摘要:最近在改bug的时候发现在windowManager.addView的时候会发生莫名其妙的崩溃,那个崩溃真的是让你心态爆炸,潜心研究了两天window相关的东西,虽然不是很深奥的东西,本人也只是弄清楚了window的添加逻辑,在此分享给大家:

脚本宝典收集整理的这篇文章主要介绍了

Android中WindowManager与WMS的解析

脚本宝典小编觉得挺不错的,现在分享给大家,也给大家做个参考,希望能帮助你少写一行代码,多一份安全和惬意。

最近在改bug的时候发现在windowManager.addView的时候会发生莫名其妙的崩溃,那个崩溃真的是让你心态爆炸,潜心研究了两天window相关的东西,虽然不是很深奥的东西,本人也只是弄清楚了window的添加逻辑,在此分享给大家:

一、悬浮窗的概念

android中,无论我们的app界面,还是系统桌面,再或者是手机下方的几个虚拟按键和最上方的状态栏,又或者是一个吐司。。。我们所看到的所有界面,都是由一个个悬浮窗口组成的。

但是这些窗口有不同的级别:

  1. 系统的是老大,是最高级别,你没见过你下载的什么app把你的下拉菜单盖住了吧-。=
  2. 其次是每一个应用,都有自己的一个应用级别窗口。
  3. 在应用之内能创建好多的界面,所以还有一种是应用内的窗口。

基于上述三种,android把悬浮窗划分成三个级别,并通过静态int型变量来表示:

     /**      * Start of system-specific window types. These are not normally      * created by applications.      **/     public static final int FIRST_SYSTEM_WINDOW   = 2000;     /**      * End of types of system windows.      **/     public static final int LAST_SYSTEM_WINDOW   = 2999;

2000~2999:在系统级别的悬浮窗范围内,一般我们要想创建是需要申请权限。

     public static final int FIRST_SUB_WINDOW = 1000;     /**      * End of types of sub-windows.      **/     public static final int LAST_SUB_WINDOW = 1999;

1000~1999:子窗口级别的悬浮窗,他如果想要创建必须在一个父窗口下。

 public static final int TYPE_BASE_APPLICATION  = 1; public static final int LAST_APPLICATION_WINDOW = 99;

1~99:应用程序级别的悬浮窗,作为每个应用程序的基窗口。

在每段的范围内都有众多个窗口类型,这个具体就不说了,因为太多了根本说不完。。

但是说了这么半天,悬浮窗到底是个啥东西,可能这个名词听得很多,但是仔细想想android中用到的哪个控件还是哪个类叫悬浮窗?没有吧,那么View总该知道吧(不知道别说你是做android的)

其实说白了悬浮窗就是一个被包裹的view。因为除了一个view他还有很多的属性:长宽深度,类型,证书等等东西,只是属性很多而且属性之间的依赖关系有一些复杂而已。简单的来说可以这么理解。

二、WindowManager介绍

上面简单介绍了悬浮窗的概念,而WindowManager是对悬浮窗进行操作的一个媒介。

WindowManager是一个接口,他是继承了ViewManager接口中的三个方法:

 public interface ViewManager {   public void addView(View view, ViewGroup.LayoutParams params);   public void updateViewLayout(View view, ViewGroup.LayoutParams params);   public void removeView(View view); }

windowManage暴露给我们的只是这个三个方法,真的是简单粗暴,但是很实用。

这三个方法看名字就知道含义了,增删改嘛,就不多说啦。

而在上面提到的对于悬浮窗的三种分类,也是WindowManager的内部类:WindowManager.LayoutParams,关于LayoutParams是什么在这里就不多说了。这不是我们的重点。

我们平时想要添加一个悬浮窗,就会使用第一个方法:

   WindowManager windowManager = getWindowManager();   windowManager.addView(.....);

我们在getWindowManager获取的类,实际上是WindowManager的是WindowManager的实现类:WindowManagerImpl。接下来我们走一下添加悬浮窗的流程。

三、悬浮窗添加流程

入口肯定是从自己的addView中,上面说到了WindowManager的实现类是WindowManagerImpl,来看一下:

     @Override     public void addView(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {     applyDefaultToken(params);     mGlobal.addView(view, params, mContext.getDisplay(), mParentWindow);   }

