JSON数据格式有两种,一种是 { } 大括号表示的JSON对象,一种是 [ ] 中括号表示的JSON数组。从OneNET获取到的数组是这样的,并用Json解析网址查看https://jsonformatter.curiousconcept.com/#(图1)。可以看到这是一个对象包含了数组又包含对象的JSON数据。比如我现在要获取id号为3300_1_5700时间为2020-12-09 20:19:30.624的数据(图1唯一展开的datastreams数组元素)它是一个JSON对象(因为它是被一个大括号包者的),所以datastreams[0]这个JSON对象时包含了datapoints和id,前者又是一个JSON数组(中括号包者),后者则是一个普通的字符串。综上,要获取图1的value值,我要通过一开始返回到的JSON数据 找到 dataJSON对象 找到 datastreamsJSON数组 找到 datapointsJSON数组 中的value字符串。
```
{ "errno": 0, "data": { "count": 10, "datastreams": [ { "datapoints": [ { "at": "2020-12-09 20:19:30.624", "value": 0 } ], "id": "3300_1_5700" }, { "datapoints": [ { "at": "2019-07-30 21:38:03.729", "value": 0 } ], "id": "3327_0_5700" }, { "datapoints": [ { "at": "2019-12-26 21:27:14.700", "value": "\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000" } ], "id": "3336_0_5514" }, { "datapoints": [ { "at": "2019-12-26 21:27:14.700", "value": "\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000" } ], "id": "3336_0_5515" }, { "datapoints": [ { "at": "2020-12-09 20:19:30.624", "value": 0 } ], "id": "3303_0_5700" }, { "datapoints": [ { "at": "2019-04-21 14:35:11.158", "value": 29.8 } ], "id": "3304_0_5700" }, { "datapoints": [ { "at": "2020-12-09 20:19:31.980", "value": 0 } ], "id": "3326_0_5700" }, { "datapoints": [ { "at": "2019-12-26 19:23:09.191", "value": false } ], "id": "3338_0_5850" }, { "datapoints": [ { "at": "2020-12-09 20:19:29.412", "value": 0 } ], "id": "3300_0_5700" }, { "datapoints": [ { "at": "2019-05-17 09:09:13.681", "value": false } ], "id": "3311_0_5850" } ] }, "error": "succ" }
```

(图1)
执行过程是,当获取到data JSON对象时,获取count字符串,这是OneNET平台给我返回的数值,功能时告诉我datastreams中一共有多少个元素,所以用遍历datastreams数组,进入datastreams后,获取id号,id号是用单片机根据NB-IoT文档(OneNET官网文档)上传到云平台的,根据这一id号来确认到底是哪一个传感器。总之什么时候用getJSONObject或getJSONaRRAY一定要看自己返回的数据是什么,是大括号还是中括号,如果都不是只是一个普通的字符串就用getString方法获取字符串,getString("value")中""写的是元素名,拿的是元素值,比如"value":0这一行,拿的就是0这个元素值。
- 1 package com.example.helloworld.learnokhttp;
- 2
- 3 import android.bluetooth.BluetoothClass;
- 4 import android.os.Bundle;
- 5 import android.view.View;
- 6 import android.widget.Button;
- 7 import android.widget.TextView;
- 8 import android.widget.Toast;
- 9
- 10 import androidx.annotation.Nullable;
- 11 import androidx.appcompat.app.AppCompatActivity;
- 12
- 13 import com.alibaba.fastjson.JSON;
- 14 import com.alibaba.fastjson.JSONArray;
- 15 import com.alibaba.fastjson.JSONObject;
- 16 import com.example.helloworld.R;
- 17 import com.example.helloworld.learnokhttp.javabean.Data;
- 18 import com.example.helloworld.learnokhttp.javabean.Datapoints;
- 19 import com.example.helloworld.learnokhttp.javabean.Datastreams;
- 20 import com.example.helloworld.learnokhttp.javabean.JsonRootBean;
- 21 import com.lzy.okgo.OkGo;
- 22 import com.lzy.okgo.adapter.Call;
- 23 import com.lzy.okgo.cache.CacheMode;
- 24 import com.lzy.okgo.callback.StringCallback;
- 25 import com.lzy.okgo.model.Response;
- 26
- 27 import org.w3c.dom.Text;
