Android实现全局悬浮框

<uses-permission android:name="android.permission.system_alert_window" />

public class floatwindow implements view.ontouchlistener {

 private context mcontext;
 private windowmanager.layoutparams mwindowparams;
 private windowmanager mwindowmanager;

 private view mfloatlayout;
 private float minviewx;
 private float minviewy;
 private float mdowninscreenx;
 private float mdowninscreeny;
 private float minscreenx;
 private float minscreeny;
 private textview infotext;

 public floatwindow(context context) {
  this.mcontext = context;
  initfloatwindow();
 }

 private void initfloatwindow() {
  layoutinflater inflater = layoutinflater.from(mcontext);
  if(inflater == null)
   return;
  mfloatlayout = (view) inflater.inflate(r.layout.layout_float, null);
  infotext = mfloatlayout.findviewbyid(r.id.textview);
  mfloatlayout.setontouchlistener(this);

  mwindowparams = new windowmanager.layoutparams();
  mwindowmanager = (windowmanager) mcontext.getsystemservice(context.window_service);
  if (build.version.sdk_int >= 26) {//8.0新特性
   mwindowparams.type = windowmanager.layoutparams.type_application_overlay;
  }else{
   mwindowparams.type = windowmanager.layoutparams.type_system_alert;
  }
  mwindowparams.format = pixelformat.rgba_8888;
  mwindowparams.flags = windowmanager.layoutparams.flag_not_focusable;
  mwindowparams.gravity = gravity.start | gravity.top;
  mwindowparams.width = windowmanager.layoutparams.wrap_content;
  mwindowparams.height = windowmanager.layoutparams.wrap_content;
 }

 @override
 public boolean ontouch(view view, motionevent motionevent) {
  return floatlayouttouch(motionevent);
 }

 private boolean floatlayouttouch(motionevent motionevent) {
  switch (motionevent.getaction()) {
   case motionevent.action_down:
    // 获取相对view的坐标，即以此view左上角为原点
    minviewx = motionevent.getx();
    minviewy = motionevent.gety();
    // 获取相对屏幕的坐标，即以屏幕左上角为原点
    mdowninscreenx = motionevent.getrawx();
    mdowninscreeny = motionevent.getrawy() - getsysbarheight(mcontext);
    minscreenx = motionevent.getrawx();
    minscreeny = motionevent.getrawy() - getsysbarheight(mcontext);
    break;
   case motionevent.action_move:
    // 更新浮动窗口位置参数
    minscreenx = motionevent.getrawx();
    minscreeny = motionevent.getrawy() - getsysbarheight(mcontext);
    mwindowparams.x = (int) (minscreenx- minviewx);
    mwindowparams.y = (int) (minscreeny - minviewy);
    // 手指移动的时候更新小悬浮窗的位置
    mwindowmanager.updateviewlayout(mfloatlayout, mwindowparams);
    break;
   case motionevent.action_up:
    // 如果手指离开屏幕时，xdowninscreen和xinscreen相等，且ydowninscreen和yinscreen相等，则视为触发了单击事件。
    if (mdowninscreenx == minscreenx && mdowninscreeny == minscreeny){

    }
    break;
  }
  return true;
 }

 public void showfloatwindow(){
  if (mfloatlayout.getparent() == null){
   displaymetrics metrics = new displaymetrics();
   // 默认固定位置，靠屏幕右边缘的中间
   mwindowmanager.getdefaultdisplay().getmetrics(metrics);
   mwindowparams.x = metrics.widthpixels;
   mwindowparams.y = metrics.heightpixels/2 - getsysbarheight(mcontext);
   mwindowmanager.addview(mfloatlayout, mwindowparams);
  }
 }

 public void updatetext(final string s) {
  infotext.settext(s);
 }

 public void hidefloatwindow(){
  if (mfloatlayout.getparent() != null)
   mwindowmanager.removeview(mfloatlayout);
 }

 public void setfloatlayoutalpha(boolean alpha){
  if (alpha)
   mfloatlayout.setalpha((float) 0.5);
  else
   mfloatlayout.setalpha(1);
 }

 // 获取系统状态栏高度
 public static int getsysbarheight(context contex) {
  class<?> c;
  object obj;
  field field;
  int x;
  int sbar = 0;
  try {
   c = class.forname("com.android.internal.r$dimen");
   obj = c.newinstance();
   field = c.getfield("status_bar_height");
   x = integer.parseint(field.get(obj).tostring());
   sbar = contex.getresources().getdimensionpixelsize(x);
  } catch (exception e1) {
   e1.printstacktrace();
  }
  return sbar;
 }
}

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.constraintlayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 xmlns:app="http://schemas.android.com/apk/res-auto">

 <imageview
  android:id="@+id/imageview"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:src="@mipmap/float_win"
  app:layout_constraintstart_tostartof="parent"
  app:layout_constrainttop_totopof="parent"/>

 <textview
  android:id="@+id/textview"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:background="#00ffffff"
  android:text="hello"
  android:textsize="12sp"
  app:layout_constraintleft_toleftof="@id/imageview"
  app:layout_constraintright_torightof="@id/imageview"
  app:layout_constrainttop_tobottomof="@id/imageview"/>

</android.support.constraint.constraintlayout>

public class mainactivity extends appcompatactivity {

 private button btnshow;
 floatwindow floatwindow;

 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);

  // 权限判断
  if (build.version.sdk_int >= 23) {
   if(!settings.candrawoverlays(getapplicationcontext())) {
    // 启动activity让用户授权
    intent intent = new intent(settings.action_manage_overlay_permission,uri.parse("package:" + getpackagename()));
    startactivityforresult(intent,10);
   } else {
    // 执行6.0以上绘制代码
    initview();
   }
  } else {
   // 执行6.0以下绘制代码
   initview();
  }
 }

 @override
 protected void onresume() {
  super.onresume();
  // 权限判断
  if (build.version.sdk_int >= 23) {
   if(settings.candrawoverlays(getapplicationcontext())) {
    initview();
   }
  } else {
   //执行6.0以下绘制代码
   initview();
  }
 }

 private void initview() {
  setcontentview(r.layout.activity_main);
  floatwindow = new floatwindow(getapplicationcontext());

  btnshow = findviewbyid(r.id.btn_show);
  btnshow.setonclicklistener(new view.onclicklistener() {
   @override
   public void onclick(view view) {
    if (null != floatwindow) {
     floatwindow.showfloatwindow();
    }
   }
  });

  button btnrefresh = findviewbyid(r.id.btn_refresh);
  btnrefresh.setonclicklistener(new view.onclicklistener() {
   @override
   public void onclick(view view) {
    int random = (int) (math.random() * 10);
    if (null != floatwindow) {
     floatwindow.updatetext(string.valueof(random));
    }
   }
  });
 }

 @override
 protected void ondestroy() {
  super.ondestroy();
  if (null != floatwindow) {
   floatwindow.hidefloatwindow();
  }
 }
}