创建一个HIDL car property
创建types.hal文件
在vendor/braisedp/interfaces/automotive/vehicle/2.0/新建文件：
// types.hal
package vendor.braisedp.hardware.automotive.vehicle@2.0;
import android.hardware.automotive.vehicle@2.0::VehiclePropertyGroup;
import android.hardware.automotive.vehicle@2.0::VehiclePropertyType;
import android.hardware.automotive.vehicle@2.0::VehicleArea;
enum ExtentVehicleProperty: int32_t{
EXT_PROP = (
0x1000
|VehiclePropertyType:INT32
|VehicleArea:GLOBAL
|VehiclePropertyGroup:VENDOR),
};
通过hidl-gen生成.bp文件
执行shell命令：
hidl-gen -h
Usage: hidl-gen -o <output path> -L <language> [-O <owner>] [-p <root path>] (-r <interface root>)+ [-R] [-v] [-d <depfile>] FQNAME...
Process FQNAME, PACKAGE(.SUBPACKAGE)*@[0-9]+.[0-9]+(::TYPE)?, to create output.
-h: Prints this menu.
-L <language>: The following options are available:
check : Parses the interface to see if valid but doesn't write any files.
c++ : (internal) (deprecated) Generates C++ interface files for talking to HIDL interfaces.
c++-headers : (internal) Generates C++ headers for interface files for talking to HIDL interfaces.
c++-sources : (internal) Generates C++ sources for interface files for talking to HIDL interfaces.
export-header : Generates a header file from @export enumerations to help maintain legacy code.
c++-impl : Generates boilerplate implementation of a hidl interface in C++ (for convenience).
c++-impl-headers: c++-impl but headers only.
c++-impl-sources: c++-impl but sources only.
c++-adapter : Takes a x.(y+n) interface and mocks an x.y interface.
c++-adapter-headers: c++-adapter but helper headers only.
c++-adapter-sources: c++-adapter but helper sources only.
c++-adapter-main: c++-adapter but the adapter binary source only.
java : (internal) Generates Java library for talking to HIDL interfaces in Java.
java-impl : Generates boilerplate implementation of a hidl interface in Java (for convenience).
java-constants : (internal) Like export-header but for Java (always created by -Lmakefile if @export exists).
vts : (internal) Generates vts proto files for use in vtsd.
makefile : (removed) Used to generate makefiles for -Ljava and -Ljava-constants.
androidbp : (internal) Generates Soong bp files for -Lc++-headers, -Lc++-sources, -Ljava, -Ljava-constants, and -Lc++-adapter.
androidbp-impl : Generates boilerplate bp files for implementation created with -Lc++-impl.
hash : Prints hashes of interface in `current.txt` format to standard out.
function-count : Prints the total number of functions added by the package or interface.
dependencies : Prints all depended types.
inheritance-hierarchy: Prints the hierarchy of inherited types as a JSON object.
format : Reformats the .hal files
-O <owner>: The owner of the module for -Landroidbp(-impl)?.
-o <output path>: Location to output files.
-p <root path>: Android build root, defaults to $ANDROID_BUILD_TOP or pwd.
-R: Do not add default package roots if not specified in -r.
-r <package:path root>: E.g., android.hardware:hardware/interfaces.
-v: verbose output.
-d <depfile>: location of depfile to write to.
，查看hidl-gen的命令格式
执行shell命令：
hidl-gen -L androidbp -r vendor.braisedp.hardware:vendor/braisedp/interfaces -r android.hidl:system/libhidl/transport braisedp.hardware.automotive.vehicle@2.0
在当前目录下输出Android.bp文件：
// This file is autogenerated by hidl-gen -Landroidbp.
hidl_interface {
name: "vendor.braisedp.hardware.automotive.vehicle@2.0",
root: "vendor.braisedp.hardware",
srcs: [
"types.hal",
],
interfaces: [
"android.hidl.base@1.0",
"android.hardware.automotive.vehicle@2.0",
],
gen_java: true,
}
配置vendor\braisedp\interfaces下的Android.bp文件：
hidl_package_root{
name: "vendor.braisedp.hardware",
path: "vendor/braisedp/interfaces",
}
执行mm命令进行编译
进入out/target/product/<product-name>/system/framework/，发现生成了两个包：
进入out/target/product/<product-name>/system/lib/，发现生成了如下.so文件:
进入out/soong/.intermediates/vendor/braisedp/interfaces/automotive/vehicle/2.0/，可以看到生成如下内容：
进入out/soong/.intermediates/vendor/braisedp/interfaces/automotive/vehicle/2.0/vendor.braisedp.hardware.automotive.vehicle@2.0_genc++_headers/gen/vendor/braisedp/hardware/automotive/vehicle/2.0/下，发现生成了.h文件:
在外部使用包
在APK中使用jar包
查看生成的jar包结构内容：
，生成了一个类ExtentVehicleProperty，查看类定义：
package vendor.braisedp.hardware.automotive.vehicle.V2_0;
import java.util.ArrayList;
public final class ExtentVechicleProperty {
public static final int EXT_PROP = 557846528;
public ExtentVechicleProperty() {
}
...
