# @ohos.thermal (Thermal Management)

The **thermal** module provides thermal level-related callback and query APIs to obtain the information required for thermal control.

> **NOTE**
>
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.

## Modules to Import

```js
import {thermal} from '@kit.BasicServicesKit';
```

## thermal.registerThermalLevelCallback<sup>9+</sup>

registerThermalLevelCallback(callback: Callback&lt;ThermalLevel&gt;): void

Subscribes to thermal level changes.

**System capability:** SystemCapability.PowerManager.ThermalManager

**Parameters**

| Name  | Type                        | Mandatory| Description                          |
| -------- | ---------------------------- | ---- | ------------------------------ |
| callback | Callback&lt;ThermalLevel&gt; | Yes  | Callback used to return thermal level. This parameter is of the function type.|

**Error codes**

For details about the error codes, see [Thermal Manager Error Codes](errorcode-thermal.md).

| ID  | Error Message   |
|---------|---------|
| 4800101 | Failed to connect to the service. |
| 401     | Parameter error. Possible causes: 1.Incorrect parameter types. |

**Example**

```js
try {
    thermal.registerThermalLevelCallback((level: thermal.ThermalLevel) => {
        console.info('thermal level is: ' + level);
    });
    console.info('register thermal level callback success.');
} catch(err) {
    console.error('register thermal level callback failed, err: ' + err);
}
```

## thermal.unregisterThermalLevelCallback<sup>9+</sup>

unregisterThermalLevelCallback(callback?: Callback\<void>): void

Unsubscribes from thermal level changes.

**System capability:** SystemCapability.PowerManager.ThermalManager

**Parameters**

| Name  | Type                | Mandatory| Description                                          |
| -------- | -------------------- | ---- | ---------------------------------------------- |
| callback | Callback&lt;void&gt; | No  | Callback that returns no value. If this parameter is not set, all callbacks will be unregistered.|

**Error codes**

For details about the error codes, see [Thermal Manager Error Codes](errorcode-thermal.md).

| ID  | Error Message   |
|---------|---------|
| 4800101 | Failed to connect to the service. |
| 401     | Parameter error. Possible causes: 1.Incorrect parameter types. |

**Example**

```js
try {
    thermal.unregisterThermalLevelCallback(() => {
        console.info('unsubscribe thermal level success.');
    });
    console.info('unregister thermal level callback success.');
} catch(err) {
    console.error('unregister thermal level callback failed, err: ' + err);
}
```

## thermal.getLevel<sup>9+</sup>

getLevel(): ThermalLevel

Obtains the current thermal level.

**System capability:** SystemCapability.PowerManager.ThermalManager

**Return value**

| Type        | Description        |
| ------------ | ------------ |
| ThermalLevel | Thermal level.|

**Error codes**

For details about the error codes, see [Thermal Manager Error Codes](errorcode-thermal.md).

| ID  | Error Message   |
|---------|---------|
| 4800101 | Failed to connect to the service. |

**Example**

```js
try {
    let level = thermal.getLevel();
    console.info('thermal level is: ' + level);
} catch(err) {
    console.error('get thermal level failed, err: ' + err);
}
```

## thermal.subscribeThermalLevel<sup>(deprecated)</sup>

subscribeThermalLevel(callback: AsyncCallback&lt;ThermalLevel&gt;): void

> **NOTE**<br>This API is deprecated since API version 9. You are advised to use [thermal.registerThermalLevelCallback](#thermalregisterthermallevelcallback9).

Subscribes to thermal level changes.

**System capability:** SystemCapability.PowerManager.ThermalManager

**Parameters**

| Name  | Type                             | Mandatory| Description                                                        |
| -------- | --------------------------------- | ---- | ------------------------------------------------------------ |
| callback | AsyncCallback&lt;ThermalLevel&gt; | Yes  | Callback used to return the result. The return value contains only one parameter, that is, thermal level.|

**Example**

```js
thermal.subscribeThermalLevel((err: Error, level: thermal.ThermalLevel) => {
    console.info('thermal level is: ' + level);
});
```

## thermal.unsubscribeThermalLevel<sup>(deprecated)</sup>

unsubscribeThermalLevel(callback?: AsyncCallback\<void>): void

> **NOTE**<br>This API is deprecated since API version 9. You are advised to use [thermal.unregisterThermalLevelCallback](#thermalunregisterthermallevelcallback9).

Unsubscribes from thermal level changes.

**System capability:** SystemCapability.PowerManager.ThermalManager

**Parameters**

| Name  | Type                     | Mandatory| Description                                          |
| -------- | ------------------------- | ---- | ---------------------------------------------- |
| callback | AsyncCallback&lt;void&gt; | No  | Callback that returns no value. If this parameter is not set, all callbacks will be unregistered.|

**Example**

```js
thermal.unsubscribeThermalLevel(() => {
    console.info('unsubscribe thermal level success.');
});
```

## thermal.getThermalLevel<sup>(deprecated)</sup>

getThermalLevel(): ThermalLevel

> **NOTE**<br>This API is deprecated since API version 9. You are advised to use [thermal.getLevel](#thermalgetlevel9).

Obtains the current thermal level.

**System capability:** SystemCapability.PowerManager.ThermalManager

**Return value**

| Type          | Description    |
| ------------ | ------ |
| ThermalLevel | Thermal level.|

**Example**

```js
let level = thermal.getThermalLevel();
console.info('thermal level is: ' + level);
```

## ThermalLevel

Enumerates thermal levels.

**System capability:** SystemCapability.PowerManager.ThermalManager

| Name      | Value  | Description                                                        |
| ---------- | ---- | ------------------------------------------------------------ |
| COOL       | 0    | The device is cool, and services are not restricted.            |
| NORMAL     | 1    | The device is in the normal temperature range but it is getting warm. You need to downgrade or reduce the load of imperceptible services.|
| WARM       | 2    | The device is warm. You need to stop or delay some imperceptible services.|
| HOT        | 3    | The device is heating up. You need to stop all imperceptible services and downgrade or reduce the load of non-critical services.|
| OVERHEATED | 4    | The device is overheated. You need to stop all imperceptible services and downgrade or reduce the load of major foreground services.|
| WARNING    | 5    | The device is overheated and is about to enter the emergency state. You need to stop all imperceptible services and downgrade major foreground services to the maximum extent.|
| EMERGENCY  | 6    | The device has entered the emergency state. You need to stop all services except those for fundamental use.|
| ESCAPE<sup>11+</sup>     | 7    | The device is about to enter the escape state. You need to stop all services and take necessary emergency measures such as data backup.<br>Note: This API is supported since API version 11.|