android hidl简单实例1
刚接触android 的hidl，项目中要用到，就尝试写了一个简单的实例。
一、定义HIDL接口文件
1.进入hardware/interfaces/目录下建立新的接口文件
首先建立对应的文件夹：android/hardware/interfaces/sample/1.0/default
接着在android/hardware/interfaces/sample/1.0/目录创建接口描述文件ISample.hal
android/hardware/interfaces/sample/1.0/ISample.hal内容如下：
package [email protected];
interface ISample {
helloWorld(string name) generates (string result);
init();
};2.通过hidl-gen工具（源码中编译生成hidl-gen）生成Sample.cpp，Sample.h ,Android.bp文件。 步骤如下：
1.source build/envsetup.sh
2.lunch 9 （根据自己的项目选）
3.export [email protected] //设置变量
4.export LOC=hardware/interfaces/sample/1.0/default/ //设置变量生成目录的所在地
5.hidl-gen -o $LOC -Lc++-impl -randroid.hardware:hardware/interfaces -randroid.hidl:system/libhidl/transport $PACKAGE
//在hardware/interfaces/sample/1.0/default/生成Sample.cpp和Sample.h
6.hidl-gen -o $LOC -Landroidbp-impl -randroid.hardware:hardware/interfaces -randroid.hidl:system/libhidl/transport $PACKAGE
//在hardware/interfaces/sample/1.0/default/生成Android.bp
7.在android目录下执行 ./hardware/interfaces/update-makefiles.sh
在hardware/interfaces/sample/1.0/目录下生成Android.bp
这时文件目录结构如下
@user-virtual-machine:~/android/hardware/interfaces/sample$ ls 1.0/
Android.bp default ISample.hal
@user-virtual-machine:~/android/hardware/interfaces/sample$ ls 1.0/default/
Android.bp Sample.cpp Sample.h
生成的代码如下：
3.android/hardware/interfaces/sample/1.0/default/Sample.h
去掉注释．采用直通模式
//extern "C" ISample* HIDL_FETCH_ISample(const char* name);android/hardware/interfaces/sample/1.0/default/Sample.h内容如下
#ifndef ANDROID_HARDWARE_SAMPLE_V1_0_SAMPLE_H
#define ANDROID_HARDWARE_SAMPLE_V1_0_SAMPLE_H
#include
#include
#include
namespace android {
namespace hardware {
namespace sample {
namespace V1_0 {
namespace implementation {
using ::android::hardware::hidl_array;
using ::android::hardware::hidl_memory;
using ::android::hardware::hidl_string;
using ::android::hardware::hidl_vec;
using ::android::hardware::Return;
using ::android::hardware::Void;
using ::android::sp;
struct Sample : public ISample {
// Methods from ::android::hardware::sample::V1_0::ISample follow.
Return helloWorld(const hidl_string& name, helloWorld_cb _hidl_cb) override;
Return init() override;
// Methods from ::android::hidl::base::V1_0::IBase follow.
};
// FIXME: most likely delete, this is only for passthrough implementations
extern "C" ISample* HIDL_FETCH_ISample(const char* name);
} // namespace implementation
} // namespace V1_0
} // namespace sample
} // namespace hardware
} // namespace android
#endif // ANDROID_HARDWARE_SAMPLE_V1_0_SAMPLE_H 4.android/hardware/interfaces/sample/1.0/default/Sample.cpp
//ISample* HIDL_FETCH_ISample(const char* /* name */) {
// return new Sample();
//}去掉上面的注释
android/hardware/interfaces/sample/1.0/default/Sample.cpp内容如下
#include "Sample.h"
namespace android {
namespace hardware {
namespace sample {
namespace V1_0 {
namespace implementation {
// Methods from ::android::hardware::sample::V1_0::ISample follow.
Return Sample::helloWorld(const hidl_string& name, helloWorld_cb _hidl_cb) {
// TODO implement
return Void();
}
Return Sample::init() {
// TODO implement
return Void();
}
// Methods from ::android::hidl::base::V1_0::IBase follow.
