1. FloatWindowView类

package comi.example.liy.firstbasicproject.entityClass;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.LinearLayout;
import android.widget.TextView;

import comi.example.liy.firstbasicproject.R;

/**
 * Created by liy on 2018-10-12 13:09
 */
public class FloatWindowView extends LinearLayout {
    private WindowManager windowManager;
    private TextView textView1;
    private TextView textView2;

    public static int viewWidth;
    public static int viewHeight;

    private int inputStartX = 0;
    private int inputStartY = 0;
    private int viewStartX = 0;
    private int viewStartY = 0;
    private int inMovingX=0;
    private int inMovingY=0;
    private WindowManager.LayoutParams mParams;

    public FloatWindowView(Context context) {
        super(context);
        windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        LayoutInflater.from(context).inflate(R.layout.float_window,this);
        View view = findViewById(R.id.float_window_layout);
        textView1 = (TextView) view.findViewById(R.id.accumulative_consumption);
        textView2 = (TextView)view.findViewById(R.id.accumulative_quantity);
        viewHeight = view.getLayoutParams().height;
        viewWidth = view.getLayoutParams().width;
    }
    @Override
    public boolean  onTouchEvent(MotionEvent event){
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                inputStartX = (int)event.getRawX();
                inputStartY = (int)event.getRawY();
                viewStartX = mParams.x;
                viewStartY = mParams.y;
                break;
            case MotionEvent.ACTION_MOVE:
                inMovingX = (int)event.getRawX();
                inMovingY = (int)event.getRawY();
                updatePosition();
                break;
            default:
                break;
        }
        Log.v("X-Y",
                "inputStartX: "+inputStartX+"\n"
                        +"inputStartY: "+inputStartY+"\n"
                        +"viewStartX: "+viewStartX+"\n"
                        +"viewStartY: "+viewStartY+"\n"
                        +"inMovingX: "+inMovingX+"\n"
                        +"inMovingY: "+inMovingY+"\n");
        return super.onTouchEvent(event);
    }

    private void updatePosition(){
        mParams.x =viewStartX + inMovingX - inputStartX;
        mParams.y =viewStartY + inMovingY- inputStartY;
        windowManager.updateViewLayout(this,mParams);
    }

    public void setmParams( WindowManager.LayoutParams params){
        mParams = params;
    }

    public void setData(String data1,String data2){
        textView1.setText(data1);
        textView2.setText(data2);
    }
}

2. float_window.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="#99149FEB"
    android:padding="5dp"
    android:layout_gravity="center"
    android:id="@+id/float_window_layout">
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView
            android:id="@+id/textView6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="本月消费(元)："
            android:textStyle="bold"
            android:textColor="@color/white"
            android:textSize="@dimen/character_3"/>
        <TextView
            android:id="@+id/accumulative_consumption"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:textStyle="bold"
            android:textColor="@color/white"
            android:textSize="@dimen/character_3"
            android:text="" />
    </LinearLayout>
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView
            android:id="@+id/textView8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:textStyle="bold"
            android:textColor="@color/white"
            android:textSize="@dimen/character_3"
            android:text="累计笔数(笔)：" />
        <TextView
            android:id="@+id/accumulative_quantity"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="@dimen/character_3"
            android:layout_weight="1"
            android:textStyle="bold"
            android:textColor="@color/white"
            android:text="" />
    </LinearLayout>
</LinearLayout>

3. FloatWindowActivity类

package comi.example.liy.firstbasicproject.ui.activity;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.Gravity;
import android.view.WindowManager;

import comi.example.liy.firstbasicproject.R;
import comi.example.liy.firstbasicproject.entityClass.FloatWindowView;
import comi.example.liy.firstbasicproject.persist.Settings;

/**
 * Created by liy on 2018-10-12 13:15
 */
public class FloatWindowActivity extends Activity {
    private Settings settings;//设置
    private FloatWindowView floatWindowView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_float_window);
        settings = Settings.getInstance(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        creatFloatWindowView();
        showFloatWindowData("200","1000");
    }

    @Override
    protected void onStop() {
        getWindowManager().removeView(floatWindowView);
        floatWindowView = null;
        super.onStop();
    }

    //创建悬浮窗
    private void creatFloatWindowView(){
        WindowManager windowManager = getWindowManager();
        int screenHeight = windowManager.getDefaultDisplay().getHeight();
        int screenWidth = windowManager.getDefaultDisplay().getWidth();
        WindowManager.LayoutParams params = new WindowManager.LayoutParams();
        if(floatWindowView == null){
            floatWindowView = new FloatWindowView(this);
            params.type = WindowManager.LayoutParams.TYPE_APPLICATION;
            params.format = PixelFormat.RGBA_8888;
            params.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE|WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;
            params.gravity = Gravity.START| Gravity.TOP;
            params.width =FloatWindowView.viewWidth;
            params.height = FloatWindowView.viewHeight;
            params.x = screenWidth;
            params.y = screenHeight/2;
            floatWindowView.setmParams(params);
            windowManager.addView(floatWindowView,params);
        }
    }

    //显示悬浮窗数据
    public void showFloatWindowData(String data1,String data2){
        floatWindowView.setData(data1,data2);
    }

}

4. activity_float_window.xml

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

</LinearLayout>

5. 显示效果如下图所示，移动手指可上下左右滑动。

floatWindow.png