Android NFC架構分析

Android中對NFC的實現代碼分布在如下幾個地方：

./frameworks/base/core/java/android/nfc/

./frameworks/base/core/java/android/nfc/tech

./frameworks/base/core/java/com/android/internal/nfc/

./external/libnfc-nxp

./packages/apps/nfc

其中

./external/libnfc-nxp是用C語言編寫的函數庫，編譯生成libnfc和libnfc_ndef兩個函數庫。libnfc是一個主要的庫，實現了NFC Stack的大部分功能，主要供NFC的服務進程調用。

libnfc_ndef是一個很小的函數庫，主要是實現NDEF消息的解析，供Framework調用。

./packages/apps/nfc是一個類似于電話本的應用程序，但這個程序在手機開機后自動啟動，一直運行，是作為NFC的服務進程存在的。是NFC架構中的核心。

./frameworks/base/core/java/android/nfc/，./frameworks/base/core/java/android/nfc/tech和./frameworks/base/core/java/com/android/internal/nfc/這三個目錄

實現了NFC的應用接口，其中./frameworks/base/core/java/com/android/internal/nfc/是一些內部類或結構，不對外開放，僅供./frameworks/base/core/java/android/nfc/和

./frameworks/base/core/java/android/nfc/tech中的類調用。

./frameworks/base/core/java/android/nfc實現了接口包com.android.nfc，./frameworks/base/core/java/android/nfc/tech實現了接口包com.android.nfc.tech.

圖示如下:

附錄：

NFC Service的說明

NFC: Move NFC service implementation out of system_server.

NFC service is now an application service in packages/apps/Nfc.

NFC service is registered through ServiceManager.addService(), and the proxy object NfcAdapter obtains a handle to it through

ServiceManager.getService().

**Important** Had to add new symbols AID_NFC / NFC_UID / android.uid.nfc and modify service_manager.c, Process.java and PackageManagerService.java

in order to force the com.android.nfc process to take a fixed uid, so that it can use ServiceManager.addService().

Most of the JNI has moved to packages/apps/Nfc/jni. However NdefRecord and NdefMessage require some in-process native code, so

android_com_NdefMessage.cpp and android_com_NdefRecord.cpp stay in frameworks/base/core/jni. They link to a very small library libnfc_ndef.so

that implements NDEF message parsing. This has been added to core.mk so all devices (even without NFC hardware) can work with NDEF data.