Binder使用示例
BInder方面的资料虽然感觉看的比较多，但是真正用的时候才发现有很多地方模棱两棵的，所以，打算用一个实例再来巩固一下binder的使用方法
首先看下目录结构：
leaves@leaves-desktop:~/android/android2/android/frameworks/tv_print/services$ ls T* TestBinderClient: Android.mk ITestBinderService.cpp TestBinderServer: Android.mk ITestBinderService.h main_testBinder.cpp testBinder.cpp TestBinderService.cpp TestBinderService.h leaves@leaves-desktop:~/android/android2/android/frameworks/tv_print/services$
TestBinderClient下面是Binder的客户端，TestBinderServer是binder的服务端
我们先来看下biner服务端代码
1、ITestBinderService.h
#ifndef ANDROID_ITESTBINDERSERVICE_H_
#define ANDROID_ITESTBINDERSERVICE_H_
#include <utils/RefBase.h>
#include <binder/IInterface.h>
#include <binder/Parcel.h>
namespace android {
class Parcel;
class ITestBinderService: public IInterface {
public:
DECLARE_META_INTERFACE(TestBinderService);
virtual int add(int a, int b) = 0;
};
class BnTestBinderService: public BnInterface<ITestBinderService> {
public:
virtual status_t onTransact(uint32_t code, const Parcel& data,
Parcel* reply, uint32_t flags = 0);
};
}
#endif /* ANDROID_ITESTBINDERSERVICE_H_ */
这里主要是定义了两个类ITestBinderService 和 BnTestBinderService，ITestBinderService 是TestBinderService 的基类，
这里主要是DECLARE_META_INTERFACE 这个宏，定义在frameworks\base\include\binder\IInterface.h文件中
#define DECLARE_META_INTERFACE(INTERFACE) \
static const android::String16 descriptor; \
static android::sp<I##INTERFACE> asInterface( \
const android::sp<android::IBinder>& obj); \
virtual const android::String16& getInterfaceDescriptor() const; \
I##INTERFACE(); \
virtual ~I##INTERFACE();
把TestBinderService代入进去
#define DECLARE_META_INTERFACE(TestBinderService) \
static const android::String16 descriptor; \
static android::sp<I##TestBinderService> asInterface( \
const android::sp<android::IBinder>& obj); \
virtual const android::String16& getInterfaceDescriptor() const; \
I##TestBinderService(); \
virtual ~I##TestBinderService(); 其中封装了实现binder所需要的一些类成员变量和成员函数，通过这些成员函数可以为一个binder实现创建proxy
2、TestBinderService.h
#ifndef ANDROID_TESTBINDERSERVICE_H_
#define ANDROID_TESTBINDERSERVICE_H_
#include <utils/KeyedVector.h>
#include "ITestBinderService.h"
namespace android {
class TestBinderService: public BnTestBinderService {
public:
static void instantiate();
int add(int a,int b);
private:
TestBinderService();
virtual ~TestBinderService();
};
}
#endif /* ANDROID_TESTBINDERSERVICE_H_ */
这个文件比较简单，主要就是定义了一个类TestBinderService，继承于前面 的BnTestBinderService，并定义了一个方法add函数和instantiate
3、TestBinderService.cpp
#define LOG_TAG "TestBinderService"
#include <utils/Log.h>
#include <binder/IServiceManager.h>
#include <binder/IPCThreadState.h>
#include "TestBinderService.h"
static int debug_flag = 1;
namespace android {
void TestBinderService::instantiate() {
LOGI("Enter TestBinderService::instantiate");
status_t st = defaultServiceManager()->addService(
String16("my.test.binder"), new TestBinderService());
LOGD("ServiceManager addService ret=%d", st);
LOGD("instantiate> end");
}
TestBinderService::TestBinderService() {
LOGD(" TestBinderServicet");
}
TestBinderService::~TestBinderService() {
LOGD("TestBinderService destroyed,never destroy normally");
}
int TestBinderService::add(int a,int b) {
LOGI("TestBinderService::add a = %d, b = %d.", a , b);
return a+b;
}
}
在instantiate函数中，将TestBinderService注册到系统的binder service列表中，这样以后就可以使用这个service提供的方法
