Android Vibrator

APP简单震动实现

一定要在AndroidManifest.xml中注册

<uses-permission android:name="android.permission.VIBRATE" />

// 震动效果的系统服务

vibrator = (Vibrator) getSystemService(VIBRATOR_SERVICE);

VibratorService来源：

在SystemServer启动的时startOtherServices()中将VibratorService 添加至ServiceManager

vibrator = new VibratorService(context);

ServiceManager.addService("vibrator", vibrator);

震动需要调用的方法有：

cancel()关闭或者停止振动器。

hasVibrator()判断硬件是否有振动器。

vibrate(long milliseconds)控制手机振动时长(毫秒)

vibrate(long[] pattern,int repeat)指定手机以pattern指定的模式振动。参数1：是一个数组，里面的数字下标为单数时，为停止(等待)时间，偶数时为震动时间，比如 [100,100] 就为停止100ms后震动100ms，参数2 repeat：重复次数,如果是-1的只振动一次,如果是0的话则一直振动。

然后就可以根据需要，调用这些方法了

比如，我们让手机让手机震动3秒就可以这么做

if (vibrator.hasVibrator()){

effect = VibrationEffect.createOneShot(3000, VibrationEffect.DEFAULT_AMPLITUDE);

vibrator.vibrate(effect);

}else {

Log.e("TOP","该设备没有震动器");

}

vibrator.vibrate(200);//振动0.2秒，这种调用方法震动也是可以的，不过已经用的越来越少了

既然VibrationEffect方式用的多了，我们不妨来看一下VibrationEffect这个类

VibrationEffect.OneShot // 一次性的震动

VibrationEffect.Waveform // 波形震动

VibrationEffect.Prebaked // 预设的震动形式

这三种震动反馈被抽象为VibrationEffect，

三种震动反馈 OneShot，Waveform，Prebaked

都继承自VibrationEffect。

eg: OneShot

/** @hide */

@TestApi

public static class OneShot extends VibrationEffect implements Parcelable {

private final long mDuration;

private final int mAmplitude;

public OneShot(Parcel in) {

mDuration = in.readLong();

mAmplitude = in.readInt();

}

public OneShot(long milliseconds, int amplitude) {

mDuration = milliseconds;

mAmplitude = amplitude;

}

@Override

public long getDuration() {

return mDuration;

}

public int getAmplitude() {

return mAmplitude;

}

/**

* Scale the amplitude of this effect.

*

* @param gamma the gamma adjustment to apply

* @param maxAmplitude the new maximum amplitude of the effect, must be between 0 and

* MAX_AMPLITUDE

* @throws IllegalArgumentException if maxAmplitude less than 0 or more than MAX_AMPLITUDE

*

* @return A {@link OneShot} effect with the same timing but scaled amplitude.

*/

public OneShot scale(float gamma, int maxAmplitude) {

if (maxAmplitude >MAX_AMPLITUDE || maxAmplitude < 0) {

throw new IllegalArgumentException(

"Amplitude is negative or greater than MAX_AMPLITUDE");

}

int newAmplitude =scale(mAmplitude, gamma, maxAmplitude);

return new OneShot(mDuration, newAmplitude);

}

/**

* Resolve default values into integer amplitude numbers.

*

* @param defaultAmplitude the default amplitude to apply, must be between 0 and

* MAX_AMPLITUDE

* @return A {@link OneShot} effect with same physical meaning but explicitly set amplitude

*

* @hide

*/

public OneShot resolve(int defaultAmplitude) {

if (defaultAmplitude >MAX_AMPLITUDE || defaultAmplitude < 0) {

throw new IllegalArgumentException(

"Amplitude is negative or greater than MAX_AMPLITUDE");

}

if (mAmplitude ==DEFAULT_AMPLITUDE) {

return new OneShot(mDuration, defaultAmplitude);

}

return this;

}

@Override

public void validate() {

if (mAmplitude < -1 || mAmplitude == 0 || mAmplitude > 255) {

throw new IllegalArgumentException(

"amplitude must either be DEFAULT_AMPLITUDE, "

+ "or between 1 and 255 inclusive (amplitude=" + mAmplitude + ")");

