Toast WindowManager$BadTokenException

Toast 作为 Android 常用的控件之一，突然在友盟统计上发现Toast报错了，那就需要麻溜的解决了。

复现

        Toast.makeText(getContext(), "我的Toast", Toast.LENGTH_SHORT).show();
        try {
            Thread.sleep(5_000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

错误日志

   android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@a22690b is not valid; is your activity running?
        at android.view.ViewRootImpl.setView(ViewRootImpl.java:679)
        at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:342)
        at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:93)
        at android.widget.Toast$TN.handleShow(Toast.java:459)
        at android.widget.Toast$TN$2.handleMessage(Toast.java:342)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6119)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

出现原因

API 25, Android 为Toast增加了一个IBinder windowToken 去处理Toast#handleShow()，从而导致了一个运行时错误:BadTokenException 。
坑的理由：
其他版本上不会出现。因为 google在该版本开始对TYPE TOAST进行管控，防止一个应用的悬浮窗一直悬浮在另一个应用上造成干扰，但是Android团队意识到这个崩溃问题，从而在API 26的时候，在Toast的内部加了try-catch保护捕获了这个错误。
目前只有7.1.1上面的Toast存在这个问题，崩溃在系统源码里。APP层可以通过自定义Toast类，反射替换TN的内部成员变量mHandler，从而添加try-catch做到workaround，所有使用Toast的地方都使用这个自定义的，不要直接使用系统原生的
具体源码对比 Toast#TN#Handler：
API25:

        public void handleShow(IBinder windowToken) {
            if (localLOGV) Log.v(TAG, "HANDLE SHOW: " + this + " mView=" + mView
                    + " mNextView=" + mNextView);
            if (mView != mNextView) {
            ...
            ...
                if (localLOGV) Log.v(TAG, "ADD! " + mView + " in " + this);
                mWM.addView(mView, mParams);
                trySendAccessibilityEvent();
            }
        }

API:26

        public void handleShow(IBinder windowToken) {
            if (localLOGV) Log.v(TAG, "HANDLE SHOW: " + this + " mView=" + mView
                    + " mNextView=" + mNextView);
            // If a cancel/hide is pending - no need to show - at this point
            // the window token is already invalid and no need to do any work.
            if (mHandler.hasMessages(CANCEL) || mHandler.hasMessages(HIDE)) {
                return;
            }
            if (mView != mNextView) {
            ...
            ...
                try {
                    mWM.addView(mView, mParams);
                    trySendAccessibilityEvent();
                } catch (WindowManager.BadTokenException e) {
                    /* ignore */
                }
            }
        }

解决方案：

public class ToastCompat {

    private static Field sField_TN;
    private static Field sField_TN_Handler; 

    static {
        if (Build.VERSION.SDK_INT == Build.VERSION_CODES.N_MR1) {
            try {
                sField_TN = Toast.class.getDeclaredField("mTN");
                sField_TN.setAccessible(true);

                sField_TN_Handler = sField_TN.getType().getDeclaredField("mHandler");
                sField_TN_Handler.setAccessible(true);
            } catch (Exception e) {
            }
        }
    }

    private static void hook(Toast toast) {
        try {
            Object tn = sField_TN.get(toast);
            Handler preHandler = (Handler) sField_TN_Handler.get(tn);
            sField_TN_Handler.set(tn, new SafelyHandlerWarpper(preHandler));
        } catch (Exception e) {
        }
    }

    public static void showToast(Context context, CharSequence cs, int length) {
        Toast toast = Toast.makeText(context, cs, length);
        if (Build.VERSION.SDK_INT == Build.VERSION_CODES.N_MR1) {
            hook(toast);
        }
        toast.show();
    }

    private static class SafelyHandlerWarpper extends Handler {

        private Handler impl;

        public SafelyHandlerWarpper(Handler impl) {
            this.impl = impl;
        }

        @Override
        public void handleMessage(Message msg) {
            try {
                impl.handleMessage(msg);
            } catch (Exception e) {
                e.printStackTrace();
            }

        }
    }
}

参考：https://cloud.tencent.com/developer/article/1034225