小熊派添加自定义JS API接口流程（以点亮LED为例）-51CTO.COM
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之前我们开发了小熊派的LED灯驱动，并且编写了相应的代码调用自己的开发驱动，但是自己写的代码只能在终端以命令的形式调用，显然这样十分的不太友好。假设小熊派是我们的一个智能设备，这个LED是我们的手电筒，通过命令行的形式打开手电筒肯定不是我们所期待的，我们更希望能够在图像界面上点一个按钮从而打开我们的手电筒，而目前OpenHarmony大多数采用JS开发应用，如果我们想要在图形界面上打开我们的手电筒，就需要自己定义一个JS的API接口来调用我们的LED。本文便介绍了如何自定义JS API从而调用自己开发的驱动。
二、流程总览
添加JS API接口–>编写接口代码–>配置HDF头文件路径–>添加编译依赖
三、添加JS API接口
打开文件foundation\ace\ace_engine_lite\frameworks\src\core\modules\app_module.h，在32行处添加如下代码
static JSIValue ToggleLed(const JSIValue thisVal, const JSIValue* args, uint8_t argsNum);
在65行处添加如下代码
JSI::SetModuleAPI(exports, "ledcontrol", AppModule::ToggleLed);
四、编写对应的驱动代码
打开foundation\ace\ace_engine_lite\frameworks\src\core\modules\app_module.cpp文件，需要在两个位置添加我们自己API的代码
4.1添加头文件
在头文件导入处添加如下头文件
#include "hdf_sbuf.h"
#include "hdf_io_service_if.h"
#define LED_WRITE_READ 1
#define LED_SERVICE "hdf_led"
4.2添加API的代码
在适当位置加入以下代码，建议在JSIValue AppModule::GetInfo函数之前
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();
}代码推荐添加位置如图所示
五、配置HDF头文件路径
打开foundation\ace\ace_engine_lite\ace_lite.gni文件，在大约80行处添加如下配置
ace_lite_include_dirs += [
"//drivers/framework/ability/sbuf/include",
"//drivers/framework/include/core",
"//drivers/framework/include/utils",
"//drivers/adapter/uhdf/posix/include",
]
六、添加编译依赖
打开foundation\ace\ace_engine_lite\frameworks\BUILD.gn，在public_deps中添加以下代码
"//drivers/adapter/uhdf/manager:hdf_core",打开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",https://harmonyos.51cto.com
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