Dialog、Toast的Window和ViewRootImpl
来源：互联网 发布：erp软件二次开发 编辑：程序博客网 时间：2024/05/20 13:36
前言
文章Activity中的Window的setContentView、遇见LayoutInflater&Factory、ViewRootImpl的独白，我不是一个View(布局篇) 分别讲述了Activity的setContentView添加View、LayoutInflater布局解析以及添加Window。文章内容都是站在Activity的角度来进行代码解析的，因此我们不再对Dialog和Toast与Activity做具体分析，主要来看看它们与Activity有什么不同之处源码:android-22。
Dialog
Dialog的构造
public class Dialog implements DialogInterface, Window.Callback, KeyEvent.Callback, OnCreateContextMenuListener,Window.OnWindowDismissedCallback{ //只有Activity的Context可以启动Dialog，因为Dialog展示的时候需要主题资源也就是ContextThemeWrapper。 Dialog(Context context, int theme, boolean createContextThemeWrapper) { if (createContextThemeWrapper) { if (theme == 0) { TypedValue outValue = new TypedValue(); context.getTheme().resolveAttribute(com.android.internal.R.attr.dialogTheme, outValue, true); theme = outValue.resourceId; } mContext = new ContextThemeWrapper(context, theme); } else { mContext = context; } //因为每个上下文环境获取的系统服务都是相同的实例，这里获取的WindowManager是Activity的WindowManager。 mWindowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE); //创建Dialog的PhoneWindow对象。 Window w = PolicyManager.makeNewWindow(mContext); mWindow = w; w.setCallback(this); w.setOnWindowDismissedCallback(this); w.setWindowManager(mWindowManager, null, null); w.setGravity(Gravity.CENTER); mListenersHandler = new ListenersHandler(this); }}Dialog添加View
和Activity相同通过setContentView初始化Window中的DecorView，并对页面View进行add。详细讲述请移动到Activity中的Window的setContentView
public class Dialog implements DialogInterface, Window.Callback, KeyEvent.Callback, OnCreateContextMenuListener,Window.OnWindowDismissedCallback{ /** * Set the screen content from a layout resource. The resource will be * inflated, adding all top-level views to the screen. * * @param layoutResID Resource ID to be inflated. */ public void setContentView(int layoutResID) { mWindow.setContentView(layoutResID); }}Dialog的展现
Dialog的展现和Activity不同是因为两者的声明周期不同，Activity的声明周期是有AMS调用而Dialog是应用程序自己调用的。ViewRootImpl的初始化在Activity会在onResume()方法之后，而是Dialog被调用show方法时触发的。
public class Dialog implements DialogInterface, Window.Callback, KeyEvent.Callback, OnCreateContextMenuListener,Window.OnWindowDismissedCallback{ /** * Start the dialog and display it on screen. The window is placed in the * application layer and opaque. Note that you should not override this * method to do initialization when the dialog is shown, instead implement * that in {@link #onStart}. */ public void show() { if (mShowing) { if (mDecor != null) { if (mWindow.hasFeature(Window.FEATURE_ACTION_BAR)) { mWindow.invalidatePanelMenu(Window.FEATURE_ACTION_BAR); } mDecor.setVisibility(View.VISIBLE); } return; } mCanceled = false; //判断是否调用onCreate方法 if (!mCreated) { dispatchOnCreate(null); } //调用onStart方法 onStart(); //获取DecorView对象实例 mDecor = mWindow.getDecorView(); if (mActionBar == null && mWindow.hasFeature(Window.FEATURE_ACTION_BAR)) { final ApplicationInfo info = mContext.getApplicationInfo(); mWindow.setDefaultIcon(info.icon); mWindow.setDefaultLogo(info.logo); mActionBar = new WindowDecorActionBar(this); } //更新Window属性参数 WindowManager.LayoutParams l = mWindow.getAttributes(); if ((l.softInputMode & WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION) == 0) { WindowManager.LayoutParams nl = new WindowManager.LayoutParams(); nl.copyFrom(l); nl.softInputMode |= WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION; l = nl; } try { //Windowmanger添加Window、ViewRootImpl初始化并绑定Window mWindowManager.addView(mDecor, l); mShowing = true; //OnShowListener监听回调 sendShowMessage(); } finally { } }}Toast
Toast的构造
