# Background Task Management

### Introduction

This sample shows how a download task can be performed at the background even if the app exits. The display effect is as follows:

![](./screenshots/device/backgroundtaskmanager_en.png)

### Concepts

If a service needs to be continued when the application or service module is running in the background (not visible to users), the application or service module can request a transient task to delay the suspension or a continuous task to prevent the suspension.

### Required Permissions

ohos.permission.KEEP_BACKGROUND_RUNNING

### Usage

1. Touch the **Download** button and exit the app. The download task is pushed to the background for execution. When a task starts to be executed in the background, a notification and the download progress will be displayed.

### Constraints

- This sample can only be run on standard-system devices.
- You need to refresh the notification window to view the download progress. In addition, the download ends when the download progress reaches 20% in this sample.
- This feature is supported form API version 9.

- This sample requires DevEco Studio 3.0 Beta4 (Build Version: 3.0.0.992, built on July 14, 2022) to compile and run.

# 后台任务管理

### 简介

本示例模拟下载功能，将下载任务通过后台任务管理进行处理，实现退出应用后任务仍能够执行，直至任务结束。实现效果如下：

![](./screenshots/device/backgroundtaskmanager.png)

### 相关概念

当应用或业务模块处于后台（无可见界面）时，如果有需要继续执行或者后续执行的业务，可基于业务类型，申请短时任务延迟挂起（Suspend）或者长时任务避免进入挂起状态。

### 相关权限

后台任务管理权限：ohos.permission.KEEP_BACKGROUND_RUNNING

### 使用说明

1.点击**下载**按钮，退出应用，将下载任务推送到后台执行。当任务在后台开始执行时会有通知提醒，且有下载任务进度显示。

### 约束与限制

1.本示例仅支持在标准系统上运行。

2.查看下载进度时需要刷新通知窗口，且下载进度到20%结束。

3.从API version 9开始支持。

4.本示例需要使用DevEco Studio 3.0 Beta4 (Build Version: 3.0.0.992, built on July 14, 2022)才可编译运行。