ISample* HIDL_FETCH_ISample(const char* /* name */) {
return new Sample();
}
//
} // namespace implementation
} // namespace V1_0
} // namespace sample
} // namespace hardware
} // namespace android
5.上面大部分都是通过hidl工具生成的，下面完善一下接口代码。
android/hardware/interfaces/sample/1.0/default/Sample.cpp
#include "Sample.h"
#define LOG_TAG "xingchen"
#include
namespace android {
namespace hardware {
namespace sample {
namespace V1_0 {
namespace implementation {
// Methods from ::android::hardware::sample::V1_0::ISample follow.
Return Sample::helloWorld(const hidl_string& name, helloWorld_cb _hidl_cb) {
// TODO implement
char buf[128];
::memset(buf,0,128);
::snprintf(buf,128,"Hello World,%s",name.c_str());
hidl_string result(buf);
_hidl_cb(result);
//ALOGI("xingchen helloWorld Sample:: ___%s__",__fun__);
ALOGI("xingchen helloWorld Sample::----");
return Void();
}
Return Sample::init() {
// TODO implement
//ALOGI("xingchen Sample:: ___%s__",__fun__);
ALOGI("xingchen Sample::---");
return Void();
}
// Methods from ::android::hidl::base::V1_0::IBase follow.
ISample* HIDL_FETCH_ISample(const char* /* name */) {
return new Sample();
}
//
} // namespace implementation
} // namespace V1_0
} // namespace sample
} // namespace hardware
} // namespace android
6.android/hardware/interfaces/sample/1.0/default/Android.bp
android/hardware/interfaces/sample/1.0/default/Android.bp内容如下
cc_library_shared {
// FIXME: this should only be -impl for a passthrough hal.
// In most cases, to convert this to a binderized implementation, you should:
// - change '-impl' to '-service' here and make it a cc_binary instead of a
// cc_library_shared.
// - add a *.rc file for this module.
// - delete HIDL_FETCH_I* functions.
// - call configureRpcThreadpool and registerAsService on the instance.
// You may also want to append '-impl/-service' with a specific identifier like
// '-vendor' or '-' etc to distinguish it.
name: "[email protected]",
relative_install_path: "hw",
// FIXME: this should be 'vendor: true' for modules that will eventually be
// on AOSP.
proprietary: true,
srcs: [
"Sample.cpp",
],
shared_libs: [
"libhidlbase",
"libhidltransport",
"libhardware",
"libutils",
"liblog",
"[email protected]",
],
} 7.到这里基本上代码就写完了，大部分都是生成的,下面开始编译.
mmm hardware/interfaces/sample/1.0/default/ 生成库文件
/vendor/lib64/hw/[email protected]
/vendor/lib/hw/[email protected]
/system/lib64/[email protected]
/system/lib/[email protected]二、构建binder service
1.现在有了库，我们还需要构建binder通信服务．
文件名：hardware/interfaces/sample/1.0/default/[email protected]
代码
service sample_service /vendor/bin/hw/[email protected]
class hal
user system
group system
seclabel u:r:init:s0 //我的android9.0的环境关闭了selinux所以加上这行2.设定sample_service服务．接下来完善服务代码：
文件路径：android/hardware/interfaces/sample/1.0/default/service.cpp
代码：
#define LOG_TAG "[email protected]"
#include
#include //need log lib
using android::hardware::sample::V1_0::ISample;
using android::hardware::defaultPassthroughServiceImplementation;
int main()
{
return defaultPassthroughServiceImplementation();
} 3.在Android.bp中添加对服务器的编译：
文件路径：android/hardware/interfaces/sample/1.0/default/Android.bp
