在Android 8.0之后版本上添加Hidl Service
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
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package android.hardware.led@
1.0;
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interface
ILed
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{
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//get led status
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get() generates (LedStatus result);
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//set led status
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set(LedStatus val) generates(int32_t ret);
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getBrightnessRange() generates(
bool ret,BrightnessRange range);
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setBrightnessValue(vec
range) generates(
bool ret);
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on() ;
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off() ;
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};
hardware/interfaces/led/1.0/types.hal
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package android.hardware.led@
1.0;
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-
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enum LedStatus : uint32_t {
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LED_ON,
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LED_OFF,
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LED_BAD_VALUE,
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};
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struct BrightnessRange {
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uint32_t
min;
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uint32_t
max;
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};
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
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#ifndef ANDROID_HARDWARE_LED_V1_0_LED_H
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#define ANDROID_HARDWARE_LED_V1_0_LED_H
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#include
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#include
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#include
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-
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namespace android {
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namespace hardware {
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namespace led {
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namespace V1_0 {
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namespace implementation {
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using ::android::hardware::led::V1_0::LedStatus;
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using ::android::hardware::led::V1_0::BrightnessRange;
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using ::android::hardware::led::V1_0::ILed;
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using ::android::hardware::hidl_array;
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using ::android::hardware::hidl_string;
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using ::android::hardware::hidl_vec;
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using ::android::hardware::Return;
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using ::android::hardware::Void;
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using ::android::sp;
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struct ledImpl :
public ILed {
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public:
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ledImpl();
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Return
get() override ;
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Return<
int32_t>
set(LedStatus val) override;
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Return<
void> on() override;
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Return<
void> off() override;
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Return<
void> getBrightnessRange(getBrightnessRange_cb _hidl_cb) override;
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Return<
bool> setBrightnessValue(
const hidl_vec<
int32_t>& range) override;
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private:
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LedStatus state;
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};
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extern
"C"
ILed* HIDL_FETCH_ILed(const char* name);
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}
// namespace implementation
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}
// namespace V1_0
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}
// namespace led
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}
// namespace hardware
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}
// namespace android
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#endif //ANDROID_HARDWARE_LED_V1_0_LED_H
hardware/interfaces/led/1.0/default/ledImpl.cpp
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#define LOG_TAG "LedService"
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#include
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#include "ledImpl.h"
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namespace android {
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namespace hardware {
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namespace led {
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namespace V1_0 {
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namespace implementation {
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ledImpl::ledImpl() {
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state = LedStatus::LED_BAD_VALUE;
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ALOGE(
"ledImpl Init status:%d", state);
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}
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Return<
void> ledImpl::on() {
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state = LedStatus::LED_ON;
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ALOGE(
"ledImpl on status:%d", state);
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return Void();
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}
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Return<
void> ledImpl::off() {
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state = LedStatus::LED_OFF;
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ALOGE(
"ledImpl off status:%d", state);
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return Void();
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}
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Return
ledImpl::get() {
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return state;
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}
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Return<
int32_t> ledImpl::
set(LedStatus val) {
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if(val == LedStatus::LED_OFF || val == LedStatus::LED_ON)
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state = val;
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else
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return
-1;
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return
0;
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}
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Return<
void> ledImpl::getBrightnessRange(getBrightnessRange_cb _hidl_cb)
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{
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ALOGE(
"ledImpl getBrightnessRange ");
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BrightnessRange range;
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range.max =
100;
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range.min =
1;
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_hidl_cb(
true,range);
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return Void();
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}
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Return<
bool> ledImpl::setBrightnessValue(
const hidl_vec<
int32_t>& range)
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{
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ALOGE(
"ledImpl getBrightnessValue ");
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auto
iter = range.begin();
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ALOGE(
"ledImpl getBrightnessValue range.begin: %d",*iter);
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iter = range.end();
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ALOGE(
"ledImpl getBrightnessValue range.end: %d",*iter);
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ALOGE(
"ledImpl getBrightnessValue range.size: %zu",range.size());
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return
true;
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}
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ILed* HIDL_FETCH_ILed(const char * /*name*/) {
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ALOGE(
"ledImpl HIDL_FETCH_ILed ");
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return
new ledImpl();
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}
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}
// namespace implementation
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}
