Android中Native向System Service进行Binder通信的示例
Native向System Service Binder通信实现：SensorService.cpp 将应用使用sensor enable和disable事件通过binder方式上报到System server的示例。
Client端实现实例
1 调用示例：例如SensorService.cpp
appRecordSdk.sendEvent(212,connection->getUid(),String16(ss.str().c_str()))
// 引入Binder客户端SDK头文件#include "../../include/binder/FadiRecordSdk.h"android::FadiRecordSdk fadiRecordSdk; // 全局单例status_t SensorService::enable(...) {...// 构造事件数据：传感器句柄|PID|UID|包名|类型|采样周期std::ostringstream ss;ss << handle << "|" << (thread ? thread->getCallingPid() : -1)<< "|" << uid << "|" << connection->getPackageName()<< "|" << (sensor ? sensor->getSensor().getType() : -1)<< "|" << samplingPeriodNs;// 通过Binder发送事件到SystemServer（消息ID=212）fadiRecordSdk.sendEvent(212, connection->getUid(), String16(ss.str().c_str()));}}
2 FadiRecordSdk.h
#ifndef ANDROID_FADIRECORD#define ANDROID_FADIRECORD#include <binder/IInterface.h>#include <binder/Parcel.h>#include <utils/String16.h>namespace android {class FadiRecordSdk {public:/*** @brief 发送事件到SystemServer* @param msgId 事件类型（如212=传感器事件）* @param arg0 附加参数（如调用方UID）* @param str 序列化的事件数据*/void sendEvent(int32_t msgId, int32_t arg0, const String16& str);// Binder事务码定义（需与AIDL接口TRANSACTION_*对齐）enum {SEND_EVENT = IBinder::FIRST_CALL_TRANSACTION + 1 // 对应TRANSACTION_sendEvent};private:static sp<IBinder> remote; // 远程服务代理（缓存在客户端）};} // namespace android#endif // ANDROID_FADIRECORD
备注这里的SEND_EVENT 对应 IFadiRecordInterface 中的TRANSACTION_sendEvent
public abstract static class Stub extends Binder implements IFadiRecordInterface {private static final String DESCRIPTOR = "com.fadi.fadirecord.IFadiRecordInterface";static final int TRANSACTION_setEnable = 1;static final int TRANSACTION_sendEvent = 2;
3 FadiRecordSdk.cpp
通过Parcel序列化数据将事件通过IAppRecordInterface.aidl接口上报到systemServe的AppRecordService服务，Parcel机制：跨进程传递的数据需序列化，支持基本类型、String、Parcelable对象等
#include "binder/FadiRecordSdk.h"#include <binder/IServiceManager.h>namespace android {sp<IBinder> FadiRecordSdk::remote = nullptr;void FadiRecordSdk::sendEvent(int32_t msgId, int32_t arg0, const String16& str) {Parcel data, reply;// 写入接口令牌（需与服务端DESCRIPTOR一致）data.writeInterfaceToken(String16("com.fadi.fadiRecord.IFadiRecordInterface"));data.writeInt32(msgId); // 事件IDdata.writeInt32(arg0); // 参数1data.writeString16(str); // 参数2（序列化数据）// 延迟初始化：首次调用时获取远程服务代理if (!remote) {remote = defaultServiceManager()->getService(String16("FadiRecordService"));}// 异步调用（FLAG_ONEWAY不等待返回）if (remote) {remote->transact(SEND_EVENT, data, &reply, IBinder::FLAG_ONEWAY);}}} // namespace android
4 Android.bp
cc_defaults {name: "libbinder_common_defaults",host_supported: true,srcs: ["Binder.cpp",..."FadiRecordSdk.cpp",...],
服务端实现实例
1. FadiRecordService 服务注册（SystemServer）
public class FadiRecordService extends SystemService {private final IFadiRecordInterface.Stub mBinder = new FadiRecordStub();@Overridepublic void onStart() {// 注册Binder服务到ServiceManagerpublishBinderService("FadiRecordService", mBinder);// 添加内部API（可选）LocalServices.addService(FadiRecordInternal.class, new FadiRecordInternal());}}
2.AIDL接口定义（IFadiRecordInterface.aidl）
FLAG_ONEWAY表示“不用等回信”
// 包名需与writeInterfaceToken()一致package com.fadi.fadiRecord;interface IFadiRecordInterface {/*** @param eventId 事件类型（如212）* @param arg 附加参数（UID等）* @param msg 格式化数据（由Native层拼接）*/oneway void sendEvent(int eventId, int arg, String msg);}
3. AppRecordService的SE-linux权限配置
相关SE-linux也是需要配置
# service_contexts.teFadiRecordService u:object_r:fadi_record_service:s0# service.tetype fadi_record_service, system_server_service, service_manager_type;
运行结果
打开一个运动app，就可以看到使用sensor的事件被从native中传递到system server中了哈
sensorDisableEvent:pid=10228,message=19|7396|10228|com.tencent.mm.plugin.sport.model.a0|19sensorEnableEvent:pid=10228,message=19|7396|10228|com.tencent.mm.plugin.sport.model.a0|19|600000000
