背景
由于项目需要在产品设置中增加storage功能，故对系统原生实现进行学习
settings_header
packages/apps/Settings/src/com/android/settings/Settings.java
loadHeadersFromResource(R.xml.settings_headers, headers);
通过查看settings_headers.xml,可以知道选项对应的Fragment。
此处以查看Storage为例，可以看到对应Memory.java
<header
android:id="@+id/storage_settings"
android:fragment="com.android.settings.deviceinfo.Memory"
android:icon="@drawable/ic_settings_storage"
android:title="@string/storage_settings" />
原生log
Memory.TAG = "MemorySettings"
打印该Log的手机没有插入外置SD Card.
Log提供了Volume, path等信息
D/MemorySettings( 5148): Volume: Phone storage ,state is: mounted ,emulated is: false, path is: /storage/sdcard0 D/MemorySettings( 5148): Volume: SD card ,state is: removed ,emulated is: false, path is: /storage/sdcard1 D/MemorySettings( 5148): default path group length = 2 D/MemorySettings( 5148): Not [sd + swap] support, add internal storage D/MemorySettings( 5148): Not [sd + swap] support, add non-emulated category, volume : /storage/sdcard0 D/MemorySettings( 5148): Not [sd + swap] support, add non-emulated category, volume : /storage/sdcard1 D/MemorySettings( 5148): onResume D/MemorySettings( 5148): dynamicUpdateUnmountDlg() D/MemorySettings( 5148): Path /storage/sdcard0 volume state is mounted D/MemorySettings( 5148): Path /storage/sdcard1 volume state is removed D/MemorySettings( 5148): current status is MTP D/MemorySettings( 5148): Dynamic Update Install Location in OnResume() D/MemorySettings( 5148): dynamicShowDefaultWriteCategory() D/MemorySettings( 5148): external storage path= /storage/sdcard1 D/MemorySettings( 5148): Path /storage/sdcard0 volume state is mounted D/MemorySettings( 5148): set the pref phone storage order D/MemorySettings( 5148): Path /storage/sdcard1 volume state is removed D/MemorySettings( 5148): set the pref sd card order D/MemorySettings( 5148): numberOfWriteDisk : 1 D/MemorySettings( 5148): get default path/storage/sdcard0 D/MemorySettings( 5148): isHwUsbDisconnected :false ,set mIsUsbCableInserted true D/MemorySettings( 5148): pluginType :2 , set mIsUsbCableInserted true D/MemorySettings( 5148): onPrepareOptionsMenu, mIsUsbCableInserted: true D/MemorySettings( 5148): onPrepareOptionsMenu, mIsUsbCableInserted: true D/MemorySettings( 5148): pluginType :2 , set mIsUsbCableInserted true D/MemorySettings( 5148): onPrepareOptionsMenu, mIsUsbCableInserted: true D/MemorySettings( 5148): pluginType :2 , set mIsUsbCableInserted true D/MemorySettings( 5148): onPrepareOptionsMenu, mIsUsbCableInserted: true D/MemorySettings( 5148): pluginType :2 , set mIsUsbCableInserted true D/MemorySettings( 5148): onPrepareOptionsMenu, mIsUsbCableInserted: true
device_info_memory.xml
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" android:title="@string/storage_settings_title"> <PreferenceScreen android:key="apk_installer" android:title="@string/akp_installer_settings_title" android:summary="@string/akp_installer_settings_summary"> </PreferenceScreen> <ListPreference android:key="app_install_location" android:title="@string/app_install_location_title" android:summary="@string/app_install_location_summary" android:persistent="false" android:entries="@array/app_install_location_entries" android:entryValues="@array/app_install_location_values"/> <PreferenceCategory android:key="memory_select" android:title="@string/select_memory" /> </PreferenceScreen>
preference的组织方式有PreferenceScreen和PreferenceCategory，PreferenceCategory是带层次组织关系而PreferenceScreen就是最平白和基础的方式。
PreferenceCategory可以将几个组建组合在一起，并加上标题。
本人理解PreferenceScreen,PreferenceCategory就是Preference的ViewGroup，类似LinearLayout和RelativeLayout的关系。参考http://blog.csdn.net/flowingflying/article/details/6671548
ListPreference在原生Camera中使用过。算有了解。
private void addCategory(StorageVolumePreferenceCategory category)
