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Android 2.1 架构解析

[日期:2014-03-16] 来源:Linux社区  作者:skdev [字体: ]

5 电池

电池涉及的功能有:BatteryStatusBatteryHealthBatteryPresentBatteryLevelPlugTypeBatteryVoltageBatteryTemperatureBatteryTechnology等,它是种从下而上的表现方式,即底层电池变化后通过uevent事件向上传递电池的当前状态。

5.1 硬件调用

文件:frameworks/base/services/jni/com_Android_server_BatteryService.cpp

#define POWER_SUPPLY_PATH "/sys/class/power_supply"

int register_android_server_BatteryService(JNIEnv* env)

{

...

DIR* dir = opendir(POWER_SUPPLY_PATH);

if (dir == NULL) {

LOGE("Could not open %s/n", POWER_SUPPLY_PATH);

return -1;

}

while ((entry = readdir(dir))) {

const char* name = entry->d_name;

 

// ignore "." and ".."

if (name[0] == '.' && (name[1] == 0 || (name[1] == '.' && name[2] == 0))) {

continue;

}

 

char buf[20];

// Look for "type" file in each subdirectory

snprintf(path, sizeof(path), "%s/%s/type", POWER_SUPPLY_PATH, name);

int length = readFromFile(path, buf, sizeof(buf));

if (length > 0) {

if (buf[length - 1] == '/n')

buf[length - 1] = 0;

 

if (strcmp(buf, "Mains") == 0) {

snprintf(path, sizeof(path), "%s/%s/online", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.acOnlinePath = strdup(path);

}

else if (strcmp(buf, "USB") == 0) {

snprintf(path, sizeof(path), "%s/%s/online", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.usbOnlinePath = strdup(path);

}

else if (strcmp(buf, "Battery") == 0) {

snprintf(path, sizeof(path), "%s/%s/status", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.batteryStatusPath = strdup(path);

snprintf(path, sizeof(path), "%s/%s/health", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.batteryHealthPath = strdup(path);

snprintf(path, sizeof(path), "%s/%s/present", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.batteryPresentPath = strdup(path);

snprintf(path, sizeof(path), "%s/%s/capacity", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.batteryCapacityPath = strdup(path);

 

snprintf(path, sizeof(path), "%s/%s/voltage_now", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0) {

gPaths.batteryVoltagePath = strdup(path);

// voltage_now is in microvolts, not millivolts

gVoltageDivisor = 1000;

} else {

snprintf(path, sizeof(path), "%s/%s/batt_vol", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.batteryVoltagePath = strdup(path);

}

 

snprintf(path, sizeof(path), "%s/%s/temp", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0) {

gPaths.batteryTemperaturePath = strdup(path);

} else {

snprintf(path, sizeof(path), "%s/%s/batt_temp", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.batteryTemperaturePath = strdup(path);

}

 

snprintf(path, sizeof(path), "%s/%s/technology", POWER_SUPPLY_PATH, name);

if (access(path, R_OK) == 0)

gPaths.batteryTechnologyPath = strdup(path);

}

}

}

closedir(dir);

扫描/sys/class/power_supply目录下的文件夹,根据其type文件里的字符串来判断是哪一种类型:MainsUSB还是Battery,然后不同的参数对应着不同的文件

 

jclass clazz = env->FindClass("com/android/server/BatteryService");

 

if (clazz == NULL) {

LOGE("Can't find com/android/server/BatteryService");

return -1;

}

 

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");

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

接口说明:

env->FindClass("com/android/server/BatteryService");获取指定文件的类。

env->GetFieldID(clazz, "mAcOnline", "Z"); 获取指定类的mAcOnline变量值。

以上代码的功能是:将frameworks/base/services/java/com/android/server/BatteryService.java里的各变量值存到全局变量里。

 

clazz = env->FindClass("android/os/BatteryManager");

if (clazz == NULL) {

LOGE("Can't find android/os/BatteryManager");

return -1;

}

gConstants.statusUnknown = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_STATUS_UNKNOWN", "I"));

gConstants.statusCharging = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_STATUS_CHARGING", "I"));

gConstants.statusDischarging = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_STATUS_DISCHARGING", "I"));

gConstants.statusNotCharging = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_STATUS_NOT_CHARGING", "I"));

gConstants.statusFull = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_STATUS_FULL", "I"));

gConstants.healthUnknown = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_HEALTH_UNKNOWN", "I"));

gConstants.healthGood = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_HEALTH_GOOD", "I"));

gConstants.healthOverheat = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_HEALTH_OVERHEAT", "I"));

gConstants.healthDead = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_HEALTH_DEAD", "I"));

gConstants.healthOverVoltage = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_HEALTH_OVER_VOLTAGE", "I"));

gConstants.healthUnspecifiedFailure = env->GetStaticIntField(clazz,

env->GetStaticFieldID(clazz, "BATTERY_HEALTH_UNSPECIFIED_FAILURE", "I"));

以上代码的功能是:将frameworks/base/core/java/android/os/BatteryManager.java里类的变量值存到全局变量里。

 

...