这里有两步:第一步是给layoutparams设置一个默认的令牌(就是token这个属性,至于这个干什么的等会再说)

   private void applyDefaultToken(@NonNull ViewGroup.LayoutParams params) {     // 设置条件:有默认令牌,而且不是子窗口级别的悬浮窗     if (mDefaultToken != null && mParentWindow == null) {       if (!(params instanceof WindowManager.LayoutParams)) {         throw new IllegalArgumentException("Params must be WindowManager.LayoutParams");       }       // 如果没有令牌就设置默认令牌       final WindowManager.LayoutParams wparams = (WindowManager.LayoutParams) params;       if (wparams.token == null) {         wparams.token = mDefaultToken;       }     }   } 

然后调用了mGlobal的addView:

   public void addView(View view, ViewGroup.LayoutParams params,       Display display, Window parentWindow) {     /**进行一系列判空操作。。。**/     if (parentWindow != null) {       parentWindow.adjustLayoutParamsForSubWindow(wparams);     } else {       // If there's no parent, then hardware acceleration for this view is       // set from the application's hardware acceleration setting.       final Context context = view.getContext();       if (context != null           && (context.getApplicationInfo().flags               & ApplicationInfo.FLAG_HARDWARE_ACCELERATED) != 0) {         wparams.flags |= WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;       }     }     ViewRootImpl root;       root = new ViewRootImpl(view.getContext(), display);       view.setLayoutParams(wparams);       mViews.add(view);       mRoots.add(root);       mParams.add(wparams);       // do this last because it fires off messages to start doing things       try {         root.setView(view, wparams, panelParentView);       } catch (RuntimeException e) {         // BadTokenException or InvalidDisplayException, clean up.         if (index >= 0) {           removeViewLocked(index, true);         }         throw e;       }     }   }

看到WindowManagerGLobal中有三个属性: mViews、mRoots、mParams,可以大胆猜测这个类中保存了我们进程中的所有视图以及相关属性。在这里主要关注一下ViewRootImpl的这个实例对象root,接下来的会走进root的setView中。

ViewRootImpl的setView方法内容有点多,我这里就截取关键的两部分:

1.

   int res; /** = WindowManagerImpl.ADD_OKAY; **/   try {     mOrigWindowType = mWindowAttributes.type;     mAttachInfo.mRecomputeGlobalAttributes = true;     collectViewAttributes();     res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,         getHostVisibility(), mDisplay.getDisplayId(), mWinFrame,         mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,         mAttachInfo.mOutsets, mAttachInfo.mDisplayCutout, mInputChannel);

创建了一个名为res的int类型变量,他要获取到的是悬浮窗添加的结果:成功或者失败。

2.

     if (res < WindowManagerGlobal.ADD_OKAY) {         mAttachInfo.mRootView = null;         mAdded = false;         mFallbackEventHandler.setView(null);         unscheduleTraversals();         setAccessibilityFocus(null, null);         switch (res) {           case WindowManagerGlobal.ADD_BAD_APP_TOKEN:           case WindowManagerGlobal.ADD_BAD_SUBWINDOW_TOKEN:             throw new WindowManager.BadTokenException(                 "Unable to add window -- token " + attrs.token                 + " is not valid; is your activity running?");           case WindowManagerGlobal.ADD_NOT_APP_TOKEN:             throw new WindowManager.BadTokenException(                 "Unable to add window -- token " + attrs.token                 + " is not for an application");           case WindowManagerGlobal.ADD_APP_EXITING:             throw new WindowManager.BadTokenException(                 "Unable to add window -- app for token " + attrs.token                 + " is exiting");           case WindowManagerGlobal.ADD_DUPLICATE_ADD:             throw new WindowManager.BadTokenException(                 "Unable to add window -- window " + mWindow                 + " has already been added");           case WindowManagerGlobal.ADD_STARTING_NOT_NEEDED:             // Silently ignore -- we would have just removed it             // right away, anyway.             return;           case WindowManagerGlobal.ADD_MULTIPLE_SINGLETON:             throw new WindowManager.BadTokenException("Unable to add window "                 + mWindow + " -- another window of type "                 + mWindowAttributes.type + " already exists");           case WindowManagerGlobal.ADD_PERMISSION_DENIED:             throw new WindowManager.BadTokenException("Unable to add window "                 + mWindow + " -- permission denied for window typ                   + mWindowAttributes.type);           case WindowManagerGlobal.ADD_INVALID_DISPLAY:               throw new WindowManager.InvalidDisplayException("Unable to add window "                   + mWindow + " -- the specified display can not be found");           case WindowManagerGlobal.ADD_INVALID_TYPE:               throw new WindowManager.InvalidDisplayException("Unable to add window "                   + mWindow + " -- the specified window type "                   + mWindowAttributes.type + " is not valid");         }         throw new RuntimeException(               "Unable to add window -- unknown error code " + res);       }

