Android程式設計 - JSON資料處理(4)

處理JSON文件

假設手機SD卡中存在「test.json」文件，內容如下：

{

   "name":"wu, ShyiShiou",

   "address":{

      "street":"no.568 jung-jeng rd.",

      "postcode":54243,

      "city":"Tasotun"

   },

   "phoneNumber":[

      {

         "type":"office",

         "number":"2563489"

      },

      {

         "type":"fax",

         "number":"2569834"

      }

   ]

}

首先要讀取「test.json」文件內容並儲存到字串變數。由於最外層為JSONObject結構，因此必須以所得到的JSON格式字串建立JSONObject物件。

  String sdcardDir = Environment.getExternalStorageDirectory().toString();

  String jsonfile = sdcardDir+ "/" + "test.json";

  FileInputStream fis = new FileInputStream(jsonfile);

  BufferedReader reader = new BufferedReader(new InputStreamReader(

            fis, "UTF-8"));

  Writer writer = new StringWriter();

  char[] buffer = new char[1024];

  int n;

  while ((n=reader.read(buffer)) != -1) writer.write(buffer, 0, n);

  fis.close();

  String jsonstr = writer.toString();

  JSONObject json = new JSONObject(jsonstr);

之後就可依據「test.json」文件結構一層一層解讀JSON資料。例如：

  String username = json.getString("name");

  JSONObject jo_address = json.getJSONObject("address");

  JSONArray ja_phone = json.getJSONArray("phoneNumber");

address的內容可再由jo_address進一步解讀，例如：

  String street = jo_address.getString("street");

而phoneNumber內容則可再由ja_phone繼續解讀，例如：

  String office_tel = ja_phone.getJSONObject(0).getString("number");