关于壁纸

获取 WallpaperManager 的实例使用其静态类getInstance(context);

WallpaperManager中的重要方法：

/**
     * Retrieve the current system wallpaper; if
     * no wallpaper is set, the system default wallpaper is returned.
     * This is returned as an
     * abstract Drawable that you can install in a View to display whatever
     * wallpaper the user has currently set. 
     *
     * @return Returns a Drawable object that will draw the wallpaper.
     */
    public Drawable getDrawable() ;

设置壁纸可用以下方法：
public void setResource(int resid);
public void setBitmap(Bitmap bitmap);
public void setStream(InputStream data);
恢复系统默认的壁纸用：
public void clear();