Android -- 桌面悬浮，QQ管家火箭实现

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/launcher_img"
        android:layout_width="200dp"
        android:layout_height="88dp"
        android:src="@drawable/launcher_bg_hold" />

</LinearLayout>

public class RocketLauncher extends LinearLayout {

    /**
     * 记录火箭发射台的宽度
     */
    public static int width;

    /**
     * 记录火箭发射台的高度
     */
    public static int height;

    /**
     * 火箭发射台的背景图片
     */
    private ImageView launcherImg;

    public RocketLauncher(Context context) {
        super(context);
        LayoutInflater.from(context).inflate(R.layout.launcher, this);
        launcherImg = (ImageView) findViewById(R.id.launcher_img);
        width = launcherImg.getLayoutParams().width;
        height = launcherImg.getLayoutParams().height;
    }

    /**
     * 更新火箭发射台的显示状态。如果小火箭被拖到火箭发射台上，就显示发射。
     */
    public void updateLauncherStatus(boolean isReadyToLaunch) {
        if (isReadyToLaunch) {
            launcherImg.setImageResource(R.drawable.launcher_bg_fire);
        } else {
            launcherImg.setImageResource(R.drawable.launcher_bg_hold);
        }
    }

}

public class MyWindowManager {

    /**
     * 小悬浮窗View的实例
     */
    private static FloatWindowSmallView smallWindow;

    /**
     * 大悬浮窗View的实例
     */
    private static FloatWindowBigView bigWindow;

    /**
     * 火箭发射台的实例
     */
    private static RocketLauncher rocketLauncher;

    /**
     * 小悬浮窗View的参数
     */
    private static LayoutParams smallWindowParams;

    /**
     * 大悬浮窗View的参数
     */
    private static LayoutParams bigWindowParams;

    /**
     * 火箭发射台的参数
     */
    private static LayoutParams launcherParams;

    /**
     * 用于控制在屏幕上添加或移除悬浮窗
     */
    private static WindowManager mWindowManager;

    /**
     * 用于获取手机可用内存
     */
    private static ActivityManager mActivityManager;

    /**
     * 创建一个小悬浮窗。初始位置为屏幕的右部中间位置。
     */
    public static void createSmallWindow(Context context) {
        WindowManager windowManager = getWindowManager(context);
        int screenWidth = windowManager.getDefaultDisplay().getWidth();
        int screenHeight = windowManager.getDefaultDisplay().getHeight();
        if (smallWindow == null) {
            smallWindow = new FloatWindowSmallView(context);
            if (smallWindowParams == null) {
                smallWindowParams = new LayoutParams();
                smallWindowParams.type = LayoutParams.TYPE_SYSTEM_ALERT;
                smallWindowParams.format = PixelFormat.RGBA_8888;
                smallWindowParams.flags = LayoutParams.FLAG_NOT_TOUCH_MODAL
                        | LayoutParams.FLAG_NOT_FOCUSABLE;
                smallWindowParams.gravity = Gravity.LEFT | Gravity.TOP;
                smallWindowParams.width = FloatWindowSmallView.windowViewWidth;
                smallWindowParams.height = FloatWindowSmallView.windowViewHeight;
                smallWindowParams.x = screenWidth;
                smallWindowParams.y = screenHeight / 2;
            }
            smallWindow.setParams(smallWindowParams);
            windowManager.addView(smallWindow, smallWindowParams);
        }
    }

    /**
     * 将小悬浮窗从屏幕上移除。
     */
    public static void removeSmallWindow(Context context) {
        if (smallWindow != null) {
            WindowManager windowManager = getWindowManager(context);
            windowManager.removeView(smallWindow);
            smallWindow = null;
        }
    }

    /**
     * 创建一个大悬浮窗。位置为屏幕正中间。
     */
    public static void createBigWindow(Context context) {
        WindowManager windowManager = getWindowManager(context);
        int screenWidth = windowManager.getDefaultDisplay().getWidth();
        int screenHeight = windowManager.getDefaultDisplay().getHeight();
        if (bigWindow == null) {
            bigWindow = new FloatWindowBigView(context);
            if (bigWindowParams == null) {
                bigWindowParams = new LayoutParams();
                bigWindowParams.x = screenWidth / 2
                        - FloatWindowBigView.viewWidth / 2;
                bigWindowParams.y = screenHeight / 2
                        - FloatWindowBigView.viewHeight / 2;
                bigWindowParams.type = LayoutParams.TYPE_PHONE;
                bigWindowParams.format = PixelFormat.RGBA_8888;
                bigWindowParams.gravity = Gravity.LEFT | Gravity.TOP;
                bigWindowParams.width = FloatWindowBigView.viewWidth;
                bigWindowParams.height = FloatWindowBigView.viewHeight;
            }
            windowManager.addView(bigWindow, bigWindowParams);
        }
    }

    /**
     * 将大悬浮窗从屏幕上移除。
     */
    public static void removeBigWindow(Context context) {
        if (bigWindow != null) {
            WindowManager windowManager = getWindowManager(context);
            windowManager.removeView(bigWindow);
            bigWindow = null;
        }
    }

