Android---->Allapps加载流程详解【AndroidICS4.0——>Launcher系列五】

工作需要总结，这样就能保证地基牢固，就能爬得更高；

----2013-01-07题记

转载请标明出处：http://blog.csdn.net/wdaming1986/article/details/8478533

前段时间研究了Launcher的AllApps的加载流程，对这个进行了一点修改，呵呵，其实也不算太难，只要把Launcher的代码都能看个80%，基本就是想怎么改就怎么改！AllApps是什么，就是在Android的IDEL界面（主界面）点击MainMenu键进入后的界面，也就是所有应用程序界面；

先来看看它是怎么被手机加载上来的？

Step1：手机第一次开机，首先加载LauncherApplication,注册一些监听，共享数据，比如：LauncherModel对象，通过((LauncherApplication)getApplication());可以获取到LauncherApplication的对象；然后再加载Launcher.java这个类，先走onCreate（）方法；里面调用如下方法：

if (!mRestoring) {
            mModel.startLoader(this, true);
        }

Step2：在Step1中这个方法调到了LauncheModel.java的类里面了，在这个方法里面主要的工作就是启动一个线程，下面我们来看看在线程的run（）方法做了哪些操作；

public void run() {
            // Optimize for end-user experience: if the Launcher is up and // running with the
            // All Apps interface in the foreground, load All Apps first. Otherwise, load the
            // workspace first (default).
            final Callbacks cbk = mCallbacks.get();
            final boolean loadWorkspaceFirst = cbk != null ? (!cbk.isAllAppsVisible()) : true;

            keep_running: {
                // Elevate priority when Home launches for the first time to avoid
                // starving at boot time. Staring at a blank home is not cool.
                synchronized (mLock) {
                    if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to " +
                            (mIsLaunching ? "DEFAULT" : "BACKGROUND"));
                    android.os.Process.setThreadPriority(mIsLaunching
                            ? Process.THREAD_PRIORITY_DEFAULT : Process.THREAD_PRIORITY_BACKGROUND);
                }
                if (loadWorkspaceFirst) {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: loading workspace");
                    loadAndBindWorkspace();
                } else {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: special: loading all apps");
                    loadAndBindAllApps();
                }

                if (mStopped) {
                    break keep_running;
                }

                // Whew! Hard work done.  Slow us down, and wait until the UI thread has
                // settled down.
                synchronized (mLock) {
                    if (mIsLaunching) {
                        if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to BACKGROUND");
                        android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
                    }
                }
                waitForIdle();

                // second step
                if (loadWorkspaceFirst) {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 2: loading all apps");
                    loadAndBindAllApps();
                } else {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 2: special: loading workspace");
                    loadAndBindWorkspace();
                }

                // Restore the default thread priority after we are done loading items
                synchronized (mLock) {
                    android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
                }
            }


            // Update the saved icons if necessary
            if (DEBUG_LOADERS) Log.d(TAG, "Comparing loaded icons to database icons");
            for (Object key : sDbIconCache.keySet()) {
                updateSavedIcon(mContext, (ShortcutInfo) key, sDbIconCache.get(key));
            }
            sDbIconCache.clear();

            // Clear out this reference, otherwise we end up holding it until all of the
            // callback runnables are done.
            mContext = null;

            synchronized (mLock) {
                // If we are still the last one to be scheduled, remove ourselves.
                if (mLoaderTask == this) {
                    mLoaderTask = null;
                }
            }
        }

其实主要的操作就是加载workspace和AllApps；loadAndBindAllApps（）这个方法就是加载AllApps的；

Step3：在这个loadAndBindAllApps（）里面，会调用loadAllAppsByBatch（），批量加载AllApps；

先根据：

final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
            mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

创建一个带有CATEGORY_LAUNCHER这种类型的mainIntent，然后再通过

List<ResolveInfo> apps=packageManager.queryIntentActivities(mainIntent, 0);

过滤出所有的apps，通过sort对apps进行排序：

Collections.sort(apps,new LauncherModel.ShortcutNameComparator(packageManager, mLabelCache));

排序完成后，然后把这些apps逐个添加到ArrayList中去：代码如下：

for (int j=0; i<N && j<batchSize; j++) {
                    // This builds the icon bitmaps.
                    mAllAppsList.add(new ApplicationInfo(packageManager, apps.get(i),
                            mIconCache, mLabelCache));
                    i++;
                }

调到AllAppsList.java中的add方法：

public void add(ApplicationInfo info) {
        if (findActivity(data, info.componentName)) {
            return;
        }
        data.add(info);
        added.add(info);
    }

这个added的定义就是：

public ArrayList<ApplicationInfo> added =
            new ArrayList<ApplicationInfo>(DEFAULT_APPLICATIONS_NUMBER);

