Binder实用指南（二） - 实战篇

本章的内容主要说明如何在JavaFramework层和Native层自定义Client-Server组件，并且使用Binder进行通信。

一、Native Binder

源码目录结构:

alps/frameworks/native/cmds/NativeBinderDemo/

|-NativeBinderDemo
|---ClientDemo.cpp: 客户端程序
|---ServerDemo.cpp：服务端程序
|---IMyService.h：自定义的MyService服务的头文件
|---IMyService.cpp：自定义的MyService服务
|---Android.mk：源码build文件

1.1 服务端

alps/frameworks/native/cmds/NativeBinderDemo/ServerDemo.cpp

获取ServiceManager，注册service.myservice服务到ServiceManager，启动服务。

#include "IMyService.h"
int main() {
sp < IServiceManager > sm = defaultServiceManager(); //获取service manager引用
sm->addService(String16("service.myservice"), new BnMyService()); //注册名为"service.myservice"的服务到service manager
ProcessState::self()->startThreadPool(); //启动线程池
IPCThreadState::self()->joinThreadPool(); //把主线程加入线程池
return 0;
}

1.2 客户端

alps/frameworks/native/cmds/NativeBinderDemo/ClientDemo.cpp

获取ServiceManager，拿到service.myservice服务，再进行类型转换成IMyService，最后调用远程方法sayHello()

#include "IMyService.h"
int main() {
sp < IServiceManager > sm = defaultServiceManager(); //获取service manager引用
sp < IBinder > binder = sm->getService(String16("service.myservice"));//获取名为"service.myservice"的binder接口
sp<IMyService> cs = interface_cast < IMyService > (binder);//将biner对象转换为强引用类型的IMyService
cs->sayHello();//利用binder引用调用远程sayHello()方法
return 0;
}

1.3 MyService

alps/frameworks/native/cmds/NativeBinderDemo/IMyService.h

申明IMyService，申明BpMyService（Binder客户端），申明BnMyService（Binder的服务端）。

#ifndef MY_SERVICE_DEMO
#define MY_SERVICE_DEMO
#include <stdio.h>
#include <binder/IInterface.h>
#include <binder/Parcel.h>
#include <binder/IBinder.h>
#include <binder/Binder.h>
#include <binder/ProcessState.h>
#include <binder/IPCThreadState.h>
#include <binder/IServiceManager.h>
using namespace android;
namespace android
{
class IMyService : public IInterface
{
public:
DECLARE_META_INTERFACE(MyService); //使用宏，申明MyService
virtual void sayHello()=0; //定义方法
};
//定义命令字段
enum
{
HELLO = 1,
};
//申明客户端BpMyService
class BpMyService: public BpInterface<IMyService> {
public:
BpMyService(const sp<IBinder>& impl);
virtual void sayHello();
};
//申明服务端BnMyService
class BnMyService: public BnInterface<IMyService> {
public:
virtual status_t onTransact(uint32_t code, const Parcel& data, Parcel* reply,
uint32_t flags = 0);
virtual void sayHello();
};
}
#endif

alps/frameworks/native/cmds/NativeBinderDemo/IMyService.cpp

#include "IMyService.h"
namespace android
{
IMPLEMENT_META_INTERFACE(MyService, "android.demo.IMyService"); //使用宏，完成MyService定义
//客户端
BpMyService::BpMyService(const sp<IBinder>& impl) :
BpInterface<IMyService>(impl) {
}
// 实现客户端sayHello方法
void BpMyService::sayHello() {
printf("BpMyService::sayHello\n");
Parcel data, reply;
data.writeInterfaceToken(IMyService::getInterfaceDescriptor());
remote()->transact(HELLO, data, &reply);
printf("get num from BnMyService: %d\n", reply.readInt32());
}
//服务端，接收远程消息，处理onTransact方法
status_t BnMyService::onTransact(uint_t code, const Parcel& data,
Parcel* reply, uint32_t flags) {
switch (code) {
case HELLO: { //收到HELLO命令的处理流程
printf("BnMyService:: got the client hello\n");
CHECK_INTERFACE(IMyService, data, reply);
sayHello();
reply->writeInt32(2015);
return NO_ERROR;
}
break;
default:
break;
}
return NO_ERROR;
}
// 实现服务端sayHello方法
void BnMyService::sayHello() {
printf("BnMyService::sayHello\n");
};
}

1.4 Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SHARED_LIBRARIES := \
libcutils \
libutils \
libbinder
LOCAL_MODULE := ServerDemo
LOCAL_SRC_FILES := \
IMyService.cpp \
ServerDemo.cpp
LOCAL_MODULE_TAGS := optional
include $(BUILD_EXECUTABLE)
include $(CLEAR_VARS)
LOCAL_SHARED_LIBRARIES := \
libcutils \
libutils \
libbinder
LOCAL_MODULE := ClientDemo
LOCAL_SRC_FILES := \
IMyService.cpp \
ClientDemo.cpp
LOCAL_MODULE_TAGS := optional
include $(BUILD_EXECUTABLE)

1.5 原理图

1.6 运行

编译：
mm alps/frameworks/native/cmds/NativeBinderDemo目录，然后到alps/out/target/product/{Project}/system/bin/会生成ClientDemo和ServerDemo

执行：

adb remount
adb push ServerDemo /system/bin
adb push ClientDemo /system/bin

开两个窗口分别执行下面两个命令便可以看到结果了：
adb shell system/bin/ServerDemo ， adb shell system/bin/ClientDemo

