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1# Worker同步调用宿主线程的接口
2<!--Kit: ArkTS-->
3<!--Subsystem: CommonLibrary-->
4<!--Owner: @lijiamin2025-->
5<!--Designer: @weng-changcheng-->
6<!--Tester: @kirl75; @zsw_zhushiwei-->
7<!--Adviser: @ge-yafang-->
8
9如果一个接口已在宿主线程中实现，Worker可以通过以下方式调用该接口。
10
11以下示例展示了Worker同步调用宿主线程接口的方法，创建worker的方法可参考[创建worker的注意事项](worker-introduction.md#创建worker的注意事项)。
12
131. 首先，在宿主线程实现需要调用的接口，并创建Worker对象，在Worker对象上注册需要调用的对象。
14
15   ```ts
16   // Index.ets
17   import { MessageEvents, worker } from '@kit.ArkTS';
18
19   class TestObj {
20     public getMessage(): string {
21       return "this is a message from TestObj";
22     }
23
24     static testObj: TestObj = new TestObj();
25   }
26
27   @Entry
28   @Component
29   struct Index {
30     @State message: string = 'Hello World';
31
32     build() {
33       Row() {
34         Column() {
35           Text(this.message)
36             .fontSize(50)
37             .fontWeight(FontWeight.Bold)
38             .onClick(() => {
39               // 创建Worker对象
40               const workerInstance: worker.ThreadWorker = new worker.ThreadWorker("entry/ets/workers/Worker.ets");
41               // 在Worker上注册需要调用的对象
42               workerInstance.registerGlobalCallObject("testObj", TestObj.testObj);
43               workerInstance.postMessage("start");
44               workerInstance.onmessage = (e: MessageEvents): void => {
45                 // 接收Worker子线程的结果
46                 console.info("mainthread: " + e.data);
47                 // 销毁Worker
48                 workerInstance.terminate();
49               }
50             })
51         }
52         .width('100%')
53       }
54       .height('100%')
55     }
56   }
57   ```
58   <!-- @[create_worker_obj](https://gitcode.com/openharmony/applications_app_samples/blob/master/code/DocsSample/ArkTS/ArkTsConcurrent/ConcurrentThreadCommunication/InterThreadCommunicationScenario/entry/src/main/ets/managers/WorkerCallGlobalUsage.ets) -->
59
602. 然后，在Worker中通过callGlobalCallObjectMethod接口可以调用宿主线程中的getMessage()方法。
61
62   ```ts
63   // Worker.ets
64   import { ErrorEvent, MessageEvents, ThreadWorkerGlobalScope, worker } from '@kit.ArkTS';
65
66   const workerPort: ThreadWorkerGlobalScope = worker.workerPort;
67
68   workerPort.onmessage = async (e: MessageEvents) => {
69     if (e.data === 'start') {
70       try {
71         // 调用方法
72         let res: string = workerPort.callGlobalCallObjectMethod("testObj", "getMessage", 0) as string;
73         console.info("worker: ", res);
74         if (res === "this is a message from TestObj") {
75           workerPort.postMessage("run function success.");
76         }
77       } catch (error) {
78         // 异常处理
79         console.error("worker: error code is " + error.code + " error message is " + error.message);
80       }
81     }
82   }
83   ```
84   <!-- @[call_main_method](https://gitcode.com/openharmony/applications_app_samples/blob/master/code/DocsSample/ArkTS/ArkTsConcurrent/ConcurrentThreadCommunication/InterThreadCommunicationScenario/entry/src/main/ets/workers/Worker.ets) -->
85