public class Toast { final Context mContext; final TN mTN;// int mDuration;//展示时间 View mNextView;//所展示的View /** * Construct an empty Toast object. You must call {@link #setView} before you * can call {@link #show}. * * @param context The context to use. Usually your {@link android.app.Application} * or {@link android.app.Activity} object. */ //Context可以为Application也可以为Activity， public Toast(Context context) { mContext = context; mTN = new TN(); mTN.mY = context.getResources().getDimensionPixelSize( com.android.internal.R.dimen.toast_y_offset); mTN.mGravity = context.getResources().getInteger( com.android.internal.R.integer.config_toastDefaultGravity); } //NotificationManagerService的客户端IBinder对 private static INotificationManager sService; private static class TN extends ITransientNotification.Stub { TN() { // XXX This should be changed to use a Dialog, with a Theme.Toast // defined that sets up the layout params appropriately. final WindowManager.LayoutParams params = mParams; params.height = WindowManager.LayoutParams.WRAP_CONTENT; params.width = WindowManager.LayoutParams.WRAP_CONTENT; params.format = PixelFormat.TRANSLUCENT; params.windowAnimations = com.android.internal.R.style.Animation_Toast; //设置Window类型为Toast params.type = WindowManager.LayoutParams.TYPE_TOAST; params.setTitle("Toast"); params.flags = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE; } } }transient_notification.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:background="?android:attr/toastFrameBackground"> <TextView android:id="@android:id/message" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:layout_gravity="center_horizontal" android:textAppearance="@style/TextAppearance.Toast" android:textColor="@color/bright_foreground_dark" android:shadowColor="#BB000000" android:shadowRadius="2.75" /></LinearLayout>Toast添加View
从Toast的调用我们开始分析Toast.makeText(MainActivity.this , "Hello World" , Toast.LENGTH_SHORT);我们主要看makeText方法。
public class Toast { /** * Make a standard toast that just contains a text view. * * @param context The context to use. Usually your {@link android.app.Application} * or {@link android.app.Activity} object. * @param text The text to show. Can be formatted text. * @param duration How long to display the message. Either {@link #LENGTH_SHORT} or * {@link #LENGTH_LONG} * */ public static Toast makeText(Context context, CharSequence text, @Duration int duration) { Toast result = new Toast(context); //获取布局解析器 LayoutInflater inflate = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); //解析transient_notification.xml生成对应的View View v = inflate.inflate(com.android.internal.R.layout.transient_notification, null); //找到View中的id为message的TextView TextView tv = (TextView)v.findViewById(com.android.internal.R.id.message); //对Textview进行文字赋值 tv.setText(text); //展示的Toast所用的View result.mNextView = v; //设置间隔时间 result.mDuration = duration; return result; }}主要是对Toast内部成员变量mNextView和mDuration进行初始化。
Toast的展示
将Toast内部的TN(ITransientNotification客户端对象)加入到INotificationManager服务端的Binder兑现的mToastQueue队列中。再由服务端循环遍历mToastQueue队列中ToastRecord对象，处理一个移除一个，每次处理的都是List的第一个ToastRecord对象。
public class Toast { //INotificationManager的客户端的Binder对象 private static INotificationManager sService; static private INotificationManager getService() { if (sService != null) { return sService; } //获取INotificationManager的客户端的Binder对象 sService = INotificationManager.Stub.asInterface(ServiceManager.getService("notification")); return sService; } /** * Show the view for the specified duration. */ public void show() { //mNextView不能为空 if (mNextView == null) { throw new RuntimeException("setView must have been called"); } //service初始哈 INotificationManager service = getService(); //获取当前Context对应的包名 String pkg = mContext.getOpPackageName(); TN tn = mTN; tn.mNextView = mNextView; try { //将TN加入INotificationManager中的mToastQueue队列 service.enqueueToast(pkg, tn, mDuration); } catch (RemoteException e) { // Empty } }}NotificationManagerService在服务端处理ITransientNotification客户端传过来的enqueueToast事件。
