05.Binder系统:第7课第6节_Binder系统_c++实现_内部机制_添加服务

学习到这个我们对Binder系统以及非常的了解了，那么我们现在添加一个binder服务会不会非常的简单呢？

假设现在我们添加一个服务，server端涉及一个BnGoodbyeService，client涉及一个BpGoodbyeService，其中实现两个函数saygoodbye，saygoodbye_to。BpGoodbyeService与BpGoodbyeService对使用同一个接口IGoodbyService。

故我们需要编写IGoodbyService.h，BnGoodbyService.cpp与BpGoodbyService.cpp三个函数。由于他和之前的Hello服务十分相似，我们把之前的IHelloService.h，BnHelloService.cpp，BpHelloService.cpp拷贝一份，然后把文件名中的Goodby替换成Hello，在其基础上进行修改：

IGoodbyeService.h


/* ²Î¿¼: frameworks\av\include\media\IMediaPlayerService.h */

#ifndef ANDROID_IGOODBYEERVICE_H
#define ANDROID_IGOODBYEERVICE_H

#include <utils/Errors.h>  // for status_t
#include <utils/KeyedVector.h>
#include <utils/RefBase.h>
#include <utils/String8.h>
#include <binder/IInterface.h>
#include <binder/Parcel.h>

#define GOODBYE_SVR_CMD_SAYGOODBYE     0
#define GOODBYE_SVR_CMD_SAYGOODBYE_TO  1


namespace android {

class IGoodbyeService: public IInterface
{
public:
    DECLARE_META_INTERFACE(GoodbyeService);
	virtual void saygoodbye(void) = 0;
	virtual int saygoodbye_to(const char *name) = 0;
};

class BnGoodbyeService: public BnInterface<IGoodbyeService>
{
public:
    virtual status_t    onTransact( uint32_t code,
                                    const Parcel& data,
                                    Parcel* reply,
                                    uint32_t flags = 0);

	virtual void saygoodbye(void);
	virtual int saygoodbye_to(const char *name);

};
}

#endif

BnGoodbyeService.cpp


/* 参考: frameworks\av\media\libmedia\IMediaPlayerService.cpp */

#define LOG_TAG "GoodbyeService"

#include "IGoodbyeService.h"


namespace android {

status_t BnGoodbyeService::onTransact( uint32_t code,
                                const Parcel& data,
                                Parcel* reply,
                                uint32_t flags)
{
	/* 解析数据,调用saygoodbye/saygoodbye_to */

    switch (code) {
        case GOODBYE_SVR_CMD_SAYGOODBYE: {
			saygoodbye();
            return NO_ERROR;
        } break;
		
        case GOODBYE_SVR_CMD_SAYGOODBYE_TO: {

			/* 从data中取出参数 */
			int32_t policy =  data.readInt32();
			String16 name16 = data.readString16();
			String8 name8(name16);

			int cnt = saygoodbye_to(name8.string());

			/* 把返回值写入reply传回去 */
			reply->writeInt32(cnt);
			
            return NO_ERROR;
        } break;
        default:
            return BBinder::onTransact(code, data, reply, flags);
    }
}

void BnGoodbyeService::saygoodbye(void)
{
	static int cnt = 0;
	ALOGI("say goodbye : %d\n", cnt++);

}

int BnGoodbyeService::saygoodbye_to(const char *name)
{
	static int cnt = 0;
	ALOGI("say goodbye to %s : %d\n", name, cnt++);
	return cnt;
}

}

BpGoodbyeService.cpp


/* 参考: frameworks\av\media\libmedia\IMediaPlayerService.cpp */

#include "IGoodbyeService.h"

namespace android {

class BpGoodbyeService: public BpInterface<IGoodbyeService>
{
public:
    BpGoodbyeService(const sp<IBinder>& impl)
        : BpInterface<IGoodbyeService>(impl)
    {
    }

	void saygoodbye(void)
	{
		/* 构造/发送数据 */

        Parcel data, reply;
        data.writeInt32(0);

        remote()->transact(GOODBYE_SVR_CMD_SAYGOODBYE, data, &reply);
	}
	
	int saygoodbye_to(const char *name)
	{
		/* 构造/发送数据 */
        Parcel data, reply;

        data.writeInt32(0);
        data.writeString16(String16(name));

        remote()->transact(GOODBYE_SVR_CMD_SAYGOODBYE_TO, data, &reply);

		return reply.readInt32();
	}

};

IMPLEMENT_META_INTERFACE(GoodbyeService, "android.media.IGoodbyeService");

