "image/category_app_13.jpg",
"url3": "image/category_app_14.jpg"
},
{
"name1": "社交",
"name2": "影音",
"name3": "安全",
"url1": "image/category_app_15.jpg",
"url2": "image/category_app_16.jpg",
"url3": "image/category_app_17.jpg"
}
],
"title": "应用"
}
]
public class CategoryInfoBean {
public String title; // title
public String name1; // 休闲
public String name2; // 棋牌
public String name3; // 益智
public String url1; // image/category_game_0.jpg
public String url2; // image/category_game_1.jpg
public String url3; // image/category_game_2.jpg
public boolean isTitle; // 自己添加的一个属性,确定是否是title
}List categoryInfoBeans = new ArrayList();
try {
JSONArray rootJsonArray = new JSONArray(jsonString);
// 遍历jsonArray
for (int i = 0; i < rootJsonArray.length(); i++) {
JSONObject itemJsonObject = rootJsonArray.getJSONObject(i);
String title = itemJsonObject.getString("title");
CategoryInfoBean titleBean = new CategoryInfoBean();
titleBean.title = title;
titleBean.isTitle = true;
categoryInfoBeans.add(titleBean);
JSONArray infosJsonArray = itemJsonObject.getJSONArray("infos");
// 遍历infosJsonArray
for (int j = 0; j < infosJsonArray.length(); j++) {
JSONObject infoJsonObject = infosJsonArray.getJSONObject(j);
String name1 = infoJsonObject.getString("name1");
String name2 = infoJsonObject.getString("name2");
String name3 = infoJsonObject.getString("name3");
String url1 = infoJsonObject.getString("url1");
String url2 = infoJsonObject.getString("url2");
String url3 = infoJsonObject.getString("url3");
CategoryInfoBean infoBean = new CategoryInfoBean();
infoBean.name1 = name1;
infoBean.name2 = name2;
infoBean.name3 = name3;
infoBean.url1 = url1;
infoBean.url2 = url2;
infoBean.url3 = url3;
categoryInfoBeans.add(infoBean);
}
}
public List parseData(String result) {
if (!TextUtils.isEmpty(result)) {
try {
categoryInfoList = new ArrayList();
JSONArray jsonArray=new JSONArray(result);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject=jsonArray.getJSONObject(i);
CategoryInfo categoryInfo=new CategoryInfo();
if (jsonObject.has("title")) {
categoryInfo.setTitle(jsonObject.getString("title"));
categoryInfo.setTitle(true);
categoryInfoList.add(categoryInfo);
}
if (jsonObject.has("info")) {
categoryInfo.setName1(jsonObject.getString("name1"));
categoryInfo.setName2(jsonObject.getString("name2"));
categoryInfo.setName3(jsonObject.getString("name3"));
categoryInfo.setUrl1(jsonObject.getString("url1"));
categoryInfo.setUrl1(jsonObject.getString("url2"));
categoryInfo.setUrl1(jsonObject.getString("url3"));
categoryInfo.setTitle(false);
categoryInfoList.add(categoryInfo);
}
}
return categoryInfoList;
} catch (JSONException e) {
e.printStackTrace();
}
}
return null;
} 
4. Gson格式化
将 java 对象 格式化为 Json 字符串.
实现步骤 :
获得需要的对象:
Student stu = new Student();
stu.setName("张三");
stu.setAge(18);
stu.setSex(true);格式化
Gson gson = new Gson();
//将 对象 转化成 json 字符串
String json = gson.toJson(stu)5. Gson解析
遇到[ ]就解析成集合，遇到{ }就解析成对象，遇到”“就解析成一个对应的基本数据类型
{
"data": [
{
"children": [
{
"id": 10007,
"title": "北京",
"type": 1,
"url": "/10007/list_1.json"
},
{
"id": 10006,
"title": "中国",
"type": 1,
"url": "/10006/list_1.json"
},
{
"id": 10008,
"title": "国际",
"type": 1,
"url": "/10008/list_1.json"
},
{
"id": 10010,
"title": "体育",
"type": 1,
"url": "/10010/list_1.json"
},
{
"id": 10091,
"title": "生活",
"type": 1,
"url": "/10091/list_1.json"
},
{
"id": 10012,
"title": "旅游",
"type": 1,
"url": "/10012/list_1.json"
},
{
"id": 10095,
"title": "科技",
"type": 1,
"url": "/10095/list_1.json"
},
{
"id": 10009,
"title": "军事",
"type": 1,
"url": "/10009/list_1.json"
},
{
"id": 10093,
"title": "时尚",
"type": 1,
"url": "/10093/list_1.json"
},
{
"id": 10011,
"title": "财经",
"type": 1,
"url": "/10011/list_1.json"
},
{
"id": 10094,
"title": "育儿",
"type": 1,
"url": "/10094/list_1.json"
},
{
"id": 10105,
"title": "汽车",
"type": 1,
"url": "/10105/list_1.json"
}
],
"id": 10000,
"title": "新闻",
"type": 1
},
{
"id": 10002,
"title": "专题",
"type": 10,
