#鸿蒙通关秘籍#如何在鸿蒙下对N-API异步操作进行优化？

异步操作优化可以通过将耗时任务用异步方式实现。首先，用napi_create_promise接口创建Promise，然后执行耗时任务并将结果传递给Promise，接着使用napi_resolve_deferred或napi_reject_deffered方法来处理结果。以下是一个示例：

cpp struct AddonData { napi_async_work asyncWork = nullptr; napi_deferred deferred = nullptr; napi_ref callback = nullptr;

double args[2] = {0};
double result = 0;
1.
2.

};

static void addExecuteCB(napi_env env, void *data) { AddonData *addonData = (AddonData *)data; addonData->result = addonData->args[0] + addonData->args[1]; }

static void addPromiseCompleteCB(napi_env env, napi_status status, void *data) { AddonData *addonData = (AddonData *)data; napi_value result = nullptr; napi_create_double(env, addonData->result, &result); napi_resolve_deferred(env, addonData->deferred, result);

if (addonData->callback != nullptr) {
    napi_delete_reference(env, addonData->callback);
}

napi_delete_async_work(env, addonData->asyncWork);
delete addonData;
addonData = nullptr;
1.
2.
3.
4.
5.
6.
7.

}

static napi_value addPromise(napi_env env, napi_callback_info info) { size_t argc = 2; napi_value args[2]; napi_value thisArg = nullptr; napi_get_cb_info(env, info, &argc, args, &thisArg, nullptr);

napi_value promise = nullptr;
napi_deferred deferred = nullptr;
napi_create_promise(env, &deferred, &promise);

auto addonData = new AddonData{
    .asyncWork = nullptr,
    .deferred = deferred,
};

napi_get_value_double(env, args[0], &addonData->args[0]);
napi_get_value_double(env, args[1], &addonData->args[1]);

napi_value resourceName = nullptr;
napi_create_string_utf8(env, "addAsyncCallback", NAPI_AUTO_LENGTH, &resourceName);
napi_create_async_work(env, nullptr, resourceName, addExecuteCB, addPromiseCompleteCB, (void *)addonData,
                       &addonData->asyncWork);

napi_queue_async_work(env, addonData->asyncWork);

return promise;
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.

}