001package com.pi4j.platform; 002 003/* 004 * #%L 005 * ********************************************************************** 006 * ORGANIZATION : Pi4J 007 * PROJECT : Pi4J :: Java Library (Core) 008 * FILENAME : PlatformManager.java 009 * 010 * This file is part of the Pi4J project. More information about 011 * this project can be found here: https://www.pi4j.com/ 012 * ********************************************************************** 013 * %% 014 * Copyright (C) 2012 - 2019 Pi4J 015 * %% 016 * This program is free software: you can redistribute it and/or modify 017 * it under the terms of the GNU Lesser General Public License as 018 * published by the Free Software Foundation, either version 3 of the 019 * License, or (at your option) any later version. 020 * 021 * This program is distributed in the hope that it will be useful, 022 * but WITHOUT ANY WARRANTY; without even the implied warranty of 023 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 024 * GNU General Lesser Public License for more details. 025 * 026 * You should have received a copy of the GNU General Lesser Public 027 * License along with this program. If not, see 028 * <http://www.gnu.org/licenses/lgpl-3.0.html>. 029 * #L% 030 */ 031 032/** 033 * <p> 034 * This class provides static methods to configure the Pi4J library's default 035 * platform. Pi4J supports the following platforms: RaspberryPi, BananaPi, BananaPro, Odroid. 036 * </p> 037 * 038 * @see <a href="https://www.pi4j.com/">https://www.pi4j.com/</a> 039 * @author Robert Savage (<a 040 * href="http://www.savagehomeautomation.com">http://www.savagehomeautomation.com</a>) 041 */ 042public class PlatformManager { 043 044 // selected platform 045 private static Platform platform = null; 046 047 /** 048 * Get the selected system platform. If 049 * a platform has not explicitly been set, then 050 * the default platform: 'RASPBERRY_PI' will be 051 * selected and returned. 052 * 053 * @return selected platform 054 */ 055 public static Platform getPlatform(){ 056 // if a platform instance has not explicitly been 057 // selected, then get the default platform 058 if(platform == null){ 059 try { 060 setPlatform(getDefaultPlatform()); 061 } catch (PlatformAlreadyAssignedException e) { 062 // we are eating this exception because it should never be thrown in this case 063 e.printStackTrace(); 064 return null; 065 } 066 } 067 return platform; 068 } 069 070 /** 071 * Set the runtime platform for Pi4J to use. This platform selection 072 * will be used to determine the default GPIO providers and I2C providers 073 * specific to the selected platform. A platform assignment can only 074 * be set once. If a second attempt to set a platform is attempted, 075 * the 'PlatformAlreadyAssignedException' will be thrown. Please 076 * note that platform assignment can be made automatically if you 077 * use a provider class prior to manually assigning a platform. 078 * 079 * @param platform platform to assign 080 * @throws PlatformAlreadyAssignedException 081 */ 082 public static void setPlatform(Platform platform) throws PlatformAlreadyAssignedException { 083 // prevent changing the platform once it has been initially set 084 if(PlatformManager.platform != null){ 085 throw new PlatformAlreadyAssignedException(PlatformManager.platform); 086 } 087 088 // set internal platform instance 089 PlatformManager.platform = platform; 090 091 // apply Pi4J platform system property 092 System.setProperty("pi4j.platform", platform.id()); 093 } 094 095 096 /** 097 * Internal method to get the default platform. It will attempt to first 098 * get the platform using the 'PI4J_PLATFORM' environment variable, if the 099 * environment variable is not configured, then it will attempt to use the 100 * system property "pi4j.platform". If the system property is not found or 101 * the value is not legal, then return the default 'RASPBERRY_PI' platform. 102 * 103 * @return default platform enumeration 104 */ 105 protected static Platform getDefaultPlatform(){ 106 // attempt to get assigned platform identifier from the environment variables 107 String envPlatformId = System.getenv("PI4J_PLATFORM"); 108 109 // attempt to get assigned platform identifier from the system properties 110 String platformId = System.getProperty("pi4j.platform", envPlatformId); 111 112 // if a platform id was found in the system properties, then 113 // attempt to lookup the platform enumeration using the platform 114 // identifier string. If found then return the platform enum. 115 if(platformId != null && !platformId.isEmpty()){ 116 Platform pltfrm = Platform.fromId(platformId); 117 if(pltfrm != null){ 118 return pltfrm; 119 } 120 } 121 122 // the RASPBERRY_PI is the default platform; 123 // (... in time perhaps some auto-platform detection could be implemented here ...) 124 return Platform.RASPBERRYPI; 125 } 126}