Android6.0源码分析之蓝牙显示接收到的文件
在蓝牙界面有个menu：显示接收到的文件。本文分析显示接收到的文件
chapter one---显示接收到的文件
/android/packages/apps/Settings/src/com/android/settings/bluetooth/文件夹下的BluetoothSettings.java开始分析
case MENU_ID_SHOW_RECEIVED:
MetricsLogger.action(getActivity(), MetricsLogger.ACTION_BLUETOOTH_FILES);
Intent intent = new Intent(BTOPP_ACTION_OPEN_RECEIVED_FILES);
getActivity().sendBroadcast(intent);
return true;当点击显示接收到的文件menu时会发送广播,发送的广播为
private static final String BTOPP_ACTION_OPEN_RECEIVED_FILES =
"android.btopp.intent.action.OPEN_RECEIVED_FILES";既然有发送广播，就要看哪个地方接收到广播并进行了处理
通过代码搜索定位到/android/packages/apps/Bluetooth/文件夹下的Androidmanifest.xml文件中进行了定义
可以看到实在opp文件夹下的BluetoothOppReceiver中进行处理的
在Constants中定义了全局变量
/** the intent that gets sent from the Settings app to show the received files */
public static final String ACTION_OPEN_RECEIVED_FILES = "android.btopp.intent.action.OPEN_RECEIVED_FILES";在BluetoothOppReceiver中当检测到该action时会进行如下处理
else if (action.equals(Constants.ACTION_OPEN_RECEIVED_FILES)) {
if (V) Log.v(TAG, "Received ACTION_OPEN_RECEIVED_FILES.");
Intent in = new Intent(context, BluetoothOppTransferHistory.class);
in.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
in.putExtra("direction", BluetoothShare.DIRECTION_INBOUND);
in.putExtra(Constants.EXTRA_SHOW_ALL_FILES, true);
context.startActivity(in);跳转到BluetoothTransferHistory，在跳转时对intent做了一些处理，首先是设置了一些flags，说明一下
Intent.FLAG_ACTIVITY_CLEAR_TOP：如果在栈中有该实例，就会去重用该实例，并且会清除掉该实例上方的所有activity，简单举个例子，如果在栈1中存在有三个实例，Acivity1，Activity2，Activity3。可以看到处于栈顶的是Activity3，也就是目前显示的是窗口3，如果从窗口3跳转到窗口2，则会销毁Activity3，并且重用Activity2，也就是说目前栈中Activity存在情况如下Activity1，Activity2。
Intent.FLAG_ACTIVITY_NEW_TASK：如果在activity节点下存在taskAffinity属性，首先看该属性值有没有进行设置
android:taskAffinity="">如果设置了该属性值，就会去查找taskAffinity对应的栈，如果栈不存在，则会新建该栈 并将activity存入，如果栈存在，则直接入栈
如果没有设置该属性或者该属性值默认为空，则直接压入当前栈。在程序中未对BluetoothTransferHistory的该属性进行设置。
接下来对BluetoothTransferHistory.java分析，该类位于\android\packages\apps\Bluetooth\src\com\android\bluetooth\opp
设计思路：对于显示蓝牙接受到的文件是利用ContentProvider来访问uri获取到已接受到的文件并显示出来。
布局文件为bluetooth_transfers_page.xml
setContentView(R.layout.bluetooth_transfers_page);该布局文件所用到的节点有些特别，分析一下
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<ListView
android:id="@+id/list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
<ViewStub
android:id="@+id/empty"
android:layout="@layout/no_transfers"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
</merge>首先最外层布局为merge，接下来是两个子view：ListView和ViewStub。ListView很常见，但很少用到merge和ViewStub布局控件
关于这些的介绍想了解的可以看相关链接，在这里不再多说
Android中include和Merge节点分析
Android中ViewStub控件分析及使用
其中merge是默认的垂直的线性布局，也就是说该布局文件中显示一个listview列表，然后是一个动态布局的ViewStub，所引用的layout文件为no_transfers
no_transfers.xml
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="@string/no_transfers"
android:gravity="center"
android:textStyle="bold"
/>显示一个textview，
<string name="no_transfers" msgid="3482965619151865672">"没有传输历史记录。"</string>listview显示的传输文件列表，布局xml介绍完后进入对Java文件的分析。
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.bluetooth_transfers_page);
mListView = (ListView)findViewById(R.id.list);
mListView.setEmptyView(findViewById(R.id.empty));
mShowAllIncoming = getIntent().getBooleanExtra(
Constants.EXTRA_SHOW_ALL_FILES, false);
String direction;