device_info_memory.xml本身并没有太多的选项，可以断定是由代码动态加入的view(preference),由此在代码里搜索包含add的方法。
将addCategory()中的代码注释，得到如下效果，可见判断正确。
该方法是private,在代码中查找使用位置，只在onCreate()中有。
if (!(FeatureOption.MTK_SHARED_SDCARD && FeatureOption.MTK_2SDCARD_SWAP)) {
Xlog.d(TAG, "Not [sd + swap] support, add internal storage");
addCategory(StorageVolumePreferenceCategory.buildForInternal(context));
}
for (StorageVolume volume : storageVolumes) {
if (FeatureOption.MTK_SHARED_SDCARD && FeatureOption.MTK_2SDCARD_SWAP) {
Xlog.d(TAG, "[sd + swap] support, add emulated category");
addCategory(StorageVolumePreferenceCategory.buildForPhysical(context, volume));
} else if (!volume.isEmulated()) {
Xlog.d(TAG, "Not [sd + swap] support, add non-emulated category, volume : " + volume.getPath());
addCategory(StorageVolumePreferenceCategory.buildForPhysical(context, volume));
}
}
与Log吻合。
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D/MemorySettings( 5148): Not [sd + swap] support, add internal storage D/MemorySettings( 5148): Not [sd + swap] support, add non-emulated category, volume : /storage/sdcard0 D/MemorySettings( 5148): Not [sd + swap] support, add non-emulated category, volume : /storage/sdcard1
而调用的函数buildForInternal，buildForPhysical只是创建StorageVolumePreferenceCategory对象时向构造函数传递了不同的volume参数。
/**
* Build category to summarize internal storage, including any emulated
* {@link StorageVolume}.
*/
public static StorageVolumePreferenceCategory buildForInternal(Context context) {
return new StorageVolumePreferenceCategory(context, null);
}
/**
* Build category to summarize specific physical {@link StorageVolume}.
*/
public static StorageVolumePreferenceCategory buildForPhysical(
Context context, StorageVolume volume) {
return new StorageVolumePreferenceCategory(context, volume);
}
StorageVolumePreferenceCategory
addCategory的参数是StorageVolumePreferenceCategory，而函数内部也是add和init方法，猜测每个选项的内容应该是在StorageVolumePreferenceCategory。
private void addCategory(StorageVolumePreferenceCategory category) {
mCategories.add(category);
getPreferenceScreen().addPreference(category);
category.init();
}
查看Log，能够看到已经打出了total size信息
D/StorageVolumePreferenceCategory( 9124): onResume D/StorageVolumePreferenceCategory( 9124): updatePreferencesFromState, state is mounted D/StorageVolumePreferenceCategory( 9124): onResume D/StorageVolumePreferenceCategory( 9124): updatePreferencesFromState, state is removed D/StorageVolumePreferenceCategory( 9124): onUsbStateChanged D/StorageVolumePreferenceCategory( 9124): onUsbStateChanged D/StorageVolumePreferenceCategory( 9124): updatePreferencesFromState, state is mounted D/StorageVolumePreferenceCategory( 9124): onUsbStateChanged D/StorageVolumePreferenceCategory( 9124): updatePreferencesFromState, state is removed D/StorageVolumePreferenceCategory( 9124): null : total size is 5279711232, avail size is 4743716864 D/StorageVolumePreferenceCategory( 9124): Phone storage : total size is 9325838336, avail size is 8014692352 D/StorageVolumePreferenceCategory( 9124): updatePreferencesFromState, state is mounted D/StorageVolumePreferenceCategory( 9124): SD card : total size is 0, avail size is 0 D/StorageVolumePreferenceCategory( 9124): updatePreferencesFromState, state is removed D/StorageVolumePreferenceCategory( 9124): updateDetails, SD card, isPrimary is false D/StorageVolumePreferenceCategory( 9124): updateDetails, mVolume is null D/StorageVolumePreferenceCategory( 9124): measureMedia is false D/StorageVolumePreferenceCategory( 9124): updateDetails, Phone storage, isPrimary is true D/StorageVolumePreferenceCategory( 9124): measureMedia is true D/StorageVolumePreferenceCategory( 9124): mDcim size is Pictures, videos 33.38MB D/StorageVolumePreferenceCategory( 9124): music size is 458752 D/StorageVolumePreferenceCategory( 9124): downloads size is 65536
