# @ohos.selectionInput.SelectionExtensionContext (划词扩展上下文)

> 2in1 24+

SelectionExtensionContext是[SelectionExtensionAbility](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-selectioninput-selectionextensionability)的上下文，继承自[ExtensionContext](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-inner-application-extensioncontext)。

每个SelectionExtensionAbility组件实例化时，系统都会自动创建对应的SelectionExtensionContext。开发者可以通过SelectionExtensionContext调用[startAbility](#startability)接口拉起同应用内其他Ability。适用于在划词扩展场景中需要跳转至应用内其他Ability的情况，帮助用户在划词操作后快速获取与划词内容关联的功能或信息。
> 说明
>
> * 本模块首批接口从API version 24开始支持。后续版本的新增接口，采用上角标单独标记接口的起始版本。
> * 本模块仅支持PC/2in1设备。开发者可通过canIUse('SystemCapability.SelectionInput.Selection')判断当前设备是否支持该功能。

## 导入模块

```ts
import { SelectionExtensionContext } from '@kit.BasicServicesKit';
```

## SelectionExtensionContext

**系统能力：** SystemCapability.SelectionInput.Selection

**模型约束：** 此接口仅可在Stage模型下使用。

### startAbility

startAbility(want: Want): Promise<void>

拉起同应用内的目标Ability，适用于在划词扩展场景中需要跳转至应用内其他Ability的情况。系统根据Want对象中指定的bundleName和abilityName匹配并调度启动目标Ability。使用Promise异步回调。关于Ability启动机制，请参见[ExtensionContext](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-inner-application-extensioncontext)。

**系统能力：** SystemCapability.SelectionInput.Selection

**模型约束：** 此接口仅可在Stage模型下使用。

**参数：**

|参数名|类型|必填|说明|
|:---|:------------------------------------------------------------------------------------------------------|:-|:-----------------------------------------------------------------------------------------------------------------------------------------|
|want|[Want](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-app-ability-want#want)|是|需要拉起的目标应用信息。主要字段包括bundleName（目标应用的Bundle名称）和abilityName（目标Ability名称）。设置后系统将根据其中指定的bundleName和abilityName查找并拉起对应的Ability。仅支持拉起同应用内的Ability。|

**返回值：**

|类型|说明|
|:------------|:---------------|
|Promise<void>|Promise对象，无返回结果。|

**错误码：**

以下错误码的详细介绍请参见[元能力子系统错误码](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/errorcode-ability)，未标明的通用错误码请参见[通用错误码](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/errorcode-universal)。

|错误码ID|错误信息|
|:-------|:-------------------------------------------------------------------------|
|16000001|The specified ability does not exist.|
|16000002|Incorrect ability type.|
|16000004|Cannot start an invisible component.|
|16000005|The specified process does not have the permission.|
|16000006|Cross-user operations are not allowed.|
|16000008|The crowdtesting application expires.|
|16000009|An ability cannot be started or stopped in Wukong mode.|
|16000010|The call with the continuation and prepare continuation flag is forbidden.|
|16000011|The context does not exist.|
|16000012|The application is controlled.|
|16000013|The application is controlled by EDM.|
|16000019|No matching ability is found.|
|16000050|Internal error.|
|16000053|The ability is not on the top of the UI.|
|16000055|Installation-free timed out.|
|16000061|Operation not supported.|
|16000069|The extension cannot start the third party application.|
|16000070|The extension cannot start the service.|
|16000083|The ExtensionAbility cannot start the ability due to system control.|
|16200001|The caller has been released.|

**示例：**

```ts
import { SelectionExtensionAbility, BusinessError } from '@kit.BasicServicesKit';
import { rpc } from '@kit.IPCKit';
import { Want } from '@kit.AbilityKit';

class SelectionAbilityStub extends rpc.RemoteObject {
  constructor(descriptor: string) {
    super(descriptor);
  }
  onRemoteMessageRequest(
    code: number,
    data: rpc.MessageSequence,
    reply: rpc.MessageSequence,
    options: rpc.MessageOption
  ): boolean | Promise<boolean> {
    console.info(`onRemoteMessageRequest code: ${code}`);
    return true;
  }
}

class SelectionExtAbility extends SelectionExtensionAbility {
  onConnect(want: Want): rpc.RemoteObject {
    try {
      // 构造Want对象，指定要拉起的目标Ability信息
      let wantAbility: Want = {
        bundleName: 'com.selection.selectionapplication',
        abilityName: 'EntryAbility',
      };
      // 拉起目标Ability，this.context由SelectionExtensionAbility实例自动提供，无需额外获取
      this.context.startAbility(wantAbility).then(() => {
        console.info(`startAbility success`);
      }).catch((err: BusinessError) => {
        console.error(`Failed to startAbility. Error code: ${err.code}, error message: ${err.message}`);
      });
    } catch (err) {
      console.error(`Failed to startAbility. Error code: ${err.code}, error message: ${err.message}`);
    }
    return new SelectionAbilityStub('remote');
  }
}
```