"url": "/10006/list_1.json",
"url1": "/10007/list1_1.json"
},
{
"id": 10003,
"title": "组图",
"type": 2,
"url": "/10008/list_1.json"
},
{
"dayurl": "",
"excurl": "",
"id": 10004,
"title": "互动",
"type": 3,
"weekurl": ""
}
],
"extend": [
10007,
10006,
10008,
10014,
10012,
10091,
10009,
10010,
10095
],
"retcode": 200
}
/**
* 网络分类信息的封装
*
* 字段名字必须和服务器返回的字段名一致, 方便gson解析
*
*/
public class NewsData {
public int retcode;
public ArrayList data;
// 侧边栏数据对象
public class NewsMenuData {
public String id;
public String title;
public int type;
public String url;
public ArrayList children;
@Override
public String toString() {
return "NewsMenuData [title=" + title + ", children=" + children
+ "]";
}
}
// 新闻页面下11个子页签的数据对象
public class NewsTabData {
public String id;
public String title;
public int type;
public String url;
@Override
public String toString() {
return "NewsTabData [title=" + title + "]";
}
}
@Override
public String toString() {
return "NewsData [data=" + data + "]";
}
} NewsData mNewsData Gson gson = new Gson();
mNewsData = gson.fromJson(result, NewsData.class);解析结果
5.1 标准解析
public class GsonTools {
public GsonTools() {
}
public static String createGsonString(Object object) {
Gson gson = new Gson();
String gsonString = gson.toJson(object);
return gsonString;
}
public static T changeGsonToBean(String gsonString, Class cls) {
Gson gson = new Gson();
T t = gson.fromJson(gsonString, cls);
return t;
}
public static T changeGsonToBean(String gsonString, Type type) {
Gson gson = new Gson();
T t = gson.fromJson(gsonString,type);
return t;
}
public static List changeGsonToList(String gsonString, Class cls) {
Gson gson = new Gson();
List list = gson.fromJson(gsonString, new TypeToken>() {
}.getType());
return list;
}
public static List> changeGsonToListMaps(String gsonString) {
List> list = null;
Gson gson = new Gson();
list = gson.fromJson(gsonString, new TypeToken>>(){}.getType());
return list;
}
public static Map changeGsonToMaps(String gsonString) {
Map map = null;
Gson gson = new Gson();
map = gson.fromJson(gsonString, new TypeToken>(){}.getType());
return map;
}
} Json的解析成 java 对象
Gson gson = new Gson();
// 将json 转化成 java 对象
Student stu = gson.fromJson(json, Student.class);
// 将 json 转化 成 List泛型
List stus = gson.fromJson(json, new TypeToken>() {}.getType());
// 将 json 转化 成 Map泛型
Map map = gson.fromJson(json, new TypeToken>() {}.getType()); 5.2 泛型解析
[
{
"des": "2005-2014 你的校园一直在这儿。中国最大的实名制SNS网络平台，大学生",
"downloadUrl": "app/com.renren.mobile.android/com.renren.mobile.android.apk",
"iconUrl": "app/com.renren.mobile.android/icon.jpg",
"id": 1580615,
"name": "人人",
"packageName": "com.renren.mobile.android",
"size": 21803987,
"stars": 2
},
{
"des": "中国电信掌上营业厅是中国电信集团【官方】唯一指定服务全国电信用户的自助服务客户端",
"downloadUrl": "app/com.ct.client/com.ct.client.apk",
"iconUrl": "app/com.ct.client/icon.jpg",
"id": 1540629,
"name": "掌上营业厅",
"packageName": "com.ct.client",
"size": 4794202,
"stars": 2
}
]
public class AppInfoBean {
public String des; // 应用的描述
public String downloadUrl; // 应用的下载地址
public String iconUrl; // 应用的图标地址
public long id; // 应用的id
public String name; // 应用的名字
public String packageName; // 应用的包名
public long size; // 应用的长度
public float stars; // 应用的评分
}public List parseJson(String jsonString) {
Gson gson = new Gson();
/*=============== 泛型解析 ===============*/
return gson.fromJson(jsonString, new TypeToken>() {
}.getType());
} Type type = new TypeToken>() {}.getType(); Gson gson = new Gson();
List list = gson.fromJson(result,new TypeToken>(){}.getType()); Map map = gson.fromJson(response,new TypeToken>(){}.getType()); public abstract class BaseProtocol<T> {
protected abstract String getInterfaceKey();
protected T parseJson(String result){
ParameterizedType genericSuperclass = (ParameterizedType) getClass().getGenericSuperclass();
Type[] types = genericSuperclass.getActualTypeArguments();
Type type = types[0];
return new Gson().fromJson(result,type);
}
}5.3 节点解析
适合属性比较多的情况，要啥取啥
