Android设备NFC TAG读取实现问题：跨设备写入失败排查

问题背景 #

实现了一个Android Activity，用于接收另一安装了指定NFC短信应用的设备发送的纯文本消息，已添加Manifest权限和Intent过滤器，但对方设备写入应用报错，无法完成NFC写入。

实现代码 #

const val MIME_TEXT_PLAIN = "text/plain"

class MainActivity : AppCompatActivity() {

    private val TAG = MainActivity::class.java.simpleName
    private lateinit var binding: ActivityMainBinding
    private var nfcAdapter: NfcAdapter? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // 初始化NfcAdapter
        nfcAdapter = NfcAdapter.getDefaultAdapter(this)

        // 检查设备是否支持NFC
        if (nfcAdapter == null) {
            Log.w(TAG, "NFC non supportato!")
            binding.nfcStatusText.text = "No NFC on this device."
        } else {
            // 设置NFC按钮点击监听
            binding.nfcButton.setOnClickListener {
                enableNfc()
            }
        }
    }

    private fun enableNfc() {
        Log.w(TAG, "Abilito l'NFC...")
        // 检查NFC是否启用
        if (!nfcAdapter?.isEnabled!!) {
            binding.nfcStatusText.text = "Turn On NFC"
        } else {
            binding.nfcStatusText.text = "Searching..."
        }
    }

    override fun onNewIntent(intent: Intent) {
        super.onNewIntent(intent)
        receiveMessageFromDevice(intent)
    }

    override fun onResume() {
        super.onResume()
        enableForegroundDispatch(this, this.nfcAdapter)
        receiveMessageFromDevice(intent)
    }

    override fun onPause() {
        super.onPause()
        disableForegroundDispatch(this, this.nfcAdapter)
    }

    private fun receiveMessageFromDevice(intent: Intent) {
        val action = intent.action
        if (NfcAdapter.ACTION_TAG_DISCOVERED == action || NfcAdapter.ACTION_TECH_DISCOVERED == action || NfcAdapter.ACTION_NDEF_DISCOVERED == action) {

            val ndefMessage = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES)
            Log.d(TAG, "Parcelables data: $ndefMessage")

            if (!ndefMessage.isNullOrEmpty()) {
                val ndefRecord = (ndefMessage[0] as NdefMessage).records[0]
                val message = ndefRecord.payload.decodeToString()
                binding.nfcStatusText.text = "Message from tag NFC: $message"
            } else {
                binding.nfcStatusText.text = "No message on tag NFC"
            }
        }
    }

    private fun enableForegroundDispatch(activity: AppCompatActivity, adapter: NfcAdapter?) {
        val intent = Intent(this, javaClass)
        intent.flags = Intent.FLAG_ACTIVITY_SINGLE_TOP

        val pendingIntent = PendingIntent.getActivity(
            this, 0, intent,
            PendingIntent.FLAG_IMMUTABLE
        )

        val filters = arrayOfNulls<IntentFilter>(1)
        val techList = arrayOf<Array<String>>()

        filters[0] = IntentFilter()
        with(filters[0]) {
            this?.addAction(NfcAdapter.ACTION_TAG_DISCOVERED)
            this?.addCategory(Intent.CATEGORY_DEFAULT)
            try {
                this?.addDataType(MIME_TEXT_PLAIN)
            } catch (ex: IntentFilter.MalformedMimeTypeException) {
                throw RuntimeException("Check your MIME type")
            }
        }

        adapter?.enableForegroundDispatch(activity, pendingIntent, filters, techList)
    }

    private fun disableForegroundDispatch(activity: AppCompatActivity, adapter: NfcAdapter?) {
        adapter?.disableForegroundDispatch(activity)
    }
}

Manifest配置 #

<uses-permission android:name="android.permission.NFC" />

 <intent-filter>
            <action android:name="android.nfc.action.NDEF_DISCOVERED" />
            <category android:name="android.intent.category.DEFAULT" />
            <data android:mimeType="text/plain" />
 </intent-filter>

问题排查及修复方案 #

• Foreground Dispatch过滤器不匹配
  enableForegroundDispatch中，ACTION_TAG_DISCOVERED不支持MIME类型过滤，只有ACTION_NDEF_DISCOVERED才会匹配text/plain类型。修改过滤器配置：

  with(filters[0]) {
      this?.addAction(NfcAdapter.ACTION_NDEF_DISCOVERED)
      this?.addCategory(Intent.CATEGORY_DEFAULT)
      try {
          this?.addDataType(MIME_TEXT_PLAIN)
      } catch (ex: IntentFilter.MalformedMimeTypeException) {
          throw RuntimeException("Check your MIME type")
      }
  }
  

• 未启用设备间传输支持
  设备间NFC传输依赖Android Beam（Android 10及以下）或系统内置的分享功能，需补充配置：

  1. 在Manifest中添加NFC功能声明：

     <uses-feature android:name="android.hardware.nfc" android:required="true" />
     

  2. Android 10及以下需启用Foreground Ndef Push：

     if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.Q) {
         nfcAdapter?.enableForegroundNdefPush(this, NdefMessage(NdefRecord.createMime(MIME_TEXT_PLAIN, ByteArray(0))))
     }
     

     Android 11+需使用NfcAdapter.setNdefPushMessageCallback替代。

• onResume中错误读取Intent
  onResume中的intent是Activity启动Intent，不是NFC触发的Intent，删除该行代码：

  // receiveMessageFromDevice(intent) 移除这行
  

• NDEF文本记录解析不规范
  NDEF文本Payload包含状态字节和语言编码，直接解码会出错，替换解析逻辑：

  private fun parseNdefTextRecord(record: NdefRecord): String {
      if (record.tnf != NdefRecord.TNF_WELL_KNOWN || !Arrays.equals(record.type, NdefRecord.RTD_TEXT)) {
          return ""
      }
      val payload = record.payload
      val languageCodeLength = payload[0].toInt() and 0x1F
      return String(payload, languageCodeLength + 1, payload.size - languageCodeLength - 1, Charsets.UTF_8)
  }
  

  在receiveMessageFromDevice中调用：

  val message = parseNdefTextRecord(ndefRecord)
  

• Manifest补充设备间传输过滤器
  添加TECH_DISCOVERED过滤器确保识别设备连接：

  <intent-filter>
      <action android:name="android.nfc.action.TECH_DISCOVERED" />
  </intent-filter>
  <meta-data
      android:name="android.nfc.action.TECH_DISCOVERED"
      android:resource="@xml/nfc_tech_filter" />
  

  在res/xml目录创建nfc_tech_filter.xml：

  <resources>
      <tech-list>
          <tech>android.nfc.tech.Ndef</tech>
          <tech>android.nfc.tech.NdefFormatable</tech>
      </tech-list>
  </resources>
  

内容的提问来源于stack exchange，提问作者Antonio