第二部分是res返回失败的所有情况,在添加成功的时候res为OKAY,而非OKAY的情况就是上述情况。

接下来来看一下添加悬浮窗的操作,就是1中mWindowSession.addToDisplay。mWindowSession类型如下:

   final IWindowSession mWindowSession;

在这里其实用到了aidl跨进程通信,最终执行该方法的类是Session:

   @Override   public int addToDisplay(IWindow window, int seq, WindowManager.LayoutParams attrs,       int viewVisibility, int displayId, Rect outFrame, Rect outContentInsets,       Rect outStableInsets, Rect outOutsets,       DisplayCutout.ParcelableWrapper outDisplayCutout, InputChannel outInputChannel) {     return mService.addWindow(this, window, seq, attrs, viewVisibility, displayId, outFrame,         outContentInsets, outStableInsets, outOutsets, outDisplayCutout, outInputChannel);   }

这个mService就是一个关键了系统类――WindowMamagerService(WMS)。到了这里我们简单过一下思路:在addView之后,通过WindowManagerGlobal进行一些相关配置,传入ViewRootImpl,再通过aidl方式发送给WMS系统服务。

可能有小伙伴会疑惑。好端端的为什么要用aidl实现?最开始本人也有这个疑惑,但是后来想了想所有的窗口无论系统窗口还是第三方app,窗口都是要通过一个类去进行添加允许判断,这里使用aidl是在合适不过的了。我们接着看一下WMS的addWindow方法:

这个addWindow方法又是一段超长的代码,所以也就不全粘,说一下他的简单流程吧,主要是分为三步:权限判断、条件筛选、添加窗口

WMS的addWindow方法:

   int res = mPolicy.checkAddPermission(attrs, appOp);   if (res != WindowManagerGlobal.ADD_OKAY) {     return res;   }

首先进行一个权限判断,

 final WindowManagerPolicy mPolicy;

WindowManagerPolicy的实现类是PhoneWindowManagerPolicy,看一下他的实现:

又是小一百行的代码,我们拆开来看:

   //排除不属于三种类型悬浮窗范围内的type   //很明显的三段排除。   if (!((type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW)       || (type >= FIRST_SUB_WINDOW && type <= LAST_SUB_WINDOW)       || (type >= FIRST_SYSTEM_WINDOW && type <= LAST_SYSTEM_WINDOW))) {     return WindowManagerGlobal.ADD_INVALID_TYPE;   }   //不是系统级别的悬浮窗直接满足条件   if (type < FIRST_SYSTEM_WINDOW || type > LAST_SYSTEM_WINDOW) {     return ADD_OKAY;   }     //以下几种不是系统警告类型的系统弹窗,会满足条件,除此之外的使用默认判断的方式     if (!isSystemAlertWindowType(type)) {       switch (type) {         case TYPE_TOAST:           outAppOp[0] = OP_TOAST_WINDOW;           return ADD_OKAY;         case TYPE_DREAM:         case TYPE_INPUT_METHOD:         case TYPE_WALLPAPER:         case TYPE_PRESENTATION:         case TYPE_PRIVATE_PRESENTATION:         case TYPE_VOICE_INTERACTION:         case TYPE_ACCESSIBILITY_OVERLAY:         case TYPE_QS_DIALOG:           // The window manager will check these.           return ADD_OKAY;       }       return mContext.checkCallingOrSelfPermission(INTERNAL_SYSTEM_WINDOW)           == PERMISSION_GRANTED ? ADD_OKAY : ADD_PERMISSION_DENIED;     }

