Android4.0中判断WIFI P2P选项是否显示的源码分析 .
下源码。
1. 查找在系统设置包中是否有WIFI DIRECT这部分代码处理。
在Android4.0的源码路径（我的是源码路径为:myandroid_4.0）/packages/apps/Settings/src/com/android/settings/wifi中发现有P2P这个文件夹，哪说明设置包里面具有WIFI DIRECT这部分的代码处理。
2. 查找在系统设置里对WIFI DIRECT是否有过滤。
跟踪Settings包源码，终于发现苗头：在WirelessSettings.java (myandroid_4.0\packages\apps\settings\src\com\android\settings) 文件中
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- ..........................................
- ...........................................
- WifiP2pManager p2p = (WifiP2pManager) activity.getSystemService(Context.WIFI_P2P_SERVICE);
- if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_WIFI_DIRECT)) {
- getPreferenceScreen().removePreference(wifiP2p);
- } else {
- mWifiP2pEnabler = new WifiP2pEnabler(activity, wifiP2p);
- }
- ...........................................
- ...........................................
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
..........................................
...........................................
WifiP2pManager p2p = (WifiP2pManager) activity.getSystemService(Context.WIFI_P2P_SERVICE);
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_WIFI_DIRECT)) {
getPreferenceScreen().removePreference(wifiP2p);
} else {
mWifiP2pEnabler = new WifiP2pEnabler(activity, wifiP2p);
}
...........................................
...........................................
} 1）分析PackageManager.FEATURE_WIFI_DIRECT：文件PackageManager.java (frameworks\base\core\java\android\content\pm) 中：
@SdkConstant(SdkConstantType.FEATURE)
public static final String FEATURE_WIFI_DIRECT = "android.hardware.wifi.direct";//即为传进去做判断的String。
2）分析getPackageManager()函数
文件SettingsPreferenceFragment.java (packages\apps\settings\src\com\android\settings)中，
- ...................................
- ...................................
- /**
- * Returns the PackageManager from the owning Activity.
- */
- protected PackageManager getPackageManager() {
- return getActivity().getPackageManager();
- }
- ...................................
- ...................................
...................................
...................................
/**
* Returns the PackageManager from the owning Activity.
*/
protected PackageManager getPackageManager() {
return getActivity().getPackageManager();
}
...................................
...................................
分析getAcivity()返回一个Activity。Activity.java (frameworks\base\core\java\android\app) 中没有 getPackageManager()函数；
由于public class Activity extends ContextThemeWrapper，所以进入文件ContextThemeWrapper.java (frameworks\base\core\java\android\view)中，
也没有getPackageManager（）函数，同理发现public class ContextThemeWrapper extends ContextWrapper，所以进入文件ContextWrapper.java (frameworks\base\core\java\android\content) ，此时终于见到getPackageManager（）踪影：
public class ContextWrapper extends Context {
Context mBase;
....................................
....................................
@Override
public PackageManager getPackageManager() {
return mBase.getPackageManager();
}
.....................................
......................................
}
继续跟踪文件Context.java (frameworks\base\core\java\android\content)，发现getPackageManager（）是一个抽象函数：
/** Return PackageManager instance to find global package information. */
public abstract PackageManager getPackageManager();
分析到这里其实我也不知到该怎么继续跟踪这个函数了，想想是否跟这个文件（因为class ContextImpl extends Context）有关联ContextImpl.java (frameworks\base\core\java\android\app)，的确找到了关心的代码：
- @Override
- public PackageManager getPackageManager() {
- if (mPackageManager != null) {
- return mPackageManager;
- }
- IPackageManager pm = ActivityThread.getPackageManager();
- if (pm != null) {
- // Doesn't matter if we make more than one instance.
- return (mPackageManager = new ApplicationPackageManager(this, pm));
- }
- return null;
- }
@Override
public PackageManager getPackageManager() {
if (mPackageManager != null) {
return mPackageManager;
}
IPackageManager pm = ActivityThread.getPackageManager();
if (pm != null) {
// Doesn't matter if we make more than one instance.
return (mPackageManager = new ApplicationPackageManager(this, pm));
}
return null;
}
因为 final class ApplicationPackageManager extends PackageManager，所以从上面代码分析getPackageManager（）返回一个ApplicationPackageManager.