int dir = getIntent().getIntExtra("direction", 0);
if (dir == BluetoothShare.DIRECTION_OUTBOUND) {
setTitle(getText(R.string.outbound_history_title));
direction = "(" + BluetoothShare.DIRECTION + " == " + BluetoothShare.DIRECTION_OUTBOUND
+ ")";
} else {
if (mShowAllIncoming) {
setTitle(getText(R.string.btopp_live_folder));
} else {
setTitle(getText(R.string.inbound_history_title));
}
direction = "(" + BluetoothShare.DIRECTION + " == " + BluetoothShare.DIRECTION_INBOUND
+ ")";
}
String selection = BluetoothShare.STATUS + " >= '200' AND " + direction;
if (!mShowAllIncoming) {
selection = selection + " AND ("
+ BluetoothShare.VISIBILITY + " IS NULL OR "
+ BluetoothShare.VISIBILITY + " == '"
+ BluetoothShare.VISIBILITY_VISIBLE + "')";
}
final String sortOrder = BluetoothShare.TIMESTAMP + " DESC";
mTransferCursor = managedQuery(BluetoothShare.CONTENT_URI, new String[] {
"_id", BluetoothShare.FILENAME_HINT, BluetoothShare.STATUS,
BluetoothShare.TOTAL_BYTES, BluetoothShare._DATA, BluetoothShare.TIMESTAMP,
BluetoothShare.VISIBILITY, BluetoothShare.DESTINATION, BluetoothShare.DIRECTION
}, selection, sortOrder);
// only attach everything to the listbox if we can access
// the transfer database. Otherwise, just show it empty
if (mTransferCursor != null) {
mIdColumnId = mTransferCursor.getColumnIndexOrThrow(BluetoothShare._ID);
// Create a list "controller" for the data
mTransferAdapter = new BluetoothOppTransferAdapter(this,
R.layout.bluetooth_transfer_item, mTransferCursor);
mListView.setAdapter(mTransferAdapter);
mListView.setScrollBarStyle(View.SCROLLBARS_INSIDE_INSET);
mListView.setOnCreateContextMenuListener(this);
mListView.setOnItemClickListener(this);
}
mNotifier = new BluetoothOppNotification(this);
mContextMenu = false;
}关键代码都在onCreate中，可以看出来通过调用managedQuery方法按指定的条件查询指定的uri，获取到cursor后传给adapter，并将adapter与listview绑定显示数据。
首先是对传输列表数据源的获取----managedQuery
public final Cursor managedQuery(Uri uri, String[] projection, String selection,
String sortOrder) {
Cursor c = getContentResolver().query(uri, projection, selection, null, sortOrder);
if (c != null) {
startManagingCursor(c);
}
return c;
}managedQuery方法定义在Activity中，可以看到首先获取到ContentResolver对象，然后调用query方法进行查询指定uri的数据。有几点需要注意，通过该方法获取到的cursor无需去调用close方法将其关闭，因为activity会在合适的时候将其关闭。但是有一点，如果你的cursor对象调用了stopManagingCursor方法时，必须手动去调用cursor.close方法将其关闭，因为此时，activity不会自动去关闭
需要传入四个参数
- uri : the uri of the content provider to query 所要查询的contentProvider的uri
- projection : projection list of columns to return 查询到后所要返回的cursor的列名，如果想要全部返回可以将参数置为null
- selection : selectio SQL WHERE clause 查询条件
- sortOrder : sortorder SQL ORDER BY clause 按某种条件排序
所查询的uri为
/**
* The content:// URI for the data table in the provider
*/
public static final Uri CONTENT_URI = Uri.parse("content://com.android.bluetooth.opp/btopp");想要读取该uri下的数据需要在Androidmanifest.xml配置文件中添加如下权限
<uses-permission android:name="android.permission.ACCESS_BLUETOOTH_SHARE" />查询到后传给adapter进行加载view
举一个例子，在item上显示远程蓝牙name的话可以使用如下代码
tv = (TextView)view.findViewById(R.id.targetdevice);
//获取到本地蓝牙适配器
BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
//获取到索引
int destinationColumnId = cursor.getColumnIndexOrThrow(BluetoothShare.DESTINATION);
//获取到本条数据中所对应的远程设备
BluetoothDevice remoteDevice = adapter.getRemoteDevice(cursor