二、JavaFramework Binder

源码目录结构:

alps/frameworks/base/cmds/FrameworkBinderDemo/

|-Server端
|---ServerDemo.java：可执行程序
|---IMyService.java: 定义IMyService接口
|---MyService.java：定义MyService
|-Client端
|---ClientDemo.java：可执行程序
|---IMyService.java: 与Server端完全一致
|---MyServiceProxy.java：定义MyServiceProxy

2.1 Server端

(1)ServerDemo.java

可执行程序

public class ServerDemo {
public static void main(String[] args) {
System.out.println("MyService Start");
//准备Looper循环执行
Looper.prepareMainLooper();
//设置为前台优先级
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_FOREGROUND);
//注册服务
ServiceManager.addService("MyService", new MyService());
Looper.loop();
}
}

(2)IMyService.java

定义sayHello()方法，DESCRIPTOR属性

public interface IMyService extends IInterface {
static final java.lang.String DESCRIPTOR = "com.yuanhh.frameworkBinder.MyServer";
public void sayHello(String str) throws RemoteException ;
static final int TRANSACTION_say = android.os.IBinder.FIRST_CALL_TRANSACTION;
}

(3)MyService.java

public class MyService extends Binder implements IMyService{
public MyService() {
this.attachInterface(this, DESCRIPTOR);
}
@Override
public IBinder asBinder() {
return this;
}
/** 将MyService转换为IMyService接口 **/
public static com.yuanhh.frameworkBinder.IMyService asInterface(
android.os.IBinder obj) {
if ((obj == null)) {
return null;
}
android.os.IInterface iInterface = obj.queryLocalInterface(DESCRIPTOR);
if (((iInterface != null)&&(iInterface instanceof com.yuanhh.frameworkBinder.IMyService))){
return ((com.yuanhh.frameworkBinder.IMyService) iInterface);
}
return null;
}
/** 服务端，接收远程消息，处理onTransact方法 **/
@Override
protected boolean onTransact(int code, Parcel data, Parcel reply, int flags)
throws RemoteException {
switch (code) {
case INTERFACE_TRANSACTION: {
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_say: {
data.enforceInterface(DESCRIPTOR);
String str = data.readString();
sayHello(str);
reply.writeNoException();
return true;
}}
return super.onTransact(code, data, reply, flags);
}
/** 自定义sayHello()方法 **/
@Override
public void sayHello(String str) {
System.out.println("MyService:: Hello, " + str);
}
}

(4) Android.mk

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := $(call all-subdir-java-files)
LOCAL_MODULE := ServerDemo
LOCAL_MODULE_TAGS := optional
include $(BUILD_JAVA_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := ServerDemo
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE_PATH := $(TARGET_OUT)/bin
LOCAL_MODULE_CLASS := UTILITY_EXECUTABLES
LOCAL_SRC_FILES := ServerDemo
include $(BUILD_PREBUILT)

(5) ServerDemo

base=/system
export CLASSPATH=$base/framework/ServerDemo.jar
exec app_process $base/bin com.shun.frameworkBinder.ServerDemo "$@"

2.2 Client端

(1)ClientDemo.java

可执行程序

public class ClientDemo {
public static void main(String[] args) throws RemoteException {
System.out.println("Client start");
IBinder binder = ServiceManager.getService("MyService"); //获取名为"MyService"的服务
IMyService myService = new MyServiceProxy(binder); //创建MyServiceProxy对象
myService.sayHello("binder"); //通过MyServiceProxy对象调用接口的方法
System.out.println("Client end");
}
}

(2)IMyService.java

与Server端的IMyService是一致，基本都是拷贝一份过来。

(3)MyServiceProxy.java

public class MyServiceProxy implements IMyService {
private android.os.IBinder mRemote; //代表BpBinder
public MyServiceProxy(android.os.IBinder remote) {
mRemote = remote;
}
public java.lang.String getInterfaceDescriptor() {
return DESCRIPTOR;
}
/** 自定义的sayHello()方法 **/
@Override
public void sayHello(String str) throws RemoteException {
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
try {
_data.writeInterfaceToken(DESCRIPTOR);
_data.writeString(str);
mRemote.transact(TRANSACTION_say, _data, _reply, 0);
_reply.readException();
} finally {
_reply.recycle();
_data.recycle();
}
}
@Override
public IBinder asBinder() {
return mRemote;
}
}

(4) Android.mk

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := $(call all-subdir-java-files)
LOCAL_MODULE := ClientDemo
LOCAL_MODULE_TAGS := optional
include $(BUILD_JAVA_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := ClientDemo
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE_PATH := $(TARGET_OUT)/bin
LOCAL_MODULE_CLASS := UTILITY_EXECUTABLES
LOCAL_SRC_FILES := ClientDemo
include $(BUILD_PREBUILT)

(5) ClientDemo

base=/system
export CLASSPATH=$base/framework/ClientDemo.jar
exec app_process $base/bin com.shun.frameworkBinder.ClientDemo "$@"

2.3 原理图

2.4 运行

编译：

mm alps/frameworks/base/cmds/FrameworkBinderDemo/目录，然后：
alps/out/target/product/{Project}/system/bin/ 生成ClientDemo和ServerDemo
alps/out/target/product/{Project}/system/framework/ 生成ClientDemo.jar和ServerDemo.jar。

执行：

adb remount
adb push ServerDemo /system/bin
adb push ClientDemo /system/bin
adb push ServerDemo.jar /system/framework/
adb push ClientDemo.jar /system/framework/

开两个窗口分别执行下面两个命令便可以看到结果了：
adb shell system/bin/ServerDemo ， adb shell system/bin/ClientDemo

文章非常好，转自 http://maoao530.github.io/2016/12/25/android-binder-02/