}

test_client.cpp


#define LOG_TAG "TestService"
//#define LOG_NDEBUG 0

#include <fcntl.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include <binder/IPCThreadState.h>
#include <binder/ProcessState.h>
#include <binder/IServiceManager.h>
#include <cutils/properties.h>
#include <utils/Log.h>

#include "IHelloService.h"
#include "IGoodbyeService.h"

using namespace android;

/* ./test_client <hello|goodbye>
 * ./test_client <hello|goodbye> <name>
 */
int main(int argc, char **argv)
{
	int cnt;
	
	if (argc < 2){
        ALOGI("Usage:\n");
        ALOGI("%s <hello|goodbye>\n", argv[0]);
        ALOGI("%s <hello|goodbye> <name>\n", argv[0]);
        return -1;
	}

	/* getService */
	/* 打开驱动, mmap */
	sp<ProcessState> proc(ProcessState::self());

	/* 获得BpServiceManager */
	sp<IServiceManager> sm = defaultServiceManager();

	if (strcmp(argv[1], "hello") == 0)
	{

		sp<IBinder> binder =
		    sm->getService(String16("hello"));

		if (binder == 0)
		{
		    ALOGI("can't get hello service\n");
			return -1;
		}

		/* service肯定是BpHelloServie指针 */
		sp<IHelloService> service =
		    interface_cast<IHelloService>(binder);


		/* 调用Service的函数 */
		if (argc < 3) {
			service->sayhello();
			ALOGI("client call sayhello");
		}
		else {
			cnt = service->sayhello_to(argv[2]);
			ALOGI("client call sayhello_to, cnt = %d", cnt);
		}
	}
	else
	{

		sp<IBinder> binder =
		    sm->getService(String16("goodbye"));

		if (binder == 0)
		{
		    ALOGI("can't get goodbye service\n");
			return -1;
		}

		/* service肯定是BpGoodbyeServie指针 */
		sp<IGoodbyeService> service =
		    interface_cast<IGoodbyeService>(binder);


		/* 调用Service的函数 */
		if (argc < 3) {
			service->saygoodbye();
			ALOGI("client call saygoodbye");
		}
		else {
			cnt = service->saygoodbye_to(argv[2]);
			ALOGI("client call saygoodbye_to, cnt = %d", cnt);
		}
	}
	
	return 0;
}

test_server.cpp


/* 参考: frameworks\av\media\mediaserver\Main_mediaserver.cpp */

#define LOG_TAG "TestService"
//#define LOG_NDEBUG 0

#include <fcntl.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include <binder/IPCThreadState.h>
#include <binder/ProcessState.h>
#include <binder/IServiceManager.h>
#include <cutils/properties.h>
#include <utils/Log.h>

#include "IHelloService.h"
#include "IGoodbyeService.h"


using namespace android;

int main(void)
{
	/* addService */

	/* while(1){ read data, 解析数据, 调用服务函数 } */

	/* 打开驱动, mmap */
	sp<ProcessState> proc(ProcessState::self());

	/* 获得BpServiceManager */
	sp<IServiceManager> sm = defaultServiceManager();

	sm->addService(String16("hello"), new BnHelloService());
	sm->addService(String16("goodbye"), new BnGoodbyeService());

	/* 循环体 */
	ProcessState::self()->startThreadPool();
	IPCThreadState::self()->joinThreadPool();

	return 0;
}

Android.mk

LOCAL_PATH:= $(call my-dir)

include $(CLEAR_VARS)

LOCAL_SRC_FILES:= \
	BnHelloService.cpp \
	BpHelloService.cpp \
	BnGoodbyeService.cpp \
	BpGoodbyeService.cpp \
	test_server.cpp

LOCAL_SHARED_LIBRARIES := \
	libcutils \
	libutils \
	liblog \
	libbinder 


LOCAL_MODULE:= test_server
LOCAL_32_BIT_ONLY := true

include $(BUILD_EXECUTABLE)

include $(CLEAR_VARS)

LOCAL_SRC_FILES:= \
	BpHelloService.cpp \
	BpGoodbyeService.cpp \
	test_client.cpp

LOCAL_SHARED_LIBRARIES := \
	libcutils \
	libutils \
	liblog \
	libbinder 


LOCAL_MODULE:= test_client
LOCAL_32_BIT_ONLY := true

include $(BUILD_EXECUTABLE)

编写完成以上代码之后，使用mmm命令编译，然后烧写到系统，实验操作参考之前：05.Binder系统:第7课第2节_Binder系统_c++实现_编译测试