文章目录
- 一、什么是JSON数据?
- 二、JSON解析方法
- 2.1、原生解析
- 2.2、Gson解析
- 2.3、FastJson解析
- 四、总结
一、什么是JSON数据?
先看下面,这里有一段JSON数据,我们根据这段数进行讲解:
{"paramz": {"feeds": [{"id": 299076,"oid": 288340,"category": "article","data": {"subject": "荔枝新闻3.0:不止是阅读","summary": "江苏广电旗下资讯类手机应用“荔枝新闻”于近期推出全新升级换代的3.0版。","cover": "/Attachs/Article/288340/3e8e2c397c70469f8845fad73aa38165_padmini.JPG","pic": "","format": "txt","changed": "2015-09-22 16:01:41"}}],"PageIndex": 1,"PageSize": 20,"TotalCount": 53521,"TotalPage": 2677}
}
其实JSON数据就是一段字符串而已,只不过有不同意义的分隔符将其分割开来而已,我们看上面的符号,里面有[] ,{}等符号,其中
[]
: 中括号代表的是一个数组;-{}
: 大括号代表的是一个对象""
: 表示的是属性值:
: 代表的是前后之间的关系,冒号前面是属性的名称,后面是属性的值,这个值可以是基本数据类型,也可以是引用数据类型。
二、JSON解析方法
2.1、原生解析
JSONObject系统自带的解析方式解析,我们先来JSONObject(系统自带的类)类中的方法:
上面用红框框出来的是我们手动解析最常用的方法了,好了,现在我们想要解析上面的一段数据,该怎么做呢?这里我写了一个解析类如下
public class JsonUtils {/*** 根据json数据解析返回一个List<HashMap<String, Object>>集合* @param json json数据* @return*/public static List<HashMap<String, Object>> getJsonList(String json) {List<HashMap<String, Object>> dataList;dataList = new ArrayList<>();try {JSONObject rootObject = new JSONObject(json);JSONObject paramzObject = rootObject.getJSONObject("paramz");JSONArray feedsArray = paramzObject.getJSONArray("feeds");for (int i = 0; i < feedsArray.length(); i++) {JSONObject sonObject = feedsArray.getJSONObject(i);JSONObject dataObject = sonObject.getJSONObject("data");String subjectStr = dataObject.getString("subject");String summaryStr = dataObject.getString("summary");String coverStr = dataObject.getString("cover");HashMap<String, Object> map = new HashMap<>();map.put("subject", subjectStr);map.put("summary", summaryStr);map.put("cover", coverStr);dataList.add(map);}return dataList;} catch (JSONException e) {e.printStackTrace();}return null;}
}
相信很简单一看就懂了吧,此方法写起来主要是比较费时间罢了,无非就是几个方法不停的调用而已,所以显得特别的费时费力,下面我又写了一个解析的方法,方法中会有一些冗余的代码,是为了更加深刻理解JSON解析而写的,实际中可以删掉,也用了一行GSON解析,GSON解析下面会见讲到:
其中DataModel对象我是将data对象使用GsonFormat插件工具生成的,使用方式可以自行搜索
public class DataModel {/*** subject : "荔枝新闻3.0:不止是阅读"* summary : "江苏广电旗下资讯类手机应用“荔枝新闻”于近期推出全新升级换代的3.0版。"* cover : "/Attachs/Article/288340/3e8e2c397c70469f8845fad73aa38165_padmini.JPG"* pic :* format : video* changed : 2015-11-07 14:35:22*/public String subject;public String summary;public String cover;public String pic;public String format;public String changed;@Overridepublic String toString() {return "DataModel{" +"subject='" + subject + '\'' +", summary='" + summary + '\'' +", cover='" + cover + '\'' +", pic='" + pic + '\'' +", format='" + format + '\'' +", changed='" + changed + '\'' +'}';}
}
/*** 根据json对象获取List<DataModel>集合* @param json 数据* @return*/public static List<DataModel> getGsonList(String json) {List<DataModel> dataList;try {JSONObject rootObject = new JSONObject(json);JSONObject paramzObject = rootObject.getJSONObject("paramz");/*** JSONArray的构造方法获取JSONArray对象*/JSONArray jsonArray = new JSONArray(paramzObject.getString("feeds"));Log.i(TAG, "jsonarray.length():"+jsonArray.length());/*** 获取JSONObject对象的属性关键字*/Iterator<String> iterators = paramzObject.keys();while (iterators.hasNext()) {Log.i(TAG, "iterators: " + iterators.next());}JSONArray feeds = paramzObject.getJSONArray("feeds");dataList = new ArrayList<>();for (int i = 0; i < feeds.length(); i++) {JSONObject jsonObject = feeds.getJSONObject(i);DataModel model = new Gson().fromJson(jsonObject.getString("data"), new TypeToken<DataModel>() {}.getType());Log.i(TAG, "DataModel: " + model.toString());dataList.add(model);}return dataList;} catch (JSONException e) {// TODO Auto-generated catch blocke.printStackTrace();}return null;}
1、对于JSONObject对象来说,想要得到一个JSONObject对象通常可以通过
JSONObject(String json)-> JSONObject rootObject = new JSONObject(json);
JSONObject getJSONObject(String name){}-> JSONObject paramzObject = rootObject.getJSONObject(“paramz”);
2、对于JSONArray对象来说,想要得到一个JSONArray对象通常可以通过
JSONArray(String json)->JSONArray jsonArray = new JSONArray(paramzObject.getString(“feeds”));
JSONObject getJSONObject(String name){}-> JSONArray feeds = paramzObject.getJSONArray(“feeds”);
2.2、Gson解析
