2011-9-22 15:41:21

 

2011-9-22 15:41:21

 getPreferences 莫非有BUG？

SurfaceHolder  的回调

surfaceCreated
surfaceChanged
surfaceDestroyed

    /**
     * A client may implement this interface to receive information about
     * changes to the surface.  When used with a {@link SurfaceView}, the
     * Surface being held is only available between calls to
     * {@link #surfaceCreated(SurfaceHolder)} and
     * {@link #surfaceDestroyed(SurfaceHolder).  The Callback is set with
     * {@link SurfaceHolder#addCallback SurfaceHolder.addCallback} method.
     */
    public interface Callback {
        /**
         * This is called immediately after the surface is first created.
         * Implementations of this should start up whatever rendering code
         * they desire.  Note that only one thread can ever draw into
         * a {@link Surface}, so you should not draw into the Surface here
         * if your normal rendering will be in another thread.
         *
         * @param holder The SurfaceHolder whose surface is being created.
         */
         在另外一个线程里进行绘画
        public void surfaceCreated(SurfaceHolder holder);

        /**
         * This is called immediately after any structural changes (format or
         * size) have been made to the surface.  You should at this point update
         * the imagery in the surface.  This method is always called at least
         * once, after {@link #surfaceCreated}.
         *
         * @param holder The SurfaceHolder whose surface has changed.
         * @param format The new PixelFormat of the surface.
         * @param width The new width of the surface.
         * @param height The new height of the surface.
         */
         发生了改变
        public void surfaceChanged(SurfaceHolder holder, int format, int width,
                int height);

        /**
         * This is called immediately before a surface is being destroyed. After
         * returning from this call, you should no longer try to access this
         * surface.  If you have a rendering thread that directly accesses
         * the surface, you must ensure that thread is no longer touching the
         * Surface before returning from this function.
         *
         * @param holder The SurfaceHolder whose surface is being destroyed.
         */
         //surface 现在关闭
        public void surfaceDestroyed(SurfaceHolder holder);
    }

  mSurfaceView = (SurfaceView) findViewById(R.id.surface_view);
  mSurfaceHolder = mSurfaceView.getHolder();
  mSurfaceHolder.addCallback(this);
  mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
  
  SurfaceView和mSurfaceHolder之间的关系
  
      /**
     * Finds a view that was identified by the id attribute from the XML that
     * was processed in {@link #onCreate}.
     *
     * @return The view if found or null otherwise.
     */
    public View findViewById(int id) {
        return getWindow().findViewById(id);
    }
   
        /**
     * Set the activity content from a layout resource.  The resource will be
     * inflated, adding all top-level views to the activity.
     *
     * @param layoutResID Resource ID to be inflated.
     */
    public void setContentView(int layoutResID) {
        getWindow().setContentView(layoutResID);
    }
   
    ContextThemeWrapper 
 
    final void attach(Context context, ActivityThread aThread,
            Instrumentation instr, IBinder token, int ident,
            Application application, Intent intent, ActivityInfo info,
            CharSequence title, Activity parent, String id,
            Object lastNonConfigurationInstance,
            HashMap<String,Object> lastNonConfigurationChildInstances,
            Configuration config) {
           
           
        attachBaseContext(context);

        mWindow = PolicyManager.makeNewWindow(this);
        mWindow.setCallback(this);
        if (info.softInputMode != WindowManager.LayoutParams.SOFT_INPUT_STATE_UNSPECIFIED) {
            mWindow.setSoftInputMode(info.softInputMode);
        }
        mUiThread = Thread.currentThread();

        mMainThread = aThread;
        mInstrumentation = instr;
        mToken = token;
        mIdent = ident;
        mApplication = application;
        mIntent = intent;
        mComponent = intent.getComponent();
        mActivityInfo = info;
        mTitle = title;
        mParent = parent;
        mEmbeddedID = id;
        mLastNonConfigurationInstance = lastNonConfigurationInstance;
        mLastNonConfigurationChildInstances = lastNonConfigurationChildInstances;

        mWindow.setWindowManager(null, mToken, mComponent.flattenToString());
        if (mParent != null) {
            mWindow.setContainer(mParent.getWindow());
        }
        mWindowManager = mWindow.getWindowManager();
        mCurrentConfig = config;
    }
   
   
 入口点
  
    public static final void main(String[] args) {
        SamplingProfilerIntegration.start();

        Process.setArgV0("<pre-initialized>");

