浅谈JSONObject解析JSON数据

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Mr_houzi
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    个人博客同步文章 https://mr-houzi.com/2018/06/...
    根据一段天气API来说一下JSONObject如何解析json数据，尽管现在在开发中使用Gson等，对于像我这样初次使用Java做开发的小白，说一下也是好的。

    JSON数据

    选取这段json数据是因为这段数据还是比较复杂的，能涵盖要说的关键点

    {
  "data": {
    "city": "深圳",
    "temphigh": "25",
    "templow": "19",
    "updatetime": "2017-11-04 13:23:00",
    "tempnow": "24",
    "sendibletemp": "27",
    "winddirect": "东北风",
    "windpower": "2级",
    "humidity": "42",
    "sunrise": "06:29",
    "sunset": "17:45",
    "weather": "多云",
    "week": "星期六",
    "nl": null,
    "date": "2017-11-04",
    "index": [
      {
        "name": "化妆指数",
        "level": "控油",
        "msg": "建议用露质面霜打底，水质无油粉底霜，透明粉饼，粉质胭脂。"
      },
      {
        "name": "感冒指数",
        "level": "易发",
        "msg": "感冒容易发生，少去人群密集的场所有利于降低感冒的几率。"
      },
      {
        "name": "洗车指数",
        "level": "不宜",
        "msg": "雨(雪)水和泥水会弄脏您的爱车，不适宜清洗车辆。"
      },
      {
        "name": "穿衣指数",
        "level": "舒适",
        "msg": "白天温度适中，但早晚凉，易穿脱的便携外套很实用。"
      },
      {
        "name": "紫外线强度指数",
        "level": "弱",
        "msg": "辐射较弱，涂擦SPF12-15、PA+护肤品。"
      },
      {
        "name": "运动指数",
        "level": "不适宜",
        "msg": "受到阵雨天气的影响，不宜在户外运动。"
      }
    ],
    "pm25": {
      "aqi": 0,
      "co": 8,
      "o3": 42,
      "pm10": 63,
      "pm2_5": 64,
      "quality": "良",
      "so2": 4,
      "no2": 11,
      "updatetime": "2017-11-04 13:00:00"
    },
    "daily": [
      {
        "date": "2017-11-04",
        "week": "星期六",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "25",
        "templow": "19",
        "weather": "多云"
      },
      {
        "date": "2017-11-05",
        "week": "星期日",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "26",
        "templow": "19",
        "weather": "多云"
      },
      {
        "date": "2017-11-06",
        "week": "星期一",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "27",
        "templow": "20",
        "weather": "多云"
      },
      {
        "date": "2017-11-07",
        "week": "星期二",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "28",
        "templow": "21",
        "weather": "多云"
      },
      {
        "date": "2017-11-08",
        "week": "星期三",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "29",
        "templow": "22",
        "weather": "多云"
      },
      {
        "date": "2017-11-09",
        "week": "星期四",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "28",
        "templow": "22",
        "weather": "多云"
      },
      {
        "date": "2017-11-03",
        "week": "星期五",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "28",
        "templow": "18",
        "weather": "晴"
      }
    ]
  },
  "status": 0,
  "msg": "ok"
}

    解析JSON

    利用JSONString进行简单解析

    我利用了RxVolley进行数据通信，t为API返回的数据

    RxVolley.get("https://chkj02.market.alicloudapi.com/qgtq?city="+city, params, new HttpCallback() {
    @Override
    public void onSuccess(String t) {
        Loger.debug("请求到的数据:" + t);
    }
});

    我们现在要获取这部分数据，该如何进行解析呢？

    首先，将t中的数据传到JSONObject类型的jsonObject中，再通过getJSONObject获取到data下的数据。

    //解析数据
JSONObject jsonObject = new JSONObject(t);
JSONObject jsonData = jsonObject.getJSONObject("data");

    此时，jsonData中数据为

    {
    "city": "深圳",
    "temphigh": "25",
    "templow": "19",
    "updatetime": "2017-11-04 13:23:00",
    "tempnow": "24",
    "sendibletemp": "27",
    "winddirect": "东北风",
    "windpower": "2级",
    "humidity": "42",
    "sunrise": "06:29",
    "sunset": "17:45",
    "weather": "多云",
    "week": "星期六",
    "nl": null,
    "date": "2017-11-04"
}

