NFC学习——NFC Enable 过程分析

拿到一台支持NFC手机或是平板设备时，在Settings->more可以看到NFC的enble，disnable的选项，还有android Beam这个东西。现在来分析NFC enable的过程

wireless_settings.xml 在Settings配置了NFC功能项：

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<CheckBoxPreference
    android:key="toggle_nfc"
    android:title="@string/nfc_quick_toggle_title"
    android:summary="@string/nfc_quick_toggle_summary"
    android:persistent="false" />

<PreferenceScreen
    android:fragment="com.android.settings.nfc.AndroidBeam"
    android:key="android_beam_settings"
    android:title="@string/android_beam_settings_title" />

    <PreferenceScreen
        android:fragment="com.android.settings.nfc.AndroidBeam"
        android:key="android_beam_settings"
        android:title="@string/android_beam_settings_title" />         xml配置的对应处理代码在：packages/apps/Settings/src/com/android/settings/WirelessSettings.java

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public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        addPreferencesFromResource(R.xml.wireless_settings);
        CheckBoxPreference nfc = (CheckBoxPreference) findPreference(KEY_TOGGLE_NFC);
        PreferenceScreen androidBeam = (PreferenceScreen) findPreference(KEY_ANDROID_BEAM_SETTINGS);

        //setp1:获取NfcEnable的实例
        mNfcEnabler = new NfcEnabler(activity, nfc, androidBeam);
        ......

        // Remove NFC if its not available
        //setp2：获取NfcAdapter实例，查看NFC功能是否可能
        mNfcAdapter = NfcAdapter.getDefaultAdapter(activity);
        if (mNfcAdapter == null) {
            getPreferenceScreen().removePreference(nfc);
            getPreferenceScreen().removePreference(androidBeam);
            mNfcEnabler = null;
        }
}

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

        addPreferencesFromResource(R.xml.wireless_settings);
        CheckBoxPreference nfc = (CheckBoxPreference) findPreference(KEY_TOGGLE_NFC);
        PreferenceScreen androidBeam = (PreferenceScreen) findPreference(KEY_ANDROID_BEAM_SETTINGS);

        //setp1:获取NfcEnable的实例
        mNfcEnabler = new NfcEnabler(activity, nfc, androidBeam);
        ......

        // Remove NFC if its not available
        //setp2：获取NfcAdapter实例，查看NFC功能是否可能
        mNfcAdapter = NfcAdapter.getDefaultAdapter(activity);
        if (mNfcAdapter == null) {
            getPreferenceScreen().removePreference(nfc);
            getPreferenceScreen().removePreference(androidBeam);
            mNfcEnabler = null;
        }
}
setp1:NFcEnable实例 packages/apps/Settings/src/com/android/settings/nfc/NfcEnabler.java 实现Preference.OnPreferenceChangeListener接口监听NFC Enable，disnable事件

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public boolean onPreferenceChange(Preference preference, Object value) {
        // Turn NFC on/off

        final boolean desiredState = (Boolean) value;
        mCheckbox.setEnabled(false);

        if (desiredState) {
           //setp3：用setp2一样的方式获取NfcAdapter实例出来nfc enable
            mNfcAdapter.enable();
        } else {
            mNfcAdapter.disable();
        }

        return false;
    }

public boolean onPreferenceChange(Preference preference, Object value) {
// Turn NFC on/off

final boolean desiredState = (Boolean) value;
mCheckbox.setEnabled(false);

        if (desiredState) {
           //setp3：用setp2一样的方式获取NfcAdapter实例出来nfc enable
            mNfcAdapter.enable();
        } else {
            mNfcAdapter.disable();
        }

return false;
} 同时也是在这个NfcEnabler.java中处理了，Nfc enble,diable时，android beam的灰亮显示问题。
Setp2：现在所有的分析点集中到了NfcAdaper这个类中，首先来看下NfcAdapter实例的获取

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public static NfcAdapter getDefaultAdapter(Context context) {

补充：综合编程 , 其他综合 ,