android开发之Json文件的读写的示例代码

<&＃63;xml version="1.0" encoding="utf-8"&＃63;>


  

  

  

// 独立写Json文件
    btnSingleWJson.setOnClickListener {
}
// 独立读Json文件
    btnSingleRJson.setOnClickListener{
}

    // 独立写Json文件
    btnSingleWJson.setOnClickListener {
      // 判断有无写SD卡的权限
      if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
        //申请写 SD 卡的权限
        ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE), COFOX_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE)
      } else {
        saveSingleJson()
      }
    }

fun saveSingleJson(){
    Toast.makeText(this, "保存独立Json文件", Toast.LENGTH_LONG).show()
    //打开要写入的json文件
    val fos = FileOutputStream(jsonFile)
    //json数据
    val products = arrayListOf()
    products.add(Product("0001", "微服务核心服务端"))
    products.add(Product("0002", "平台管理android端"))
    products.add(Product("0003", "平台管理web端"))
    products.add(Product("0004", "企业用户android端"))
    products.add(Product("0005", "终端用户wx/android/web端"))
    products.add(Product("0006", "android全功能端"))
    products.add(Product("0007", "明月端"))
    //创建JsonWrite对象
    val writer = JsonWriter(OutputStreamWriter(fos, "utf-8"))
    writer.setIndent("  ")
    writer.beginArray()
    for (product in products){
      writer.beginObject()
      writer.name("id").value(product.id)
      writer.name("name").value(product.name)
      writer.endObject()
    }
    writer.endArray()
    writer.close()
  }

val jsOnFile= "/sdcard/cofoxtest.json"

    // 独立读Json文件
    btnSingleRJson.setOnClickListener {
      val fis = FileInputStream(jsonFile)
      var reader = JsonReader(InputStreamReader(fis,"utf-8"))
      val products = ArrayList()
      reader.beginArray()
      while (reader.hasNext()){
        var id = ""
        var name = ""
        reader.beginObject()
        while (reader.hasNext()) {
          var field = reader.nextName()
          if (field.equals("id")){
            id = reader.nextString()
          }else if (field.equals("name")){
            name = reader.nextString()
          }else{
            reader.skipValue()
          }
        }
        reader.endObject()
        products.add(Product(id, name))
      }
      reader.endArray()
      reader.close()

      if (products != null) {
        var result = ""
        for (product in products) {
          result += "id:" + product.id + " name:" + product.name + "\n"
          ttvwJson.setText(result)
        }
      }
    }

  override fun onRequestPermissionsResult(requestCode: Int, permissions: Array, grantResults: IntArray) {
    when (requestCode) {
      COFOX_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE -> {
        if (grantResults.size > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
          saveSingleJson()
        } else {
          Toast.makeText(this, "您拒绝了写入", Toast.LENGTH_LONG).show()
        }
      }
    }
  }