Android手機內的全域性懸浮框，可拖動。而且不需要系統許可權！下面的是主要程式碼：

package cn.net.owen.floatview;

import android.app.Service;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.IBinder;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import
 
 android.view.View;
import android.view.WindowManager;
import android.widget.FrameLayout;

/**
 *
 */
public class FloatViewService extends Service implements View.OnTouchListener{

    private String TAG = "FloatViewService";

    private float mTouchStartX;
    private float mTouchStartY;
    private
 
 float x;
    private float y;
    //定義浮動窗口布局
    FrameLayout mFloatLayout;
    WindowManager.LayoutParams wmParams;
    //建立浮動視窗設定佈局引數的物件
    WindowManager mWindowManager;

    public FloatViewService() {
    }

    @Override
    public IBinder onBind(Intent intent) {
        throw new UnsupportedOperationException("Not yet implemented"
 
);
    }

    @Override
    public void onCreate() {
        super.onCreate();
        createFloatView();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mFloatLayout != null) {
            mWindowManager.removeView(mFloatLayout);
        }
    }

    private void createFloatView() {
        wmParams = new WindowManager.LayoutParams();
        mWindowManager = (WindowManager) getApplication().getSystemService(getApplication().WINDOW_SERVICE);
        wmParams.type = WindowManager.LayoutParams.TYPE_TOAST;
        //設定圖片格式，效果為背景透明
        wmParams.format = PixelFormat.RGBA_8888;
        //設定浮動視窗不可聚焦（實現操作除浮動視窗外的其他可見視窗的操作）
        wmParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
        wmParams.format = PixelFormat.TRANSLUCENT;

        //調整懸浮窗顯示的停靠位置為左側置頂
        wmParams.gravity = Gravity.LEFT | Gravity.TOP;

        // 以螢幕左上角為原點，設定x、y初始值
        wmParams.x = 500;
        wmParams.y =800;

        //設定懸浮視窗長寬資料
        wmParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
        wmParams.height = WindowManager.LayoutParams.WRAP_CONTENT;

        LayoutInflater inflater = LayoutInflater.from(getApplication());
        //獲取浮動視窗檢視所在佈局
        mFloatLayout = (FrameLayout) inflater.inflate(R.layout.float_view, null);
        //新增mFloatLayout
        mWindowManager.addView(mFloatLayout, wmParams);

        //浮動視窗按鈕
        mFloatLayout.setOnTouchListener(this);

        mFloatLayout.measure(View.MeasureSpec.makeMeasureSpec(0,
                View.MeasureSpec.UNSPECIFIED), View.MeasureSpec
                .makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
    }

    private float StartX;
    private float StartY;

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        //獲取相對螢幕的座標，即以螢幕左上角為原點
        x = event.getRawX();
        y = event.getRawY() - 25;   //25是系統狀態列的高度
        Log.i("currP", "currX" + x + "====currY" + y);
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                //獲取相對View的座標，即以此View左上角為原點
                mTouchStartX = event.getX();
                mTouchStartY = event.getY();
                StartX = x;
                StartY = y;
                Log.i("startP", "startX" + mTouchStartX + "====startY" + mTouchStartY);

                break;
            case MotionEvent.ACTION_MOVE:
                if (Math.abs(x - StartX) > 5 && Math.abs(y - StartY) > 5) {
                    updateViewPosition();
                }
                break;

            case MotionEvent.ACTION_UP:
                 if (Math.abs(x - StartX) > 5 && Math.abs(y - StartY) > 5) {
                    updateViewPosition();
                    mTouchStartX = mTouchStartY = 0;
                }
                break;
        }
        return true;
    }

    private void updateViewPosition() {
        //更新浮動視窗位置引數
        wmParams.x = (int) (x - mTouchStartX);
        wmParams.y = (int) (y - mTouchStartY);
        mWindowManager.updateViewLayout(mFloatLayout, wmParams);
    }
}

如果只想在單個應用內全域性執行，可以在退出應用時停止服務執行。

package cn.net.owen.floatview;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        startService(new Intent(this,FloatViewService.class));
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
//        stopService(new Intent(this,FloatViewService.class));
    }
}