Gson的节点对象
| 节点对象 | 说明 |
|---|---|
| JsonElement | 所有的节点都是JsonElement对象 |
| JsonPrimitive | 基本的数据类型的节点对象， JsonElement的子类 |
| JsonNull | 代表空节点对象，即有key，value为空，JsonElement 的子类 |
| JsonObject | 对象 数据类型的节点对象, JsonElement的子类 |
| JsonArray | 数组 数据类型的节点对象, JsonElement的子类 |
5.4 JsonElement的取值
JsonPrimitive : value 的 取值对应 java
int，double，float，long，short，boolean，char，byte，String，BigDecimal，BigInteger，Number
JsonObject : value 的 取值对应 java 的 Object 对象
JsonArray : value 的 取值对应 java 的 List 及其子类对象
//1、获得 解析者
JsonParser parser = new JsonParser();
//2、获得 根节点元素
JsonElement root = parser.parse(json);
//3、根据 文档判断根节点属于 什么类型的 Gson节点对象
//假如文档 显示 根节点 为对象类型
// 获得 根节点 的实际 节点类型
JsonObject element = root.getAsJsonObject();
//4、取得 节点 下 的某个节点的 value
// 获得 name 节点的值，name 节点为基本数据节点
JsonPrimitive nameJson = element.getAsJsonPrimitive("name");
String name = nameJson.getAsString();
// 获得 students 节点的值, students 节点为 数组数据节点
JsonArray arrayJson = element.getAsJsonArray("students");
// 获得数据 的长度
int size = arrayJson.size();
for(int i = 0; i < size; i++) {
//获得每一个json 元素
JsonElement e = arrayJson.get(i);
// 通过元素 得到需要的节点值 TODO:
}public List parseJson(String jsonString) {
Gson gson = new Gson();
/*=============== 泛型解析 ===============*/
// return gson.fromJson(jsonString, new TypeToken>() {
// }.getType());
/*=============== 结点解析 ===============*/
List appInfoBeans = new ArrayList();
// 获得json的解析器
JsonParser parser = new JsonParser();
JsonElement rootJsonElement = parser.parse(jsonString);
// JsonElement-->转换成jsonArray
JsonArray rootJsonArray = rootJsonElement.getAsJsonArray();
// 遍历jsonArray
for (JsonElement itemJsonElement : rootJsonArray) {
// jsonElement-->转换成JsonObject
JsonObject itemJsonObject = itemJsonElement.getAsJsonObject();
// 得到具体的jsonPrimitivie
JsonPrimitive desPrimitivie = itemJsonObject.getAsJsonPrimitive("des");
// jsonPrimitivie-->转换成具体的类型
String des = desPrimitivie.getAsString();
// 得到具体的jsonPrimitivie
JsonPrimitive downloadUrlPrimitivie = itemJsonObject.getAsJsonPrimitive("downloadUrl");
// jsonPrimitivie-->转换成具体的类型
String downloadUrl = downloadUrlPrimitivie.getAsString();
String iconUrl = itemJsonObject.get("iconUrl").getAsString();
long id = itemJsonObject.get("id").getAsLong();
String name = itemJsonObject.get("name").getAsString();
String packageName = itemJsonObject.get("packageName").getAsString();
long size = itemJsonObject.get("size").getAsLong();
float stars = itemJsonObject.get("stars").getAsFloat();
AppInfoBean info = new AppInfoBean();
info.des = des;
info.downloadUrl = downloadUrl;
info.iconUrl = iconUrl;
info.id = id;
info.name = name;
info.packageName = packageName;
info.size = size;
info.stars = stars;
// 添加到集合
appInfoBeans.add(info);
}
// 返回结果
return appInfoBeans;
} com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON
Gson gson = new Gson();
JsonReader reader = new JsonReader(new StringReader(result1));
reader.setLenient(true);
Userinfo userinfo1 = gson.fromJson(reader, Userinfo.class);String trimmed = result1.trim();
gson.fromJson(trimmed, T);com.google.gson.internal.LinkedTreeMap cannot be cast to com.google.smartcit
public static List changeGsonToList(String gsonString, Class cls) {
Gson gson = new Gson();
List list = gson.fromJson(gsonString, new TypeToken>() {
}.getType());
return list;
} public static List getObjectList(String jsonString,Class cls){
List list = new ArrayList();
try {
Gson gson = new Gson();
JsonArray arry = new JsonParser().parse(jsonString).getAsJsonArray();
for (JsonElement jsonElement : arry) {
list.add(gson.fromJson(jsonElement, cls));
}
} catch (Exception e) {
e.printStackTrace();
}
return list;
}
5.5 处理json格式特殊字符
public static String changeStr(String json){
json = json.replaceAll(",", "，");
json = json.replaceAll(":", "：");
json = json.replaceAll("\\[", "【");
json = json.replaceAll("\\]", "】");
json = json.replaceAll("\\{", "<");
json = json.replaceAll("\\}", ">");
json = json.replaceAll("\"", "”");
return json.toString();
}