Android之 BatteryService

核心提示：电池的信息，电压，Android之 BatteryService，温度，充电状态等等，还有变量， 如下：//##在BatteryService.java中声明的变量private boolean mAcOnline;private boolean mUsbOnline;private int mBatteryStatu

电池的信息，电压，温度，充电状态等等，都是由BatteryService来提供的。BatteryService是跑在system_process当中，在系统初始化的时候启动，如下

在BatteryService.java中：

Log.i(TAG, "Starting Battery Service.");

BatteryService battery = new BatteryService(context);

ServiceManager.addService("battery", battery);

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1. 数据来源

BatteryService通过JNI(com_android_server_BatteryService.cpp)读取数据。BatteryService通过JNI注册的不仅有函数，还有变量。 如下：

//##############在BatteryService.java中声明的变量################

private boolean mAcOnline;

private boolean mUsbOnline;

private int mBatteryStatus;

private int mBatteryHealth;

private boolean mBatteryPresent;

private int mBatteryLevel;

private int mBatteryVoltage;

private int mBatteryTemperature;

private String mBatteryTechnology;

//在BatteryService.java中声明的变量，在com_android_server_BatteryService.cpp中共用，即在com_android_server_BatteryService.cpp中其实操作的也是BatteryService.java中声明的变量

gFieldIds.mAcOnline = env->GetFieldID(clazz, "mAcOnline", "Z");

gFieldIds.mUsbOnline = env->GetFieldID(clazz, "mUsbOnline", "Z");

gFieldIds.mBatteryStatus = env->GetFieldID(clazz, "mBatteryStatus", "I");

gFieldIds.mBatteryHealth = env->GetFieldID(clazz, "mBatteryHealth", "I");

gFieldIds.mBatteryPresent = env->GetFieldID(clazz, "mBatteryPresent", "Z");

gFieldIds.mBatteryLevel = env->GetFieldID(clazz, "mBatteryLevel", "I");

gFieldIds.mBatteryTechnology = env->GetFieldID(clazz, "mBatteryTechnology", "Ljava/lang/String;");

gFieldIds.mBatteryVoltage = env->GetFieldID(clazz, "mBatteryVoltage", "I");