public class NotificationManagerService extends SystemService { //是否是系统调用 private static boolean isCallerSystem() { return isUidSystem(Binder.getCallingUid()); } private final IBinder mService = new INotificationManager.Stub() { @Override public void enqueueToast(String pkg, ITransientNotification callback, int duration){ if (DBG) { Slog.i(TAG, "enqueueToast pkg=" + pkg + " callback=" + callback + " duration=" + duration); } if (pkg == null || callback == null) { Slog.e(TAG, "Not doing toast. pkg=" + pkg + " callback=" + callback); return ; } //判断是否是系统调动或者是Android系统应用程序进行调用 final boolean isSystemToast = isCallerSystem() || ("android".equals(pkg)); //Toast或者通知权限被禁用 if (ENABLE_BLOCKED_TOASTS && !noteNotificationOp(pkg, Binder.getCallingUid())) { if (!isSystemToast) { Slog.e(TAG, "Suppressing toast from package " + pkg + " by user request."); return; } } //mToastQueue加锁 synchronized (mToastQueue) { int callingPid = Binder.getCallingPid(); long callingId = Binder.clearCallingIdentity(); try { ToastRecord record; //寻找当前callback在mToastQueue中的索引，没找到则返回-1 int index = indexOfToastLocked(pkg, callback); // If it's already in the queue, we update it in place, we don't // move it to the end of the queue. //index>=0表示mToastQueue中有该callback的索引，record进行更新展示时间 if (index >= 0) { record = mToastQueue.get(index); record.update(duration); } else { // Limit the number of toasts that any given package except the android // package can enqueue. Prevents DOS attacks and deals with leaks. //不是系统的Toast if (!isSystemToast) { int count = 0; final int N = mToastQueue.size(); for (int i=0; i<N; i++) { final ToastRecord r = mToastQueue.get(i); //判断当前的Toast是不是同一个包发出的 if (r.pkg.equals(pkg)) { count++; //当前包的需要展示的Toast缓存数量>=50 if (count >= MAX_PACKAGE_NOTIFICATIONS) { Slog.e(TAG, "Package has already posted " + count + " toasts. Not showing more. Package=" + pkg); return; } } } } //根据callback等信息构造ToastRecord对象 record = new ToastRecord(callingPid, pkg, callback, duration); //将新的ToastRecord对象加入到队列总 mToastQueue.add(record); //加入之后当前的索引是lenth-1 index = mToastQueue.size() - 1; //将当前包对应的线程切换为前台线程 keepProcessAliveLocked(callingPid); } // If it's at index 0, it's the current toast. It doesn't matter if it's // new or just been updated. Call back and tell it to show itself. // If the callback fails, this will remove it from the list, so don't // assume that it's valid after this. //如果之前队列中没有正在处理的消息，那么处理当前这个ToastRecord if (index == 0) { showNextToastLocked(); } } finally { Binder.restoreCallingIdentity(callingId); } } } }}NotificationManagerService使用先进先出（FIFO）的方式处理mToastQueue队列中的消息。
- 服务端的处理
public class NotificationManagerService extends SystemService { void showNextToastLocked() { //获取队列第一个ToastRecord ToastRecord record = mToastQueue.get(0); while (record != null) { if (DBG) Slog.d(TAG, "Show pkg=" + record.pkg + " callback=" + record.callback); try { //调用客户端Binder对应的TN.show方法。 record.callback.show(); scheduleTimeoutLocked(record); return; } catch (RemoteException e) { Slog.w(TAG, "Object died trying to show notification " + record.callback + " in package " + record.pkg); // remove it from the list and let the process die //当前Toast客户端Binder方法调用抛出异常 //移除当前ToastRecord int index = mToastQueue.indexOf(record); if (index >= 0) { mToastQueue.remove(index); } //切换当前ToastRecord进程 keepProcessAliveLocked(record.pid); //遍历对象变为列表下一个oastRecord对象 if (mToastQueue.size() > 0) { record = mToastQueue.get(0); } else { record = null; } } } }}- 客户端的处理
private static class TN extends ITransientNotification.Stub { /** * schedule handleShow into the right thread */ @Override public void show() { if (localLOGV) Log.v(TAG, "SHOW: " + this); mHandler.post(mShow); } final Runnable mShow = new Runnable() { @Override public void run() { handleShow(); } }; //展示Toast public void handleShow() { if (localLOGV) Log.v(TAG, "HANDLE SHOW: " + this + " mView=" + mView + " mNextView=" + mNextView); //判断mNextView是否展示过 if (mView != mNextView) { // remove the old view if necessary //移除当前展示的Toast handleHide(); mView = mNextView; //获取当前的应用程序的上下文环境 Context context = mView.getContext().getApplicationContext(); //获取当前包名 String packageName = mView.getContext().getOpPackageName(); if (context == null) { context = mView.getContext(); } //获取上下文环境的WindowManagerImpl mWM = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE); // We can resolve the Gravity here by using the Locale for getting // the layout direction final Configuration config = mView.getContext().getResources().getConfiguration(); final int gravity = Gravity.getAbsoluteGravity(mGravity, config.getLayoutDirection()); //设置参数的重力防线 mParams.gravity = gravity; if ((gravity & Gravity.HORIZONTAL_GRAVITY_MASK) == Gravity.FILL_HORIZONTAL) { mParams.horizontalWeight = 1.0f; } if ((gravity & Gravity.VERTICAL_GRAVITY_MASK) == Gravity.FILL_VERTICAL) { mParams.verticalWeight = 1.0f; } //设置参数的坐标和偏移量 mParams.x = mX; mParams.y = mY; mParams.verticalMargin = mVerticalMargin; mParams.horizontalMargin = mHorizontalMargin; mParams.packageName = packageName; //如果mView添加过，那么先把mView从WindowManager中移除。 if (mView.getParent() != null) { if (localLOGV) Log.v(TAG, "REMOVE! " + mView + " in " + this); mWM.removeView(mView); } if (localLOGV) Log.v(TAG, "ADD! " + mView + " in " + this); //把需要展示的View添加在WindowManager中 mWM.addView(mView, mParams); trySendAccessibilityEvent(); } }}Toast的消失
系统的Toast的hide都是在INotificationManager的服务端Binder中发起的，但最终的执行都是在INotificationManager的客户端Binder中执行的。
- 服务端
public class NotificationManagerService extends SystemService { private final class WorkerHandler extends Handler{ @Override public void handleMessage(Message msg){ switch (msg.what){ case MESSAGE_TIMEOUT: //调用当前的Toast的hide handleTimeout((ToastRecord)msg.obj); break; case MESSAGE_SAVE_POLICY_FILE: handleSavePolicyFile(); break; case MESSAGE_SEND_RANKING_UPDATE: handleSendRankingUpdate(); break; case MESSAGE_LISTENER_HINTS_CHANGED: handleListenerHintsChanged(msg.arg1); break; case MESSAGE_LISTENER_NOTIFICATION_FILTER_CHANGED: handleListenerInterruptionFilterChanged(msg.arg1); break; } } } //让当前Toast展示一段时间后消失 private void scheduleTimeoutLocked(ToastRecord r){ //移除mHandler关于这个TaostRecord的所有Message mHandler.removeCallbacksAndMessages(r); Message m = Message.obtain(mHandler, MESSAGE_TIMEOUT, r); long delay = r.duration == Toast.LENGTH_LONG ? LONG_DELAY : SHORT_DELAY; //发送一个delayed=duration的MESSAGE_TIMEOUT事件 mHandler.sendMessageDelayed(m, delay); } //使Toast消失 private void handleTimeout(ToastRecord record){ if (DBG) Slog.d(TAG, "Timeout pkg=" + record.pkg + " callback=" + record.callback); synchronized (mToastQueue) { //找当前ToastRecord在mToastQueue队列中的索引 int index = indexOfToastLocked(record.pkg, record.callback); if (index >= 0) { cancelToastLocked(index); } } } //调用当前索引=index的ToastRecord.callback.hide void cancelToastLocked(int index) { ToastRecord record = mToastQueue.get(index); try { ////调用客户端Binder对应的TN.hide方法。 record.callback.hide(); } catch (RemoteException e) { Slog.w(TAG, "Object died trying to hide notification " + record.callback + " in package " + record.pkg); // don't worry about this, we're about to remove it from // the list anyway } //移除处理完的ToastRecord mToastQueue.remove(index); keepProcessAliveLocked(record.pid); if (mToastQueue.size() > 0) { // Show the next one. If the callback fails, this will remove // it from the list, so don't assume that the list hasn't changed // after this point. //处理队列中的下一个ToastRecord showNextToastLocked(); } }}- 客户端
private static class TN extends ITransientNotification.Stub { /** * schedule handleHide into the right thread */ @Override public void hide() { if (localLOGV) Log.v(TAG, "HIDE: " + this); mHandler.post(mHide); } final Runnable mHide = new Runnable() { @Override public void run() { handleHide(); // Don't do this in handleHide() because it is also invoked by handleShow() mNextView = null; } }; public void handleHide() { if (localLOGV) Log.v(TAG, "HANDLE HIDE: " + this + " mView=" + mView); if (mView != null) { // note: checking parent() just to make sure the view has // been added... i have seen cases where we get here when // the view isn't yet added, so let's try not to crash. if (mView.getParent() != null) { if (localLOGV) Log.v(TAG, "REMOVE! " + mView + " in " + this); //调用WindowManager的removeView移除mView mWM.removeView(mView); } mView = null; } }}总结
通过分析Activity、Dialog、Toast通过对ViewRootImpl的更细节的分析，所有添加在窗口上的View都有一个ViewRootImpl作为它的Parent，处理View的布局、事件处理等。
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