然后通过开启线程callback回调到Launcher.java的bindAllApplications（）方法中：

final ArrayList<ApplicationInfo> added = mAllAppsList.added;
                mAllAppsList.added = new ArrayList<ApplicationInfo>();

                mHandler.post(new Runnable() {
                    public void run() {
                        final long t = SystemClock.uptimeMillis();
                        if (callbacks != null) {
                            if (first) {
                                callbacks.bindAllApplications(added);
                            } else {
                                callbacks.bindAppsAdded(added);
                            }
                            if (DEBUG_LOADERS) {
                                Log.d(TAG, "bound " + added.size() + " apps in "
                                    + (SystemClock.uptimeMillis() - t) + "ms");
                            }
                        } else {
                            Log.i(TAG, "not binding apps: no Launcher activity");
                        }
                    }
                });

Step4：在Launcher.java中bindAllApplications（）方法中做的事：如果有对话框存在，就remove对话框，主要是

mAppsCustomizeContent.setApps(apps);

Step5:在AppsCustomizePagedView.java中的setApps()中主要做的事就是，赋值给mApps，再次对apps进行排序，计算apps的页数和widget占用的页数；代码如下：

public void setApps(ArrayList<ApplicationInfo> list) {
        mApps = list;
        Collections.sort(mApps, LauncherModel.APP_NAME_COMPARATOR);
        updatePageCounts();

        // The next layout pass will trigger data-ready if both widgets and apps are set, so 
        // request a layout to do this test and invalidate the page data when ready.
        if (testDataReady()) requestLayout();
    }

updatePageCounts()就是计算apps的页数和widget的页数；

Step6：而进入这个allapps的时候，就是进入到AppsCustomizePagedView.java这个类的时候会调用

onMeasure（）这个方法；在这个里面首先会对allapps和widgets进行校验，

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int width = MeasureSpec.getSize(widthMeasureSpec);
        int height = MeasureSpec.getSize(heightMeasureSpec);
        if (!isDataReady()) {
            if (testDataReady()) {
                setDataIsReady();
                setMeasuredDimension(width, height);
                onDataReady(width, height);
            }
        }

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

通过testDataReady（）这个方法来校验是否他们为空！如果为空就不加载他们；代码如下：

/**
     * This differs from isDataReady as this is the test done if isDataReady is not set.
     */
    private boolean testDataReady() {
        // We only do this test once, and we default to the Applications page, so we only really
        // have to wait for there to be apps.
        // TODO: What if one of them is validly empty
        return !mApps.isEmpty() && !mWidgets.isEmpty();
    }

当allapps和widgets的数据都准备好了的时候，给这个view设置宽和高setMeasuredDimension(width, height);

然后调用onDataReady(width, height);在这个方法中会计算占用的页数，内容的宽度，细胞的数量，强制措施，以更新重新计算差距，存储页面，刷新数据显示上来通过invalidatePageData(Math.max(0, page), hostIsTransitioning);

这个调用到了PageView.java这个类（Launcher的主要精华类，写得相当有水准，看了好几遍，每次看都有收获）在这个方法里面主要做的是

（1）先加载apps和widgets的view，通过方法：

// Update all the pages
            syncPages();

public void syncPages() {
        removeAllViews();
        cancelAllTasks();

        Context context = getContext();
        for (int j = 0; j < mNumWidgetPages; ++j) {
            PagedViewGridLayout layout = new PagedViewGridLayout(context, mWidgetCountX,
                    mWidgetCountY);
            setupPage(layout);
            addView(layout, new PagedViewGridLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                    LayoutParams.MATCH_PARENT));
        }

        for (int i = 0; i < mNumAppsPages; ++i) {
            PagedViewCellLayout layout = new PagedViewCellLayout(context);
            setupPage(layout);
            addView(layout);
        }
    }

（2）再刷新数据到每页的view界面中，通过方法：

 // Load any pages that are necessary for the current window of views
            loadAssociatedPages(mCurrentPage, immediateAndOnly);
            requestLayout();

在PageView.java中的loadAssociatedPages（）方法中里面调用的主要的方法syncPageItems(i, (i == page) && immediateAndOnly);这个通过接口调到了AppsCustomizePagedView.java中的syncPageItems（）方法中去了：

@Override
    public void syncPageItems(int page, boolean immediate) {
        if (page < mNumAppsPages) {
            syncAppsPageItems(page, immediate);
        } else {
            syncWidgetPageItems(page - mNumAppsPages, immediate);
        }
    }