}

if (mDuration <= 0) {

throw new IllegalArgumentException(

"duration must be positive (duration=" + mDuration + ")");

}

}

@Override

public boolean equals(Object o) {

if (!(o instanceof VibrationEffect.OneShot)) {

return false;

}

VibrationEffect.OneShot other = (VibrationEffect.OneShot) o;

return other.mDuration == mDuration && other.mAmplitude == mAmplitude;

}

@Override

public int hashCode() {

int result = 17;

result += 37 * (int) mDuration;

result += 37 * mAmplitude;

return result;

}

@Override

public String toString() {

return "OneShot{mDuration=" + mDuration + ", mAmplitude=" + mAmplitude + "}";

}

@Override

public void writeToParcel(Parcel out, int flags) {

out.writeInt(PARCEL_TOKEN_ONE_SHOT);

out.writeLong(mDuration);

out.writeInt(mAmplitude);

}

@UnsupportedAppUsage

public static final @android.annotation.NonNull Parcelable.CreatorCREATOR =

new Parcelable.Creator<OneShot>() {

@Override

public OneShot createFromParcel(Parcel in) {

// Skip the type token

in.readInt();

return new OneShot(in);

}

@Override

public OneShot[] newArray(int size) {

return new OneShot[size];

}

};

}

VibratorEffect创造一个 OneShot震动

public static VibrationEffectcreateOneShot(long milliseconds, int amplitude) {

if (VibrateUtils.canConvertToPrebaked(milliseconds, ActivityThread.currentPackageName())) {

if (amplitude ==DEFAULT_AMPLITUDE) amplitude = 255;

return VibrateUtils.toPrebakedEffectByDur(milliseconds, amplitude);

}

VibrationEffect effect = new OneShot(milliseconds, amplitude);

effect.validate();

return effect;

}

因此可以用一下方式启动震动

effect = VibrationEffect.createOneShot(3000, VibrationEffect.DEFAULT_AMPLITUDE);

vibrator.vibrate(effect);

间歇性震动如下：

以前常用方式vibrate(long[] pattern,int repeat)

现在多用方式VibrationEffect

if (vibrator.hasVibrator()){

vibrator.cancel();

effect = VibrationEffect.createWaveform(new long[]{100,100}, 0);

vibrator.vibrate(effect);

}else {

Log.e("TOP","该设备没有震动器");

}

注Android S ，有很多改动包括VibratorService.java

现在从简单的马达框架入手进行讲解。

以Android 9为例子

整个马达框架比较简单，安卓官方已经帮我们实现了framework到HAL层，下面实现的就只有驱动层。接下来我们梳理一下从上层到底层怎么流程。

1、APP层

import android.os.Vibrator;

import android.widget.ToggleButton;

public class MainActivity extends Activity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

private Vibrator vibrator=null;

vibrator=(Vibrator)this.getSystemService(VIBRATOR_SERVICE);

toggleButton1=(ToggleButton)findViewById(R.id.toggleButton1);

/*短震动*/

toggleButton1.setOnCheckedChangeListener(new ToggleButton.OnCheckedChangeListener() {

@Override

public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

if(isChecked){

Log.i(TAG,"toggleButton1 enter vibrator.vibrate");

//设置震动周期，第二个参数为 -1表示只震动一次

vibrator.vibrate(new long[]{1000, 10, 100, 1000},-1);

}else{

//取消震动

Log.i(TAG,"toggleButton1 enter vibrator.cancel()");

vibrator.cancel();

}

}

});

}

}

上面展示了一个最简单的马达震动应用代码，获得服务后即可调用接口进行驱动。

2、framework层

代码路径：frameworks\base\services\core\java\com\android\server\VibratorService.java

@Override // Binder call

public voidvibrate(int uid, String opPkg, VibrationEffect effect, int usageHint,

IBinder token) {

Trace.traceBegin(Trace.TRACE_TAG_VIBRATOR, "vibrate");

try {

if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.VIBRATE)

!= PackageManager.PERMISSION_GRANTED) {

throw new SecurityException("Requires VIBRATE permission");

}

if (token == null) {

Slog.e(TAG, "token must not be null");

return;

}

verifyIncomingUid(uid);

if (!verifyVibrationEffect(effect)) {

return;