}

static void setBooleanField(JNIEnv* env, jobject obj, const char* path, jfieldID fieldID)

{

const int SIZE = 16;

char buf[SIZE];

 

jboolean value = false;

if (readFromFile(path, buf, SIZE) > 0) {

if (buf[0] == '1') {

value = true;

}

}

env->SetBooleanField(obj, fieldID, value);

}

 

static void setIntField(JNIEnv* env, jobject obj, const char* path, jfieldID fieldID)

{

const int SIZE = 128;

char buf[SIZE];

 

jint value = 0;

if (readFromFile(path, buf, SIZE) > 0) {

value = atoi(buf);

}

env->SetIntField(obj, fieldID, value);

}

 

static void setVoltageField(JNIEnv* env, jobject obj, const char* path, jfieldID fieldID)

{

const int SIZE = 128;

char buf[SIZE];

 

jint value = 0;

if (readFromFile(path, buf, SIZE) > 0) {

value = atoi(buf);

value /= gVoltageDivisor;

}

env->SetIntField(obj, fieldID, value);

}

static void android_server_BatteryService_update(JNIEnv* env, jobject obj)

{

setBooleanField(env, obj, gPaths.acOnlinePath, gFieldIds.mAcOnline);

setBooleanField(env, obj, gPaths.usbOnlinePath, gFieldIds.mUsbOnline);

setBooleanField(env, obj, gPaths.batteryPresentPath, gFieldIds.mBatteryPresent);

 

setIntField(env, obj, gPaths.batteryCapacityPath, gFieldIds.mBatteryLevel);

setVoltageField(env, obj, gPaths.batteryVoltagePath, gFieldIds.mBatteryVoltage);

setIntField(env, obj, gPaths.batteryTemperaturePath, gFieldIds.mBatteryTemperature);

 

const int SIZE = 128;

char buf[SIZE];

 

if (readFromFile(gPaths.batteryStatusPath, buf, SIZE) > 0)

env->SetIntField(obj, gFieldIds.mBatteryStatus, getBatteryStatus(buf));

else

env->SetIntField(obj, gFieldIds.mBatteryStatus,

gConstants.statusUnknown);

 

if (readFromFile(gPaths.batteryHealthPath, buf, SIZE) > 0)

env->SetIntField(obj, gFieldIds.mBatteryHealth, getBatteryHealth(buf));

 

if (readFromFile(gPaths.batteryTechnologyPath, buf, SIZE) > 0)

env->SetObjectField(obj, gFieldIds.mBatteryTechnology, env->NewStringUTF(buf));

}

 

static JNINativeMethod sMethods[] = {

/* name, signature, funcPtr */

{"native_update", "()V", (void*)android_server_BatteryService_update},

};

接口说明:

env->SetIntField(obj, fieldID, value); 将指定类的变量以整型付值。

env->SetBooleanField(obj, fieldID, value); 将指定类的变量以布尔付值。

以上代码的功能是:

将全局变量的值付给frameworks/base/core/java/android/os/BatteryManager.java里类的变量;并且将ative_updateandroid_server_BatteryService_update绑定。

5.2 电池服务

文件:frameworks/base/services/java/com/android/server/BatteryService.java

mUEventObserver.startObserving("SUBSYSTEM=power_supply");

private UEventObserver mUEventObserver = new UEventObserver() {

@Override

public void onUEvent(UEventObserver.UEvent event) {

update();

}

};

监控uevent事件,响应SUBSYSTEM=power_supply的事件。

private synchronized final void update() {

native_update();

...

if (mAcOnline) {

mPlugType = BatteryManager.BATTERY_PLUGGED_AC;

} else if (mUsbOnline) {

mPlugType = BatteryManager.BATTERY_PLUGGED_USB;

} else {

mPlugType = BATTERY_PLUGGED_NONE;

}

...

sendIntent();

...

}

 

private final void sendIntent() {

//Pack up the values and broadcast them to everyone

Intent intent = new Intent(Intent.ACTION_BATTERY_CHANGED);

intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);

try {

mBatteryStats.setOnBattery(mPlugType == BATTERY_PLUGGED_NONE, mBatteryLevel);

} catch (RemoteException e) {

// Should never happen.

}

 

int icon = getIcon(mBatteryLevel);

 

intent.putExtra(BatteryManager.EXTRA_STATUS, mBatteryStatus);

intent.putExtra(BatteryManager.EXTRA_HEALTH, mBatteryHealth);

intent.putExtra(BatteryManager.EXTRA_PRESENT, mBatteryPresent);

intent.putExtra(BatteryManager.EXTRA_LEVEL, mBatteryLevel);

intent.putExtra(BatteryManager.EXTRA_SCALE, BATTERY_SCALE);

intent.putExtra(BatteryManager.EXTRA_ICON_SMALL, icon);

intent.putExtra(BatteryManager.EXTRA_PLUGGED, mPlugType);

intent.putExtra(BatteryManager.EXTRA_VOLTAGE, mBatteryVoltage);

intent.putExtra(BatteryManager.EXTRA_TEMPERATURE, mBatteryTemperature);

intent.putExtra(BatteryManager.EXTRA_TECHNOLOGY, mBatteryTechnology);

