# Network Sharing (For System Applications Only)

## Introduction

The Network Sharing module allows you to share your device's Internet connection with other connected devices by means of Wi-Fi hotspot, Bluetooth, and USB sharing. It also allows you to query the network sharing state and shared mobile data volume.

> **NOTE**
> To maximize the application running efficiency, most API calls are called asynchronously in callback or promise mode. The following code examples use the promise mode. For details about the APIs, see [API Reference](../reference/apis-network-kit/js-apis-net-sharing-sys.md).

## Basic Concepts

- Wi-Fi sharing: Shares the network through a Wi-Fi hotspot.
- Bluetooth sharing: Shares the network through Bluetooth.
- USB tethering: Shares the network using a USB flash drive.

## **Constraints**

- Programming language: JS
- The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.

## When to Use

Typical network sharing scenarios are as follows:

- Enabling Network Sharing
- Disabling network sharing
- Obtaining the data traffic of the shared network

The following describes the development procedure specific to each application scenario.

## Available APIs

For the complete list of APIs and example code, see [Network Sharing](../reference/apis-network-kit/js-apis-net-sharing-sys.md).

| API                                                                  | Description                                                                                                   |
| --------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------- |
| isSharingSupported(callback: AsyncCallback\<boolean>): void;    | Checks whether the system supports network sharing. This API uses an asynchronous callback to return the result.                                                      |
| isSharing(callback: AsyncCallback\<boolean>): void;             | Checks whether network sharing is active. This API uses an asynchronous callback to return the result.                                                                  |
| startSharing(type: SharingIfaceType, callback: AsyncCallback\<void>): void;  | Starts network sharing. This API uses an asynchronous callback to return the result.               |
| stopSharing(type: SharingIfaceType, callback: AsyncCallback\<void>): void;  | Stops network sharing. This API uses an asynchronous callback to return the result.            |
| getStatsRxBytes(callback: AsyncCallback\<number>): void;         | Obtains the received data traffic during network sharing, in KB. This API uses an asynchronous callback to return the result.                                                       |
| getStatsTxBytes(callback: AsyncCallback\<number>): void;         | Obtains the sent data traffic during network sharing, in KB. This API uses an asynchronous callback to return the result.                                                       |
| getStatsTotalBytes(callback: AsyncCallback\<number>): void;      | Obtains the total data traffic during network sharing, in KB. This API uses an asynchronous callback to return the result.                                                       |
| getSharingIfaces(state: SharingIfaceState, callback: AsyncCallback\<Array\<string>>): void;  | Obtains the names of network interface cards (NICs) in the specified network sharing state.. This API uses an asynchronous callback to return the result.|
| getSharingState(type: SharingIfaceType, callback: AsyncCallback\<SharingIfaceState>): void;  | Obtains the network sharing state of the specified type. This API uses an asynchronous callback to return the result. |
| getSharableRegexes(type: SharingIfaceType, callback: AsyncCallback\<Array\<string>>): void;  | Obtains regular expressions of NICs of a specified type. This API uses an asynchronous callback to return the result.|
| on(type: 'sharingStateChange', callback: Callback\<boolean>): void;        | Subscribes to network sharing state changes.                                                               |
| off(type: 'sharingStateChange', callback?: Callback\<boolean>): void;      | Unsubscribes from network sharing state changes.                                                               |
| unction on(type: 'interfaceSharingStateChange', callback: Callback\<{ type: SharingIfaceType, iface: string, state: SharingIfaceState }>): void;    | Subscribes to network sharing state changes of the specified NIC.   |
| off(type: 'interfaceSharingStateChange', callback?: Callback\<{ type: SharingIfaceType, iface: string, state: SharingIfaceState }>): void; | Unsubscribes from network sharing state changes of the specified NIC.            |
| on(type: 'sharingUpstreamChange', callback: Callback\<NetHandle>): void;               | Subscribes to upstream NIC changes.                                                                        |
| off(type: 'sharingUpstreamChange', callback?: Callback\<NetHandle>): void;             | Unsubscribes from upstream NIC changes.                                                                        |

## Enabling Network Sharing

1. Import the **sharing** namespace from **@kit.NetworkKit**.
2. Subscribe to network sharing state changes.
3. Call **startSharing** to start network sharing of the specified type.
4. Return the callback for successfully starting network sharing.

```ts
// Import the sharing namespace from @kit.NetworkKit.
import { sharing } from '@kit.NetworkKit';
import { BusinessError } from '@kit.BasicServicesKit';

// Subscribe to network sharing state changes.
sharing.on('sharingStateChange', (data: boolean) => {
  console.log(JSON.stringify(data));
});

// Call startSharing to start network sharing of the specified type.
sharing.startSharing(sharing.SharingIfaceType.SHARING_WIFI).then(() => {
  console.log('start wifi sharing successful');
}).catch((error: BusinessError) => {
  console.log('start wifi sharing failed');
});
```

## Disabling network sharing

### How to Develop

1. Import the **sharing** namespace from **@kit.NetworkKit**.
2. Subscribe to network sharing state changes.
3. Call **stopSharing** to stop network sharing of the specified type.
4. Return the callback for successfully stopping network sharing.

```ts
// Import the sharing namespace from @kit.NetworkKit.
import { sharing } from '@kit.NetworkKit';
import { BusinessError } from '@kit.BasicServicesKit';

// Subscribe to network sharing state changes.
sharing.on('sharingStateChange', (data: boolean) => {
  console.log(JSON.stringify(data));
});

// Call stopSharing to stop network sharing of the specified type.
sharing.stopSharing(sharing.SharingIfaceType.SHARING_WIFI).then(() => {
  console.log('start wifi sharing successful');
}).catch((error: BusinessError) => {
  console.log('start wifi sharing failed');
});
```

## Obtaining the data traffic of the shared network

### How to Develop

1. Import the **sharing** namespace from **@kit.NetworkKit**.
2. Call **startSharing** to start network sharing of the specified type.
3. Call **getStatsTotalBytes** to obtain the data traffic generated during data sharing.
4. Call **stopSharing** to stop network sharing of the specified type and clear the data volume of network sharing.

```ts
// Import the sharing namespace from @kit.NetworkKit.
import { sharing } from '@kit.NetworkKit';
import { BusinessError } from '@kit.BasicServicesKit';

// Call startSharing to start network sharing of the specified type.
sharing.startSharing(sharing.SharingIfaceType.SHARING_WIFI).then(() => {
  console.log('start wifi sharing successful');
}).catch((error: BusinessError) => {
  console.log('start wifi sharing failed');
});

// Call getStatsTotalBytes to obtain the data traffic generated during data sharing.
sharing.getStatsTotalBytes().then((data: number) => {
  console.log(JSON.stringify(data));
}).catch((error: BusinessError) => {
  console.log(JSON.stringify(error));
});

// Call stopSharing to stop network sharing of the specified type and clear the data volume of network sharing.
sharing.stopSharing(sharing.SharingIfaceType.SHARING_WIFI).then(() => {
  console.log('start wifi sharing successful');
}).catch((error: BusinessError) => {
  console.log('start wifi sharing failed');
});

// Call getStatsTotalBytes again. The data volume of network sharing has been cleared.
sharing.getStatsTotalBytes().then((data: number) => {
  console.log(JSON.stringify(data));
}).catch((error: BusinessError) => {
  console.log(JSON.stringify(error));
});
```