}

// If our current vibration is longer than the new vibration and is the same amplitude,

// then just let the current one finish.

synchronized (mLock) {

if (effect instanceof VibrationEffect.OneShot

&& mCurrentVibration != null

&& mCurrentVibration.effect instanceof VibrationEffect.OneShot) {

VibrationEffect.OneShot newOneShot = (VibrationEffect.OneShot) effect;

VibrationEffect.OneShot currentOneShot =

(VibrationEffect.OneShot) mCurrentVibration.effect;

if (mCurrentVibration.hasTimeoutLongerThan(newOneShot.getDuration())

&& newOneShot.getAmplitude() == currentOneShot.getAmplitude()) {

if (DEBUG) {

Slog.d(TAG,

"Ignoring incoming vibration in favor of current vibration");

}

return;

}

}

// If the current vibration is repeating and the incoming one is non-repeating,

// then ignore the non-repeating vibration. This is so that we don't cancel

// vibrations that are meant to grab the attention of the user, like ringtones and

// alarms, in favor of one-shot vibrations that are likely quite short.

if (!isRepeatingVibration(effect)

&& mCurrentVibration != null

&& isRepeatingVibration(mCurrentVibration.effect)) {

if (DEBUG) {

Slog.d(TAG, "Ignoring incoming vibration in favor of alarm vibration");

}

return;

}

Vibration vib = new Vibration(token, effect, usageHint, uid, opPkg);

linkVibration(vib);

long ident = Binder.clearCallingIdentity();

try {

doCancelVibrateLocked();

startVibrationLocked(vib);

addToPreviousVibrationsLocked(vib);

} finally {

Binder.restoreCallingIdentity(ident);

}

}

} finally {

Trace.traceEnd(Trace.TRACE_TAG_VIBRATOR);

}

}

接口里面会判断一下权限，根据应用层传递的不同effect值，有不同的震动效果。然后就调用到JNI层，调用顺序大概如下：

startVibrationLocked

startVibrationInnerLocked

doVibratorOn

vibratorOn

3、JNI层

代码路径：frameworks\base\services\core\jni\com_android_server_VibratorService.cpp

static voidvibratorOn(JNIEnv* /* env */, jobject /* clazz */, jlong timeout_ms)

{

Status retStatus = halCall(&V1_0::IVibrator::on, timeout_ms).withDefault(Status::UNKNOWN_ERROR);

if (retStatus != Status::OK) {

ALOGE("vibratorOn command failed (%" PRIu32 ").", static_cast<uint32_t>(retStatus));

}

}

static void vibratorOff(JNIEnv* /* env */, jobject /* clazz */)

{

Status retStatus = halCall(&V1_0::IVibrator::off).withDefault(Status::UNKNOWN_ERROR);

if (retStatus != Status::OK) {

ALOGE("vibratorOff command failed (%" PRIu32 ").", static_cast<uint32_t>(retStatus));

}

}

static const JNINativeMethod method_table[] = {

{

"vibratorExists", "()Z", (void*)vibratorExists },

{

"vibratorInit", "()V", (void*)vibratorInit },

{

"vibratorOn", "(J)V", (void*)vibratorOn },

{

"vibratorOff", "()V", (void*)vibratorOff },

{

"vibratorSupportsAmplitudeControl", "()Z", (void*)vibratorSupportsAmplitudeControl},

{

"vibratorSetAmplitude", "(I)V", (void*)vibratorSetAmplitude},

{

"vibratorPerformEffect", "(JJ)J", (void*)vibratorPerformEffect}

};

int register_android_server_VibratorService(JNIEnv *env)

{

return jniRegisterNativeMethods(env, "com/android/server/VibratorService",

method_table, NELEM(method_table));

}

以马达的On和off为例，会调用到HAL层的on和off方法。

4、HIDL层

代码路径：hardware\interfaces\vibrator\1.0\default\Vibrator.cpp

Return<Status> Vibrator::on(uint32_t timeout_ms) {

int32_t ret = mDevice->vibrator_on(mDevice, timeout_ms);

if (ret != 0) {

ALOGE("on command failed : %s", strerror(-ret));

return Status::UNKNOWN_ERROR;

