一、JS API接口开发
二、运行测试

📝 编写通过JS应用控制LED灯

在本示例将演示如何在系统中添加自定义JS API，达到能通过JS应用关闭灯、开启灯以及翻转灯的状态。希望通过本教程的学习，开发者能掌握如何在OpenHarmony中自定义JS API。

注: 在学习本教程之前，请确保已经完成编写一个点亮LED灯程序实验，因为本实验将依赖编写一个点亮LED灯程序实验中开发的驱动，以下教程篇幅较长，请耐心仔细阅读。

一、JS API接口开发

添加控制LED灯的JS API接口

修改foundation\ace\ace_engine_lite\frameworks\src\core\modules\app_module.h，加入toggleLed JS API,（"##start##"和"##end##"仅用来标识位置，添加完配置后删除这两行）

public:
ACE_DISALLOW_COPY_AND_MOVE(AppModule);
AppModule() = default;
~AppModule() = default;
static JSIValue GetInfo(const JSIValue thisVal, const JSIValue *args, uint8_t argsNum);
static JSIValue Terminate(const JSIValue thisVal, const JSIValue *args, uint8_t argsNum);
##start##
static JSIValue ToggleLed(const JSIValue thisVal, const JSIValue* args, uint8_t argsNum);
##end##
#ifdef FEATURE_SCREEN_ON_VISIBLE
    static JSIValue ScreenOnVisible(const JSIValue thisVal, const JSIValue *args, uint8_t argsNum);
#endif

void InitAppModule(JSIValue exports)
{
    JSI::SetModuleAPI(exports, "getInfo", AppModule::GetInfo);
    JSI::SetModuleAPI(exports, "terminate", AppModule::Terminate);
##start##
    JSI::SetModuleAPI(exports, "ledcontrol", AppModule::ToggleLed);
##end##
#ifdef FEATURE_SCREEN_ON_VISIBLE
    JSI::SetModuleAPI(exports, "screenOnVisible", AppModule::ScreenOnVisible);
#endif
}

编写控制LED灯c++ 业务代码

在foundation\ace\ace_engine_lite\frameworks\src\core\modules\app_module.cpp中加入控制LED灯c++ 业务代码（"##start##"和"##end##"仅用来标识位置，添加完配置后删除这两行）。

#include "app_module.h"
#include "ace_log.h"
#include "js_app_context.h"
#ifdef FEATURE_SCREEN_ON_VISIBLE
#include "js_async_work.h"
#include "product_adapter.h"
#endif

##start##
#include "hdf_sbuf.h"
#include "hdf_io_service_if.h"

#define LED_WRITE_READ 1
#define LED_SERVICE "hdf_led"
##end##

namespace OHOS {
namespace ACELite {
const char * const AppModule::FILE_MANIFEST = "manifest.json";
const char * const AppModule::KEY_APP_NAME = "appName";
const char * const AppModule::KEY_VERSION_NAME = "versionName";
const char * const AppModule::KEY_VERSION_CODE = "versionCode";

struct AsyncParams : public MemoryHeap {
    ACE_DISALLOW_COPY_AND_MOVE(AsyncParams);
    AsyncParams() : result(nullptr), callback(nullptr), context(nullptr) {}

    JSIValue result;
    JSIValue callback;
    JSIValue context;
};
#endif

##start##

static int OnDevEventReceived(void *priv, uint32_t id, struct HdfSBuf *data)
{
    uint32_t value;
    HdfSbufReadUint32(data, &value);
    HILOG_ERROR(HILOG_MODULE_ACE,"%s: dev event received: %u %u\n", (char *)priv, id, value);

    return HDF_SUCCESS;
}

static int GpioWriteRead(struct HdfIoService *serv, int32_t eventData, int32_t *val)
{
    int ret = HDF_FAILURE;
    struct HdfSBuf *data = HdfSBufObtainDefaultSize();
    struct HdfSBuf *reply = HdfSBufObtainDefaultSize();

    if (data == NULL || reply == NULL) {
        HILOG_ERROR(HILOG_MODULE_ACE,"fail to obtain sbuf data\n");
        return ret;
    }

    if (!HdfSbufWriteUint8(data, (uint8_t)eventData))
    {
        HILOG_ERROR(HILOG_MODULE_ACE,"fail to write sbuf\n");
        HdfSBufRecycle(data);
        HdfSBufRecycle(reply);
        return ret;
    }

    ret = serv->dispatcher->Dispatch(&serv->object, LED_WRITE_READ, data, reply);
    if (ret != HDF_SUCCESS)
    {
        HILOG_ERROR(HILOG_MODULE_ACE,"fail to send service call\n");
        HdfSBufRecycle(data);
        HdfSBufRecycle(reply);
        return ret;
    }
    if (!HdfSbufReadInt32(reply, val))
    {
        HILOG_ERROR(HILOG_MODULE_ACE,"fail to get service call reply\n");
        ret = HDF_ERR_INVALID_OBJECT;
        HdfSBufRecycle(data);
        HdfSBufRecycle(reply);
        return ret;
    }
    HILOG_ERROR(HILOG_MODULE_ACE,"Get reply is: %d\n", val);

