原址
前面几篇博客中系统地介绍了本地服务的注册、检索以及使用过程。这篇博客我们将完成一个属于自己的本地服务:AllenService。
由前面的学习知道，要完成一个自己的本地服务，需要有IAllenService接口、BnAllenService服务Stub、AllenService、BpAllenService。UML图如下：
各文件的路径如下：
frameworks/base/include/allen/IAllenService.h,AllenService.h
frameworks/base/libs/allen/IAllenService.cpp,AllenService.cpp
frameworks/base/cmds/allen/main_allenclient.cpp,main_allenservice.cpp
1.IAllenService.h文件
该头文件中包含了接口描述符以及枚举类。另外，与Android中的服务接口文件类似，这里将BnAllenService的定义也放在该头文件中，所以该头文件的代码如下：
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#ifndef FRAMEWORKS_BASE_INCLUDE_IALLENSERVICE_H_#define FRAMEWORKS_BASE_INCLUDE_IALLEN_SERVICE_H_#include <utils/Errors.h>#include <utils/KeyedVector.h>#include <utils/RefBase.h>#include <utils/String8.h>#include <binder/IInterface.h>#include <binder/Parcel.h>#include <AllenService.h>namespace android{ #define MATH_ERROR int32(-1) #define ALLEN_DESCRIPTOR "android.allen.IAllenService" enum{ ALLEN_PRINT=IBinder::FIRST_CALL_TRANSACTION, ALLEN_ADD, ALLEN_SUB }; class IAllenService:public IInterface { public: //宏定义 DECLARE_META_INTERFACE(AllenService); virtual status_t print(const char*str)=0; virtual int32 add(int32 a,int32 b)=0; virtual int32 sub(int32 a,int32 b)=0; }; class BnAllenService:public BnInterface<IAllenService> { public: virtual status_t onTransact(uint32_t code, const Parcel& data, Parcel*reply, uint32_t flags=0); };};//namespace android#endif
- AllenService.h
AllenService头文件的代码如下：
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#ifndef FRAMEWORKS_BASE_INCLUDE_ALLEN_ALLENSERVICE_H_#define FRAMEWORKS_BASE_INCLUDE_ALLEN_ALLENSERVICE_H_#include <utils/Log.h>#include <utils/threads.h>#include <utils/List.h>#include <utils/Errors.h>#include <utils/KeyedVector.h>#include <utils/String8.h>#include <utils/Vector.h>#include <IAllenService.h>namespace android{ class AllenService:public BnAllenService{ public: static void instantiate(); virtual status_t print(const char*str); virtual int32 add(int32 a,int32 b); virtual int32 sub(int32 a,int32 b); virtual status_t onTransact( uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags); private: AllenService(); virtual ~AllenService(); };}; //namespace android#endif
- IAllenService.cpp
该文件中不仅有IAllenService中宏接口的实现，还有BnAllenService的实现，另外，还有BpAllenService的定义以及实现。
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#include <stdint.h>#include <sys/types.h>#include <binder/Parcel.h>#include <binder/IMemory.h>#include <allen/IAllenService.h>#include <allen/AllenService.h>#include <utils/Errors.h>namespace android{ class BpAllenService: public BpInterface<IAllenService> { public: BpAllenService(const sp<IBinder>& impl):BpInterface<IAllenService>(impl) { } virtual status_t print(const char*str) { Parcel data,reply; data.writeInterfaceToken(IAllenService::getInterfaceDescriptor()); data.writeCString(str); status_t status=remote()->transact(ALLEN_PRINT,data,&reply); if(status!=NO_ERROR){ LOGE("print str error:%s",strerror(-status)); }else{ status=reply.readInt32(); } return status; } virtual int32 add(int32 a,int32 b) { Parcel data,reply; data.writeInterfaceToken(IAllenService::getInterfaceDescriptor()); data.writeInt32(a); data.writeInt32(b); status_t status=remote()->transact(ALLEN_ADD,data,&reply); return reply.readInt32(); } virtual int32 sub(int32 a,int32 b) { Parcel data,reply; data.writeInterfaceToken(IAllenService::getInterfaceDescriptor()); data.writeInt32(a); data.writeInt32(b); status_t status=remote()->transact(ALLEN_SUB,data,&reply); return