bài học Android cơ bản

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1. Sensors
2. Monitoring
the Battery
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1. Sensors
The emulator does not provide any sensor data. All sensor
testing must be done on a physical device. Alternatively,
OpenIntents.org also provides a handy Sensor Simulator:

This tool simulates accelerometer, compass, and
temperature sensors, and it transmits data to the emulator.
Android devices have a variety of sensors :
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1. Sensors
TYPE_ACCELEROMETER: Measures acceleration in three
directions; values are in SI units (m/s2).
TYPE_GYROSCOPE: Measures angular orientation in three
directions; values are angles in degrees.
TYPE_LIGHT: Measures ambient light; values are in SI lux
units.
TYPE_MAGNETIC_FIELD: Measures magnetism in three
directions; the compass values are in micro-Tesla (uT).
TYPE_PRESSURE: Measures barometric pressure.
TYPE_PROXIMITY: Measures the distance to an object;
values are in centimeters, or “near” versus “far.”
TYPE_RELATIVE_HUMIDITY: Measures the relative humidity.
TYPE_AMBIENT_TEMPERATURE: Measures temperature.

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1. Sensors
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Here are the major classes related to sensor.
Class Comment
Sensor
Class representing a sensor. Use
getSensorList(int) to get the list of available
Sensors.
SensorEvent
This class represents a Sensor event and holds
informations such as the sensor's type, the time-
stamp, accuracy and of course the sensor's data.
SensorEventListener
An interface: Used for receiving notifications from
the SensorManager when sensor values have
changed.
SensorManager SensorManager lets you access the device's
sensors. Get an instance of this class by calling
Context.getSystemService() with the argument
SENSOR_SERVICE.
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1. Sensors
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Working with Sensor
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To get a Sensor, you need to use SensorManager.
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1. Sensors
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Working with Sensor
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Register EventListener to it.
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Working with Sensor
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UnRegister EventListener.
Register in the onResume method and
Unregister in the onPause method
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SensorManager.SENSOR_DELAY
Frequence Comment
SENSOR_DELAY_FASTEST get sensor data as fast as
possible
SENSOR_DELAY_NORMAL rate (default) suitable for
screen orientation changes
SENSOR_DELAY_GAME rate suitable for games
SENSOR_DELAY_UI rate suitable for the user
interface
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1. Sensors
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Receive SensorEvent
Normally, onSensorChanged is the method in which
we need to put your sensor handle logic.
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SensorEvent
Type Name Comment
public int accuracy The accuracy of this event.
public Sensor sensor The sensor that generated this
event.
public long timestamp The time in nanosecond at which
the event happened
public final float[] values The length and contents of the
values array depends on which
sensor type is being monitored.
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1. Sensors
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Sensor.TYPE_TEMPERATURE
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Sensor.TYPE_TEMPERATURE
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Sensor.TYPE_LIGHT
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1. Sensors
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Sensor.TYPE_LIGHT
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1. Sensors
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Sensor.TYPE_PRESSURE
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1. Sensors
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Sensor.TYPE_PRESSURE
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1. Sensors
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Sensor. TYPE_PROXIMITY
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Sensor. TYPE_PROXIMITY
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1. Sensors
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Sensor. TYPE_PROXIMITY
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Sensor.TYPE_ACCELEROMETER
The accelerometer values are represented in SI units
(m/s2). The device at right has the bottom of the device
screen pointing toward the center of gravity. Gravity on
Earth is 9.80665 m/s2.
All values are in SI units (m/s2)
values[0]: Acceleration minus Gx on
the x-axis
values[1]: Acceleration minus Gy on
the y-axis
values[2]: Acceleration minus Gz on
the z-axis
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Sensor.TYPE_ACCELEROMETER
Use to Accelerometer to detect SHAKING Device
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Sensor.TYPE_ACCELEROMETER
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Sensor.TYPE_ACCELEROMETER
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Sensor.TYPE_GYROSCOPE
measure, or maintain, the orientation of a device.
rate of rotation around a particular axis
values[0]: Angular speed around the x-axis
values[1]: Angular speed around the y-axis
values[2]: Angular speed around the z-axis
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1. Sensors
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Sensor.TYPE_GYROSCOPE