        Looper.prepareMainLooper();
        if (sMainThreadHandler == null) {
            sMainThreadHandler = new Handler();
        }

        ActivityThread thread = new ActivityThread();
        thread.attach(false);

        if (false) {
            Looper.myLooper().setMessageLogging(new
                    LogPrinter(Log.DEBUG, "ActivityThread"));
        }

        Looper.loop();

        if (Process.supportsProcesses()) {
            throw new RuntimeException("Main thread loop unexpectedly exited");
        }

        thread.detach();
        String name = (thread.mInitialApplication != null)
            ? thread.mInitialApplication.getPackageName()
            : "<unknown>";
        Slog.i(TAG, "Main thread of " + name + " is now exiting");
    }
   
    把本对象设置成tls
   
    final ApplicationThread mAppThread = new ApplicationThread();
   
    你还创建了一个ApplicationThread对象
   
    Activity Service ？
   
    ActivityManager ！
   
   
   

首先，从SDK中和源码中都可以获知，ActivityGroup类的父类是Activity，也就是说二者具有相同的接口和生命周期，同Activity一样，也有onCreate()、onPause()等函数可供我们重载。

父类

在ActivityGroup的源码中有成员变量

protected LocalActivityManager mLocalActivityManager;

该变量在ActivityGroup的构造函数中创建并初始化，可见，ActivityGroup的功能实现肯定是要委托给这个对象来完成了。为了给用户开放对此对象的访问，ActivityGroup提供了

    public final LocalActivityManager getLocalActivityManager() {

        return mLocalActivityManager;

    }

本地对象管理

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        Bundle states = savedInstanceState != null

                ? (Bundle) savedInstanceState.getBundle(STATES_KEY) : null;

        mLocalActivityManager.dispatchCreate(states);

}

 
下面，我们就来看一下LocalActivityManager的源码。

在该类中，提供了一个私有类

private static class LocalActivityRecord extends Binder {

        LocalActivityRecord(String _id, Intent _intent) {

            id = _id;

            intent = _intent;

        }

        final String id;                // Unique name of this record.

        Intent intent;                  // Which activity to run here.

        ActivityInfo activityInfo;      // Package manager info about activity.

        Activity activity;              // Currently instantiated activity.

        Window window;                  // Activity's top-level window.

        Bundle instanceState;           // Last retrieved freeze state.

        int curState = RESTORED;        // Current state the activity is in.

    }

用于保存Activity的信息，并提供了

    private final Map<String, LocalActivityRecord> mActivities

            = new HashMap<String, LocalActivityRecord>();

    private final ArrayList<LocalActivityRecord> mActivityArray

            = new ArrayList<LocalActivityRecord>();

采用这样的数据结构用于对所有嵌入的子Activity信息进行保存处理。其中前者用于通过String快速查找，后者用于以数组的方式快速访问，是典型的以空间换时间的的方式。

hashmap和数组

    public void dispatchCreate(Bundle state) {

        if (state != null) {

            final Iterator<String> i = state.keySet().iterator();

            while (i.hasNext()) {

                try {

                    final String id = i.next();

                    final Bundle astate = state.getBundle(id);

                    LocalActivityRecord r = mActivities.get(id);
                                      
                    if (r != null) {

                        r.instanceState = astate;

                    } else {

                        r = new LocalActivityRecord(id, null);

                        r.instanceState = astate;

                        mActivities.put(id, r);

                        mActivityArray.add(r);

                    }

                } catch (Exception e) {

……

                }

            }

        }

       

        mCurState = CREATED;

    }
   
    dispatchCreate
   
   

从这里我们可以看出，当有一个ActivityGroup被Create的时候，就会有对应的Activity信息被保存到数组中。

当我们调用LocalActivityManager的startActivity()以产生Window的时候，我们也可以看到

 

public Window startActivity(String id, Intent intent) {

                   ……

        LocalActivityRecord r = mActivities.get(id);

        if (r == null) {

            r = new LocalActivityRecord(id, intent);

            adding = true;

        }

                   ……

        if (adding) {

            mActivities.put(id, r);

            mActivityArray.add(r);

        }

        ……

    }

有了这个数组，就可以遍历到ActivityGroup中嵌入的Activitys了，从而可以实现ActivityGroup的功能。

以上的分析结果产生的类图如下：

dispatchCreate

    public ActivityGroup(boolean singleActivityMode) {
        mLocalActivityManager = new LocalActivityManager(this, singleActivityMode);
    }