示例：

悬浮框的xml代码：（layout_float.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"
    android:background="@mipmap/ic_float_btn">


</LinearLayout>

悬浮框的java代码： 

package com.chy.searchbar;

import android.app.Activity;
import android.content.Context;
import android.graphics.PixelFormat;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.RelativeLayout;

import com.chy.marketconditions.R;

/**
 * 悬浮框(只能靠左或靠右)
 * */
public class AsideFloatButton extends RelativeLayout {
    // 悬浮栏位置
    private final static int LEFT = 0;
    private final static int RIGHT = 1;
    private final static int TOP = 3;
    private final static int BUTTOM = 4;

    private int dpi;
    private int screenHeight;
    private int screenWidth;
    private WindowManager.LayoutParams wmParams;
    private WindowManager wm;
    private float x, y;
    private float mTouchStartX;
    private float mTouchStartY;
    private int lastX;
    private int lastY;
    private boolean isScroll;
    private boolean isDrag;// 判断是否能够点击


    /**
     * 创建按钮
     * */
    public AsideFloatButton(Activity activity) {
        super(activity);
        init(activity);
    }

    private void init(Activity activity){
        if (wm == null){
            wm = (WindowManager) activity.getSystemService(Context.WINDOW_SERVICE);
            LayoutInflater.from(activity).inflate(R.layout.layout_float, this);
            //setBackgroundResource(R.mipmap.ic_search);// 设置背景图标(也可以在xml中设置)
            DisplayMetrics dm = new DisplayMetrics();
            activity.getWindowManager().getDefaultDisplay().getMetrics(dm);
            //通过像素密度来设置按钮的大小
            dpi = dpi(dm.densityDpi);
            //屏宽
            screenWidth = wm.getDefaultDisplay().getWidth();
            //屏高
            screenHeight = wm.getDefaultDisplay().getHeight();
            //布局设置
            wmParams = new WindowManager.LayoutParams();
            // 设置window type
            wmParams.type = WindowManager.LayoutParams.TYPE_APPLICATION;
            wmParams.format = PixelFormat.RGBA_8888; // 设置图片格式，效果为背景透明
            wmParams.gravity = Gravity.LEFT | Gravity.TOP;
            // 设置Window flag
            wmParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
            wmParams.width = dpi;
            wmParams.height = dpi;
            // 初始位置
            wmParams.x = (screenWidth - dpi);
            wmParams.y = (screenHeight - dpi*6);
            wm.addView(this, wmParams);
            hide();
        }
    }

    /**
     * 根据密度选择控件大小
     *
     */
    private int dpi(int densityDpi) {
        if (densityDpi <= 120) {
            return 36;
        } else if (densityDpi <= 160) {
            return 48;
        } else if (densityDpi <= 240) {
            return 72;
        } else if (densityDpi <= 320) {
            return 96;
        }
        return 108;
    }

    public void show() {
        if (isShown()) {
            return;
        }
        setVisibility(View.VISIBLE);
    }


    public void hide() {
        setVisibility(View.GONE);
    }

    public void destory() {
        hide();
        wm.removeViewImmediate(this);
    }



    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // 获取相对屏幕的坐标， 以屏幕左上角为原点
        x = event.getRawX();
        y = event.getRawY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                setPressed(true);//默认是点击事件
                isDrag=false;//默认是非拖动而是点击事件
                getParent().requestDisallowInterceptTouchEvent(true);//父布局不要拦截子布局的监听
                lastX= (int) x;
                lastY= (int) 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();
                break;
            case MotionEvent.ACTION_MOVE:
                if (isScroll) {
                    int dx= (int) (x-lastX);
                    int dy= (int) (y-lastY);
                    //这里修复一些华为手机无法触发点击事件
                    int distance= (int) Math.sqrt(dx*dx+dy*dy);
                    isDrag = distance>0;//只有位移大于0说明拖动了
                    if(!isDrag) break;

                    // 更新悬浮按钮坐标位置
                    updateViewPosition();
                } else {
                    // 当前不处于连续滑动状态 则滑动小于图标1/3则不滑动
                    if (Math.abs(mTouchStartX - event.getX()) > dpi / 3
                            || Math.abs(mTouchStartY - event.getY()) > dpi / 3) {
                        updateViewPosition();
                    } else {
                        break;
                    }
                }
                isScroll = true;
                break;
            case MotionEvent.ACTION_UP:
                // 拖动
                if (isScroll) {
                    //如果是拖动状态下即非点击按压事件
                    setPressed(!isDrag);
                    // 悬浮框移动到左边或者右边(注释掉改方法即可拖拽到任意位置)
                    autoView();
                } else {
                    // 当前显示功能区，则隐藏
                    // setBackgroundDrawable(openDrawable);
                    // invalidate();
                }
                isScroll = false;
                mTouchStartX = mTouchStartY = 0;
                break;
        }
        //如果不是拖拽，那么就不消费这个事件，以免影响点击事件的处理
        //拖拽事件要自己消费
        return isDrag || super.onTouchEvent(event);
    }



    /**
     * 自动移动位置
     */
    private void autoView() {
        // 得到view在屏幕中的位置
        int[] location = new int[2];
        getLocationOnScreen(location);
        //左侧
        if (location[0] < screenWidth / 2 - getWidth() / 2) {
            updateViewPosition(LEFT);
        } else {
            updateViewPosition(RIGHT);
        }
    }

    /**
     * 手指释放更新悬浮窗位置
     *
     */
    private void updateViewPosition(int l) {
        switch (l) {
            case LEFT:
                wmParams.x = 0;
                break;
            case RIGHT:
                int x = screenWidth - dpi;
                wmParams.x = x;
                break;
            case TOP:
                wmParams.y = 0;
                break;
            case BUTTOM:
                wmParams.y = screenHeight - dpi;
                break;
        }
        wm.updateViewLayout(this, wmParams);
    }

    // 更新浮动窗口位置参数
    private void updateViewPosition() {
        wmParams.x = (int) (x - mTouchStartX);
        //是否存在状态栏（提升滑动效果）
        // 不设置为全屏（状态栏存在） 标题栏是屏幕的1/25
        wmParams.y = (int) (y - mTouchStartY - screenHeight / 25);
        wm.updateViewLayout(this, wmParams);
    }

}

使用方法： 

// 悬浮按钮
floatButton = new AsideFloatButton(this);
floatButton.show();
// 绑定悬浮按钮点击事件
floatButton.setOnClickListener(floatClick);

...
...
...
/**
 * 悬浮按钮点击事件
 * */
 View.OnClickListener floatClick = new View.OnClickListener() {
    @Override
    public void onClick(View v) {
            if (floatButton != null){
                floatButton.hide();// 隐藏
            }
           
    }
 };

...
...
...
 @Override
    protected void onPause() {
        super.onPause();
        floatButton.show();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        floatButton.destory();
    }