- 28
- 29 import java.util.Iterator;
- 30 import java.util.List;
- 31
- 32 public class OkHttpGoActivity extends AppCompatActivity implements View.OnClickListener {
- 33
- 34 private String url = "https://api.heclouds.com/devices/523698851/datapoints";//
- 35 private Button btn_get,btn_resolvebyfastjson;
- 36 private TextView tv_result,tv_wendu,tv_do,tv_ph,tv_tds,tv_zhuodu;
- 37
- 38 @Override
- 39 protected void onCreate(@Nullable Bundle savedInstanceState) {
- 40 super.onCreate(savedInstanceState);
- 41 setContentView(R.layout.activity_okhttpgo);
- 42
- 43 setTitle("用封装的方法获取数据");
- 44
- 45 btn_get = findViewById(R.id.btn_get);
- 46 btn_resolvebyfastjson = findViewById(R.id.btn_resolvebyfastjson);
- 47 tv_result = findViewById(R.id.tv_result);
- 48 tv_wendu = findViewById(R.id.tv_wendu);
- 49 tv_do = findViewById(R.id.tv_do);
- 50 tv_ph = findViewById(R.id.tv_ph);
- 51 tv_tds = findViewById(R.id.tv_tds);
- 52 tv_zhuodu = findViewById(R.id.tv_zhuodu);
- 53 btn_get.setOnClickListener(this);
- 54 btn_resolvebyfastjson.setOnClickListener(this);
- 55 }
- 56
- 57 @Override
- 58 protected void onDestroy() {
- 59 super.onDestroy();
- 60 //Activity销毁时,取消网络请求
- 61 OkGo.getInstance().cancelTag(this);
- 62 }
- 63
- 64 /**
- 65 *先用okhttpgo拿一次数据
- 66 *@author home
- 67 *@time 2021/2/24 10:23
- 68 */
- 69 private void getByOkGo() {
- 70 OkGo.<String>get(url)//文档说的第一行泛型一定要添加是指这里
- 71 .headers("api-key", "4VdbaFeRQZRwaSTWNhWxb2UEHaw=")//设备的api-key
- 72 .headers("Content-Type","application/json")
- 73 .tag(this)
- 74 .execute(new StringCallback() {
- 75 @Override
- 76 public void onSuccess(Response<String> response) {//请求成功回调onSuccess方法
- 77 tv_result.setText(response.body());//文档中有说明,body是返回的数据
- 78 }
- 79
- 80 @Override
- 81 public void onError(Response<String> response) {
- 82 Toast.makeText(getApplicationContext(), "接口请求错误!", Toast.LENGTH_LONG).show();
- 83 }
- 84 });
- 85 }
- 86
- 87 /**
- 88 *OkHttpGo与FastJson结合,并显示到界面
- 89 *@author home
- 90 *@time 2021/2/24 10:25
- 91 */
- 92 private void jsonToJavaListByFastJson() {
- 93 OkGo.<String>get(url)//文档说的第一行泛型一定要添加是指这里
- 94 .headers("api-key", "4VdbaFeRQZRwaSTWNhWxb2UEHaw=")//设备的api-key
- 95 .headers("Content-Type","application/json")
- 96 .tag(this)
- 97 .execute(new StringCallback() {
- 98 @Override
- 99 public void onSuccess(Response<String> response) {//请求成功回调onSuccess方法
- 100
- 101 String value = "", id = "";
- 102 int count = 0;
- 103
- 104 JSONObject jsonObjectData = JSONObject.parseObject(response.body()).getJSONObject("data");//获取json对象后再获取json对象,即第二层data
- 105 count = jsonObjectData.getIntValue("count");//count是Datastreams数组的下标值
- 106 JSONArray jsonArrayDatastreams = jsonObjectData.getJSONArray("datastreams");//获取json数组即datastearms
- 107
- 108 for(int j = 0; j < count; j++) {//遍历Datastreams数组
- 109 JSONObject jsonObjectIndex = jsonArrayDatastreams.getJSONObject(j);
- 110 id = jsonObjectIndex.getString("id");
