使用Gson解析json数据

Gson解析系列阅读

• Gson使用指南

• 使用Gson解析复杂的JSON数据

• 使用Gson解析json数据

• Gson全解析

• 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<CategoryInfoBean> categoryInfoBeans = new ArrayList<CategoryInfoBean>();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<CategoryInfo> parseData(String result) {        if (!TextUtils.isEmpty(result)) {            try {                categoryInfoList = new ArrayList<CategoryInfo>();                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<NewsMenuData> 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<NewsTabData> 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> T changeGsonToBean(String gsonString, Class<T> cls) {        Gson gson = new Gson();        T t = gson.fromJson(gsonString, cls);        return t;    }    public static <T> T changeGsonToBean(String gsonString, Type type) {        Gson gson = new Gson();        T t = gson.fromJson(gsonString,type);        return t;    }    public static <T> List<T> changeGsonToList(String gsonString, Class<T> cls) {        Gson gson = new Gson();        List<T> list = gson.fromJson(gsonString, new TypeToken<List<T>>() {        }.getType());        return list;    }    public static <T> List<Map<String, T>> changeGsonToListMaps(String gsonString) {        List<Map<String, T>> list = null;        Gson gson = new Gson();        list = gson.fromJson(gsonString, new TypeToken<List<Map<String, T>>>(){}.getType());        return list;    }    public static <T> Map<String, T> changeGsonToMaps(String gsonString) {        Map<String, T> map = null;        Gson gson = new Gson();        map = gson.fromJson(gsonString, new TypeToken<Map<String, T>>(){}.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<Student> stus = gson.fromJson(json, new TypeToken<List<Student>>() {}.getType());// 将 json 转化 成 Map泛型 Map<String,String> map = gson.fromJson(json, new TypeToken<Map<String,String>>() {}.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<AppInfoBean> parseJson(String jsonString) {        Gson gson = new Gson();        /*=============== 泛型解析 ===============*/        return gson.fromJson(jsonString, new TypeToken<List<AppInfoBean>>() {        }.getType());    }

Type type = new TypeToken<ArrayList<String>>() {}.getType();  

Gson gson = new Gson();List<HomeBean> list = gson.fromJson(result,new TypeToken<List< HomeBean>>(){}.getType());

Map<String,String> map = gson.fromJson(response,new TypeToken<Map<String,String>>(){}.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<AppInfoBean> parseJson(String jsonString) {        Gson gson = new Gson();        /*=============== 泛型解析 ===============*/        // return gson.fromJson(jsonString, new TypeToken<List<AppInfoBean>>() {        // }.getType());        /*=============== 结点解析 ===============*/        List<AppInfoBean> appInfoBeans = new ArrayList<AppInfoBean>();        // 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 <T> List<T> changeGsonToList(String gsonString, Class<T> cls) {        Gson gson = new Gson();        List<T> list = gson.fromJson(gsonString, new TypeToken<List<T>>() {        }.getType());        return list;    }

public static <T> List<T> getObjectList(String jsonString,Class<T> cls){          List<T> list = new ArrayList<T>();          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();    }