官方的一个简单示例
// START SNIPPET: blink-gpio-snippet /* * #%L * ********************************************************************** * ORGANIZATION : Pi4J * PROJECT : Pi4J :: Java Examples * FILENAME : BlinkGpioExample.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 - 2016 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 * <http://www.gnu.org/licenses/lgpl-3.0.html>. * #L% */ import com.pi4j.io.gpio.GpioController; import com.pi4j.io.gpio.GpioFactory; import com.pi4j.io.gpio.GpioPinDigitalInput; import com.pi4j.io.gpio.GpioPinDigitalOutput; import com.pi4j.io.gpio.PinPullResistance; import com.pi4j.io.gpio.RaspiPin; import com.pi4j.io.gpio.event.GpioPinDigitalStateChangeEvent; import com.pi4j.io.gpio.event.GpioPinListenerDigital; /** * This example code demonstrates how to perform simple * blinking LED logic of a GPIO pin on the Raspberry Pi * using the Pi4J library. * * @author Robert Savage */ public class BlinkGpioExample { public static void main(String[] args) throws InterruptedException { System.out.println("<--Pi4J--> GPIO Blink Example ... started."); // create gpio controller final GpioController gpio = GpioFactory.getInstance(); // provision gpio pin #01 & #03 as an output pins and blink final GpioPinDigitalOutput led1 = gpio.provisionDigitalOutputPin(RaspiPin.GPIO_01); final GpioPinDigitalOutput led2 = gpio.provisionDigitalOutputPin(RaspiPin.GPIO_03); // provision gpio pin #02 as an input pin with its internal pull down resistor enabled final GpioPinDigitalInput myButton = gpio.provisionDigitalInputPin(RaspiPin.GPIO_02, PinPullResistance.PULL_DOWN); // create and register gpio pin listener myButton.addListener(new GpioPinListenerDigital() { @Override public void handleGpioPinDigitalStateChangeEvent(GpioPinDigitalStateChangeEvent event) { // when button is pressed, speed up the blink rate on LED #2 if(event.getState().isHigh()){ led2.blink(200); } else{ led2.blink(1000); } } }); // continuously blink the led every 1/2 second for 15 seconds led1.blink(500, 15000); // continuously blink the led every 1 second led2.blink(1000); System.out.println(" ... the LED will continue blinking until the program is terminated."); System.out.println(" ... PRESS <CTRL-C> TO STOP THE PROGRAM."); // keep program running until user aborts (CTRL-C) while(true) { Thread.sleep(500); } // stop all GPIO activity/threads // (this method will forcefully shutdown all GPIO monitoring threads and scheduled tasks) // gpio.shutdown(); <--- implement this method call if you wish to terminate the Pi4J GPIO controller } } //END SNIPPET: blink-gpio-snippet
操作输出
package com.xyes.pi4j.test; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.URL; import com.pi4j.io.gpio.GpioController; import com.pi4j.io.gpio.GpioFactory; import com.pi4j.io.gpio.GpioPinDigitalOutput; import com.pi4j.io.gpio.RaspiPin; public class EnvTest { public static void main(String[] args) { URL url = null; byte[] buffer = null; try { url = new URL("http://www.baidu.com"); InputStream stream = url.openStream(); ByteArrayOutputStream out = new ByteArrayOutputStream(); copy(stream, out); out.close(); stream.close(); buffer = out.toByteArray(); } catch (Exception e1) { e1.printStackTrace(); } final GpioController controller = GpioFactory.getInstance(); final GpioPinDigitalOutput LED = controller.provisionDigitalOutputPin(RaspiPin.GPIO_15); for (byte b : buffer) { if (b > 100) { LED.high(); } else { LED.low(); } System.out.println("-->" + b); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } public static void copy(InputStream in, OutputStream out) throws IOException { byte[] buffer = new byte[1024]; int len = 0; while ((len = in.read(buffer)) > 0) { out.write(buffer, 0, len); } } } 操作输入
import com.pi4j.io.gpio.GpioController; import com.pi4j.io.gpio.GpioFactory; import com.pi4j.io.gpio.GpioPinDigitalInput; import com.pi4j.io.gpio.GpioPinDigitalOutput; import com.pi4j.io.gpio.RaspiPin; import com.pi4j.io.gpio.event.GpioPinListener; public class ButtonTest implements GpioPinListener { private static final GpioController CONTROLLER = GpioFactory.getInstance(); private static final GpioPinDigitalInput BUTTON = CONTROLLER.provisionDigitalInputPin(RaspiPin.GPIO_16); private static final GpioPinDigitalOutput LED = CONTROLLER.provisionDigitalOutputPin(RaspiPin.GPIO_15); public static void main(String[] args) { new ButtonTest().run(); } public void run() { while (true) { if (BUTTON.isHigh()) { LED.high(); } else { LED.low(); } try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } } 监听器方式读取输入
import java.util.Scanner; import com.pi4j.io.gpio.GpioController; import com.pi4j.io.gpio.GpioFactory; import com.pi4j.io.gpio.GpioPinDigitalInput; import com.pi4j.io.gpio.GpioPinDigitalOutput; import com.pi4j.io.gpio.RaspiPin; import com.pi4j.io.gpio.event.GpioPinDigitalStateChangeEvent; import com.pi4j.io.gpio.event.GpioPinListenerDigital; public class GpioListener implements GpioPinListenerDigital { private static final GpioController CONTROLLER = GpioFactory.getInstance(); private static final GpioPinDigitalInput BUTTON = CONTROLLER.provisionDigitalInputPin(RaspiPin.GPIO_16); private static final GpioPinDigitalOutput LED = CONTROLLER.provisionDigitalOutputPin(RaspiPin.GPIO_15); public static void main(String[] args) { new GpioListener().run(); } public void run() { BUTTON.addListener(this); Scanner scanner = new Scanner(System.in); scanner.nextLine(); } @Override public void handleGpioPinDigitalStateChangeEvent(GpioPinDigitalStateChangeEvent event) { boolean state = event.getState().isHigh(); System.out.println("--->pin:" + event.getPin() + "|state:" + state); if (state) { LED.high(); } else { LED.low(); } } }
