突破小米悬浮窗权限控制–不需要权限的悬浮窗

在上一篇文章讲了Android的Toast拓展，在原生Toast基础上对显示时长和显示动画做了二次封装，强化了Toast的部分功能。也分析了对于二次封装的ExToast设计原理，以及Toast的关键点。如果不了解的可以看看下面的链接。

Toast拓展–自定义显示时间和动画

常用悬浮窗与Toast

之前分析过，Toast其实就是系统悬浮窗的一种，那它跟常用的系统悬浮窗有什么区别呢？

先看一下常用的Andoird系统悬浮窗写法:

// 获取应用的Context
mContext = context.getApplicationContext();
// 获取WindowManager
mWindowManager = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
mView = setUpView(context);

final WindowManager.LayoutParams params = new WindowManager.LayoutParams();
// 类型
params.type = WindowManager.LayoutParams.TYPE_SYSTEM_ALERT;

int flags = WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM;
params.flags = flags;
params.format = PixelFormat.TRANSLUCENT;
params.width = LayoutParams.MATCH_PARENT;
params.height = LayoutParams.MATCH_PARENT;
params.gravity = Gravity.CENTER;
mWindowManager.addView(mView, params);

再看看在Toast源码里面的写法关键代码:

final WindowManager.LayoutParams params = mParams;
params.height = WindowManager.LayoutParams.WRAP_CONTENT;
params.width = WindowManager.LayoutParams.WRAP_CONTENT;
params.format = PixelFormat.TRANSLUCENT;
params.windowAnimations = com.android.internal.R.style.Animation_Toast;
// 类型
params.type = WindowManager.LayoutParams.TYPE_TOAST;
params.setTitle("Toast");
params.flags = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
        | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
        | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE;
...    
// 获取应用的context
Context context = mView.getContext().getApplicationContext();
// 获取WindowManager
mWM = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
...
if (mView.getParent() != null) {
    mWM.removeView(mView);
}
mWM.addView(mView, mParams);    

上面的两段代码大致流程都是一样的:创建WindowManager.LayoutParams做窗口的配置->通过context获取WindowManager服务->通过WindowManager服务添加悬浮窗View

主要的不同点在于WindowManager.LayoutParams的type。
WindowManager.LayoutParams的type有很多种，包括各种系统对话框，锁屏窗口，电话窗口等等，但这些窗口基本上都是需要权限的。

而我们平时使用的Toast，并不需要权限就能显示，那就可以尝试直接把悬浮窗的类型设成TYPE_TOAST，来定制一个不需要权限的悬浮窗。

下面是demo代码:

import android.content.Context;
import android.graphics.PixelFormat;
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.TextView;

public class ADToast implements View.OnTouchListener {

    Context mContext;
    WindowManager.LayoutParams params;
    WindowManager mWM;
    View mView;

    private float mTouchStartX;
    private float mTouchStartY;
    private float x;
    private float y;

    public ADToast(Context context){
        this.mContext = context;
        params = new WindowManager.LayoutParams();
        params.height = WindowManager.LayoutParams.WRAP_CONTENT;
        params.width = WindowManager.LayoutParams.WRAP_CONTENT;
        params.format = PixelFormat.TRANSLUCENT;
        params.windowAnimations = R.style.anim_view;
        // 悬浮窗类型，整个demo的关键点
        params.type = WindowManager.LayoutParams.TYPE_TOAST;
        params.gravity = Gravity.LEFT | Gravity.TOP;
        params.setTitle("Toast");
        params.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
                | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
        mWM = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
        LayoutInflater inflate = (LayoutInflater)
                mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mView = inflate.inflate(R.layout.float_tips_layout, null);
        mView.setOnTouchListener(this);
    }

    public void show(){
        TextView tv = (TextView)mView.findViewById(R.id.message);
        tv.setText("悬浮窗");
        if (mView.getParent() != null) {
            mWM.removeView(mView);
        }
        mWM.addView(mView, params);
    }

    public void hide(){
        if(mView!=null){
            mWM.removeView(mView);
        }
    }

    public void setText(String text){
        TextView tv = (TextView)mView.findViewById(R.id.message);
        tv.setText(text);
    }

    private void updateViewPosition(){
        //更新浮动窗口位置参数
        params.x=(int) (x-mTouchStartX);
        params.y=(int) (y-mTouchStartY);
        mWM.updateViewLayout(mView, params);  //刷新显示
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        //获取相对屏幕的坐标，即以屏幕左上角为原点
        x = event.getRawX();
        y = event.getRawY();
        Log.i("currP", "currX"+x+"====currY"+y);
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:    //捕获手指触摸按下动作
                //获取相对View的坐标，即以此View左上角为原点
                mTouchStartX =  event.getX();
                mTouchStartY =  event.getY();
                Log.i("startP","startX"+mTouchStartX+"====startY"+mTouchStartY);
                break;
            case MotionEvent.ACTION_MOVE:   //捕获手指触摸移动动作
                updateViewPosition();
                break;
            case MotionEvent.ACTION_UP:    //捕获手指触摸离开动作
                updateViewPosition();
                break;
        }
        return true;
    }
}

float_tips_layout.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:gravity="center"
    android:orientation="vertical"
    android:background="@android:color/black">

