在Android 8.0之后版本上添加Hidl Service

目录

1. 编写hal文件并编译

2. 实现Hidl Interface

3. 编写hdil service

4. 配置manifest.xml

  5. hidl client端调用

 5.1 实现java调用hidl service的例子

5.2 实现C++ 调用hidl service的例子

6. github地址

---

本文以LED为例在aosp上添加HIDL，以熟悉整个过程。

1. 编写hal文件并编译

    在hardware/interfaces/目录下创建led文件夹和基版本1.0，这个版本号分为两部分，major.minor。major版本不变得话，只能添加api，不能修改。

创建ILed.hal和types.hal

hardware/interfaces/led/1.0/ILed.hal

package [email protected];
 
interface ILed
{
  //get led status 
  get() generates (LedStatus result);
  
  
  //set led status 
  set(LedStatus  val) generates(int32_t  ret);
  
  getBrightnessRange() generates(bool ret,BrightnessRange range);
  
  setBrightnessValue(vec range) generates(bool ret);
  
  on() ;
  
  off() ;
 
};

hardware/interfaces/led/1.0/types.hal

package [email protected];


enum LedStatus : uint32_t {
	LED_ON,
	LED_OFF,
	LED_BAD_VALUE,
};


struct BrightnessRange {
    uint32_t min;
 
    uint32_t max;
};

添加完后，执行hardware/interfaces/update-makefiles.sh 会自动生成编译编译脚本，然后在

hardware/interfaces/led/1.0/ 路径下执行mm，会生成所需要得hidl库，接下来我们需要实现hidl interface，供client调用。

 

2. 实现Hidl Interface

首先实现ILed interface的子类ledImpl 得头文件和对应得cpp。

hardware/interfaces/led/1.0/default/ledImpl.h

#ifndef ANDROID_HARDWARE_LED_V1_0_LED_H
#define ANDROID_HARDWARE_LED_V1_0_LED_H
#include 

#include 

#include 




namespace android {
namespace hardware {
namespace led {
namespace V1_0 {
namespace implementation {

using ::android::hardware::led::V1_0::LedStatus;
using ::android::hardware::led::V1_0::BrightnessRange;
using ::android::hardware::led::V1_0::ILed;
using ::android::hardware::hidl_array;
using ::android::hardware::hidl_string;
using ::android::hardware::hidl_vec;
using ::android::hardware::Return;
using ::android::hardware::Void;
using ::android::sp;
	
	
struct ledImpl : public ILed {
	public:
		ledImpl();
		Return  get() override ;
		Return set(LedStatus val) override;
		Return on() override;
		Return off() override;
		Return getBrightnessRange(getBrightnessRange_cb _hidl_cb) override;
		Return setBrightnessValue(const hidl_vec& range) override;
	private:
		LedStatus state;
};
	
extern "C" ILed* HIDL_FETCH_ILed(const char* name);
}  // namespace implementation
}  // namespace V1_0
}  // namespace led
}  // namespace hardware
}  // namespace android

#endif //ANDROID_HARDWARE_LED_V1_0_LED_H

hardware/interfaces/led/1.0/default/ledImpl.cpp

#define LOG_TAG "LedService"

#include 
#include "ledImpl.h"

namespace android {
namespace hardware {
namespace led {
namespace V1_0 {
namespace implementation {

ledImpl::ledImpl() {
	state = LedStatus::LED_BAD_VALUE;
	ALOGE("ledImpl Init status:%d", state);
}

Return ledImpl::on() {
	state = LedStatus::LED_ON;
	ALOGE("ledImpl on status:%d", state);
    return Void();
}

Return ledImpl::off() {
	state = LedStatus::LED_OFF;
	ALOGE("ledImpl off status:%d", state);	
    return Void();
}

Return  ledImpl::get() {
	return state;
}
Return ledImpl::set(LedStatus val) {
	if(val == LedStatus::LED_OFF || val == LedStatus::LED_ON)
		state = val;
	else
		return -1;
	return 0;
}

Return ledImpl::getBrightnessRange(getBrightnessRange_cb _hidl_cb)
{
	ALOGE("ledImpl getBrightnessRange ");
	BrightnessRange range;
	range.max = 100;
	range.min = 1;
	_hidl_cb(true,range);
	return Void();
	
}
  
Return ledImpl::setBrightnessValue(const hidl_vec& range)
{
	ALOGE("ledImpl getBrightnessValue ");
	auto iter = range.begin();
	ALOGE("ledImpl getBrightnessValue range.begin: %d",*iter);
	iter = range.end();
	ALOGE("ledImpl getBrightnessValue range.end: %d",*iter);
	ALOGE("ledImpl getBrightnessValue range.size: %zu",range.size());
	return true;
}

ILed* HIDL_FETCH_ILed(const char * /*name*/) {
	ALOGE("ledImpl HIDL_FETCH_ILed ");	
    return new ledImpl();
}