}
，可以看到，生成了一个final类，并指定了一个final int类型的静态成员EXT_PROP
在native中使用动态库
查看生成的types.h头文件内容：
#ifndef HIDL_GENERATED_VENDOR_BRAISEDP_HARDWARE_AUTOMOTIVE_VEHICLE_V2_0_TYPES_H
#define HIDL_GENERATED_VENDOR_BRAISEDP_HARDWARE_AUTOMOTIVE_VEHICLE_V2_0_TYPES_H
#include <android/hardware/automotive/vehicle/2.0/types.h>
#include <hidl/HidlSupport.h>
#include <hidl/MQDescriptor.h>
#include <utils/NativeHandle.h>
#include <utils/misc.h>
namespace vendor {
namespace braisedp {
namespace hardware {
namespace automotive {
namespace vehicle {
namespace V2_0 {
// Forward declaration for forward reference support:
enum class ExtentVehicleProperty : int32_t;
enum class ExtentVehicleProperty : int32_t {
EXT_PROP = 557846528 /* (0x1000 | VehiclePropertyType:INT32 | VehicleArea:GLOBAL | VehiclePropertyGroup:VENDOR) */,
};
...
} // namespace V2_0
} // namespace vehicle
} // namespace automotive
} // namespace hardware
} // namespace braisedp
} // namespace vendor
#endif // HIDL_GENERATED_VENDOR_BRAISEDP_HARDWARE_AUTOMOTIVE_VEHICLE_V2_0_TYPES_H
，生成了一个枚举类ExtentVehicleProperty，并指定了一个成员EXT_PROP
创建一个AIDL car property属性
在/vendor/braisedp/vehicle/aidl/vendor/braisedp/vehicle/ExtentVehicleProperty.aidl中创建内容：
package vendor.braisedp.vehicle;
import android.hardware.automotive.vehicle.VehiclePropertyGroup;
import android.hardware.automotive.vehicle.VehiclePropertyType;
import android.hardware.automotive.vehicle.VehicleArea;
@Backing(type="int")
enum ExtentVehicleProperty{
EXT_PROP = 0x1000 + VehiclePropertyGroup.VENDOR + VehicleArea.GLOBAL + VehiclePropertyType.INT32,
}
，并编写/vendor/braisedp/vehicle/aidl/Android.bp文件:
aidl_interface{
name : "vendor.braisedp.vehicle",
srcs : ["vendor/braisedp/vehicle/ExtentVehicleProperty.aidl"],
unstable: true,
vendor_available: true,
imports:["android.hardware.automotive.vehicle.property-V2"],
backend:{
java : {
enabled : true,
sdk_version: "module_current",
apex_available:["com.android.car.framework",],
},
cpp : {
enabled : false,
},
ndk : {
enabled : true,
vndk:{
enabled: false,
}
},
},
}
，打包后，可以在out/soong/.intermediates下看到对应的jar包。
集成property至car-lib
在外部开发时，会用到包android.car，于是要将生成的Property信息放入到该包中，修改/packages/services/Car/car-lib/src/android/car/VehiclePropertyIds.java，加入：
@RequiresPermission(Car.PERMISSION_CAR_INFO)
public static final int EXT_PROP = 557846528;
，并在toString方法中加入：
case EXT_PROP:
return "EXT_PROP";
，执行命令m update-api，看到/packages/services/Car/car-lib/api/current.txt内增加了如下内容：
field @RequiresPermission(android.car.Car.PERMISSION_CAR_INFO) public static final int EXT_PROP = 557846528; // 0x21401000
在car-lib下执行mm命令，输出android.car.jar包，查看android.car.jar包中VehiclePropertyIds的内容：
public static final int EXT_PROP = 557846528;
，多出了一个静态成员，同样，在toString方法中：
case 557846528:
return "EXT_PROP";
，多出了相应的条目