}

return Status::OK;

}

Return<Status> Vibrator::off() {

int32_t ret = mDevice->vibrator_off(mDevice);

if (ret != 0) {

ALOGE("off command failed : %s", strerror(-ret));

return Status::UNKNOWN_ERROR;

}

return Status::OK;

}

HIDL层是较新的安卓版本才引入的，是连接HAL层和JNI层的桥梁。

5、HAL层

代码路径：hardware\libhardware\modules\vibrator\vibrator.c

static const char THE_DEVICE[] = "/sys/class/timed_output/vibrator/enable";

static int sendit(unsigned int timeout_ms)

{

char value[TIMEOUT_STR_LEN]; /* large enough for millions of years */

snprintf(value, sizeof(value), "%u", timeout_ms);

return write_value(THE_DEVICE, value);

}

static int vibra_on(vibrator_device_t* vibradev __unused, unsigned int timeout_ms)

{

/* constant on, up to maximum allowed time */

return sendit(timeout_ms);

}

static int vibra_off(vibrator_device_t* vibradev __unused)

{

return sendit(0);

}

static int vibra_open(const hw_module_t* module, const char* id __unused,

hw_device_t** device __unused) {

bool use_led;

if (vibra_exists()) {

ALOGD("Vibrator using timed_output");

use_led = false;

} else if (vibra_led_exists()) {

ALOGD("Vibrator using LED trigger");

use_led = true;

} else {

ALOGE("Vibrator device does not exist. Cannot start vibrator");

return -ENODEV;

}

vibrator_device_t *vibradev = calloc(1, sizeof(vibrator_device_t));

if (!vibradev) {

ALOGE("Can not allocate memory for the vibrator device");

return -ENOMEM;

}

vibradev->common.tag = HARDWARE_DEVICE_TAG;

vibradev->common.module = (hw_module_t *) module;

vibradev->common.version = HARDWARE_DEVICE_API_VERSION(1,0);

vibradev->common.close = vibra_close;

if (use_led) {

vibradev->vibrator_on = vibra_led_on;

vibradev->vibrator_off = vibra_led_off;

} else {

vibradev->vibrator_on = vibra_on;

vibradev->vibrator_off = vibra_off;

}

*device = (hw_device_t *) vibradev;

return 0;

}

其实开启和关闭马达的工作很简单，就是往节点"/sys/class/timed_output/vibrator/enable"写入震动时间，所以可以想得到驱动层只需要提供一个节点供上层操作就好。

6、驱动层

马达的驱动是基于kernel提供的timed_output框架完成的：

代码路径：kernel-4.4\drivers\staging\android\timed_output.c

代码比较简单，提供接口给驱动在"/sys/class/timed_output/"路径下面建立自己的节点，并提供节点的device attribute的操作接口，当我们写节点的时候就会调用到enable_store函数，并调用注册驱动的enable函数

static struct class *timed_output_class;

static ssize_t enable_store(struct device *dev, struct device_attribute *attr,

const char *buf, size_t size)

{

struct timed_output_dev *tdev = dev_get_drvdata(dev);

int value;

int rc;

rc = kstrtoint(buf, 0, &value);

if (rc != 0)

return -EINVAL;

tdev->enable(tdev, value);

return size;

}

static DEVICE_ATTR_RW(enable);

static struct attribute *timed_output_attrs[] = {

&dev_attr_enable.attr,

NULL,

};

ATTRIBUTE_GROUPS(timed_output);

static int create_timed_output_class(void)

{

if (!timed_output_class) {

timed_output_class = class_create(THIS_MODULE, "timed_output");

if (IS_ERR(timed_output_class))

return PTR_ERR(timed_output_class);

atomic_set(&device_count, 0);

timed_output_class->dev_groups = timed_output_groups;

}

return 0;

}

int timed_output_dev_register(struct timed_output_dev *tdev)

{

int ret;

if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)

return -EINVAL;

ret = create_timed_output_class();

if (ret < 0)

return ret;

tdev->index = atomic_inc_return(&device_count);

tdev->dev = device_create(timed_output_class, NULL,

MKDEV(0, tdev->index), NULL, "%s", tdev->name);

if (IS_ERR(tdev->dev))

return PTR_ERR(tdev->dev);

dev_set_drvdata(tdev->dev, tdev);

tdev->state = 0;

return 0;