里面就是刷新apps或者是widget的每一页；
再来看看syncAppsPageItems（）这个方法：

public void syncAppsPageItems(int page, boolean immediate) {
        // ensure that we have the right number of items on the pages
        int numCells = mCellCountX * mCellCountY;
        int startIndex = page * numCells;
        int endIndex = Math.min(startIndex + numCells, mApps.size());
        PagedViewCellLayout layout = (PagedViewCellLayout) getPageAt(page);

        layout.removeAllViewsOnPage();
        ArrayList<Object> items = new ArrayList<Object>();
        ArrayList<Bitmap> images = new ArrayList<Bitmap>();
        for (int i = startIndex; i < endIndex; ++i) {
            ApplicationInfo info = mApps.get(i);
            PagedViewIcon icon = (PagedViewIcon) mLayoutInflater.inflate(
                    R.layout.apps_customize_application, layout, false);
            icon.applyFromApplicationInfo(info, true, mHolographicOutlineHelper);
            icon.setOnClickListener(this);
            icon.setOnLongClickListener(this);
            icon.setOnTouchListener(this);
            icon.setOnKeyListener(this);

            int index = i - startIndex;
            int x = index % mCellCountX;
            int y = index / mCellCountX;
            layout.addViewToCellLayout(icon, -1, i, new PagedViewCellLayout.LayoutParams(x,y, 1,1));

            items.add(info);
            images.add(info.iconBitmap);
        }

        layout.createHardwareLayers();

        /* TEMPORARILY DISABLE HOLOGRAPHIC ICONS
        if (mFadeInAdjacentScreens) {
            prepareGenerateHoloOutlinesTask(page, items, images);
        }
        */
    }

当你看到这个addViewToCellLayout（）方法的时候，我相信你就会有“山穷水复疑无路，柳暗花明又一村”的感觉了！这就是加载每个icon到view的那个位置；
syncWidgetPageItems（）这个也是同理，代码我相信大家自己都能看明白了吧！

Step7：而这个widgets的数据是怎么加载上来的呢？？？这个是在Launcher.java中的onCreate（）方法中一步一步加载的：

（1）在Launcher.java中的onCreate（）方法中：

// Update customization drawer _after_ restoring the states
        if (mAppsCustomizeContent != null) {
            mAppsCustomizeContent.onPackagesUpdated();
        }

（2）调用到AppsCustomizePagedView.java中的onPackagesUpdated（）的方法，这个里面主要做的是启动一个延迟的线程来加载widgets

public void onPackagesUpdated() {
        // TODO: this isn't ideal, but we actually need to delay here. This call is triggered
        // by a broadcast receiver, and in order for it to work correctly, we need to know that
        // the AppWidgetService has already received and processed the same broadcast. Since there
        // is no guarantee about ordering of broadcast receipt, we just delay here. Ideally,
        // we should have a more precise way of ensuring the AppWidgetService is up to date.
        postDelayed(new Runnable() {
           public void run() {
               updatePackages();
           }
        }, 500);
    }

（3）通过updatePackages（）这个方法来实现的加载widgets的下面来看看代码：

public void updatePackages() {
        // Get the list of widgets and shortcuts
        boolean wasEmpty = mWidgets.isEmpty();
        mWidgets.clear();
        List<AppWidgetProviderInfo> widgets =
            AppWidgetManager.getInstance(mLauncher).getInstalledProviders();
        Intent shortcutsIntent = new Intent(Intent.ACTION_CREATE_SHORTCUT);
        List<ResolveInfo> shortcuts = mPackageManager.queryIntentActivities(shortcutsIntent, 0);
        for (AppWidgetProviderInfo widget : widgets) {
            if (widget.minWidth > 0 && widget.minHeight > 0) {
                mWidgets.add(widget);
            } else {
                Log.e(LOG_TAG, "Widget " + widget.provider + " has invalid dimensions (" +
                        widget.minWidth + ", " + widget.minHeight + ")");
            }
        }
        mWidgets.addAll(shortcuts);
        Collections.sort(mWidgets,
                new LauncherModel.WidgetAndShortcutNameComparator(mPackageManager));
        updatePageCounts();

        if (wasEmpty) {
            // The next layout pass will trigger data-ready if both widgets and apps are set, so request
            // a layout to do this test and invalidate the page data when ready.
            if (testDataReady()) requestLayout();
        } else {
            cancelAllTasks();
            invalidatePageData();
        }
    }

相信大家看到这里，根据上面的分析，就应该明白了mWidgets数据的加载过程了吧！

Step8：置于里面的click事件就查看onClick（）方法；

长按是调用到父类的PagedViewWithDraggableItems.java的onLongClick()事件：

@Override
    public boolean onLongClick(View v) {
        // Return early if this is not initiated from a touch
        if (!v.isInTouchMode()) return false;
        // Return early if we are still animating the pages
        if (mNextPage != INVALID_PAGE) return false;
        // When we have exited all apps or are in transition, disregard long clicks
        if (!mLauncher.isAllAppsCustomizeOpen() ||
                mLauncher.getWorkspace().isSwitchingState()) return false;

        return beginDragging(v);
    }

然后回调子类的AppsCustomizePagedView.java的beginDragging（）方法的：

private void beginDraggingApplication(View v) {
        mLauncher.getWorkspace().onDragStartedWithItem(v);
        mLauncher.getWorkspace().beginDragShared(v, this);
    }

以后的流程大家可以自己跟跟，就明白拖拽事件的传递了，其实和Folder的拖拽是类似的原理；

今天就总结到这里吧！

2013年1月7日22:35于北京