3) 分析getPackageManager().hasSystemFeature（PackageManager.FEATURE_WIFI_DIRECT）
由上面分析而知，getPackageManager().hasSystemFeature函数应该调到文件ApplicationPackageManager.java (frameworks\base\core\java\android\app) ，
- final class ApplicationPackageManager extends PackageManager {
- ..............................
- ..............................
- @Override
- public boolean hasSystemFeature(String name) {
- try {
- return mPM.hasSystemFeature(name);
- } catch (RemoteException e) {
- throw new RuntimeException("Package manager has died", e);
- }
- }
- ..............................
- ...............................
- }
final class ApplicationPackageManager extends PackageManager {
..............................
..............................
@Override
public boolean hasSystemFeature(String name) {
try {
return mPM.hasSystemFeature(name);
} catch (RemoteException e) {
throw new RuntimeException("Package manager has died", e);
}
}
..............................
...............................
} mPM.hasSystemFeature(name)经过AIDL实际上调用到文件PackageManagerService.java (frameworks\base\services\java\com\android\server\pm)
- public class PackageManagerService extends IPackageManager.Stub {
- ....................................
- ....................................
- public boolean hasSystemFeature(String name) {
- synchronized (mPackages) {
- return mAvailableFeatures.containsKey(name);
- }
- }
- ...................................
- ...................................
- }
public class PackageManagerService extends IPackageManager.Stub {
....................................
....................................
public boolean hasSystemFeature(String name) {
synchronized (mPackages) {
return mAvailableFeatures.containsKey(name);
}
}
...................................
...................................
} mAvailableFeatures里面的内容是通过读取/system/etc/permissions下面的文档。具体代码如下所示：
- void readPermissions() {
- // Read permissions from .../etc/permission directory.
- File libraryDir = new File(Environment.getRootDirectory(), "etc/permissions");
- if (!libraryDir.exists() || !libraryDir.isDirectory()) {
- Slog.w(TAG, "No directory " + libraryDir + ", skipping");
- return;
- }
- if (!libraryDir.canRead()) {
- Slog.w(TAG, "Directory " + libraryDir + " cannot be read");
- return;
- }
- // Iterate over the files in the directory and scan .xml files
- for (File f : libraryDir.listFiles()) {
- // We'll read platform.xml last
- if (f.getPath().endsWith("etc/permissions/platform.xml")) {
- continue;
- }
- if (!f.getPath().endsWith(".xml")) {
- Slog.i(TAG, "Non-xml file " + f + " in " + libraryDir + " directory, ignoring");
- continue;
- }
- if (!f.canRead()) {
- Slog.w(TAG, "Permissions library file " + f + " cannot be read");
- continue;
- }
- readPermissionsFromXml(f);
- }
- // Read permissions from .../etc/permissions/platform.xml last so it will take precedence
- final File permFile = new File(Environment.getRootDirectory(),
- "etc/permissions/platform.xml");
- readPermissionsFromXml(permFile);
- }
- private void readPermissionsFromXml(File permFile) {
- FileReader permReader = null;
- try {
- permReader = new FileReader(permFile);
- } catch (FileNotFoundException e) {
- Slog.w(TAG, "Couldn't find or open permissions file " + permFile);
- return;
- }
- try {
- XmlPullParser parser = Xml.newPullParser();
- parser.setInput(permReader);
- XmlUtils.beginDocument(parser, "permissions");
- while (true) {
- XmlUtils.nextElement(parser);
- if (parser.getEventType() == XmlPullParser.END_DOCUMENT) {
- break;
- }
- String name = parser.getName();
- if ("group".equals(name)) {
- String gidStr = parser.getAttributeValue(null, "gid");
- if (gidStr != null) {
- int gid = Integer.parseInt(gidStr);
- mGlobalGids = appendInt(mGlobalGids, gid);
- } else {
- Slog.w(TAG, "<group> without gid at "
- + parser.getPositionDescription());
- }
- XmlUtils.skipCurrentTag(parser);
- continue;
- }
- ...................
