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原文地址：http://www.android100.org/html/201306/20/3224.html
运行效果：
其中，
这一块就是悬浮窗，可以随意拖动，动态显示当前内存使用量。
下面看一下代码是如何实现的：
悬浮窗的实现是用了一个service，为什么要用service呢？了解service特点的大体就会明白。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; @Override public 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() { // 获取WindowManager wm = (WindowManager) getApplicationContext().getSystemService("window"); // 设置LayoutParams(全局变量）相关参数 wmParams = new WindowManager.LayoutParams(); wmParams.type = 2002; wmParams.flags |= 8; wmParams.gravity = Gravity.LEFT | Gravity.TOP; // 调整悬浮窗口至左上角 // 以屏幕左上角为原点，设置x、y初始值 wmParams.x = 0; wmParams.y = 0; // 设置悬浮窗口长宽数据 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) { // 获取相对屏幕的坐标，即以屏幕左上角为原点 x = event.getRawX(); y = event.getRawY() - 25; // 25是系统状态栏的高度 Log.i("currP", "currX" + x + "====currY" + y);// 调试信息 switch (event.getAction()) { case MotionEvent.ACTION_DOWN: state = MotionEvent.ACTION_DOWN; StartX = x; StartY = y; // 获取相对View的坐标，即以此View左上角为原点 mTouchStartX = event.getX(); mTouchStartY = event.getY(); Log.i("startP", "startX" + mTouchStartX + "====startY" + mTouchStartY);// 调试信息 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() { @Override public void onClick(View v) { // TODO Auto-generated method stub Intent 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 stub dataRefresh(); 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() { // 更新浮动窗口位置参数 wmParams.x = (int) (x - mTouchStartX); wmParams.y = (int) (y - mTouchStartY); wm.updateViewLayout(view, wmParams); } @Override public void onStart(Intent intent, int startId) { Log.d("FloatService", "onStart"); setForeground(true); super.onStart(intent, startId); } @Override public void onDestroy() { handler.removeCallbacks(task); Log.d("FloatService", "onDestroy"); wm.removeView(view); super.onDestroy(); } @Override public IBinder onBind(Intent intent) { return null; } }
其主要功能部分在creatView方法里：
private void createView() { // 获取WindowManager wm = (WindowManager) getApplicationContext().getSystemService("window"); // 设置LayoutParams(全局变量）相关参数 wmParams = new WindowManager.LayoutParams(); wmParams.type = 2002; wmParams.flags |= 8; wmParams.gravity = Gravity.LEFT | Gravity.TOP; // 调整悬浮窗口至左上角 // 以屏幕左上角为原点，设置x、y初始值 wmParams.x = 0; wmParams.y = 0; // 设置悬浮窗口长宽数据 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) { // 获取相对屏幕的坐标，即以屏幕左上角为原点 x = event.getRawX(); y = event.getRawY() - 25; // 25是系统状态栏的高度 Log.i("currP", "currX" + x + "====currY" + y);// 调试信息 switch (event.getAction()) { case MotionEvent.ACTION_DOWN: state = MotionEvent.ACTION_DOWN; StartX = x; StartY = y; // 获取相对View的坐标，即以此View左上角为原点 mTouchStartX = event.getX(); mTouchStartY = event.getY(); Log.i("startP", "startX" + mTouchStartX + "====startY" + mTouchStartY);// 调试信息 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() { @Override public void onClick(View v) { // TODO Auto-generated method stub Intent serviceStop = new Intent(); serviceStop.setClass(FloatService.this, FloatService.class); stopService(serviceStop); } }); }
首先，代码里面用到了 WindowManager借口，整 个Android的窗口机制是基于一个叫做 WindowManager，这个接口可以添加view到屏幕，也可以从屏幕删除view。它面向的对象一端是屏幕，另一端就是View，直接忽略我们以 前的Activity或者Dialog之类的东东。其实我们的Activity或者Diolog底层的实现也是通过WindowManager，这个 WindowManager是全局的，整个系统就是这个唯一的东东。它是显示View的最底层了。（该段文字来自网络）其方法很简单，基本用到的就三个addView，removeView，updateViewLayout。另：在设置View高度和宽度的时候一 个错误，即在View的构造函数中获取getWidth()和getHeight()，当一个view对象创建时，android并不知道其大小，所以 getWidth()和getHeight()返回的结果是0，真正大小是在计算布局时才会计算，所以会发现一个有趣的事，即在onDraw( ) 却能取得长宽的原因。使用一下方法即可：
width = activity.getWindowManager().getDefaultDisplay().getWidth();
height = activity.getWindowManager().getDefaultDisplay().getHeight();
下面是LayoutParams，设置他的属性：
在这里是设置成了所有应用程序之上，状态栏之下的形式，当移动的时候，会调用case MotionEvent.ACTION_MOVE:
下面的代码主要是：
private void updateViewPosition() { // 更新浮动窗口位置参数 wmParams.x = (int) (x - mTouchStartX); wmParams.y = (int) (y - mTouchStartY); wm.updateViewLayout(view, wmParams); }
从新设置浮动栏的位置参数。这样就实现了拖动的功能。其内存数据是如何获取及及时更新的呢？
我们注意到了handler：
handler.postDelayed(task, delaytime); private Runnable task = new Runnable() { public void run() { // TODO Auto-generated method stub dataRefresh(); handler.postDelayed(this, delaytime); wm.updateViewLayout(view, wmParams); } };
我们找到dataRefresh方法，delaytime是设置的1000，也就是每一秒钟更新一次数据。
public void dataRefresh() { tx.setText("" + memInfo.getmem_UNUSED(this) + "KB"); tx1.setText("" + memInfo.getmem_TOLAL() + "KB"); }
最后，看下memInfo的定义：
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; // 系统内存 String path = "/proc/meminfo"; // 存储器内容 String content = null; BufferedReader br = null; try { br = new BufferedReader(new FileReader(path), 8); String line; if ((line = br.readLine()) != null) { // 采集内存信息 content = line; } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (br != null) { try { br.close(); } catch (IOException e) { e.printStackTrace(); } } } // beginIndex int begin = content.indexOf(‘:‘); // endIndex int end = content.indexOf(‘k‘); // 采集数量的内存 content = content.substring(begin + 1, end).trim(); // 转换为Int型 mTotal = Integer.parseInt(content); return mTotal; } }
里面只定义了两个方法，获取总内存和使用内存。
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原文地址：http://www.cnblogs.com/LoveJulin/p/4267460.html
