悬浮窗是在系统上显示的内容，好像微信视频聊天时的小窗口一样，在退出软件后依然存在的一个窗口，本博客以窗口中放一个button组件为例，简单展示悬浮窗，其中包括了对Android 6.0以下、Android 6.0到Android 8.0、Android 8.0以上版本的处理，下面开始介绍实现方法：

1、MainActivity中的代码

public Button mFloatingButton;  @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);   //初始化view  initView(); } //初始化view private void initView() {  mFloatingButton=(Button) findViewById(R.id.floating_btn);  mFloatingButton.setOnClickListener(this); }  public void startFloatingButtonService(View view) {  Log.e("测试流程", "测试流程");  if (FloatingService_Button.isStarted) {   Log.e("测试流程2", "测试流程2");   return;  }  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {//判断系统版本   if (!Settings.canDrawOverlays(this)) {    Toast.makeText(this, "当前无权限，请授权", Toast.LENGTH_SHORT);    Log.e("测试流程3", "测试流程3");    startActivityForResult(new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:" + getPackageName())), 0);   } else {    Log.e("测试流程4", "测试流程4");    startService(new Intent(MainActivity.this, FloatingService_Button.class));   }  } else {   startService(new Intent(MainActivity.this, FloatingService_Button.class));  }  }  @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {  if (requestCode == 0) {   if (!Settings.canDrawOverlays(this)) {    Log.e("测试流程5", "测试流程5");    Toast.makeText(this, "授权失败", Toast.LENGTH_SHORT).show();   } else {    Log.e("测试流程6", "测试流程6");    Toast.makeText(this, "授权成功", Toast.LENGTH_SHORT).show();    startService(new Intent(MainActivity.this, FloatingService_Button.class));   }  } }  @Override public void onClick(View v) {  switch (v.getId()){   case R.id.floating_btn :    startFloatingButtonService(v);    break;  } }

思路简单解释：点击弹出悬浮窗按钮时，获取版本并判断“Build.VERSION.SDK_INT >= Build.VERSION_CODES.M”如果系统版本在6.0以下这不需要请求权限，如果系统版本在6.0以上需要进行权限检测以及请求，获取权限后，弹出悬浮框

2、activity_main.xml代码

   

简单解释：xml中没什么特别东西，线性布局中放一个按钮

3、FloatingService_Button的代码

public static boolean isStarted = false;  private WindowManager windowManager; private WindowManager.LayoutParams layoutParams;  private Button button;  @Override public void onCreate() {  super.onCreate();  Log.e("进入服务1", "进入服务1");  isStarted = true;  windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);  layoutParams = new WindowManager.LayoutParams();  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {   layoutParams.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;  } else {   layoutParams.type = WindowManager.LayoutParams.TYPE_PHONE;  }  layoutParams.format = PixelFormat.RGBA_8888;  layoutParams.gravity = Gravity.LEFT | Gravity.TOP;  layoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;  layoutParams.width = 500;  layoutParams.height = 100;  layoutParams.x = 300;  layoutParams.y = 300; }  @Nullable @Override public IBinder onBind(Intent intent) {  Log.e("进入服务2", "进入服务2");   return null; }  @Override public int onStartCommand(Intent intent, int flags, int startId) {  Log.e("进入服务3", "进入服务3");  showFloatingWindow();  return super.onStartCommand(intent, flags, startId); }  private void showFloatingWindow() {  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {//判断系统版本   if (Settings.canDrawOverlays(this)) {    button = new Button(getApplicationContext());    button.setText("我是个button窗口");    button.setBackgroundColor(Color.BLUE);    windowManager.addView(button, layoutParams);     button.setOnTouchListener(new FloatingOnTouchListener());   }  } else {   button = new Button(getApplicationContext());   button.setText("我是个button窗口");   button.setBackgroundColor(Color.BLUE);   windowManager.addView(button, layoutParams);    button.setOnTouchListener(new FloatingOnTouchListener());  } }  private class FloatingOnTouchListener implements View.OnTouchListener {  private int x;  private int y;   @Override  public boolean onTouch(View view, MotionEvent event) {   switch (event.getAction()) {    case MotionEvent.ACTION_DOWN:     x = (int) event.getRawX();     y = (int) event.getRawY();     break;    case MotionEvent.ACTION_MOVE:     int nowX = (int) event.getRawX();     int nowY = (int) event.getRawY();     int movedX = nowX - x;     int movedY = nowY - y;     x = nowX;     y = nowY;     layoutParams.x = layoutParams.x + movedX;     layoutParams.y = layoutParams.y + movedY;     windowManager.updateViewLayout(view, layoutParams);     break;    default:     break;   }   return false;  } }

思路简单解释：首先获取WindowManager服务，然后定义并设置在window上显示的layoutParams（此处需注意Android 8.0以上版本中LayoutParam里的type变量变为TYPE_APPLICATION_OVERLAY与Android 8.0以下版本LayoutParam里的type变量TYPE_PHONE不一样，需要通过判断系统版本进行区分），然后定义并设置在layoutParams上面显示的Button按钮以及监听事件（此处的监听事件主要是悬浮窗口拖动的监听）最后将设置好的button与layoutParams添加入window中

4、AndroidManifest.xml中权限添加