    HdfSBufRecycle(data);
    HdfSBufRecycle(reply);
    return ret;
}

JSIValue AppModule::ToggleLed(const JSIValue thisVal, const JSIValue *args, uint8_t argsNum)
{
    HILOG_ERROR(HILOG_MODULE_ACE, "led button pressed.");

    struct HdfIoService *serv = HdfIoServiceBind(LED_SERVICE);
    if (serv == NULL)
    {
        HILOG_ERROR(HILOG_MODULE_ACE,"fail to get service2 %s\n", LED_SERVICE);
        return JSI::CreateUndefined();
    }

    if ((args == nullptr) || (argsNum == 0) || (JSI::ValueIsUndefined(args[0]))) {
        return JSI::CreateUndefined();
    }

    JSIValue success = JSI::GetNamedProperty(args[0], CB_SUCCESS);
    JSIValue fail = JSI::GetNamedProperty(args[0], CB_FAIL);
    JSIValue complete = JSI::GetNamedProperty(args[0], CB_COMPLETE);

    int32_t num = (int32_t)JSI::GetNumberProperty(args[0], "code");

    int32_t replyData = 0;

    if (GpioWriteRead(serv, num, &replyData))
    {
        HILOG_ERROR(HILOG_MODULE_ACE,"fail to send event\n");
        JSI::CallFunction(fail, thisVal, nullptr, 0);
        JSI::CallFunction(complete, thisVal, nullptr, 0);
        JSI::ReleaseValueList(success, fail, complete);
        return JSI::CreateUndefined();
    }

    JSIValue result = JSI::CreateObject();
    JSI::SetNumberProperty(result, "led_status", replyData);

    JSIValue argv[ARGC_ONE] = {result};
    JSI::CallFunction(success, thisVal, argv, ARGC_ONE);
    JSI::CallFunction(complete, thisVal, nullptr, 0);
    JSI::ReleaseValueList(success, fail, complete, result);

    HdfIoServiceRecycle(serv);

    return JSI::CreateUndefined();
}

##end##

JSIValue AppModule::GetInfo(const JSIValue thisVal, const JSIValue *args, uint8_t argsNum)
{
    JSIValue result = JSI::CreateUndefined();

    cJSON *manifest = ReadManifest();
    if (manifest == nullptr) {
        HILOG_ERROR(HILOG_MODULE_ACE, "Fail to get the content of manifest.");
        return result;
    }

    cJSON *appName = cJSON_GetObjectItem(manifest, KEY_APP_NAME);
    cJSON *versionName = cJSON_GetObjectItem(manifest, KEY_VERSION_NAME);
    cJSON *versionCode = cJSON_GetObjectItem(manifest, KEY_VERSION_CODE);

    result = JSI::CreateObject();
    if (appName != nullptr && appName->type == cJSON_String) {
        JSI::SetStringProperty(result, KEY_APP_NAME, appName->valuestring);
    }
    if (versionName != nullptr && versionName->type == cJSON_String) {
        JSI::SetStringProperty(result, KEY_VERSION_NAME, versionName->valuestring);
    }
    if (versionCode != nullptr && versionCode->type == cJSON_Number) {
        JSI::SetNumberProperty(result, KEY_VERSION_CODE, versionCode->valuedouble);
    }
    cJSON_Delete(manifest);
    manifest = nullptr;
    return result;
}

配置HDF头文件路径

在foundation\ace\ace_engine_lite\ace_lite.gni中添加HDF头文件路径。

ace_lite_include_dirs += [
    "//drivers/framework/ability/sbuf/include",
    "//drivers/framework/include/core",
    "//drivers/framework/include/utils",
    "//drivers/adapter/uhdf/posix/include",
]

添加编译依赖
修改foundation\ace\ace_engine_lite\frameworks\BUILD.gn，在public_deps中添加以下代码
```
"//drivers/adapter/uhdf/manager:hdf_core",
```
修改foundation\ace\ace_engine_lite\test\ace_test_config.gni，在extra_deps中添加以下代码
```
"//drivers/adapter/uhdf/manager:hdf_core",
```

二、运行测试

示例代码编译、烧录后，参考如何在开发板上安装HAP应用教程安装applications/BearPi/BearPi-HM_Micro/tools/hap_tools/hap_example目录下的LED.hap应用进行测试