后面的几段代码会频繁出现最后的这段代码:mContext.checkCallingOrSelfPermission,具体实现的类是ContextFixture:

     @Override     public int checkCallingOrSelfPermission(String permission) {       if (mPermissionTable.contains(permission)           || mPermissionTable.contains(PERMISSION_ENABLE_ALL)) {         logd("checkCallingOrSelfPermission: " + permission + " return GRANTED");         return PackageManager.PERMISSION_GRANTED;       } else {         logd("checkCallingOrSelfPermission: " + permission + " return DENIED");         return PackageManager.PERMISSION_DENIED;       }     }

这里会使用默认权限判断的方式,要么允许对应权限,要么就是拥有全部权限,否则就会返回DENIED。

这个说完接着回到checkPermission方法。

     //对于系统进程直接满足允许     final int callingUid = Binder.getCallingUid();     if (UserHandle.getAppId(callingUid) == Process.SYSTEM_UID) {       return ADD_OKAY;     }

说实话下面这一段代码我看的不是很明白,只是看到了这里对8.0之后做了版本限制,直接使用默认检查方式。

     ApplicationInfo appInfo;     try {       appInfo = mContext.getPackageManager().getApplicationInfoAsUser(               attrs.packageName,               0 /* flags */,               UserHandle.getUserId(callingUid));     } catch (PackageManager.NameNotFoundException e) {       appInfo = null;     }     if (appInfo == null || (type != TYPE_APPLICATION_OVERLAY && appInfo.targetSdkVersion >= O)) {              return (mContext.checkCallingOrSelfPermission(INTERNAL_SYSTEM_WINDOW)           == PERMISSION_GRANTED) ? ADD_OKAY : ADD_PERMISSION_DENIED;     }

这段是要从PackageManager中获取ApplicationInfo,如果获取失败会抛出NameNotFound异常。所以下面的判断是在异常的时候使用默认权限处理方式。