- ...................
- else if ("feature".equals(name)) {
- String fname = parser.getAttributeValue(null, "name");
- if (fname == null) {
- Slog.w(TAG, "<feature> without name at "
- + parser.getPositionDescription());
- } else {
- //Log.i(TAG, "Got feature " + fname);
- FeatureInfo fi = new FeatureInfo();
- fi.name = fname;
- mAvailableFeatures.put(fname, fi);
- }
- XmlUtils.skipCurrentTag(parser);
- continue;
- } else {
- XmlUtils.skipCurrentTag(parser);
- continue;
- }
- }
- permReader.close();
- } catch (XmlPullParserException e) {
- Slog.w(TAG, "Got execption parsing permissions.", e);
- } catch (IOException e) {
- Slog.w(TAG, "Got execption parsing permissions.", e);
- }
- }
void readPermissions() {
// Read permissions from .../etc/permission directory.
File libraryDir = new File(Environment.getRootDirectory(), "etc/permissions");
if (!libraryDir.exists() || !libraryDir.isDirectory()) {
Slog.w(TAG, "No directory " + libraryDir + ", skipping");
return;
}
if (!libraryDir.canRead()) {
Slog.w(TAG, "Directory " + libraryDir + " cannot be read");
return;
}
// Iterate over the files in the directory and scan .xml files
for (File f : libraryDir.listFiles()) {
// We'll read platform.xml last
if (f.getPath().endsWith("etc/permissions/platform.xml")) {
continue;
}
if (!f.getPath().endsWith(".xml")) {
Slog.i(TAG, "Non-xml file " + f + " in " + libraryDir + " directory, ignoring");
continue;
}
if (!f.canRead()) {
Slog.w(TAG, "Permissions library file " + f + " cannot be read");
continue;
}
readPermissionsFromXml(f);
}
// Read permissions from .../etc/permissions/platform.xml last so it will take precedence
final File permFile = new File(Environment.getRootDirectory(),
"etc/permissions/platform.xml");
readPermissionsFromXml(permFile);
}
private void readPermissionsFromXml(File permFile) {
FileReader permReader = null;
try {
permReader = new FileReader(permFile);
} catch (FileNotFoundException e) {
Slog.w(TAG, "Couldn't find or open permissions file " + permFile);
return;
}
try {
XmlPullParser parser = Xml.newPullParser();
parser.setInput(permReader);
XmlUtils.beginDocument(parser, "permissions");
while (true) {
XmlUtils.nextElement(parser);
if (parser.getEventType() == XmlPullParser.END_DOCUMENT) {
break;
}
String name = parser.getName();
if ("group".equals(name)) {
String gidStr = parser.getAttributeValue(null, "gid");
if (gidStr != null) {
int gid = Integer.parseInt(gidStr);
mGlobalGids = appendInt(mGlobalGids, gid);
} else {
Slog.w(TAG, "<group> without gid at "
+ parser.getPositionDescription());
}
XmlUtils.skipCurrentTag(parser);
continue;
}
...................
...................