- 111 JSONArray jsonArrayDatapoints = jsonObjectIndex.getJSONArray("datapoints");
- 112 JSONObject jsonObjectValue = jsonArrayDatapoints.getJSONObject(0);//Datapoints数组只有一个元素(对象),所以下标是1
- 113 value = jsonObjectValue.getString("value");
- 114 switch (id) {
- 115 case "3303_0_5700": //温度
- 116 //System.out.println("温度" + value + id);
- 117 tv_wendu.setText("温度" + value + "\t设备号" + id);
- 118 break;
- 119 case "3300_0_5700": //溶解氧
- 120 //System.out.println("DO" + value + id);
- 121 tv_do.setText("溶解氧" + value + "\t设备号" + id);
- 122 break;
- 123 case "3327_0_5700": //电导率
- 124 //System.out.println("电导率" + value + id);
- 125 tv_tds.setText("TDS" + value + "\t设备号" + id);
- 126 break;
- 127 case "3326_0_5700": //ph
- 128 //System.out.println("ph" + value + id);
- 129 tv_ph.setText("PH" + value + "\t设备号" + id);
- 130 break;
- 131 case "3300_1_5700": //浊度
- 132 //System.out.println("浊度" + value + id);
- 133 tv_zhuodu.setText("浊度" + value + "\t设备号" + id);
- 134 break;
- 135 }
- 136 }
- 137 }
- 138
- 139 @Override
- 140 public void onError(Response<String> response) {
- 141 Toast.makeText(getApplicationContext(), "接口请求错误!", Toast.LENGTH_LONG).show();
- 142 }
- 143 });
- 144
- 145 }
- 146
- 147 @Override
- 148 public void onClick(View view) {
- 149 switch (view.getId()) {
- 150 case R.id.btn_get: //使用原生的okhttp请求网络数据
- 151 getByOkGo();//用okgo方法获取数据
- 152 break;
- 153 case R.id.btn_resolvebyfastjson:
- 154 jsonToJavaListByFastJson();
- 155 break;
- 156 }
- 157 }
- 158
- 159
- 160 }
布局文件
- 1 <?xml version="1.0" encoding="utf-8"?>
- 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- 3 android:orientation="vertical" android:layout_width="match_parent"
- 4 android:layout_height="match_parent">
- 5
- 6 <Button
- 7 android:id="@+id/btn_get"
- 8 android:layout_width="match_parent"
- 9 android:layout_height="wrap_content"
- 10 android:text="get方法获取数据"
- 11 android:textAllCaps="false"/>
- 12
- 13 <Button
- 14 android:id="@+id/btn_resolvebyfastjson"
- 15 android:layout_width="match_parent"
- 16 android:layout_height="wrap_content"
- 17 android:text="通过fastjson解析"
- 18 android:textAllCaps="false"/>
- 19
- 20 <TextView
- 21 android:id="@+id/tv_result"
- 22 android:layout_width="match_parent"
- 23 android:layout_height="wrap_content"/>
- 24
- 25
- 26 <TextView
- 27 android:id="@+id/tv_wendu"
- 28 android:layout_width="match_parent"
- 29 android:layout_height="wrap_content"/>
- 30
- 31 <TextView
- 32 android:id="@+id/tv_do"
- 33 android:layout_width="match_parent"
- 34 android:layout_height="wrap_content"/>
- 35
- 36 <TextView
- 37 android:id="@+id/tv_ph"
- 38 android:layout_width="match_parent"
- 39 android:layout_height="wrap_content"/>
- 40
- 41 <TextView
- 42 android:id="@+id/tv_tds"
- 43 android:layout_width="match_parent"
- 44 android:layout_height="wrap_content"/>
- 45
- 46 <TextView
- 47 android:id="@+id/tv_zhuodu"
- 48 android:layout_width="match_parent"
- 49 android:layout_height="wrap_content"/>
- 50
- 51 </LinearLayout>
最后的效果(图2)

(图2)