android懸浮窗–擷取記憶體

        首先，得先說明，這個例子並不是我寫的，是從eoeAndroid的一個文章上面看到的，下載了他的原始碼，然後分析一下，供學習共用。（另外，對於其代碼有所修改，以便於更好的說明問題，另：同時把原始碼上傳，：http://download.csdn.net/detail/aomandeshangxiao/3880055）

         一開始，我們先看一下運行效果：

其中，

這一塊就是懸浮窗，可以隨意拖動，動態顯示當前記憶體使用量量。

        下面看一下代碼是如何?的：

懸浮窗的實現是用了一個service，為什麼要用service呢？瞭解service特點的大體就會明白。下面看一下：

public class FloatService extends Service {WindowManager wm = null;WindowManager.LayoutParams wmParams = null;View view;private float mTouchStartX;private float mTouchStartY;private float x;private float y;int state;TextView tx1;TextView tx;ImageView iv;private float StartX;private float StartY;int delaytime=1000;@Overridepublic void onCreate() {Log.d("FloatService", "onCreate");super.onCreate();view = LayoutInflater.from(this).inflate(R.layout.floating, null);tx = (TextView) view.findViewById(R.id.memunused);tx1 = (TextView) view.findViewById(R.id.memtotal);tx.setText("" + memInfo.getmem_UNUSED(this) + "KB");tx1.setText("" + memInfo.getmem_TOLAL() + "KB");iv = (ImageView) view.findViewById(R.id.img2);iv.setVisibility(View.GONE);createView();handler.postDelayed(task, delaytime);}private void createView() {// 擷取WindowManagerwm = (WindowManager) getApplicationContext().getSystemService("window");// 設定LayoutParams(全域變數）相關參數wmParams = new WindowManager.LayoutParams();wmParams.type = 2002;wmParams.flags |= 8;wmParams.gravity = Gravity.LEFT | Gravity.TOP; // 調整懸浮視窗至左上方// 以螢幕左上方為原點，設定x、y初始值wmParams.x = 0;wmParams.y = 0;// 設定懸浮視窗長寬資料wmParams.width = WindowManager.LayoutParams.WRAP_CONTENT;wmParams.height = WindowManager.LayoutParams.WRAP_CONTENT;wmParams.format = 1;wm.addView(view, wmParams);view.setOnTouchListener(new OnTouchListener() {public boolean onTouch(View v, MotionEvent event) {// 擷取相對螢幕的座標，即以螢幕左上方為原點x = event.getRawX();y = event.getRawY() - 25; // 25是系統狀態列的高度Log.i("currP", "currX" + x + "====currY" + y);// 調試資訊switch (event.getAction()) {case MotionEvent.ACTION_DOWN:state = MotionEvent.ACTION_DOWN;StartX = x;StartY = y;// 擷取相對View的座標，即以此View左上方為原點mTouchStartX = event.getX();mTouchStartY = event.getY();Log.i("startP", "startX" + mTouchStartX + "====startY"+ mTouchStartY);// 調試資訊break;case MotionEvent.ACTION_MOVE:state = MotionEvent.ACTION_MOVE;updateViewPosition();break;case MotionEvent.ACTION_UP:state = MotionEvent.ACTION_UP;updateViewPosition();showImg();mTouchStartX = mTouchStartY = 0;break;}return true;}});iv.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent serviceStop = new Intent();serviceStop.setClass(FloatService.this, FloatService.class);stopService(serviceStop);}});}public void showImg() {if (Math.abs(x - StartX) < 1.5 && Math.abs(y - StartY) < 1.5&& !iv.isShown()) {iv.setVisibility(View.VISIBLE);} else if (iv.isShown()) {iv.setVisibility(View.GONE);}}private Handler handler = new Handler();private Runnable task = new Runnable() {public void run() {// TODO Auto-generated method stubdataRefresh();handler.postDelayed(this, delaytime);wm.updateViewLayout(view, wmParams);}};public void dataRefresh() {tx.setText("" + memInfo.getmem_UNUSED(this) + "KB");tx1.setText("" + memInfo.getmem_TOLAL() + "KB");}private void updateViewPosition() {// 更新浮動視窗位置參數wmParams.x = (int) (x - mTouchStartX);wmParams.y = (int) (y - mTouchStartY);wm.updateViewLayout(view, wmParams);}@Overridepublic void onStart(Intent intent, int startId) {Log.d("FloatService", "onStart");setForeground(true);super.onStart(intent, startId);}@Overridepublic void onDestroy() {handler.removeCallbacks(task);Log.d("FloatService", "onDestroy");wm.removeView(view);super.onDestroy();}@Overridepublic IBinder onBind(Intent intent) {return null;}}

