# Device Management

> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
> - The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.
> - The APIs of this module are system APIs and cannot be called by third-party applications.


## Modules to import:

```
import deviceManager from '@ohos.distributedHardware.deviceManager';
```


## deviceManager.createDeviceManager

createDeviceManager(bundleName: string, callback: AsyncCallback<DeviceManager>): void

Creates a **DeviceManager** instance.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

- **Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | bundleName | string | Yes| Bundle name of the application.|
  | callback | AsyncCallback<[DeviceManager](#devicemanager)> | Yes| Callback invoked to return the **DeviceManager** instance created.|

- Example
  ```
  deviceManager.createDeviceManager("ohos.samples.jshelloworld", (err, data) => {     
      if (err) { 
          console.info("createDeviceManager err:" + JSON.stringify(err));    
          return;
      }
      console.info("createDeviceManager success");
      this.dmInstance = data;
  });
  ```


## DeviceStateChangeAction

Enumerates the device states.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

| Name| Default Value| Description|
| -------- | -------- | -------- |
| ONLINE | 0 | The device is online.|
| READY | 1 | The device is ready, and the device information has been synchronized.|
| OFFLINE | 2 | The device is offline.|
| CHANGE | 3 | The device information is changed.|


## DeviceType

Enumerates the device types.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

| Name| Default Value| Description|
| -------- | -------- | -------- |
| SPEAKER | 0x0A | Smart speaker.|
| PHONE | 0x0E | Phone.|
| TABLET | 0x11 | Tablet.|
| WEARABLE | 0x6D | Wearable.|
| TV | 0x9C | Smart TV.|
| CAR | 0x83 | Car.|
| UNKNOWN_TYPE | 0 | Unknown device type.|


## DeviceInfo

Defines device information.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| deviceId | number | Yes| Unique device identifier.|
| deviceName | string | Yes| Device name.|
| deviceType | [DeviceType](#devicetype) | Yes| Device type.|
| networkId<sup>8+</sup> | string | Yes | Device networkId. |


## DeviceManager

Provides APIs to obtain information about trusted devices and local devices. Before calling any API in **DeviceManager**, you must use **createDeviceManager** to create a **DeviceManager** instance, for example, **dmInstance**.


### release

release(): void

Releases the **DeviceManager** instance that is no longer used.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

- Example
  ```
  dmInstance.release();
  ```


### getTrustedDeviceListSync

getTrustedDeviceListSync(): Array&lt;DeviceInfo&gt;

Obtains all trusted devices synchronously.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

- Return value
  | Name| Description|
  | -------- | -------- |
  | Array&lt;[DeviceInfo](#deviceinfo)&gt; | List of trusted devices obtained.|

- Example
  ```
  var deviceInfoList = dmInstance.getTrustedDeviceListSync();
  ```


### on('deviceStateChange')

on(type: 'deviceStateChange',  callback: Callback&lt;{ action: DeviceStateChangeAction, device: DeviceInfo }&gt;): void

Subscribes to changes in the device state.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

- **Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | type | string | Yes| Event type. The value is **deviceStateChange**, which indicates a device state change event.|
  | callback | Callback&lt;{&nbsp;action:&nbsp;[DeviceStateChangeAction](#devicestatechangeaction),&nbsp;device:&nbsp;[DeviceInfo](#deviceinfo)&nbsp;}&gt; | Yes| Callback invoked to return the device information and state.|

- Example
  ```
  dmInstance.on('deviceStateChange', (data) => {      
        console.info("deviceStateChange on:" + JSON.stringify(data));
      }
  );
  ```


### off('deviceStateChange')

off(type: 'deviceStateChange', callback?: Call	back&lt;{ action: DeviceStateChangeAction, device: DeviceInfo }&gt;): void

Unsubscribes from changes in the device state.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

- **Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | type | string | Yes| Event type. The value **deviceStateChange** indicates an event of device state change.|
  | callback | Callback&lt;{&nbsp;action:&nbsp;[DeviceStateChangeAction](#devicestatechangeaction),&nbsp;device:&nbsp;[DeviceInfo](#deviceinfo)&nbsp;&nbsp;}&gt; | Yes| Callback invoked to return the device information and state.|

- Example
  ```
  dmInstance.off('deviceStateChange', (data) => {      
        console.info('deviceStateChange' + JSON.stringify(data));
     }
  );
  ```


### on('serviceDie')

on(type: 'serviceDie', callback: () =&gt; void): void

Subscribes to dead events of the **DeviceManager** service.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

- **Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | type | string | Yes| Event type. The value **serviceDie** indicates an event reported when the **DeviceManager** service is terminated unexpectedly.|
  | callback | ()&nbsp;=&gt;&nbsp;void | Yes| Callback invoked when a dead event of the **DeviceManager** service occurs.|

- Example
  ```
  dmInstance.on("serviceDie", () => {      
        console.info("serviceDie on");
     }
  );
  ```


### off('serviceDie')

off(type: 'serviceDie', callback?: () =&gt; void): void

Unsubscribes from dead events of the **DeviceManager** service.

**System capability**: SystemCapability.DistributedHardware.DeviceManager

- **Parameters**
  | Name| Type| Mandatory| Description|
  | -------- | -------- | -------- | -------- |
  | type | string | Yes| Event type. The value **serviceDie** indicates an event reported when the **DeviceManager** service is terminated unexpectedly.|
  | callback | ()&nbsp;=&gt;&nbsp;void | No| Callback used to return the dead event of the **DeviceManager** service.|

- Example
  ```
  dmInstance.off("serviceDie", () => {      
        console.info("serviceDie off");
    }
  );
  ```