.getString(destinationColumnId));
//获取到name
String deviceName = BluetoothOppManager.getInstance(context).getDeviceName(remoteDevice);
tv.setText(deviceName);显示接收到的文件源码其实实现起来不难，就是借助contentResolver来读取uri的数据并显示出来，那么数据必须要通过contentprovider的方式保存，但是接收到的文件时保存在哪个contentprovider？？如何进行保存？会保存哪些信息？有哪些列？接下来就进行分析
首先根据uri---com.android.bluetooth.opp去查找清单配置文件
<provider android:name=".opp.BluetoothOppProvider"
android:authorities="com.android.bluetooth.opp"
android:exported="true"
android:process="@string/process">
<path-permission
android:pathPrefix="/btopp"
android:permission="android.permission.ACCESS_BLUETOOTH_SHARE" />
</provider>可以发现存储所用的provider为BluetoothOppProvider.java，正好借此机会分析下provider的用法。
chapter two-----存储接收到的文件的ContentProvider
该类位于\android\packages\apps\Bluetooth\src\com\android\bluetooth\opp文件夹下，直接继承与ContentProvider。希望是在对contentProvider有一定的了解后阅读如下分析
provider属于组件，需要再清单配置文件中进行配置
<provider android:name=".opp.BluetoothOppProvider"
android:authorities="com.android.bluetooth.opp"
android:exported="true"
android:process="@string/process">
<path-permission
android:pathPrefix="/btopp"
android:permission="android.permission.ACCESS_BLUETOOTH_SHARE" />
</provider>自定义一个provider需要添加如下属性authorities：域名，如果需要访问权限，就规定所需要的访问权限
java代码中的处理如下
首先对于BluetoothOppProvider的uri进行解析
定义一个urimatcher对象，以供应用对uri进行访问解析数据
/** URI matcher used to recognize URIs sent by applications */
private static final UriMatcher sURIMatcher = new UriMatcher(UriMatcher.NO_MATCH);接下来为urimatcher对象注册路径，在源码中只注册了两个
/** URI matcher constant for the URI of the entire share list 返回整个数据列表*/
private static final int SHARES = 1;
/** URI matcher constant for the URI of an individual share 返回一条记录*/
private static final int SHARES_ID = 2;
static {
sURIMatcher.addURI("com.android.bluetooth.opp", "btopp", SHARES);
sURIMatcher.addURI("com.android.bluetooth.opp", "btopp/#", SHARES_ID);
}紧接着看到源码中创建了数据库，也就是说contentprovider将数据存储到数据库
数据库的name为：btop.db
/** Database filename */
private static final String DB_NAME = "btopp.db";所创建的列包括14个，如下所示
private void createTable(SQLiteDatabase db) {
try {
db.execSQL("CREATE TABLE " + DB_TABLE + "(" + BluetoothShare._ID
+ " INTEGER PRIMARY KEY AUTOINCREMENT," + BluetoothShare.URI + " TEXT, "
+ BluetoothShare.FILENAME_HINT + " TEXT, " + BluetoothShare._DATA + " TEXT, "
+ BluetoothShare.MIMETYPE + " TEXT, " + BluetoothShare.DIRECTION + " INTEGER, "
+ BluetoothShare.DESTINATION + " TEXT, " + BluetoothShare.VISIBILITY
+ " INTEGER, " + BluetoothShare.USER_CONFIRMATION + " INTEGER, "
+ BluetoothShare.STATUS + " INTEGER, " + BluetoothShare.TOTAL_BYTES
+ " INTEGER, " + BluetoothShare.CURRENT_BYTES + " INTEGER, "
+ BluetoothShare.TIMESTAMP + " INTEGER," + Constants.MEDIA_SCANNED
+ " INTEGER); ");
} catch (SQLException ex) {
Log.e(TAG, "couldn't create table in downloads database");
throw ex;
}
}介绍一个小知识，在数据库类的oncreate方法中可以直接并且只调用createTable方法，但是在更新数据库时需要先将数据库删除然后再调用createTable创建，删除数据库方法如下
private void dropTable(SQLiteDatabase db) {
try {
db.execSQL("DROP TABLE IF EXISTS " + DB_TABLE);
} catch (SQLException ex) {
Log.e(TAG, "couldn't drop table in downloads database");
throw ex;
}
}数据库实在provider的oncreate方法中进行创建的
然后就会provider对数据库进行增删改查操作--
未完待续
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