 

if (false) {

Log.d(TAG, "updateBattery level:" + mBatteryLevel +

" scale:" + BATTERY_SCALE + " status:" + mBatteryStatus +

" health:" + mBatteryHealth +" present:" + mBatteryPresent +

" voltage: " + mBatteryVoltage +

" temperature: " + mBatteryTemperature +

" technology: " + mBatteryTechnology +

" AC powered:" + mAcOnline + " USB powered:" + mUsbOnline +

" icon:" + icon );

}

 

ActivityManagerNative.broadcastStickyIntent(intent, null);

}

以上代码的功能是:

通过native_update();更新各状态变量的值,如:

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;

private boolean mBatteryLevelCritical;

然后通过:

intent.putExtra(BatteryManager.EXTRA_STATUS, mBatteryStatus);

intent.putExtra(BatteryManager.EXTRA_HEALTH, mBatteryHealth);

intent.putExtra(BatteryManager.EXTRA_PRESENT, mBatteryPresent);

intent.putExtra(BatteryManager.EXTRA_LEVEL, mBatteryLevel);

intent.putExtra(BatteryManager.EXTRA_SCALE, BATTERY_SCALE);

intent.putExtra(BatteryManager.EXTRA_ICON_SMALL, icon);

intent.putExtra(BatteryManager.EXTRA_PLUGGED, mPlugType);

intent.putExtra(BatteryManager.EXTRA_VOLTAGE, mBatteryVoltage);

intent.putExtra(BatteryManager.EXTRA_TEMPERATURE, mBatteryTemperature);

intent.putExtra(BatteryManager.EXTRA_TECHNOLOGY, mBatteryTechnology);

ActivityManagerNative.broadcastStickyIntent(intent, null);

发布给各实体窗口取用,EXTRA_STATUS等对应的字符是:

文件:frameworks/base/core/java/android/os/BatteryManager.java

public static final String EXTRA_STATUS = "status";

public static final String EXTRA_HEALTH = "health";

public static final String EXTRA_PRESENT = "present";

public static final String EXTRA_LEVEL = "level";

public static final String EXTRA_SCALE = "scale";

public static final String EXTRA_ICON_SMALL = "icon-small";

public static final String EXTRA_PLUGGED = "plugged";

public static final String EXTRA_VOLTAGE = "voltage";

public static final String EXTRA_TEMPERATURE = "temperature";

public static final String EXTRA_TECHNOLOGY = "technology";

5.3 显示电池状态

文件:packages/apps/DeskClock/src/com/android/deskclock/DeskClock.java

private final BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {

@Override

public void onReceive(Context context, Intent intent) {

final String action = intent.getAction();

if (Intent.ACTION_DATE_CHANGED.equals(action)) {

refreshDate();

} else if (Intent.ACTION_BATTERY_CHANGED.equals(action)) {

handleBatteryUpdate(

intent.getIntExtra("status", BATTERY_STATUS_UNKNOWN),

intent.getIntExtra("level", 0));

} else if (Intent.ACTION_DOCK_EVENT.equals(action)) {

int state = intent.getIntExtra(Intent.EXTRA_DOCK_STATE, -1);

if (DEBUG) Log.d(LOG_TAG, "ACTION_DOCK_EVENT, state=" + state);

if (state == Intent.EXTRA_DOCK_STATE_UNDOCKED) {

if (mLaunchedFromDock) {

// moveTaskToBack(false);

finish();

}

mLaunchedFromDock = false;

}

}

}

};

// Adapted from KeyguardUpdateMonitor.java

private void handleBatteryUpdate(int plugStatus, int batteryLevel) {

final boolean pluggedIn = (plugStatus == BATTERY_STATUS_CHARGING || plugStatus == BATTERY_STATUS_FULL);

if (pluggedIn != mPluggedIn) {

setWakeLock(pluggedIn);

 

if (pluggedIn) {

// policy: update weather info when attaching to power

requestWeatherDataFetch();

}

}

if (pluggedIn != mPluggedIn || batteryLevel != mBatteryLevel) {

mBatteryLevel = batteryLevel;

mPluggedIn = pluggedIn;

refreshBattery();

}

}

 

private void refreshBattery() {

if (mBatteryDisplay == null) return;

 

if (mPluggedIn /* || mBatteryLevel < LOW_BATTERY_THRESHOLD */) {

mBatteryDisplay.setCompoundDrawablesWithIntrinsicBounds(

0, 0, android.R.drawable.ic_lock_idle_charging, 0);

mBatteryDisplay.setText(

getString(R.string.battery_charging_level, mBatteryLevel));

mBatteryDisplay.setVisibility(View.VISIBLE);

} else {

mBatteryDisplay.setVisibility(View.INVISIBLE);

}

}

由以上代码可知,程序通过接收广播信息,获取电池的当前节数:intent.getIntExtra("level", 0));,然后再将其显示。

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