allprojects {
	repositories {
		...
		maven { url 'https://jitpack.io' }
	}
}

dependencies {
        implementation 'com.github.Dovar66:DToast:1.1.7'
	//implementation 'com.github.Dovar66:DToast:1.1.8'//for androidx
}

//使用默认布局
DToast.make(mContext)
       .setText(R.id.tv_content_default, msg)
       .setGravity(Gravity.BOTTOM | Gravity.CENTER, 0, 30)
       .show();
       
//通过setView()设置自定义的Toast布局            
DToast.make(mContext)
       .setView(View.inflate(mContext, R.layout.layout_toast_center, null))
       .setText(R.id.tv_content_custom, msg)
       .setGravity(Gravity.CENTER, 0, 0)
       .showLong();

1.当通知权限被关闭时在华为等手机上Toast不显示；

2.Toast的队列机制在不同手机上可能会不相同；

3.Toast的BadTokenException问题；

4.Android8.0之后的token null is not valid问题；

5.Android7.1之后，不允许同时展示两个TYPE_TOAST弹窗(实测部分机型问题)。

1.通知权限未被关闭时，使用SystemToast(修复了问题2和问题3的系统Toast);
2.通知权限被关闭时，如果系统版本为Android8.0/8.1则通过hook绕过通知栏权限，否则使用DovaToast(自定义的TYPE_TOAST弹窗);
3.当使用DovaToast出现token null is not valid时，尝试使用ActivityToast(自定义的TYPE_APPLICATION_ATTACHED_DIALOG
弹窗，只有当传入Context为Activity时，才会启用ActivityToast).

1.你的应用设置的targetSdkVersion>=26.
2.通知栏权限被关闭(通知栏权限默认都是打开的).
3.非MIUI设备(MIUI弹吐司不需要通知栏权限).
4.运行设备的系统版本在Android9.0及以上。

看下方Toast源码中的show()方法，通过AIDL获取到INotificationManager，并将接下来的显示流程控制权
交给NotificationManagerService。
NMS中会对Toast进行权限校验，当通知权限校验不通过时，Toast将不做展示。
当然不同ROM中NMS可能会有不同，比如MIUI就对这部分内容进行了修改，所以小米手机关闭通知权限不会导致Toast不显示。

  /**
     * Show the view for the specified duration.
     */
    public void show() {
        if (mNextView == null) {
            throw new RuntimeException("setView must have been called");
        }

        INotificationManager service = getService();
        String pkg = mContext.getOpPackageName();
        TN tn = mTN;
        tn.mNextView = mNextView;

        try {
            service.enqueueToast(pkg, tn, mDuration);
        } catch (RemoteException e) {
            // Empty
        }
    }

DovaToast通过使用TYPE_TOAST实现全局弹窗功能，不使用系统Toast,也没有使用NMS服务，因此不受通知权限限制。

 我找了四台设备，创建两个Gravity不同的Toast并调用show()方法,结果出现了四种展示效果：

        * 荣耀5C-android7.0（只看到展示第一个Toast）
        * 小米8-MIUI10（只看到展示第二个Toast，即新的Toast.show会中止当前Toast的展示）
        * 红米6pro-MIUI9（两个Toast同时展示）
        * 荣耀5C-android6.0（第一个TOAST展示完成后，第二个才开始展示）

 DToast中多个弹窗连续出现时：

        1.相同优先级时，会终止上一个，直接展示后一个；
        2.不同优先级时，如果后一个的优先级更高则会终止上一个，直接展示后一个。

UI线程发生阻塞，导致TN.show()没有及时执行，当NotificationManager的检测超时后便会删除WMS中的该token，即造成token失效。

Google在API26中修复了这个问题，即增加了try-catch:

            // Since the notification manager service cancels the token right
            // after it notifies us to cancel the toast there is an inherent
            // race and we may attempt to add a window after the token has been
            // invalidated. Let us hedge against that.
            try {
                mWM.addView(mView, mParams);
                trySendAccessibilityEvent();
            } catch (WindowManager.BadTokenException e) {
                /* ignore */
            }

  //捕获8.0之前Toast的BadTokenException，Google在Android 8.0的代码提交中修复了这个问题
     private void hook(Toast toast) {
         try {
             Field sField_TN = Toast.class.getDeclaredField("mTN");
             sField_TN.setAccessible(true);
             Field sField_TN_Handler = sField_TN.getType().getDeclaredField("mHandler");
             sField_TN_Handler.setAccessible(true);

             Object tn = sField_TN.get(toast);
             Handler preHandler = (Handler) sField_TN_Handler.get(tn);
             sField_TN_Handler.set(tn, new SafelyHandlerWrapper(preHandler));
         } catch (Exception e) {
             e.printStackTrace();
         }
     }


     public class SafelyHandlerWrapper extends Handler {
         private Handler impl;