我们如果懂得了上面的手动解析方式的话,那么对于Gson解析而言,就太简单了,下面我们就开始解析下面一段JSON数据:
{"homeadlist": [{"id": 1,"imgurl": "/img/homead/a73b3f1d-0f14-429d-9d0f-70643fb0f0eb.jpg","jumpflag": 0,"jumpurl": "","posflag": 1,"remark": "1111","cityid": 1},{"id": 12,"imgurl": "/img/homead/eb442fbf-49db-4ba6-a102-d781505f426d.jpg","jumpflag": 0,"jumpurl": "","posflag": 2,"remark": "","cityid": 1},{"id": 14,"imgurl": "/img/homead/68109460-635d-4c5c-8be8-64d7c7889d18.jpg","jumpflag": 0,"jumpurl": "http://shiranlife.kuaizhan.com/","posflag": 4,"remark": "","cityid": 1}]
}
首先我们使用GsonFormat工具生成一个类HomeadListModel:
public class HomeadListModel {/*** code : 1* data : {"homeadlist":[{"id":1,"imgurl":"/img/homead/a73b3f1d-0f14-429d-9d0f-70643fb0f0eb.jpg","jumpflag":0,"jumpurl":"","posflag":1,"remark":"1111","cityid":1},{"id":12,"imgurl":"/img/homead/eb442fbf-49db-4ba6-a102-d781505f426d.jpg","jumpflag":0,"jumpurl":"","posflag":2,"remark":"","cityid":1},{"id":14,"imgurl":"/img/homead/68109460-635d-4c5c-8be8-64d7c7889d18.jpg","jumpflag":0,"jumpurl":"http://shiranlife.kuaizhan.com/","posflag":4,"remark":"","cityid":1}]}*/public int code;public DataBean data;public static class DataBean {public List<HomeadlistBean> homeadlist;public static class HomeadlistBean {public int id;public String imgurl;public int jumpflag;public String jumpurl;public int posflag;public String remark;public int cityid;}}
}
我们使用OKHttpClient,代码如下
OkHttpClient.Builder builder = new OkHttpClient.Builder();Request request = new Request.Builder().url(url).get().build();builder.build().newCall(request).enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {}@Overridepublic void onResponse(Call call, Response response) throws IOException {Gson gson = new Gson();/*** java.lang.IllegalStateException: closed* 因为OkHttp请求回调中response.body().string()只能有效调用一次**/String string = response.body().string();Log.i("aaa", "response: " + string);/*** 重新构建一个response 因为response.body().string()调用一次之后流就断掉了,只能有效调用一次*/MediaType mediaType = response.body().contentType();Response response1 = response.newBuilder().body(ResponseBody.create(mediaType, string)).build();String string1 = response1.body().string();Log.i("aaa", "response1: " + string1);/*** 将json数据转换为对象*/HomeadListModel model = gson.fromJson(string1, HomeadListModel.class);//HomeadListModel model2 = gson.fromJson(string1, new TypeToken<HomeadListModel>() {}.getType());/*** 将对象转换为json数据*/String jsonString = gson.toJson(model);Log.i("aaa", "onResponse2: " + jsonString);for (HomeadListModel.DataBean.HomeadlistBean data : model.data.homeadlist) {mData.add(imageUrl + data.imgurl);}runOnUiThread(new Runnable() {@Overridepublic void run() {mAdapter.notifyDataSetChanged();}});}});
我们想要将一个json数据转换为对象的话需要使用fromJson(String json, Class classOfT) /fromJson(String json, Type typeOfT),当我们需要将对象转换为String的时候根据String toJson(Object src)方法即可。这里需要注意一点,如果response.body().string()调用大于一次的话,就会报错java.lang.IllegalStateException: closed,因为response.body().string()调用一次之后流就断掉了,需要重新构建一个response;
2.3、FastJson解析
这个解析和Gson解析差不多,也是一行就搞定了,也是对上面的Gson数据进行解析,想要将json数据解析成对象需要使用 parseObject()方法,参数可以传Class,也可以传Type;当需要通过对象得到String字符串时候使用String json1 = JSONObject.toJSONString(model)即可,下面贴上代码
OkHttpClient.Builder builder = new OkHttpClient.Builder();Request request = new Request.Builder().url(url).get().build();builder.build().newCall(request).enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {}@Overridepublic void onResponse(Call call, Response response) throws IOException {String json = response.body().string();/*** 根据json数据获取对象*/HomeadListModel model = JSONObject.parseObject(json, new TypeToken<HomeadListModel>() {}.getType());
// HomeadListModel model2 = JSONObject.parseObject(json, HomeadListModel.class);/*** 根据对象获取json数据*/String json1 = JSONObject.toJSONString(model);Log.i("aaa", "fastJson: " + json1);for (HomeadListModel.DataBean.HomeadlistBean data : model.data.homeadlist) {mData.add(imageUrl + data.imgurl);}runOnUiThread(new Runnable() {@Overridepublic void run() {mAdapter.notifyDataSetChanged();}});}});
四、总结
上面写了三种解析JSON数据的方法,第一种是最麻烦的,但是不一定是最差的,后面两种Gson和FastJson都是最常用的方法。