    然后通过getString进行读值即可

    //解析天气
String jsonTemplow = jsonData.getString("templow");
String jsonTempHigh = jsonData.getString("temphigh");
String jsonWeather = jsonData.getString("weather");
String jsonTempnow = jsonData.getString("tempnow");
String jsonWinddirect = jsonData.getString("winddirect");
String jsonWindpower = jsonData.getString("windpower");
String jsonHumidity = jsonData.getString("humidity");

    利用JSONArray进行复杂解析

    这次，我们要获取这部分数据

    首先，将t中的数据传到JSONObject类型的jsonObject中，再通过getJSONObject获取到data下的数据。然后jsonArray通过getJSONArray获得index下的数据

    //解析数据
JSONObject jsonObject = new JSONObject(t);
JSONObject jsonData = jsonObject.getJSONObject("data");
JSONArray jsonIndex =jsonData.getJSONArray("index");
JSONArray jsonDaily =jsonData.getJSONArray("daily");

    方法一

    此时，jsonDaily中数据为

    [
      {
        "date": "2017-11-04",
        "week": "星期六",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "25",
        "templow": "19",
        "weather": "多云"
      },
      {
        "date": "2017-11-05",
        "week": "星期日",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "26",
        "templow": "19",
        "weather": "多云"
      },
      {
        "date": "2017-11-06",
        "week": "星期一",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "27",
        "templow": "20",
        "weather": "多云"
      },
      {
        "date": "2017-11-07",
        "week": "星期二",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "28",
        "templow": "21",
        "weather": "多云"
      },
      {
        "date": "2017-11-08",
        "week": "星期三",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "29",
        "templow": "22",
        "weather": "多云"
      },
      {
        "date": "2017-11-09",
        "week": "星期四",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "28",
        "templow": "22",
        "weather": "多云"
      },
      {
        "date": "2017-11-03",
        "week": "星期五",
        "sunrise": "06:29",
        "sunset": "17:45",
        "temphigh": "28",
        "templow": "18",
        "weather": "晴"
      }
]

    把jsonDaily中按分类进行解析，分为几个ArrayList<>,dates、weeks、weathers等，然后进行for循环。

    List<String> dates = new ArrayList<>();
List<String> weeks = new ArrayList<>();
List<String> weathers = new ArrayList<>();

int j=1;
for (int i=0;i<jsonArray.length();i++){
    JSONObject partDaily = jsonArray.getJSONObject(i);
    JSONString date = partDaily.getString("date");
    dates.add(date);
    JSONString week = partDaily.getString("week");
    weeks.add(week);
    JSONString weather = partDaily.getString("weather");
    weathers.add(weather);
}

    方法二

    此时，jsonIndex中数据为

     [
      {
        "name": "化妆指数",
        "level": "控油",
        "msg": "建议用露质面霜打底，水质无油粉底霜，透明粉饼，粉质胭脂。"
      },
      {
        "name": "感冒指数",
        "level": "易发",
        "msg": "感冒容易发生，少去人群密集的场所有利于降低感冒的几率。"
      },
      {
        "name": "洗车指数",
        "level": "不宜",
        "msg": "雨(雪)水和泥水会弄脏您的爱车，不适宜清洗车辆。"
      },
      {
        "name": "穿衣指数",
        "level": "舒适",
        "msg": "白天温度适中，但早晚凉，易穿脱的便携外套很实用。"
      },
      {
        "name": "紫外线强度指数",
        "level": "弱",
        "msg": "辐射较弱，涂擦SPF12-15、PA+护肤品。"
      },
      {
        "name": "运动指数",
        "level": "不适宜",
        "msg": "受到阵雨天气的影响，不宜在户外运动。"
      }
]

    jsonArray为二维数组，我们通过两个嵌套循环进行遍历。首先，外层根据数组长度进行for循环遍历；然后内层使用迭代器进行遍历。

    String[] jsonIndex = new String[20];//数组长度声明为20确保够用
int j=1;
for (int i=0;i<jsonArray.length();i++){
    JSONObject partIndex = jsonArray.getJSONObject(i);
    Iterator iterator = partIndex.keys();
    String key;
    while(iterator.hasNext()){
        //hasNext方法，只是判断下一个元素的有无，并不移动指针
        key = (String) iterator.next();//next方法，向下移动指针，并且返回指针指向的元素，如果指针指向的内存中没有元素，会报异常
        jsonIndex[j] = partIndex.getString(key);
        j++;
    }
}

    这样此指数数据就被我们成功解析，然后存入jsonIndex数组中。

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    Mr_houzi
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