// namespace V1_0
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}
// namespace led
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}
// namespace hardware
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}
// namespace android
hardware/interfaces/led/1.0/default/Android.bp
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cc_library_shared {
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name:
"[email protected]",
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defaults: [
"hidl_defaults"],
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srcs: [
"ledImpl.cpp"],
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shared_libs: [
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"libhidlbase",
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"libhidltransport",
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"libhardware",
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"liblog",
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"libutils",
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],
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}
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cc_binary {
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name:
"[email protected]",
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init_rc: [
"[email protected]"],
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srcs: [
"service.cpp",
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"ledImpl.cpp"],
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shared_libs: [
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"liblog",
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"libhardware",
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"libhidlbase",
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"libhidltransport",
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"libutils",
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],
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}
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
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#define LOG_TAG "[email protected]"
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#include
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#include
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#include "ledImpl.h"
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using android::hardware::led::V1_0::ILed;
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using android::hardware::led::V1_0::implementation::ledImpl;
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using android::hardware::defaultPassthroughServiceImplementation;
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using android::hardware::configureRpcThreadpool;
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using android::hardware::joinRpcThreadpool;
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using android::sp;
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int main() {
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#if 0
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// Passthrough dlopen so方式
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return defaultPassthroughServiceImplementation
();
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#else
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// Binder 方式
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sp
service =
new ledImpl();
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configureRpcThreadpool(
1,
true
/*callerWillJoin*/);
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if(android::OK != service->registerAsService())
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return
1;
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joinRpcThreadpool();
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#endif
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}
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/
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<hal format="hidl">
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<name>android.hardware.led
name>
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<transport>hwbinder
transport> //hwbinder 或者passthrough （直通模式）
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<version>1.0
version>
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<interface>
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<name>ILed
name>
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<instance>default
instance>
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interface>
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hal>
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：
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LOCAL_JAVA_LIBRARIES += android.hardware.led-V1.0-java
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/*
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LOCAL_STATIC_JAVA_LIBRARIES += android.hardware.led-V1.0-java-static
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*/
或将以下内容添加到 Android.bp 中：
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shared_libs: [
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/* … */
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"android.hardware.led-V1.0-java",
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],
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：
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import android.hardware.led.V1_0.ILed;
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...
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// retry to wait until the service starts up if it is in the manifest
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ILed server =
ILed.getService(
/* retry */);
// throws NoSuchElementException if not available
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server.on();
5.2 实现C++ 调用hidl service的例子
首先将 HAL 库添加到 makefile 中：
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Make：LOCAL_SHARED_LIBRARIES += android.hardware.led@1.
0
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Soong：shared_libs: [ …, android.hardware.led@1.
0 ]
接下来，添加 HAL 头文件：
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#include
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…
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// in code:
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sp
client = ILed::getService();
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client->on();
下面是我的Demo clinet
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#define LOG_TAG "LED_CLINET"
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#include
<android/hardware/led/1.0/ILed.h>
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#include
<log/log.h>
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using android::hardware::led::V1_0::ILed;
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using android::hardware::led::V1_0::LedStatus;
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using android::hardware::led::V1_0::BrightnessRange;
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using android::hardware::hidl_vec;
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using android::sp;
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int main(){
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// BrightnessRange range;
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sp
<ILed> service = ILed::getService();
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if( service == nullptr ){
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ALOGE("Can't find ILed service...");
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return -1;
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}
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ALOGE("ILed ON");
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service->on();
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ALOGE("ILed OFF");
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service->off();
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ALOGE("ILed set");
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service->set(LedStatus::LED_ON);
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ALOGE("ILed get");
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LedStatus ret = service->get();
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ALOGE("ILed get: %d",ret);
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service->getBrightnessRange([](bool ret1,BrightnessRange range){
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ALOGE("ILed getBrightnessRange ret: %d",ret1);
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ALOGE("ILed getBrightnessRange Max: %d",range.max);
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ALOGE("ILed getBrightnessRange Min: %d",range.min);
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});
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int32_t array[] = {5, 6, 7};
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hidl_vec
<int32_t> hv1 = std::vector
<int32_t>(array, array + 3);
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bool ret2 = service->setBrightnessValue(hv1);
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ALOGE("ILed getBrightnessValue bool: %d",ret2);
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return 0;
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}
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