其主要功能部分在creatView方法裡：

private void createView() {// 擷取WindowManagerwm = (WindowManager) getApplicationContext().getSystemService("window");// 設定LayoutParams(全域變數）相關參數wmParams = new WindowManager.LayoutParams();wmParams.type = 2002;wmParams.flags |= 8;wmParams.gravity = Gravity.LEFT | Gravity.TOP; // 調整懸浮視窗至左上方// 以螢幕左上方為原點，設定x、y初始值wmParams.x = 0;wmParams.y = 0;// 設定懸浮視窗長寬資料wmParams.width = WindowManager.LayoutParams.WRAP_CONTENT;wmParams.height = WindowManager.LayoutParams.WRAP_CONTENT;wmParams.format = 1;wm.addView(view, wmParams);view.setOnTouchListener(new OnTouchListener() {public boolean onTouch(View v, MotionEvent event) {// 擷取相對螢幕的座標，即以螢幕左上方為原點x = event.getRawX();y = event.getRawY() - 25; // 25是系統狀態列的高度Log.i("currP", "currX" + x + "====currY" + y);// 調試資訊switch (event.getAction()) {case MotionEvent.ACTION_DOWN:state = MotionEvent.ACTION_DOWN;StartX = x;StartY = y;// 擷取相對View的座標，即以此View左上方為原點mTouchStartX = event.getX();mTouchStartY = event.getY();Log.i("startP", "startX" + mTouchStartX + "====startY"+ mTouchStartY);// 調試資訊break;case MotionEvent.ACTION_MOVE:state = MotionEvent.ACTION_MOVE;updateViewPosition();break;case MotionEvent.ACTION_UP:state = MotionEvent.ACTION_UP;updateViewPosition();showImg();mTouchStartX = mTouchStartY = 0;break;}return true;}});iv.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent serviceStop = new Intent();serviceStop.setClass(FloatService.this, FloatService.class);stopService(serviceStop);}});}

首先，代碼裡面用到了 WindowManager借口，整個Android的視窗機制是基於一個叫做 WindowManager，這個介面可以添加view到螢幕，也可以從螢幕刪除view。它面向的對象一端是螢幕，另一端就是View，直接忽略我們以前的Activity或者Dialog之類的東東。其實我們的Activity或者Diolog底層的實現也是通過WindowManager，這個 WindowManager是全域的，整個系統就是這個唯一的東東。它是顯示View的最底層了。（該段文字來自網路）其方法很簡單，基本用到的就三個addView，removeView，updateViewLayout。另：在設定View高度和寬度的時候一個錯誤，即在View的建構函式中擷取getWidth()和getHeight()，當一個view對象建立時，android並不知道其大小，所以getWidth()和getHeight()返回的結果是0，真正大小是在計算布局時才會計算，所以會發現一個有趣的事，即在onDraw( ) 卻能取得長寬的原因。使用一下方法即可：

width = activity.getWindowManager().getDefaultDisplay().getWidth();   height = activity.getWindowManager().getDefaultDisplay().getHeight(); 

下面是LayoutParams，設定他的屬性：詳情請看上一篇文章：

http://blog.csdn.net/aomandeshangxiao/article/details/7040486

在這裡是設定成了所有應用程式之上，狀態列之下的形式，當移動的時候，會調用case MotionEvent.ACTION_MOVE:

下面的代碼主要是：

private void updateViewPosition() {// 更新浮動視窗位置參數wmParams.x = (int) (x - mTouchStartX);wmParams.y = (int) (y - mTouchStartY);wm.updateViewLayout(view, wmParams);}

從新設定浮動欄的位置參數。這樣就實現了拖動的功能。其記憶體資料是如何擷取及及時更新的呢？

我們注意到了handler：

handler.postDelayed(task, delaytime);                                                                                                                                                                                                                                   private Runnable task = new Runnable() {public void run() {// TODO Auto-generated method stubdataRefresh();handler.postDelayed(this, delaytime);wm.updateViewLayout(view, wmParams);}};             

我們找到dataRefresh方法，delaytime是設定的1000，也就是每一秒鐘更新一次資料。

public void dataRefresh() {tx.setText("" + memInfo.getmem_UNUSED(this) + "KB");tx1.setText("" + memInfo.getmem_TOLAL() + "KB");}

最後，看下memInfo的定義：

public class memInfo {public static long getmem_UNUSED(Context mContext) {long MEM_UNUSED;ActivityManager am = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);ActivityManager.MemoryInfo mi = new ActivityManager.MemoryInfo();am.getMemoryInfo(mi);MEM_UNUSED = mi.availMem / 1024;return MEM_UNUSED;}public static long getmem_TOLAL() {long mTotal;// 系統記憶體String path = "/proc/meminfo";// 儲存空間內容String content = null;BufferedReader br = null;try {br = new BufferedReader(new FileReader(path), 8);String line;if ((line = br.readLine()) != null) {// 採集記憶體資訊content = line;}} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {if (br != null) {try {br.close();} catch (IOException e) {e.printStackTrace();}}}// beginIndexint begin = content.indexOf(':');// endIndexint end = content.indexOf('k');// 採集數量的記憶體content = content.substring(begin + 1, end).trim();// 轉換為Int型mTotal = Integer.parseInt(content);return mTotal;}}

裡面只定義了兩個方法，擷取總記憶體和使用記憶體。