问题
How can I detect whenever the power cord is unplugged from electrical socket using JSR 256?
回答1:
You would add javax.microedition.io.Connector.sensor to the API Permissions tab of the Application Descriptor of the project properties.
回答2:
From a quick look at the specifications of the JSR:
(you might want to look for code examples, starting with Appendix D of the spec itself, the latest JavaME SDK, Sony Ericsson developer website, then google)
As always, I would be worried about fragmentation in the diverse implementations of the JSR, but here's my first idea:
import javax.microedition.sensor.*;
SensorInfo[] powerSensorInfoArray = SensorManager.findSensors("power","ambient");
//let's assume there is one SensorInfo in the array.
//open a connection to the sensor.
SensorConnection connection = (SensorConnection)Connector.open(powerSensorInfoArray[0].getUrl(), Connector.READ);
// add a DataListener to the connection
connection.setDataListener(new MyDataListener(), 1);
// implement the data listener
public class MyDataListener implements DataListener {
public void dataReceived(SensorConnection aSensor, Data[] aDataArray, boolean isDataLost) {
//let's assume there is only one channel for the sensor and no data was lost.
// figure out what kind of data the channel provides.
int dataType = aDataArray[0].getChannelInfo().getDataType();
//now, I suggest you switch on dataType and print the value on the screen
// experimentation on the JSR256 implementation you're targetting seems to be
// the only way to figure out out power data is formatted and what values mean.
//only one of the following 3 lines will work:
double[] valueArray = aDataArray[0].getDoubleValues();
int[] valueArray = aDataArray[0].getIntValues();
Object[] valueArray = aDataArray[0].getObjectValues();
// let's assume one value in the valueArray
String valueToPrint = "" + valueArray[0];
// see what happens with that and you plug or unplug the power supply cable.
}
}
You'll need to add javax.microedition.io.Connector.sensor to your MIDlet permissions.
-------EDIT------
Documentation from the JSR-256 implementation on Sony-Ericsson Satio phone (S60 5th edition):
The battery charge sensor has the following characteristics:
Quantity: battery_charge
Context type: device
URL: sensor:battery_charge;contextType=device;model=SonyEricsson
Channels: (index: name, range, unit)
0: battery_charge, 0-100, percent
1: charger_state, 0-1, boolean
来源：https://stackoverflow.com/questions/950172/jsr-256-battery-events