reply.readInt32(); } }; //宏实现 IMPLEMENT_META_INTERFACE(AllenService,ALLEN_DESCRIPTOR) status BnAllenService::onTransact(uint32_t code,const Parcel& data,Parcel* reply,uint32_t flags) { switch(code){ case ALLEN_PRINT:{ CHECK_INTERFACE(IAllenService,data,reply); const char*str=data.readCString(); reply->writeInt32(print(str)); return NO_ERROR; }break; case ALLEN_ADD:{ CHECK_INTERFAC(IAllenService,data,reply); int32 a=data.readInt32(); int32 b=data.readInt32(); reply->writeInt32(this->add(a,b)); return NO_ERROR; }break; case ALLEN_SUB:{ CHECK_INTERFACE(IAllenService,data,reply); int32 a=data.readInt32(); int32 b=data.readInt32(); reply->writeInt32(this->sub(a,b)); return NO_ERROR; }break; default: return BBinder::onTransact(code,data,reply,flags); } }};
4.AllenService.cpp
该文件实现服务接口。代码如下：
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namespace android{ void AllenService::instantiate(){ defaultServiceManager()->addService( String16(ALLEN_DESCRIPTOR),new AllenService()); } status_t AllenService::print(const char*str){ LOGI("%s\n",str); printf("%s\n",str); return NO_ERROR; } int32 AllenService::add(int32 a,int32 b){ LOGI("a=%d,b=%d",a,b); return a+b; } int32 AllenService::sub(int32 a,int32 b){ LOGI("a=%d,b=%d",a,b); return a-b; }};
5.main_allenservice.cpp
创建好AllenService后，如果想要运行它，就需要有服务客户端和Service Server进程，服务代理运行在服务客户端中，服务运行在Service Server进程中。如下图所示：
main_allenservice.cpp的代码如下：
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int main(int argc,char** argv){ sp<ProcessState>proc(ProcessState::self()); sp<IServiceManager>sm=defaultServiceManager(); LOGI("ServiceManager: %p",sm.get()); AllenService::instantiate(); ProcessState::self()->startThreadPool(); ProcessState::self()->joinThreadPool(); return 0;}
6.main_allenclient.cpp
main_allenclient.cpp的代码如下：
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int main(int argc,char *argv[]){ LOGI("allenservice cleint is now starting"); sp<IServiceManager>sm=defaultServiceManager(); sp<IBinder>binder; sp<IAllenService>allenService; do{ binder=sm->getService(String16(ALLEN_DESCRIPTOR)); if(binder!=0) { break; } LOGI("AllenService is not working,try again..."); usleep(500000); }while(true); allenService=interface_cast<IAllenService>(binder); allenService->print("Hello world!\nI'm Allen and I'm coning.\n"); allenService->add(3,6); allenService->sub(1,1); return 0;}
7.编译AllenService系统服务
若想编译AllenService服务代码，需要将AllenService的源码包含进Android平台源码中，再进行整体编译。首先保证头文件在/frameworks/base/include/allen下，源代码文件在/frameworks/base/libs/allen下，而后编写Android.mk文件，编写完成后，将其放到源代码目录中，以便将源代码与Android平台代码一起编译。
Android.mk文件内容如下：
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LOCAL_PATH:=$(call my-dir)include &(CLEAR_VARS)LOCAL_SRC_FILES:= \ IAllenService.cpp \ AllenService.cppLOCAL_SHARED_LIBRARES :=\ libcutils \ libutils \ libbinder \LOCAL_PRELINK_MODULE := falseLOCAL_MODULE :=liballeninclude $(BUILD_SHARED_LIBRARY)
接着，编写运行main_allenservice.cpp和main_allenclient.cpp的Android.mk文件，内容如下：
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LOCAL_PATH:= $(call my-dir)include $(CLEAR_VARS)LOCAL_SRC_FILES:= \ main_allenserver.cppLOCAL_SHARED_LIBRARIES := \ libutils \ libbinder \ liballen base := $(LOCAL_APTH)/../..LOCAL_MODULE:= allenserviceincldue $(BUILD_EXECUTABLE)include $(CLEAR_VARS)LOCAL_SRC_FILES:= \ main_allenclient.cppLOCAL_SHARED_LIBRARIES := \ libutils \ libbinder \ liballenbase :=$(LOCAL_PATH)/../.. LOCAL_MODULE:=allenclientinclude $(BUILD_EXECUTABLE)