public void updateApproximate(long totalSize, long availSize)
根据Log找到函数updateApproximate
approximate
英 [ə'prɒksɪmət] 美 [əˈprɑksəmɪt]
：大约； 近似的； 约计； 使近似
添加打印formatSize，与界面数值一致
D/StorageVolumePreferenceCategory(10244): Phone storage : total size is 9325838336, avail size is 8028520448 V/StorageVolumePreferenceCategory(10244): formatSize(totalSize):8.69GB V/StorageVolumePreferenceCategory(10244): formatSize(availSize):7.48GB D/StorageVolumePreferenceCategory(10244): updatePreferencesFromState, state is mounted D/StorageVolumePreferenceCategory(10244): SD card : total size is 0, avail size is 0 V/StorageVolumePreferenceCategory(10244): formatSize(totalSize):0.00B V/StorageVolumePreferenceCategory(10244): formatSize(availSize):0.00B D/StorageVolumePreferenceCategory(10244): updatePreferencesFromState, state is removed D/StorageVolumePreferenceCategory(10244): null : total size is 5279711232, avail size is 4743725056 V/StorageVolumePreferenceCategory(10244): formatSize(totalSize):4.92GB V/StorageVolumePreferenceCategory(10244): formatSize(availSize):4.42GB
数据源
updateApproximate已经解决了界面的问题，调用updateApproximate则是数据源从何而来？
消息机制表明数据源通知界面更新是通过进程间通信。
private Handler mUpdateHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_UI_UPDATE_APPROXIMATE:
final long[] size = (long[]) msg.obj;
updateApproximate(size[0], size[1]);
break;
case MSG_UI_UPDATE_DETAILS:
final MeasurementDetails details = (MeasurementDetails) msg.obj;
updateDetails(details);
break;
}
}
};
而代码在中有MeasurementReceiver mReceiver，可以理解整个流程是观察者模式。
private MeasurementReceiver mReceiver = new MeasurementReceiver() {
@Override
public void updateApproximate(StorageMeasurement meas, long totalSize, long availSize) {
mUpdateHandler.obtainMessage(MSG_UI_UPDATE_APPROXIMATE, new long[] {
totalSize, availSize }).sendToTarget();
}
@Override
public void updateDetails(StorageMeasurement meas, MeasurementDetails details) {
mUpdateHandler.obtainMessage(MSG_UI_UPDATE_DETAILS, details).sendToTarget();
}
};
StorageMeasurement.java
MeasurementReceiver的定义在StorageMeasurement.java
StorageMeasurement没有继承其他类，也没有实现接口，提供的public member只有如下几个。此类高内聚低耦合，感觉可以直接使用该类，移植方便。
public static StorageMeasurement getInstance(Context context, StorageVolume volume)
public void cleanUp()
public void invalidate()
public void measure()
public void setReceiver(MeasurementReceiver receiver)
从设计模式来看，采用单例的一种情况是该类向其他类提供服务，而搜索getInstance()引用的位置，查看对public方法的调用，可以了解到如何使用该类。
Erase
Erase选项和点击进入的界面
通过前面的内容可以知道，磁盘选项是通过addCategory添加，但是addCategory的log，调用位置和参数，代码中搜索erase都不能找到erase相关信息。
可能是erase依赖addCategory的结果，但是在addCategory()之后的代码也看不到任何erase相关信息。
不能理清逻辑，则通过搜索的办法找线索
grep -rHni erase packages/apps/Settings/src/com/android/settings/deviceinfo/ 找不到包含erase的行
grep -rHni erase packages/apps/Settings/src/com/android/settings/ 能找到包含erase的行
将包含erase的行的输出保存到临时文件1，用vim处理只包含类名。然后查找deviceinfo目录下使用了这些类名的文件（之前搜索erase的类都在deviceInfo目录）。
结果是只有StorageVolumePreferenceCategory用到了MediaFormat
$ cat 1 | uniq > 2 $ a=`cat 2` $ for i in $a; do echo "grep $i"; grep -rHni $i packages/apps/Settings/src/com/android/settings/deviceinfo/; done grep PrivacySettings grep ApnEditor grep MediaFormat packages/apps/Settings/src/com/android/settings/deviceinfo/StorageVolumePreferenceCategory.java:728: com.android.settings.MediaFormat.class); grep MasterClearConfirm grep AdvancedMasterClearConfirm grep applications/ManageApplications grep MasterClear grep CredentialStorage grep ChartNetworkSeriesView
在MediaFormat中查找onClick()，有两处，打log验证，OK！
小结
至此，对HiCam需要的Storage了解完成了第一阶段调研。
从UI入手，但是不纠结于UI的实现，用UI基本的设计思想来理清思路。
从代码中不能直接找到Erase的逻辑时，能够合理而不盲目的使用搜索的办法。
磁盘的知识
volume
http://en.wikipedia.org/wiki/Volume_(computing)
http://vbird.dic.ksu.edu.tw/linux_basic/0420quota_3.php