    /**
     * 创建一个火箭发射台，位置为屏幕底部。
     */
    public static void createLauncher(Context context) {
        WindowManager windowManager = getWindowManager(context);
        int screenWidth = windowManager.getDefaultDisplay().getWidth();
        int screenHeight = windowManager.getDefaultDisplay().getHeight();
        if (rocketLauncher == null) {
            rocketLauncher = new RocketLauncher(context);
            if (launcherParams == null) {
                launcherParams = new LayoutParams();
                launcherParams.x = screenWidth / 2 - RocketLauncher.width / 2;
                launcherParams.y = screenHeight - RocketLauncher.height;
                launcherParams.type = LayoutParams.TYPE_PHONE;
                launcherParams.format = PixelFormat.RGBA_8888;
                launcherParams.gravity = Gravity.LEFT | Gravity.TOP;
                launcherParams.width = RocketLauncher.width;
                launcherParams.height = RocketLauncher.height;
            }
            windowManager.addView(rocketLauncher, launcherParams);
        }
    }

    /**
     * 将火箭发射台从屏幕上移除。
     */
    public static void removeLauncher(Context context) {
        if (rocketLauncher != null) {
            WindowManager windowManager = getWindowManager(context);
            windowManager.removeView(rocketLauncher);
            rocketLauncher = null;
        }
    }

    /**
     * 更新火箭发射台的显示状态。
     */
    public static void updateLauncher() {
        if (rocketLauncher != null) {
            rocketLauncher.updateLauncherStatus(isReadyToLaunch());
        }
    }

    /**
     * 更新小悬浮窗的TextView上的数据，显示内存使用的百分比。
     * 
     * @param context
     *            可传入应用程序上下文。
     */
    public static void updateUsedPercent(Context context) {
        if (smallWindow != null) {
            TextView percentView = (TextView) smallWindow
                    .findViewById(R.id.percent);
            percentView.setText(getUsedPercentValue(context));
        }
    }

    /**
     * 是否有悬浮窗(包括小悬浮窗和大悬浮窗)显示在屏幕上。
     * 
     * @return 有悬浮窗显示在桌面上返回true，没有的话返回false。
     */
    public static boolean isWindowShowing() {
        return smallWindow != null || bigWindow != null;
    }

    /**
     * 判断小火箭是否准备好发射了。
     * 
     * @return 当火箭被发到发射台上返回true，否则返回false。
     */
    public static boolean isReadyToLaunch() {
        if ((smallWindowParams.x > launcherParams.x && smallWindowParams.x
                + smallWindowParams.width < launcherParams.x
                + launcherParams.width)
                && (smallWindowParams.y + smallWindowParams.height > launcherParams.y)) {
            return true;
        }
        return false;
    }

    /**
     * 如果WindowManager还未创建，则创建一个新的WindowManager返回。否则返回当前已创建的WindowManager。
     * 
     * @param context
     *            必须为应用程序的Context.
     * @return WindowManager的实例，用于控制在屏幕上添加或移除悬浮窗。
     */
    private static WindowManager getWindowManager(Context context) {
        if (mWindowManager == null) {
            mWindowManager = (WindowManager) context
                    .getSystemService(Context.WINDOW_SERVICE);
        }
        return mWindowManager;
    }

    /**
     * 如果ActivityManager还未创建，则创建一个新的ActivityManager返回。否则返回当前已创建的ActivityManager。
     * 
     * @param context
     *            可传入应用程序上下文。
     * @return ActivityManager的实例，用于获取手机可用内存。
     */
    private static ActivityManager getActivityManager(Context context) {
        if (mActivityManager == null) {
            mActivityManager = (ActivityManager) context
                    .getSystemService(Context.ACTIVITY_SERVICE);
        }
        return mActivityManager;
    }

    /**
     * 计算已使用内存的百分比，并返回。
     * 
     * @param context
     *            可传入应用程序上下文。
     * @return 已使用内存的百分比，以字符串形式返回。
     */
    public static String getUsedPercentValue(Context context) {
        String dir = "/proc/meminfo";
        try {
            FileReader fr = new FileReader(dir);
            BufferedReader br = new BufferedReader(fr, 2048);
            String memoryLine = br.readLine();
            String subMemoryLine = memoryLine.substring(memoryLine
                    .indexOf("MemTotal:"));
            br.close();
            long totalMemorySize = Integer.parseInt(subMemoryLine.replaceAll(
                    "\\D+", ""));
            long availableSize = getAvailableMemory(context) / 1024;
            int percent = (int) ((totalMemorySize - availableSize)
                    / (float) totalMemorySize * 100);
            return percent + "%";
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "悬浮窗";
    }

    /**
     * 获取当前可用内存，返回数据以字节为单位。
     * 
     * @param context
     *            可传入应用程序上下文。
     * @return 当前可用内存。
     */
    private static long getAvailableMemory(Context context) {
        ActivityManager.MemoryInfo mi = new ActivityManager.MemoryInfo();
        getActivityManager(context).getMemoryInfo(mi);
        return mi.availMem;
    }

}