创建ServiceAbility

1. 创建ServiceAbility。

   通过DevEco Studio开发平台创建ServiceAbility时，DevEco Studio会默认生成onStart、onStop、onCommand方法，其他方法需要开发者自行实现，接口说明参见前述章节。开发者也可以添加其他Ability请求与ServiceAbility交互时的处理方法，示例如下：

   import { Want } from '@kit.AbilityKit';
   import { rpc } from '@kit.IPCKit';
   import { hilog } from '@kit.PerformanceAnalysisKit';
   
   const TAG: string = '[Sample_FAModelAbilityDevelop]';
   const domain: number = 0xFF00;
   
   class FirstServiceAbilityStub extends rpc.RemoteObject {
     constructor(des: Object) {
       if (typeof des === 'string') {
         super(des);
       } else {
         return;
       }
     }
   
     onRemoteMessageRequest(code: number, data: rpc.MessageSequence, reply: rpc.MessageSequence, option: rpc.MessageOption): boolean {
       hilog.info(domain, TAG, 'ServiceAbility onRemoteRequest called');
       if (code === 1) {
         let string = data.readString();
         hilog.info(domain, TAG, `ServiceAbility string=${string}`);
         let result = Array.from(string).sort().join('');
         hilog.info(domain, TAG, `ServiceAbility result=${result}`);
         reply.writeString(result);
       } else {
         hilog.info(domain, TAG, 'ServiceAbility unknown request code');
       }
       return true;
     }
   }
   
   class ServiceAbility {
     onStart(): void {
       hilog.info(domain, TAG, 'ServiceAbility onStart');
     }
   
     onStop(): void {
       hilog.info(domain, TAG, 'ServiceAbility onStop');
     }
   
     onCommand(want: Want, startId: number): void {
       hilog.info(domain, TAG, 'ServiceAbility onCommand');
     }
   
     onConnect(want: Want): rpc.RemoteObject {
       hilog.info(domain, TAG, 'ServiceAbility onConnect' + want);
       return new FirstServiceAbilityStub('test');
     }
   
     onDisconnect(want: Want): void {
       hilog.info(domain, TAG, 'ServiceAbility onDisconnect' + want);
     }
   }
   
   export default new ServiceAbility();

2. 注册ServiceAbility。

   ServiceAbility需要在应用配置文件config.json中进行注册，注册类型type需要设置为service。"visible"属性表示ServiceAbility是否可以被其他应用调用，true表示可以被其他应用调用，false表示不能被其他应用调用（仅应用内可以调用）。若ServiceAbility需要被其他应用调用，注册ServiceAbility时需要设置"visible"为true，同时需要设置支持关联启动。ServiceAbility的启动规则详见FA模型组件启动规则章节。

   {
     // ...
     "module": {
       // ...
       "abilities": [
         // ...
         {
           "name": ".ServiceAbility",
           "srcLanguage": "ets",
           "srcPath": "ServiceAbility",
           "icon": "$media:icon",
           "description": "$string:ServiceAbility_desc",
           "type": "service",
           "visible": true
         },
         // ...
       ]
       // ...
     }
   }