最后还以一步检查操作,关系不大就不看了。到这里checkPermission方法就结束了。

权限检查的步骤已经结束,接着就是根据上述获取到的结果进行条件筛选。

   if (res != WindowManagerGlobal.ADD_OKAY) {     return res;   }

首先在权限检查的步骤获取权限失败,那么会直接返回,不会执行条件筛选的步骤。而真正的条件筛选步骤代码也是很多,我这里直接粘过来然后说了。

       //111111111111111       if (!mDisplayReady) {         throw new IllegalStateException("Display has not been initialialized");       }       final DisplayContent displayContent = getDisplayContentOrCreate(displayId);       if (displayContent == null) {         Slog.w(TAG_WM, "Attempted to add window to a display that does not exist: "             + displayId + ". Aborting.");         return WindowManagerGlobal.ADD_INVALID_DISPLAY;       }       if (!displayContent.hasAccess(session.mUid)           && !mDisplayManagerInternal.isUidPresentOnDisplay(session.mUid, displayId)) {         Slog.w(TAG_WM, "Attempted to add window to a display for which the application "             + "does not have access: " + displayId + ". Aborting.");         return WindowManagerGlobal.ADD_INVALID_DISPLAY;       }       if (mWindowMap.containsKey(client.asBinder())) {         Slog.w(TAG_WM, "Window " + client + " is already added");         return WindowManagerGlobal.ADD_DUPLICATE_ADD;       }       //22222222222222       if (type >= FIRST_SUB_WINDOW && type <= LAST_SUB_WINDOW) {         parentWindow = windowForClientLocked(null, attrs.token, false);         if (parentWindow == null) {           Slog.w(TAG_WM, "Attempted to add window with token that is not a window: "              + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_SUBWINDOW_TOKEN;         }         if (parentWindow.mAttrs.type >= FIRST_SUB_WINDOW             && parentWindow.mAttrs.type <= LAST_SUB_WINDOW) {           Slog.w(TAG_WM, "Attempted to add window with token that is a sub-window: "               + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_SUBWINDOW_TOKEN;         }       }       //333333333333333       if (type == TYPE_PRIVATE_PRESENTATION && !displayContent.isPrivate()) {         Slog.w(TAG_WM, "Attempted to add private presentation window to a non-private display. Aborting.");         return WindowManagerGlobal.ADD_PERMISSION_DENIED;       }       //444444444444444       AppWindowToken atoken = null;       final boolean hasParent = parentWindow != null;       // Use existing parent window token for child windows since they go in the same token       // as there parent window so we can apply the same policy on them.       WindowToken token = displayContent.getWindowToken(           hasParent ? parentWindow.mAttrs.token : attrs.token);       // If this is a child window, we want to apply the same type checking rules as the       // parent window type.       final int rootType = hasParent ? parentWindow.mAttrs.type : type;       boolean addToastWindowRequiresToken = false;       if (token == null) {         if (rootType >= FIRST_APPLICATION_WINDOW && rootType <= LAST_APPLICATION_WINDOW) {           Slog.w(TAG_WM, "Attempted to add application window with unknown token "              + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }         if (rootType == TYPE_INPUT_METHOD) {           Slog.w(TAG_WM, "Attempted to add input method window with unknown token "              + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }         if (rootType == TYPE_VOICE_INTERACTION) {           Slog.w(TAG_WM, "Attempted to add voice interaction window with unknown token "              + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }         if (rootType == TYPE_WALLPAPER) {           Slog.w(TAG_WM, "Attempted to add wallpaper window with unknown token "              + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }         if (rootType == TYPE_DREAM) {           Slog.w(TAG_WM, "Attempted to add Dream window with unknown token "              + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }         if (rootType == TYPE_QS_DIALOG) {           Slog.w(TAG_WM, "Attempted to add QS dialog window with unknown token "              + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }         if (rootType == TYPE_ACCESSIBILITY_OVERLAY) {           Slog.w(TAG_WM, "Attempted to add Accessibility overlay window with unknown token "               + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }         if (type == TYPE_TOAST) {           // Apps targeting SDK above N MR1 cannot arbitrary add toast windows.           if (doesAddToastWindowRequireToken(attrs.packageName, callingUid,               parentWindow)) {             Slog.w(TAG_WM, "Attempted to add a toast window with unknown token "                 + attrs.token + ". Aborting.");             return WindowManagerGlobal.ADD_BAD_APP_TOKEN;           }         }         final IBinder binder = attrs.token != null ? attrs.token : client.asBinder();         final boolean isRoundedCornerOverlay =             (attrs.privateFlags & PRIVATE_FLAG_IS_ROUNDED_CORNERS_OVERLAY) != 0;         token = new WindowToken(this, binder, type, false, displayContent,             session.mCanAddInternalSystemWindow, isRoundedCornerOverlay);       } else if (rootType >= FIRST_APPLICATION_WINDOW && rootType <= LAST_APPLICATION_WINDOW) {         atoken = token.asAppWindowToken();         if (atoken == null) {           Slog.w(TAG_WM, "Attempted to add window with non-application token "              + token + ". Aborting.");           return WindowManagerGlobal.ADD_NOT_APP_TOKEN;         } else if (atoken.removed) {           Slog.w(TAG_WM, "Attempted to add window with exiting application token "              + token + ". Aborting.");           return WindowManagerGlobal.ADD_APP_EXITING;         } else if (type == TYPE_APPLICATION_STARTING && atoken.startingWindow != null) {           Slog.w(TAG_WM, "Attempted to add starting window to token with already existing"               + " starting window");           return WindowManagerGlobal.ADD_DUPLICATE_ADD;         }       } else if (rootType == TYPE_INPUT_METHOD) {         if (token.windowType != TYPE_INPUT_METHOD) {           Slog.w(TAG_WM, "Attempted to add input method window with bad token "               + attrs.token + ". Aborting.");            return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }       } else if (rootType == TYPE_VOICE_INTERACTION) {         if (token.windowType != TYPE_VOICE_INTERACTION) {           Slog.w(TAG_WM, "Attempted to add voice interaction window with bad token "               + attrs.token + ". Aborting.");            return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }       } else if (rootType == TYPE_WALLPAPER) {         if (token.windowType != TYPE_WALLPAPER) {           Slog.w(TAG_WM, "Attempted to add wallpaper window with bad token "               + attrs.token + ". Aborting.");            return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }       } else if (rootType == TYPE_DREAM) {         if (token.windowType != TYPE_DREAM) {           Slog.w(TAG_WM, "Attempted to add Dream window with bad token "               + attrs.token + ". Aborting.");            return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }       } else if (rootType == TYPE_ACCESSIBILITY_OVERLAY) {         if (token.windowType != TYPE_ACCESSIBILITY_OVERLAY) {           Slog.w(TAG_WM, "Attempted to add Accessibility overlay window with bad token "               + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }       } else if (type == TYPE_TOAST) {         // Apps targeting SDK above N MR1 cannot arbitrary add toast windows.         addToastWindowRequiresToken = doesAddToastWindowRequireToken(attrs.packageName,             callingUid, parentWindow);         if (addToastWindowRequiresToken && token.windowType != TYPE_TOAST) {           Slog.w(TAG_WM, "Attempted to add a toast window with bad token "               + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }       } else if (type == TYPE_QS_DIALOG) {         if (token.windowType != TYPE_QS_DIALOG) {           Slog.w(TAG_WM, "Attempted to add QS dialog window with bad token "               + attrs.token + ". Aborting.");           return WindowManagerGlobal.ADD_BAD_APP_TOKEN;         }       } else if (token.asAppWindowToken() != null) {         Slog.w(TAG_WM, "Non-null appWindowToken for system window of rootType=" + rootType);         // It is not valid to use an app token with other system types; we will         // instead make a new token for it (as if null had been passed in for the token).         attrs.token = null;         token = new WindowToken(this, client.asBinder(), type, false, displayContent,             session.mCanAddInternalSystemWindow);       }       //5555555555555       final WindowState win = new WindowState(this, session, client, token, parentWindow,           appOp[0], seq, attrs, viewVisibility, session.mUid,           session.mCanAddInternalSystemWindow);       if (win.mDeathRecipient == null) {         // Client has apparently died, so there is no reason to         // continue.         Slog.w(TAG_WM, "Adding window client " + client.asBinder()             + " that is dead, aborting.");         return WindowManagerGlobal.ADD_APP_EXITING;       }       if (win.getDisplayContent() == null) {         Slog.w(TAG_WM, "Adding window to Display that has been removed.");         return WindowManagerGlobal.ADD_INVALID_DISPLAY;       }       final boolean hasStatusBarServicePermission =           mContext.checkCallingOrSelfPermission(permission.STATUS_BAR_SERVICE)               == PackageManager.PERMISSION_GRANTED;       mPolicy.adjustWindowParamsLw(win, win.mAttrs, hasStatusBarServicePermission);       win.setShowToOwnerOnlyLocked(mPolicy.checkShowToOwnerOnly(attrs));       res = mPolicy.prepareAddWindowLw(win, attrs);       if (res != WindowManagerGlobal.ADD_OKAY) {         return res;       }       final boolean openInputChannels = (outInputChannel != null           && (attrs.inputFeatures & INPUT_FEATURE_NO_INPUT_CHANNEL) == 0);       if (openInputChannels) {         win.openInputChannel(outInputChannel);       }       //666666666666666       if (type == TYPE_TOAST) {         if (!getDefaultDisplayContentLocked().canAddToastWindowForUid(callingUid)) {           Slog.w(TAG_WM, "Adding more than one toast window for UID at a time.");           return WindowManagerGlobal.ADD_DUPLICATE_ADD;         }                  if (addToastWindowRequiresToken             || (attrs.flags & LayoutParams.FLAG_NOT_FOCUSABLE) == 0             || mCurrentFocus == null             || mCurrentFocus.mOwnerUid != callingUid) {           mH.sendMessageDelayed(               mH.obtainMessage(H.WINDOW_HIDE_TIMEOUT, win),               win.mAttrs.hideTimeoutMilliseconds);         }       }