else if ("feature".equals(name)) {
String fname = parser.getAttributeValue(null, "name");
if (fname == null) {
Slog.w(TAG, "<feature> without name at "
+ parser.getPositionDescription());
} else {
//Log.i(TAG, "Got feature " + fname);
FeatureInfo fi = new FeatureInfo();
fi.name = fname;
mAvailableFeatures.put(fname, fi);
}
XmlUtils.skipCurrentTag(parser);
continue;
} else {
XmlUtils.skipCurrentTag(parser);
continue;
}
}
permReader.close();
} catch (XmlPullParserException e) {
Slog.w(TAG, "Got execption parsing permissions.", e);
} catch (IOException e) {
Slog.w(TAG, "Got execption parsing permissions.", e);
}
}
3. 验证上面代码分析的正确性。
1） 启动一个ANDROID 4.0的模拟器，然后通过adb shell进入/system/etc/permissions目录下查看，
# cd /system/etc/permissions
# ls
com.android.location.provider.xml
platform.xml
#
的确没有android.hardware.wifi.direct.xml文件。
2） 因为在源码/frameworks/base/data/etc中有android.hardware.wifi.direct.xml文件，所以我手动拷贝此文件到out/target/product/generic/system/etc/permissions/
目录下，然后编译源码，然后用命令行指定编译完成的system.img,userdata.img,ramdisk.img来启动模拟器：
XXX@XXX:~/Android_code/system_img$ /home/XXX/Android_install/android-sdk-linux_x86/tools/emulator -system system.img -data userdata.img -ramdisk ramdisk.img -partition-size 256 -avd Android4.0.3-APILevel15
然后在模拟器设置中看到了WiFi Direct的设置项了，如图所示：
只是点击时弹出错误框提示“Couldn't start Wi-Fi Direct”,简单的跟踪了一下是WifiP2pService.java中有WifiNative.startP2pSupplicant()的一个判断，跟到JNI层
WifiP2pService.java (frameworks\base\wifi\java\android\net\wifi\p2p)
static jboolean android_net_wifi_startP2pSupplicant(JNIEnv* env, jobject)
{
return (jboolean)(::wifi_start_p2p_supplicant() == 0); //这个应该是硬件方面的判断。
}
没有再继续跟踪下去了，至少关于WIFI P2P设置的过滤过程已经清楚了
android4.0.3_wifiP2P
一：android4.0.3 wifi p2p各层次的代码分布 JAVA app -> JAVA Manager -> JAVA Service -> JNI -> HAL stub
JAVA app代码位置：
Android sdk\samples\android-15\WiFiDirectDemo
JAVA Manager代码位置：
frameworks\base\wifi\java\android\net\wifi\p2p\WifiP2pManager.java
JAVA Service代码位置：
frameworks\base\wifi\java\android\net\wifi\p2p\WifiP2pService.java frameworks\base\wifi\java\android\net\wifi\WifiNative.java
JNI代码位置：
Frameworks\base\core\jni\android_net_wifi_Wifi.cpp
HAL stub代码位置:
hardware\libhardware_legacy\wifi\wifi.c
hardware\libhardware_legacy\include\hardware_legacy\wifi.h
Setting代码位置： Packages\apps\Settings\src\com\android\settings\wifi\p2p
JAVA Manager与JAVA Service之间的通信需要通过AIDL来实现的，即IWifiP2pManager.aidl,它用来定义接口，经过aidl工具会被编译成IWifiP2pManager.java文件，JAVA Service会去实现这些接口供Manager调用。 JAVA Service通过调用android\net\wifi目录下的WifiNative.java文件里面的native方法，从而调用到JNI层。JNI层就是去实现WifiNative.java中那些native定义的方法。
二：分析代码： JAVA app主要做了以下几件
A.enable wifi p2p，这个实际上是去调用setting的功能。
B.扫描wifi p2p设备，并显示在一个列表中。
C.在列表中选择某个设备进行连接，连接后显示GO的信息，并且根据角色的不同做不同的 事情，GO开启一个新的线程FileServerAsyncTask用于
// After the group negotiation, we assign the group owner as the file
// server. The file server is single threaded, single connection server socket. 而client则是
// The other device acts as the client. In this case, we enable the // get file button. 这样就可以实现文件的传送了。
D.断开连接
