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android - 使用 Android 原生 Binder 发送自定义对象

转载 作者:行者123 更新时间:2023-12-03 13:24:28 25 4
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我只能找到有关 Parcelable 的 Java 示例。
我的目标是在原生 C++(不是 NDK)中创建一个简单的服务和客户端,它将使用 Binder 接收和发送序列化的自定义对象。

MyClass
+ std::string
+ enum
+ int
+ bool

最佳答案

由于您使用的是 Android 5.1,我将坚持使用 Lollipop 上可用的内容。有更好的工具,如 aidl-cpp实现这一点可以省去很多手工滚动样板代码的麻烦。
首先,为 IFooService.h 中的服务制作接口(interface).

class IFooService: public IInterface {
public:
DECLARE_META_INTERFACE(FooService);
virtual int myFunc(const String8& str, int enumParam, int intParam, int boolParam) = 0;

};
然后为服务编写编码代码,根据问题中的要求实现一个功能
class BnFooService: public BnInterface<IFooService>
{
public:
virtual status_t onTransact( uint32_t code,
const Parcel& data,
Parcel* reply,
uint32_t flags = 0);
};

enum {
MY_FUNC = IBinder::FIRST_CALL_TRANSACTION,
};

/* BinderProxy code, for clients of the service to call into the service and have
the paremeters marshalled properly across the Binder interface. Executes in the
client process context

*/
class BpFooService: public BpInterface<IFooService> {
public:
virtual int myFunc(const String8& str, int enumParam, int intParam, int boolParam) {
//2 Parcel objects, 1 to write the data to and another to receive it in
Parcel data, reply;
//This serves as the token for the Binder framework for a sanity check
data.writeInterfaceToken(IFooService::getInterfaceDescriptor());
data.writeString8(str);
data.writeInt32(enumParam);
data.writeInt32(intParam);
data.writeInt32(boolParam);
return remote()->transact(MY_FUNC, data, &reply);
}
}

IMPLEMENT_META_INTERFACE(MediaPlayerService, "com.somedomain.IFooService");

/* Actual Binder implementation of the service which unpacks the data from the
incoming Parcel and handles the call accordingly
*/
status_t BnFooService::onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags) {
switch (code) {
case MY_FUNC: {
//The same token is checked
CHECK_INTERFACE(IFooService, data, reply);
//Read off in exact same order as written to the data Parcel above
String8 str = data.readString8();
int enumParam = data.readInt32();
int intParam = data.readInt32();
int boolParam = data.readInt32();
reply->writeInt32(myFunc(str, enumParam, intParam, boolParam));
return NO_ERROR;
}
break;
default:

}
然后创建 main_foo.cpp使用如下一些代码作为服务进程的入口点:
int main() {
if(!FooService::publish()) { //Call into your code to register with ServiceManager
ALOGE("Can't instantiate FooService! Exiting");
return 1;
}
ProcessState::self()->startThreadPool(); //Required for the binder threads
IPCThreadState::self()->joinThreadPool(); //Infinite loop that waits for inbound connections
}
最后,在 FooService.cpp 中实现服务的接口(interface)。
bool FooService::publish() {
defaultServiceManager()->addService(String16("foo_service"), new FooService());
sp<IBinder> binder = defaultServiceManager()->checkService(String16("foo_service"));
while(binder == NULL && /*some upper time limit*/){
ALOGI("Waiting for foo_service");
}
return binder != NULL;
}

int FooService::myFunc(const String8& str, int enumParam, int intParam, int boolParam) {
//business logic
return 0;
}
请注意这是 不是 适用于常规应用程序开发人员但适用于 的代码原生服务 在 Android 框架中运行,如 InputFlinger , SurfaceFlinger等。此代码需要框架头文件,如 Parcel.h , IInterface.h等在 SDK 中不可用。

关于android - 使用 Android 原生 Binder 发送自定义对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/36618274/

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