这里讲筛选部分大体分成这么几个步骤:

  1. 系统以及初始化的一些判断:就像最开始的四个判断。
  2. 子窗口类型时候的对父窗口的相关筛选(父是否为空,以及父亲的类型判断)
  3. 一种特殊的私有类型条件筛选,该类型属于系统类型
  4. 涉及证书(token)的窗口类型条件筛选。
  5. 状态栏权限条件筛选
  6. 吐司类型的条件筛选

在代码中对应的步骤有明确的标注,而具体的代码大多只是一些判断,所以在感觉没有细说的必要了。

在条件筛选完成之后,剩下的类型都是符合添加的类型,从现在开始就开始对不同的type进行不同的添加。经过多到加工后,将OKAY返回。

如果能从添加窗口的步骤返回,就说明一定是OKAY的。那么我们可以一步步跳回层层调用的代码,最终在ViewRootImpl中,对没有添加成功的抛出异常。

       if (res < WindowManagerGlobal.ADD_OKAY) {           mAttachInfo.mRootView = null;           mAdded = false;           mFallbackEventHandler.setView(null);           unscheduleTraversals();           setAccessibilityFocus(null, null);           switch (res) {             case WindowManagerGlobal.ADD_BAD_APP_TOKEN:             case WindowManagerGlobal.ADD_BAD_SUBWINDOW_TOKEN:               throw new WindowManager.BadTokenException(                   "Unable to add window -- token " + attrs.token                   + " is not valid; is your activity running?");             case WindowManagerGlobal.ADD_NOT_APP_TOKEN:               throw new WindowManager.BadTokenException(                   "Unable to add window -- token " + attrs.token                   + " is not for an application");             case WindowManagerGlobal.ADD_APP_EXITING:               throw new WindowManager.BadTokenException(                   "Unable to add window -- app for token " + attrs.token                   + " is exiting");             case WindowManagerGlobal.ADD_DUPLICATE_ADD:               throw new WindowManager.BadTokenException(                   "Unable to add window -- window " + mWindow                   + " has already been added");             case WindowManagerGlobal.ADD_STARTING_NOT_NEEDED:               // Silently ignore -- we would have just removed it               // right away, anyway.               return;             case WindowManagerGlobal.ADD_MULTIPLE_SINGLETON:               throw new WindowManager.BadTokenException("Unable to add window "                   + mWindow + " -- another window of type "                   + mWindowAttributes.type + " already exists");             case WindowManagerGlobal.ADD_PERMISSION_DENIED:               throw new WindowManager.BadTokenException("Unable to add window "                   + mWindow + " -- permission denied for window type "                   + mWindowAttributes.type);             case WindowManagerGlobal.ADD_INVALID_DISPLAY:               throw new WindowManager.InvalidDisplayException("Unable to add window "                   + mWindow + " -- the specified display can not be found");             case WindowManagerGlobal.ADD_INVALID_TYPE:               throw new WindowManager.InvalidDisplayException("Unable to add window "                   + mWindow + " -- the specified window type "                   + mWindowAttributes.type + " is not valid");           }           throw new RuntimeException(               "Unable to add window -- unknown error code " + res);         }

对于OKAY的,在ViewRootImpl中会做一些其他的操作,反正我是没看懂-。=、

四、小结

到这里WMS的添加悬浮窗口的流程差不多就过了一遍了。可能有些地方说的不是很细,大家下来可以关注一下个别几个点。整个过程有这么几个需要强调的地方。

  • 函数循环嵌套,共同消费返回值。
  • 异常循环嵌套
  • 个别地方对M和O以上的系统进行了限制

如果在添加悬浮窗的时候使用了不同的type,可能会发生异常:本人拿了一个8.0的手机,分别对窗口type设置为OVERLAY和ERROR。因为ERROR类型是被弃用的,我发现使用ERROR会抛出异常,而OVERLAY不会。同样的拿了一个6.0的手机添加ERROR类型就没有异常抛出,肯定是上述的问题导致的,但是具体在哪一块我还没有找到,因为整个流程的出口太多了-。=。

此外在WindowManagerGlobal.addView方法中,有一个地方:

   if (parentWindow != null) {     parentWindow.adjustLayoutParamsForSubWindow(wparams);   } else {

这个方法是对于有子窗口类型的证书处理,网上查了一下该方法在四点几、六点几和8.0是不同的,也就是说对证书的处理方式变化了,这里本人还没有细看,有兴趣的盆友可以研究一下然后评论交流一番。

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