1.我以B为例，说明层次间的调用过程
1)文件WiFiDirectActivity.java a) JAVA app通过
intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
receiver=newWiFiDirectBroadcastReceiver(manager,channel, this); registerReceiver(receiver, intentFilter); 注册自己关心的几类广播事件。
b) 当用户点击搜索图标后，就会调用manager.discoverPeers()
2)文件WifiP2pManager.java JAVA Manger层的discoverPeers()函数会被调用到，它通过 sendMessage(DISCOVER_PEERS, 0, c.putListener(listener))，把命令发送到JAVA Service。
3)文件WifiP2pService.java JAVA Service层根据自己的状态机的当前状态处理JAVA Manger层发送过来的 DISCOVER_PEERS请求。
以P2pEnabledState状态为例，processMessage()处理函数根据message.what进入到 WifiP2pManager.DISCOVER_PEERS case，调用WifiNative.p2pFind()。
4)文件WifiNative.java p2pFind()会去调用native函数doBooleanCommand(),该函数在此文件中只有native的 声明，它的定义是在JNI层。
5)文件android_net_wifi_Wifi.cpp doBooleanCommand()函数在这里定义，它通过调用自己文件的doCommand()函数，再调 用::wifi_command(cmd, replybuf, &reply_len)。
6)文件wifi.c wifi_command()是HAL层的函数，它通过调用wifi_send_command()，把请求发送到 wpa_supplicant，wpa_supplicant就会与wifi driver通信。
这样顺序调用就完成了，然后一层层return回去，到3)的WifiNative.p2pFind调用处。
根据调用返回的结果判断是DISCOVER_PEERS_SUCCEEDED或者是 DISCOVER_PEERS_FAILED， 这里以成功为例。在这里JAVA Service层通过 replyToMessage(message, WifiP2pManager.DISCOVER_PEERS_FAILED, WifiP2pManager.ERROR);
消息送回到JAVA Manger层。
7)文件WifiP2pManager.java handleMessage()函数用于接收JAVA Service层返回的消息，通过对message.what的判 断，进入到case WifiP2pManager.DISCOVER_PEERS_SUCCEEDED，然后调用 ((ActionListener) listener).onSuccess()。其中ActionListener是一个interface.
8)文件WiFiDirectActivity.java JAVA app层有重写JAVA Manger层的interface ActionListener的方法，所以，最后调 用到的是JAVA app中的onSuccess()。
２．接收service发来的广播事件
1)文件WifiP2pService.java 前面提到JAVA app有注册自己关心的几类广播事件。 当前JAVA Service处在P2pEnabledState状态， 当它收到WifiMonitor.P2P_DEVICE_FOUND_EVENT事件后，会调用 sendP2pPeersChangedBroadcast()把消息广播出去。
2)WiFiDirectBroadcastReceiver.java onReceive()函数会接收到注册过的广播消息。
3.注册回调函数 １)文件WiFiDirectBroadcastReceiver.java 前面讲到onReceive()接收到JAVA Service发来的广播，然后它通过 WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)判断 后，调用manager.requestPeers(channel, (PeerListListener)
activity.getFragmentManager()
.findFragmentById(R.id.frag_list))，
这个函数也会一层层的最终调用到底层，该函数的第２个参数实际上是注册一个 回凋函数，因为PeerListListener是一个interface,它有个 onPeersAvailable()方法。
2)文件WifiP2pManager.java 当JAVA Manger的handleMessage()收到JAVA Service发送过来的 WifiP2pManager.RESPONSE_PEERS事件后,就会调用之前注册的回凋函数 ((PeerListListener) listener).onPeersAvailable(peers)， 因为PeerListListener是interface,实际上是调用到了它的实现类的函数，即 DeviceListFragment.java文件中的onPeersAvailable() 3)文件DeviceListFragment.java onPeersAvailable()函数被调用，它负责get device list,从而让GUI显示出来
补充： External\wpa_supplicant\wpa_ctrl.h 提供接口给HAL层与driver通信。 frameworks\base\core\java\com\android\internal\util\StateMachine.java frameworks\base\core\java\com\android\internal\util\State.java 这两个类在JAVA Service有使用到。 在JAVA Service层中的状态机中，带WifiP2pManager的message是JAVA Manger层发送过来的，带WifiMonitor是底层发送过来的。 JAVA Service层状态机关系： Android的class StateMachine有层的概念即父状态和子状态，通过 addState(A, B)函数后，A就成为了B的子状态
HAL层与driver通信 wpa_supplicant ？？？这部分的东西还没有去了解，可以参照以下 网站 http://blog.csdn.net/samssm/article/details/6637320