}

现在我们看一下基于上面框架书写的马达驱动：

static void vibrator_off(void)

{

gpio_direction_output(gpio, !en_value);

wake_unlock(&vibdata.wklock); //震动关闭就可以释放 wake_lock锁

}

void motor_enable(struct timed_output_dev *sdev,int value)

{

mutex_lock(&vibdata.lock); //关键代码段,同一时间只允许一个线程执行

/* cancelprevious timer and set GPIO according to value */

hrtimer_cancel(&vibdata.timer); //当先前定时器完成后关闭这个定时器

cancel_work_sync(&vibdata.work); //当上次震动完成后关闭这次动作

if(value)

{

wake_lock(&vibdata.wklock); //开始震动打开wake lock锁不允许休眠

gpio_direction_output(gpio, en_value);

if(value > 0)

{

if(value > MAX_TIMEOUT)

value= MAX_TIMEOUT;

hrtimer_start(&vibdata.timer,

ktime_set(value / 1000, (value % 1000) * 1000000),

HRTIMER_MODE_REL);

}

}

else

vibrator_off();

mutex_unlock(&vibdata.lock);

}

struct timed_output_dev motot_driver = {

.name ="vibrator", //注意这个名字,由于HAL层里面的设备为//"/sys/class/timed_output/vibrator/enable"

//因此这个名字必须为"vibrator"

.enable= motor_enable,

.get_time= get_time,

};

static enum hrtimer_restart vibrator_timer_func(struct hrtimer *timer) //定时器结束时候的回调函数

{

schedule_work(&vibdata.work); //定时器完成了执行work队列回调函数来关闭电机

return HRTIMER_NORESTART;

}

static void vibrator_work(struct work_struct *work)

{

vibrator_off();

}

static int motor_probe(struct platform_device *pdev)

{

struct device_node *node = pdev->dev.of_node;

enum of_gpio_flags flags;

int ret =0;

hrtimer_init(&vibdata.timer,CLOCK_MONOTONIC, HRTIMER_MODE_REL);

vibdata.timer.function= vibrator_timer_func;

INIT_WORK(&vibdata.work,vibrator_work);

...

ret=timed_output_dev_register(&motot_driver);

if (ret< 0)

goto err_to_dev_reg;

return 0;

err_to_dev_reg:

mutex_destroy(&vibdata.lock);

wake_lock_destroy(&vibdata.wklock);

printk("vibrator err!:%d\n",ret);

return ret;

}

1、驱动接受上层传递震动时长

驱动接收上层传递过来的是震动时长，单位为毫秒。在驱动里注册一个定时器，定时器倒计时到期后会唤醒注册的工作队列，最终会执行vibrator_work()函数去关闭马达震动。

2、马达驱动注册

调用timed_output框架提供的timed_output_dev_register()接口将我们的马达驱动注册进系统，这里的关键就是我们需要自定义struct timed_output_dev结构体，填充enable和get_time函数。enable函数用来开启马达的震动：

void motor_enable(struct timed_output_dev *sdev,int value)

{

mutex_lock(&vibdata.lock); //关键代码段,同一时间只允许一个线程执行

/* cancelprevious timer and set GPIO according to value */

hrtimer_cancel(&vibdata.timer); //当先前定时器完成后关闭这个定时器

cancel_work_sync(&vibdata.work); //当上次震动完成后关闭这次动作

if(value)

{

wake_lock(&vibdata.wklock); //开始震动打开wake lock锁不允许休眠

gpio_direction_output(gpio, en_value);

if(value > 0)

{

if(value > MAX_TIMEOUT)

value= MAX_TIMEOUT;

hrtimer_start(&vibdata.timer,

ktime_set(value / 1000, (value % 1000) * 1000000),

HRTIMER_MODE_REL);

}

}

else

vibrator_off();

mutex_unlock(&vibdata.lock);

}

开启震动的操作也很简单，只是写一下GPIO，然后重新开启定时器，倒计时的时间就是写入节点的值，到时间再把马达关闭就好。

Android Vibrator

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