com.pi4j.jni.SerialInterrupt Maven / Gradle / Ivy
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package com.pi4j.jni;
/*
* #%L
* **********************************************************************
ORGANIZATION : Pi4J
PROJECT : Pi4J :: Java Library (Core)
FILENAME : SerialInterrupt.java
This file is part of the Pi4J project. More information about
this project can be found here: http://www.pi4j.com/
**********************************************************************
* %%
* Copyright (C) 2012 - 2018 Pi4J
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import com.pi4j.util.NativeLibraryLoader;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
*
* This class provides static methods to configure the native Pi4J library to listen to serial
* interrupts and invoke callbacks into this class. Additionally, this class provides a listener
* registration allowing Java consumers to subscribe to serial data receive events.
*
*
* @see http://www.pi4j.com/
* @author Robert Savage (http://www.savagehomeautomation.com)
*/
public class SerialInterrupt {
private static Map listeners = new ConcurrentHashMap<>();
// private constructor
private SerialInterrupt() {
// forbid object construction
}
static {
// Load the platform library
NativeLibraryLoader.load("libpi4j.so");
}
/**
*
* This method is used to instruct the native code to setup a monitoring thread to monitor
* interrupts that represent changes to the selected serial port.
*
*
* @param fileDescriptor the serial file descriptor/handle
* @return A return value of a negative number represents an error. A return value of '0'
* represents success and that the serial port is already being monitored. A return value
* of '1' represents success and that a new monitoring thread was created to handle the
* requested serial port.
*/
public static native int enableSerialDataReceiveCallback(int fileDescriptor);
/**
*
* This method is used to instruct the native code to stop the monitoring thread monitoring
* interrupts on the selected serial port.
*
*
* @param fileDescriptor the serial file descriptor/handle
* @return A return value of a negative number represents an error. A return value of '0'
* represents success and that no existing monitor was previously running. A return
* value of '1' represents success and that an existing monitoring thread was stopped
* for the requested serial port.
*/
public static native int disableSerialDataReceiveCallback(int fileDescriptor);
/**
*
* This method is provided as the callback handler for the Pi4J native library to invoke when a
* GPIO interrupt is detected. This method should not be called from any Java consumers. (Thus
* is is marked as a private method.)
*
*
* @param fileDescriptor the serial file descriptor/handle
* //@param data byte array of data received on this event from the serial receive buffer
*/
private static void onDataReceiveCallback(int fileDescriptor, byte[] data) {
// notify event listeners
if(listeners.containsKey(fileDescriptor)){
SerialInterruptListener listener = listeners.get(fileDescriptor);
if(listener != null) {
SerialInterruptEvent event = new SerialInterruptEvent(listener, fileDescriptor, data);
listener.onDataReceive(event);
}
}
//System.out.println("SERIAL PORT [" + fileDescriptor + "] DATA LENGTH = " + data.length + " / " + new String(data));
}
/**
*
* Java consumer code can all this method to register itself as a listener for pin state
* changes.
*
*
* @see com.pi4j.jni.SerialInterruptListener
* @see com.pi4j.jni.SerialInterruptEvent
*
* @param fileDescriptor the serial file descriptor/handle
* @param listener A class instance that implements the GpioInterruptListener interface.
*/
public static synchronized void addListener(int fileDescriptor, SerialInterruptListener listener) {
if (!listeners.containsKey(fileDescriptor)) {
listeners.put(fileDescriptor, listener);
enableSerialDataReceiveCallback(fileDescriptor);
}
}
/**
*
* Java consumer code can all this method to unregister itself as a listener for pin state
* changes.
*
*
* @see com.pi4j.jni.SerialInterruptListener
* @see com.pi4j.jni.SerialInterruptEvent
*
* @param fileDescriptor the serial file descriptor/handle
*/
public static synchronized void removeListener(int fileDescriptor) {
if (listeners.containsKey(fileDescriptor)) {
listeners.remove(fileDescriptor);
disableSerialDataReceiveCallback(fileDescriptor);
}
}
/**
*
* Returns true if the listener is already registered for event callbacks.
*
*
* @see com.pi4j.jni.SerialInterruptListener
* @see com.pi4j.jni.SerialInterruptEvent
*
* @param fileDescriptor the serial file descriptor/handle
*/
public static synchronized boolean hasListener(int fileDescriptor) {
return listeners.containsKey(fileDescriptor);
}
}