}  // namespace implementation
}  // namespace V1_0
}  // namespace led
}  // namespace hardware
}  // namespace android

hardware/interfaces/led/1.0/default/Android.bp

cc_library_shared {
    name: "[email protected]",
    defaults: ["hidl_defaults"],
    srcs: ["ledImpl.cpp"],
    shared_libs: [
        "libhidlbase",
        "libhidltransport",
        "libhardware",
        "liblog",
        "libutils",
        "[email protected]",
    ], 
}

cc_binary {
    name: "[email protected]",
    init_rc: ["[email protected]"],
    srcs: ["service.cpp",
      "ledImpl.cpp"],

    shared_libs: [
        "liblog",
        "libhardware",
        "libhidlbase",
        "libhidltransport",
        "libutils",
        "[email protected]",
    ], 

}

3. 编写hdil service

  接下来，使用相应功能填写存根并设置守护进程。可以使用passthrough方式和binder方式，示例：

hardware/interfaces/led/1.0/default/service.cpp

 #define LOG_TAG "[email protected]"

#include 
#include 
#include "ledImpl.h"
using android::hardware::led::V1_0::ILed;
using android::hardware::led::V1_0::implementation::ledImpl;
using android::hardware::defaultPassthroughServiceImplementation;
using android::hardware::configureRpcThreadpool;
using android::hardware::joinRpcThreadpool;
using android::sp;


int main() {
#if 0 
// Passthrough   dlopen so方式
    return defaultPassthroughServiceImplementation(); 
#else
// Binder 方式
  sp service = new ledImpl();
  configureRpcThreadpool(1, true /*callerWillJoin*/);
    if(android::OK !=  service->registerAsService())
      return 1; 
    joinRpcThreadpool();
#endif
}

4. 配置manifest.xml

  add the code to the manifest.xm 以至于hwservicemanager 查找到指定的hidl service

   About HIDL configures

   device///manifest.xml

 
    android.hardware.led
    hwbinder  //hwbinder 或者passthrough （直通模式）  
    1.0
    
     ILed
     default
    
   

  5. hidl client端调用

  hidl service运行后，可以通过C++和Java两种方式调用，非常方便，通过java直接访问，就省去了jni。

 5.1 实现java调用hidl service的例子

  将以下内容添加到 Android.mk 中：

 LOCAL_JAVA_LIBRARIES += android.hardware.led-V1.0-java

/*
 LOCAL_STATIC_JAVA_LIBRARIES += android.hardware.led-V1.0-java-static
*/

  或将以下内容添加到 Android.bp 中：

  shared_libs: [
   /* … */
   "android.hardware.led-V1.0-java",
  ],

  该库还存在静态版：android.hardware.led-V1.0-java-static。

  将以下内容添加到您的 Java 文件中：

  import android.hardware.led.V1_0.ILed;
  ...
  // retry to wait until the service starts up if it is in the manifest
  ILed server = ILed.getService(/* retry */); // throws NoSuchElementException if not available
  server.on();

 

5.2 实现C++ 调用hidl service的例子

 首先将 HAL 库添加到 makefile 中：

  Make：LOCAL_SHARED_LIBRARIES += [email protected]
  Soong：shared_libs: [ …, [email protected] ]

 接下来，添加 HAL 头文件：

  #include 
  …
  // in code:
  sp client = ILed::getService();
  client->on();

下面是我的Demo clinet

 #define LOG_TAG "LED_CLINET"
#include 
#include 

using android::hardware::led::V1_0::ILed;
using android::hardware::led::V1_0::LedStatus;
using android::hardware::led::V1_0::BrightnessRange;
using android::hardware::hidl_vec;
using android::sp;


int main(){
	// BrightnessRange range;
	sp service = ILed::getService();
	if( service == nullptr ){
		ALOGE("Can't find ILed service...");
		return -1;
	}
	ALOGE("ILed ON");
	service->on();
	
	ALOGE("ILed OFF");
	service->off();
	
	ALOGE("ILed set");
	service->set(LedStatus::LED_ON);

	ALOGE("ILed get");
	LedStatus ret = service->get();
	ALOGE("ILed get: %d",ret);
	
	service->getBrightnessRange([](bool ret1,BrightnessRange range){
		ALOGE("ILed getBrightnessRange ret: %d",ret1);
		ALOGE("ILed getBrightnessRange Max: %d",range.max);
		ALOGE("ILed getBrightnessRange Min: %d",range.min);
	});
	int32_t array[] = {5, 6, 7};
	hidl_vec hv1 = std::vector(array, array + 3);
	bool ret2 = service->setBrightnessValue(hv1);
	ALOGE("ILed getBrightnessValue bool: %d",ret2);
	return 0;
}

6. github地址

 需要看代码的可以去我的github，里面有相关的hidl代码，和C++调用示例

gitHub地址链接