该service提供了一个add 方法，返回两个数的和
再来看下clinet端 的代码
1、ITestBinderService.cpp
#define LOG_TAG "ITeeveePlayerService"
#include <utils/Log.h>
#include "../TestBinderServer/ITestBinderService.h"
namespace android {
enum {
TEST_ADD = IBinder::FIRST_CALL_TRANSACTION,
};
class BpTestBinderService: public BpInterface<ITestBinderService> {
public:
BpTestBinderService(const sp<IBinder>& impl) :
BpInterface<ITestBinderService> (impl) {
}
int add(int a, int b) {
Parcel data, reply;
LOGI("Enter BpTestBinderService add,a = %d , b = %d", a, b);
data.writeInterfaceToken(ITestBinderService::getInterfaceDescriptor());
data.writeInt32(a);
data.writeInt32(b);
remote()->transact(TEST_ADD, data, &reply);
int sum = reply.readInt32();
LOGI("BpTestBinderService sum = %d", sum);
return sum;
}
};
IMPLEMENT_META_INTERFACE(TestBinderService, "android.test.ITestBinderService");
// ----------------------------------------------------------------------
status_t BnTestBinderService::onTransact(uint32_t code, const Parcel& data,
Parcel* reply, uint32_t flags) {
switch (code) {
case TEST_ADD: {
CHECK_INTERFACE(ITestBinderService, data, reply);
int a = data.readInt32();
int b = data.readInt32();
LOGI("Enter BnTestBinderService add,a = %d , b = %d", a, b);
int sum = 0;
sum = add(a, b);
LOGI("BnTestBinderService sum = %d", sum);
reply->writeInt32(sum);
return sum;
}
default:
return BBinder::onTransact(code, data, reply, flags);
}
}
}
定义了一个类BpTestBinderService，提供add方法，该方法通过调用远端的binder service提供的服务返回两个数的和
重载了BnTestBinderService的onTransact方法，使其在TEST_ADD时调用add方法
这个文件里面也使用了一个宏IMPLEMENT_META_INTERFACE，也是定义在frameworks\base\include\binder\IInterface.h文件中
#define IMPLEMENT_META_INTERFACE(INTERFACE, NAME) \
const android::String16 I##INTERFACE::descriptor(NAME); \
const android::String16& \
I##INTERFACE::getInterfaceDescriptor() const { \
return I##INTERFACE::descriptor; \
} \
android::sp<I##INTERFACE> I##INTERFACE::asInterface( \
const android::sp<android::IBinder>& obj) \
{ \
android::sp<I##INTERFACE> intr; \
if (obj != NULL) { \
intr = static_cast<I##INTERFACE*>( \
obj->queryLocalInterface( \
I##INTERFACE::descriptor).get()); \
if (intr == NULL) { \
intr = new Bp##INTERFACE(obj); \
} \
} \
return intr; \
} \
I##INTERFACE::I##INTERFACE() { } \
I##INTERFACE::~I##INTERFACE() { } 代入展开后：
#define IMPLEMENT_META_INTERFACE(TestBinderService, "android.test.ITestBinderService") \
const android::String16 ITestBinderService::descriptor("android.test.ITestBinderService"); \
const android::String16& \
ITestBinderService::getInterfaceDescriptor() const { \
return ITestBinderService::descriptor; \
} \
android::sp<ITestBinderService> ITestBinderService::asInterface( \
const android::sp<android::IBinder>& obj) \
{ \
android::sp<ITestBinderService> intr; \
if (obj != NULL) { \
intr = static_cast<ITestBinderService*>( \
obj->queryLocalInterface( \
ITestBinderService::descriptor).get()); \
if (intr == NULL) { \
intr = new BpTestBinderService(obj); \
} \
} \
return intr; \
} \
ITestBinderService::ITestBinderService() { } \
ITestBinderService::~ITestBinderService() { }
这里重点看 一下asInterface函数，IBinder::queryLocalInterface函数位于framework/base/libs/binder/Binder.cpp文件中
sp<IInterface> IBinder::queryLocalInterface(const String16& descriptor)
{
return NULL;
}由此可见，最终会调用下面语句：
intr = new BpTestBinderService(obj)
这样，server和client端的binder代码主写好了，接着就需要把binder service加入到binder中