在文件最后面加上以下代码
cc_binary {
name: "[email protected]",
defaults: ["hidl_defaults"],
proprietary: true,
relative_install_path: "hw",
srcs: ["service.cpp"],
init_rc: ["[email protected]"],
shared_libs: [
"libhidlbase",
"libhidltransport",
"libhardware",
"libutils",
"liblog",
"[email protected]",
],
}4.android/hardware/interfaces/sample/1.0/default/如下
为了让服务器被客户端访问到，还需要在device/autochips/ac8257_demo/manifest.xml（不同厂商路径不同）添加如下：
android.hardware.sample
hwbinder
1.0
ISample
default
5.mmm编译生成库文件和service文件
mmm hardware/interfaces/sample/1.0/default/ 生成库文件和service文件
/vendor/lib64/hw/[email protected]
/vendor/lib/hw/[email protected]
/system/lib64/[email protected]
/system/lib/[email protected]
/vendor/etc/init/[email protected] (在out目录删除文件，项目全编的时候不会生成)
/vendor/bin/hw/[email protected](在out目录删除文件，项目全编的时候不会生成)6.修改build/make/target/product/vndk/28.txt和 build/make/target/product/vndk/current.txt
添加如下，记得按照字母排列顺序位置添加
+VNDK-core: [email protected]
三、添加测试程序
/hardware/interfaces/sample/client/helloworld.cpp
文件路径：/hardware/interfaces/sample/client/helloworld.cpp
代码：
#include
#include
#include
#include
#include
#include
using android::hardware::sample::V1_0::ISample;
using android::sp;
using android::hardware::hidl_string;
int main()
{
android::sp service = ISample::getService();
if(service == nullptr){
printf("xingchen Failed to get service\n");
return -1;
}
printf("xingchen succeed to get service\n");
service->init();
return 0;
} /hardware/interfaces/sample/client/Android.mk
文件路径：/hardware/interfaces/sample/client/Android.mk
代码：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_PROPRIETARY_MODULE := true
LOCAL_MODULE := helloworld
LOCAL_SRC_FILES := helloworld.cpp
LOCAL_SHARED_LIBRARIES := \
liblog \
libhidlbase \
libutils \
[email protected] \
include $(BUILD_EXECUTABLE)四、把上面的service，rc和client端的可执行文件helloworld打包进固件.
/device/autochips/ac8257/device.mk文件中加入代码
PRODUCT_PACKAGES += helloworld
PRODUCT_PACKAGES += \
[email protected] \
[email protected]五、全编整个工程并烧入机器。
在全编之前可以把out目录下的上面mmm出来的文件删除,确保全编的时候相关文件可以一起编译出来。
cd out/target/product/ac8257_demo/
find ./system -name "*android.hardware.sample*" | xargs rm -rf
find ./vendor -name "*android.hardware.sample*" | xargs rm -rf/vendor/lib64/hw/[email protected]
/vendor/lib/hw/[email protected]
/system/lib64/[email protected]
/system/lib/[email protected]
/vendor/etc/init/[email protected]
/vendor/bin/hw/[email protected] (服务端)
/vendor/bin/helloworld (客户端)六、启动机器 ps - A | grep [email protected] 发现server已经起来了
logcat -s xingchen & 然后执行客户端helloworld
客户端已经成功调用服务器的接口.
七、遇到的问题
1. 在调试的时候手动执行/vendor/bin/hw/[email protected]出现
CANNOT LINK EXECTABLE ...... :library ......;错误
原因是在hardware/interfaces/sample/1.0/default/Android.bp中加入了"[email protected]"导致的，删除即可。
cc_binary {
name: "[email protected]",
defaults: ["hidl_defaults"],
proprietary: true,
relative_install_path: "hw",
srcs: ["service.cpp"],
init_rc: ["[email protected]"],
shared_libs: [
"libhidlbase",
"libhidltransport",
"libhardware",
"libutils",
"liblog",
"[email protected]",
"[email protected]", //加入这行导致,删除即可，网上参考，想不到这个地方是个坑
],
}