gpio.java

## gpio.java
public class GPIO {

	public String port;
	public int pin;

	//get direction of gpio
	public String getInOut()
	{
		String command = String.format("cat /sys/class/gpio/%s/direction",this.port);
		try {
			Process p = Runtime.getRuntime().exec(new String[] {"su", "-c", command});
			BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
			StringBuilder text = new StringBuilder();
			String line;
			while((line = reader.readLine()) != null){
				text.append(line);
				text.append("\n");
			}
			String retour= text.toString();
			return retour;
		} catch (IOException e) {
			return "";
		}
	}

	// get state of gpio for input and output
	//test if gpio is configurate
	public int getState()
	{
		String command = String.format("cat /sys/class/gpio/%s/value",this.port);
		try {
			Process p = Runtime.getRuntime().exec(new String[] {"su", "-c", command});
			BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
			StringBuilder text = new StringBuilder();
			String line;
			while((line = reader.readLine()) != null){
				text.append(line);
				text.append("\n");
			}
			try {
				String retour= text.toString();
				if(retour.equals("")){
					return -1;
				} else 	{
				    return Integer.parseInt(retour.substring(0, 1));
				}
			} catch(NumberFormatException nfe) {
				return -1;
			}
		} catch (IOException e) {
			return -1;
		}
	}

	//set value of the output
	public boolean setState(int value){
		String command = String.format("echo %d > /sys/class/gpio/%s/value", value,this.port);
		try {
			String[] test = new String[] {"su", "-c", command};
			Runtime.getRuntime().exec(test);
			return true;
		} catch (IOException e) {
			return false;
		}
	}

	// set direction
	public boolean setInOut(String direction){
		String command = String.format("echo %s > /sys/class/gpio/%s/direction", direction,this.port);
		try {
			Runtime.getRuntime().exec(new String[] {"su", "-c", command});
			return true;
		} catch (IOException e) {
			return false;
		}
	}

	//export gpio
	public boolean activationPin(){
		String command = String.format("echo %d > /sys/class/gpio/export", this.pin);
		try {
			Runtime.getRuntime().exec(new String[] {"su", "-c", command});
			return true;
		} catch (IOException e) {
			return false;
		}
	}

	// unexport gpio
	public boolean desactivationPin(){
		String command = String.format("echo %d > /sys/class/gpio/unexport", this.pin);
		try {
			Runtime.getRuntime().exec(new String[] {"su", "-c", command});
			return true;
		} catch (IOException e) {
			return false;
		}
	}

	//init the pin
	public int initPin(String direction){
		int retour=0;
		boolean ret=true;

		// see if gpio is already set
		retour=getState();
		if (retour==-1) {
			// unexport the gpio
			ret=desactivationPin();
			if(ret==false){ retour=-1; }

			//export the gpio
			ret=activationPin();
			if(ret==false){ retour=-2; }
		}

		// get If gpio direction is define
		String ret2 = getInOut();
		if (!ret2.contains(direction))
		{
			// set the direction (in or out)
			ret=setInOut(direction);
			if(ret==false){ retour=-3; }
		}

		return retour;
	}

	//Constructor
	public GPIO( int pin){
		this.port = "gpio"+pin;
		this.pin = pin;
	}
}