    <TextView
        android:id="@+id/message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginStart="32dp"
        android:layout_marginEnd="32dp"
        android:lineSpacingExtra="16dp"
        android:maxLines="2"
        android:textColor="@android:color/white"
        android:shadowColor="#bbffffff"
        android:shadowRadius="2.75"
        android:textSize="40sp"
        />

</LinearLayout>

然而，这种使用方式，在小米最新的MIUI8系统上行不通！

使用N5原生6.0系统测试通过，使用一加3测试通过，使用魅族pro5测试通过。只有小米MIUI8，对Toast类型悬浮窗做了权限控制。

实测在MIUI8中，打开悬浮窗权限可以显示这种Toast类型的悬浮窗。而使用原生Toast类，却不需要权限就可以显示，看来小米的系统在framework层对Toast类型的权限做了特殊处理。

但是，只要Toast能显示，就说明肯定有方法绕过去。最好的方法，就是把小米改动的framework层代码扒出来，看看原生Toast和自定义Toast类型悬浮窗在权限处理上的区别是什么，但是有一定的难度，在研究了一天无果后，先使用了第二种更容易实现的方法。

既然原生Toast不需要权限，那我们就在原生Toast的基础上继续封装拓展。上一篇Toast拓展文章已经对Toast的二次封装解释的比较详细了，下面直接上Demo代码。

import android.content.Context;
import android.content.res.Resources;
import android.os.Handler;
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.TextView;
import android.widget.Toast;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class MiExToast implements View.OnTouchListener {
    private static final String TAG = "ExToast";

    public static final int LENGTH_ALWAYS = 0;
    public static final int LENGTH_SHORT = 2;
    public static final int LENGTH_LONG = 4;

    private Toast toast;
    private Context mContext;
    private int mDuration = LENGTH_SHORT;
    private int animations = -1;
    private boolean isShow = false;

    private Object mTN;
    private Method show;
    private Method hide;
    private WindowManager mWM;
    private WindowManager.LayoutParams params;
    private View mView;

    private float mTouchStartX;
    private float mTouchStartY;
    private float x;
    private float y;

    private Handler handler = new Handler();

    public MiExToast(Context context){
        this.mContext = context;
        if (toast == null) {
            toast = new Toast(mContext);
        }
        LayoutInflater inflate = (LayoutInflater)
                mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mView = inflate.inflate(R.layout.float_tips_layout, null);
        mView.setOnTouchListener(this);
    }

    private Runnable hideRunnable = new Runnable() {
        @Override
        public void run() {
            hide();
        }
    };

    /**
     * Show the view for the specified duration.
     */
    public void show(){
        if (isShow) return;
        TextView tv = (TextView)mView.findViewById(R.id.message);
        tv.setText("悬浮窗");
        toast.setView(mView);
        initTN();
        try {
            show.invoke(mTN);
        } catch (InvocationTargetException | IllegalAccessException e) {
            e.printStackTrace();
        }
        isShow = true;
        //判断duration，如果大于#LENGTH_ALWAYS 则设置消失时间
        if (mDuration > LENGTH_ALWAYS) {
            handler.postDelayed(hideRunnable, mDuration * 1000);
        }
    }

    /**
     * Close the view if it‘s showing, or don‘t show it if it isn‘t showing yet.
     * You do not normally have to call this.  Normally view will disappear on its own
     * after the appropriate duration.
     */
    public void hide(){
        if(!isShow) return;
        try {
            hide.invoke(mTN);
        } catch (InvocationTargetException | IllegalAccessException e) {
            e.printStackTrace();
        }
        isShow = false;
    }

    public void setView(View view) {
        toast.setView(view);
    }

    public View getView() {
        return toast.getView();
    }

    /**
     * Set how long to show the view for.
     * @see #LENGTH_SHORT
     * @see #LENGTH_LONG
     * @see #LENGTH_ALWAYS
     */
    public void setDuration(int duration) {
        mDuration = duration;
    }

    public int getDuration() {
        return mDuration;
    }

    public void setMargin(float horizontalMargin, float verticalMargin) {
        toast.setMargin(horizontalMargin,verticalMargin);
    }

    public float getHorizontalMargin() {
        return toast.getHorizontalMargin();
    }

    public float getVerticalMargin() {
        return toast.getVerticalMargin();
    }

    public void setGravity(int gravity, int xOffset, int yOffset) {
        toast.setGravity(gravity,xOffset,yOffset);
    }

    public int getGravity() {
        return toast.getGravity();
    }

    public int getXOffset() {
        return toast.getXOffset();
    }

    public int getYOffset() {
        return toast.getYOffset();
    }

    public static MiExToast makeText(Context context, CharSequence text, int duration) {
        Toast toast = Toast.makeText(context,text,Toast.LENGTH_SHORT);
        MiExToast exToast = new MiExToast(context);
        exToast.toast = toast;
        exToast.mDuration = duration;

