Raspberry Pi＋Spring Boot + Pi4J で 信号機 WebAPI を簡単に作成してみる ref: http://qiita.com/hase5021/items/7905638abaf30684de69

pom.xml

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.pi4j</groupId>
            <artifactId>pi4j-core</artifactId>
            <version>1.0</version>
        </dependency>
    </dependencies>

TrafficLightController.java

import com.pi4j.io.gpio.*;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TrafficLightController {

    private GpioController gpio;

    private GpioPinDigitalOutput pinRed;
    private GpioPinDigitalOutput pinYellow;
    private GpioPinDigitalOutput pinGreen;

    /**
     * GPIOピン初期化処理
     */
    private void initialize() {
        if (gpio == null) {
            gpio = GpioFactory.getInstance();
            pinGreen = gpio.provisionDigitalOutputPin(RaspiPin.GPIO_27, "GreenLED", PinState.LOW);
            pinYellow = gpio.provisionDigitalOutputPin(RaspiPin.GPIO_28, "YellowLED", PinState.LOW);
            pinRed = gpio.provisionDigitalOutputPin(RaspiPin.GPIO_29, "RedLED", PinState.LOW);
        }

        pinGreen.low();
        pinYellow.low();
        pinRed.low();
    }

    /**
     * 全灯：緑・黄・赤
     */
    @RequestMapping("/")
    public void all() {
        initialize();
        pinRed.high();
        pinYellow.high();
        pinGreen.high();
    }

    /**
     * 点灯：緑
     */
    @RequestMapping("/green")
    public void green() {
        initialize();
        pinGreen.high();
    }

    /**
     * 点灯：黄
     */
    @RequestMapping("/yellow")
    public void yellow() {
        initialize();
        pinYellow.high();
    }

    /**
     * 点灯：赤
     */
    @RequestMapping("/red")
    public void red() {
        initialize();
        pinRed.high();
    }

}