这里有两种方法：
1、在system_init.cpp中添加
TestBinderService::instantiate();
如果是在这里加的话可以去掉TestBinderService中实现的instantiate方法，同时将TestBinderService继承自BinderService，因为在BinderService实现了这一方法，同时将其添加到binder service
2、以单独的程序启动
main_testBinder.cpp
#include <binder/IPCThreadState.h>
#include <binder/ProcessState.h>
#include <binder/IServiceManager.h>
#include <utils/Log.h>
#include "TestBinderService.h"
using namespace android;
int main(int argc, char** argv)
{
sp<ProcessState> proc(ProcessState::self());
sp<IServiceManager> sm = defaultServiceManager();
LOGI("TestBinderService before");
TestBinderService::instantiate();
LOGI("TestBinderService End");
ProcessState::self()->startThreadPool();
IPCThreadState::self()->joinThreadPool();
return 0;
}
这里调用的是TestBinderService自己的instantiate来添加的
再来看下测试case,testBinder.cpp
#define LOG_TAG "TestBinserService"
#include <utils/Log.h>
#include <nativehelper/jni.h>
#include <nativehelper/JNIHelp.h>
#include <android_runtime/AndroidRuntime.h>
#include <binder/IServiceManager.h>
#include "../TestBinderServer/ITestBinderService.h"
#include "TestBinderService.h"
using namespace android;
int main(int argc, char** argv)
{
int sum = 0;
sp<ITestBinderService> mTestBinserService;
if (mTestBinserService.get() == 0) {
sp<IServiceManager> sm = defaultServiceManager();
sp<IBinder> binder;
do {
binder = sm->getService(String16("my.test.binder"));
if (binder != 0)
break;
LOGI("getService fail");
usleep(500000); // 0.5 s
} while (true);
mTestBinserService = interface_cast<ITestBinderService> (binder);
LOGE_IF(mTestBinserService == 0, "no ITestBinserService!?");
}
sum = mTestBinserService->add(3, 4);
LOGI("sum = %d", sum);
return 0;
}
这里先根据名字获取Service，再使用其提供的相应 服务
看下串口打印，
启动service:
C:\adb>adb shell # cd /system/bin cd /system/bin # chmod 777 main_* chmod 777 main_* # ./main_testBinder ./main_testBinder
client:
I/ServiceManager( 1369): Waiting for service my.test.binder... I/ServiceManager( 1369): Waiting for service my.test.binder... I/ServiceManager( 1369): Waiting for service my.test.binder... I/ServiceManager( 1369): Waiting for service my.test.binder... I/ServiceManager( 1369): Waiting for service my.test.binder... I/PlayServiceManager-JNI( 1369): getService fail I/ServiceManager( 1369): Waiting for service my.test.binder... I/ServiceManager( 1369): Waiting for service my.test.binder... I/ServiceManager( 1369): Waiting for service my.test.binder... I/ServiceManager( 1369): Waiting for service my.test.binder... I/ ( 1373): TestBinderService before I/TestBinderService( 1373): Enter TestBinderService::instantiate D/TestBinderService( 1373): TestBinderServicet D/TestBinderService( 1373): ServiceManager addService ret=0 D/TestBinderService( 1373): instantiate> end I/ ( 1373): TestBinderService End I/ITeeveePlayerService( 1369): Enter BpTestBinderService add,a = 3 , b = 4 I/ITeeveePlayerService( 1373): Enter BnTestBinderService add,a = 3 , b = 4 I/TestBinderService( 1373): TestBinderService::add a = 3, b = 4. I/ITeeveePlayerService( 1373): BnTestBinderService sum = 7 I/ITeeveePlayerService( 1369): BpTestBinderService sum = 7 I/PlayServiceManager-JNI( 1369): sum = 7前面 的Waiting for service my.test.binder...是在还没有启动service的时候打印出来的
这样，需要使用TestBinserService 提供的服务时，只需要先获取其service,再使用其提供的方法
相关代码：
http://download.csdn.net/detail/new_abc/4673623