        return exToast;
    }

    public static MiExToast makeText(Context context, int resId, int duration)
            throws Resources.NotFoundException {
        return makeText(context, context.getResources().getText(resId), duration);
    }

    public void setText(int resId) {
        setText(mContext.getText(resId));
    }

    public void setText(CharSequence s) {
        toast.setText(s);
    }

    public int getAnimations() {
        return animations;
    }

    public void setAnimations(int animations) {
        this.animations = animations;
    }

    private void initTN() {
        try {
            Field tnField = toast.getClass().getDeclaredField("mTN");
            tnField.setAccessible(true);
            mTN = tnField.get(toast);
            show = mTN.getClass().getMethod("show");
            hide = mTN.getClass().getMethod("hide");

            Field tnParamsField = mTN.getClass().getDeclaredField("mParams");
            tnParamsField.setAccessible(true);
            params = (WindowManager.LayoutParams) tnParamsField.get(mTN);
            params.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
                    | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;

            /**设置动画*/
            if (animations != -1) {
                params.windowAnimations = animations;
            }

            /**调用tn.show()之前一定要先设置mNextView*/
            Field tnNextViewField = mTN.getClass().getDeclaredField("mNextView");
            tnNextViewField.setAccessible(true);
            tnNextViewField.set(mTN, toast.getView());

            mWM = (WindowManager)mContext.getApplicationContext().getSystemService(Context.WINDOW_SERVICE);
        } catch (Exception e) {
            e.printStackTrace();
        }
        setGravity(Gravity.LEFT | Gravity.TOP,0 ,0);
    }

    private void updateViewPosition(){
        //更新浮动窗口位置参数
        params.x=(int) (x-mTouchStartX);
        params.y=(int) (y-mTouchStartY);
        mWM.updateViewLayout(toast.getView(), params);  //刷新显示
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        //获取相对屏幕的坐标，即以屏幕左上角为原点
        x = event.getRawX();
        y = event.getRawY();
        Log.i("currP", "currX"+x+"====currY"+y);
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:    //捕获手指触摸按下动作
                //获取相对View的坐标，即以此View左上角为原点
                mTouchStartX =  event.getX();
                mTouchStartY =  event.getY();
                Log.i("startP","startX"+mTouchStartX+"====startY"+mTouchStartY);
                break;
            case MotionEvent.ACTION_MOVE:   //捕获手指触摸移动动作
                updateViewPosition();
                break;
            case MotionEvent.ACTION_UP:    //捕获手指触摸离开动作
                updateViewPosition();
                break;
        }
        return true;
    }

}

example:

MiExToast miToast = new MiExToast(getApplicationContext());
miToast.setDuration(MiExToast.LENGTH_ALWAYS);
miToast.setAnimations(R.style.anim_view);
miToast.show();

上面的Demo类是基于上一篇文章Toast拓展–自定义显示时间和动画，进行再次拓展做出来的，它只是一个Demo，并不是工具类，不能直接拿来使用。

下面根据这个Demo，我们来分析它的原理。

下面有三个关键点:
1. Toast是可以自定义View的
2. 悬浮窗的触摸需要修改WindowManager.LayoutParams.flags，设置WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
3. 刷新悬浮窗，只需要获得WindowManager实例，调用updateViewLayout并传入View和LayoutParams即可

经过上一篇文章的讲解，对于Toast的LayoutParams实例我们可以通过反射获得，并且给他设置上可触摸的flag。关注上面代码的initTN()方法，获得的LayoutParams实例需要保持引用，因为后面还需要用上。

Field tnParamsField = mTN.getClass().getDeclaredField("mParams");
tnParamsField.setAccessible(true);
params = (WindowManager.LayoutParams) tnParamsField.get(mTN);
params.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
    | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;

然后是对二次封装的Demo类MiExToast里面的Toast实例设置View。这个应该很容易理解，Toast是可以自定义View的，设置自己的View作为悬浮窗。同时，可以对View添加一些自定义的Touch事件，在这个Demo中用户可以随意拖动悬浮窗。

public void init(){
    mView = inflate.inflate(R.layout.float_tips_layout, null);
    mView.setOnTouchListener(this);
    toast.setView(mView);
}

@Override
public boolean onTouch(View v, MotionEvent event) {
    //获取相对屏幕的坐标，即以屏幕左上角为原点
    x = event.getRawX();
    y = event.getRawY();
    ...
    return true;
}

最后就是对悬浮窗的更新，只需要通过context获取到WindowManager，即可调用updateViewLayout对悬浮窗进行更新。

private WindowManager.LayoutParams params;

private void updateViewPosition(){
    mWM.updateViewLayout(toast.getView(), params);  //刷新显示
}

大致原理就是这样，借助原生Toast显示自定义的悬浮窗，越过小米MIUI8对于Toast类型悬浮窗的权限封锁。

最后上一个小米系统示例图:

转载请注明出处！