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

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

         @Override
         public void handleMessage(Message msg) {
             impl.handleMessage(msg);//需要委托给原Handler执行
         }
     }

public int checkAddPermission(WindowManager.LayoutParams attrs, int[] outAppOp) {
    int type = attrs.type;

    outAppOp[0] = AppOpsManager.OP_NONE;

    if (!((type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW)
            || (type >= FIRST_SUB_WINDOW && type <= LAST_SUB_WINDOW)
            || (type >= FIRST_SYSTEM_WINDOW && type <= LAST_SYSTEM_WINDOW))) {
        return WindowManagerGlobal.ADD_INVALID_TYPE;
    }

    if (type < FIRST_SYSTEM_WINDOW || type > LAST_SYSTEM_WINDOW) {
        // Window manager will make sure these are okay.
        return WindowManagerGlobal.ADD_OKAY;
    }
    String permission = null;
    switch (type) {
        case TYPE_TOAST:
            // XXX right now the app process has complete control over
            // this...  should introduce a token to let the system
            // monitor/control what they are doing.
            outAppOp[0] = AppOpsManager.OP_TOAST_WINDOW;
            break;
        case TYPE_DREAM:
        case TYPE_INPUT_METHOD:
        case TYPE_WALLPAPER:
        case TYPE_PRIVATE_PRESENTATION:
        case TYPE_VOICE_INTERACTION:
        case TYPE_ACCESSIBILITY_OVERLAY:
        case TYPE_QS_DIALOG:
            // The window manager will check these.
            break;
        case TYPE_PHONE:
        case TYPE_PRIORITY_PHONE:
        case TYPE_SYSTEM_ALERT:
        case TYPE_SYSTEM_ERROR:
        case TYPE_SYSTEM_OVERLAY:
            permission = android.Manifest.permission.SYSTEM_ALERT_WINDOW;
            outAppOp[0] = AppOpsManager.OP_SYSTEM_ALERT_WINDOW;
            break;
        default:
            permission = android.Manifest.permission.INTERNAL_SYSTEM_WINDOW;
    }
    if (permission != null) {
        ...
    }
    return WindowManagerGlobal.ADD_OKAY;
}

public int checkAddPermission(WindowManager.LayoutParams attrs, int[] outAppOp) {
    int type = attrs.type;

    outAppOp[0] = AppOpsManager.OP_NONE;

    if (!((type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW)
            || (type >= FIRST_SUB_WINDOW && type <= LAST_SUB_WINDOW)
            || (type >= FIRST_SYSTEM_WINDOW && type <= LAST_SYSTEM_WINDOW))) {
        return WindowManagerGlobal.ADD_INVALID_TYPE;
    }

    if (type < FIRST_SYSTEM_WINDOW || type > LAST_SYSTEM_WINDOW) {
        // Window manager will make sure these are okay.
        return ADD_OKAY;
    }

    if (!isSystemAlertWindowType(type)) {
        switch (type) {
            case TYPE_TOAST:
                // Only apps that target older than O SDK can add window without a token, after
                // that we require a token so apps cannot add toasts directly as the token is
                // added by the notification system.
                // Window manager does the checking for this.
                outAppOp[0] = OP_TOAST_WINDOW;
                return ADD_OKAY;
            case TYPE_DREAM:
            case TYPE_INPUT_METHOD:
            case TYPE_WALLPAPER:
            case TYPE_PRESENTATION:
            case TYPE_PRIVATE_PRESENTATION:
            case TYPE_VOICE_INTERACTION:
            case TYPE_ACCESSIBILITY_OVERLAY:
            case TYPE_QS_DIALOG:
                // The window manager will check these.
                return ADD_OKAY;
        }
        return mContext.checkCallingOrSelfPermission(INTERNAL_SYSTEM_WINDOW)
                == PERMISSION_GRANTED ? ADD_OKAY : ADD_PERMISSION_DENIED;
    }
}

DToast的弹窗策略就是同一时间最多只展示一个弹窗，逻辑上就避免了此问题。因此仅捕获该异常。

1.1.5
    新增IToast.setText(idRes,text)方法
    [修复]issue#6
1.1.3
    [修复]issue#7
1.1.2
    新增思路：对Toast的INotificationManager对象进行hook可以成功绕过通知栏权限，但9.0之后Android限制调用非公开API，所以9.0之后此方法不可用。
    代码更新：新增hook INotificationManager操作，在Android8.0/8.1上采用hook方式绕过通知栏权限。

Copyright (c) 2019 Dovar66

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.