달란트(Talanton)

나는 webiopi라는 라즈베리파이 상에서 web으로 GPIO를 제어하는 프로그램을 참조하여

자바 스프링으로 유사한 기능을 제어하려고 하고 있다.

webiopi는 REST API를 사용하여 GPIO를 제어하고 있어서 자바 스프링에서 REST API를 어떻게 처리하는지 파악하고 있다.

이 글에서는 webiopi에서 제공하는 REST API 기능에 대하여 자바 스프링으로 처리하기 위한 전 단계로 REST API 처리를 위한 Controller, Method 및 입력 파라미터 파싱에 대하여 알아본다.

1. Get GPIO function

  - HTTP GET /GPIO/(gpioNumber)/function

package com.talanton.rest.controller;

import org.springframework.http.HttpStatus;

import org.springframework.http.ResponseEntity;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

@RestController

@RequestMapping("/GPIO")

public class GpioController {

@RequestMapping(value="/{gpioNumber}/function", method=RequestMethod.GET)

public ResponseEntity<String> getFunction(@PathVariable("gpioNumber") Integer gpioNumber) {

ResponseEntity<String> entity = null;

String result = gpioNumber + " : in";

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

}

2. Set GPIO function

  - HTTP POST /GPIO/(gpioNumber)/function/("in" or "out" or "pwm")

@RequestMapping(value="/{gpioNumber}/function/{value}", method=RequestMethod.POST)

public ResponseEntity<String> postFunction(@PathVariable("gpioNumber") Integer gpioNumber, @PathVariable("value") String value) {

ResponseEntity<String> entity = null;

String result = gpioNumber + " : " + value;

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

3. Get GPIO value

  - HTTP GET /GPIO/(gpioNumber)/value

@RequestMapping(value="/{gpioNumber}/value", method=RequestMethod.GET)

public ResponseEntity<String> getValue(@PathVariable("gpioNumber") Integer gpioNumber) {

ResponseEntity<String> entity = null;

String result = gpioNumber + " : 0";

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

4. Set GPIO value

  - HTTP POST /GPIO/(gpioNumber)/value/(0 or 1)

@RequestMapping(value="/{gpioNumber}/value/{value}", method=RequestMethod.POST)

public ResponseEntity<String> postValue(@PathVariable("gpioNumber") Integer gpioNumber, @PathVariable("value") Integer value) {

ResponseEntity<String> entity = null;

String result = gpioNumber + " : " + value;

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

5. Output a single pulse

  - HTTP POST /GPIO/(gpioNumber)/pulse/

@RequestMapping(value="/{gpioNumber}/pulse", method=RequestMethod.POST)

public ResponseEntity<String> postPulse(@PathVariable("gpioNumber") Integer gpioNumber) {

ResponseEntity<String> entity = null;

String result = gpioNumber + " : " + "pulse";

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

6. Output bit sequence

  - HTTP POST /GPIO/(gpioNumber)/sequence/(delay),(sequence)

@RequestMapping(value="/{gpioNumber}/sequence/{delay},{sequence}", method=RequestMethod.POST)

public ResponseEntity<String> postSequence(@PathVariable("gpioNumber") Integer gpioNumber,

@PathVariable("delay") Integer delay, @PathVariable("sequence") String sequence) {

ResponseEntity<String> entity = null;

String result = gpioNumber + " : " + "sequence : " + delay + " : " + sequence;

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

7. Output PWM with a duty cycle ratio

  - HTTP POST /GPIO/(gpioNumber)/pulseRatio/(ratio)

// 소수점 데이터를 입력받기 위한 방법 {variable:.+}

// 참고 : http://stackoverflow.com/questions/16332092/spring-mvc-pathvariable-with-dot-is-getting-truncated

@RequestMapping(value="/{gpioNumber}/pulseRatio/{ratio:.+}", method=RequestMethod.POST)

public ResponseEntity<String> postPulseRatio(@PathVariable("gpioNumber") Integer gpioNumber,

@PathVariable("ratio") Float ratio) {

ResponseEntity<String> entity = null;

String result = gpioNumber + " : pulseRatio : " + ratio;

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

8. Output PWM with an angle for servos

  - HTTP POST /GPIO/(gpioNumber)/pulseAngle/(angle)

@RequestMapping(value="/{gpioNumber}/pulseAngle/{angle}", method=RequestMethod.POST)

public ResponseEntity<String> postPulseAngle(@PathVariable("gpioNumber") Integer gpioNumber,

@PathVariable("angle") Integer angle) {

ResponseEntity<String> entity = null;

String result = gpioNumber + " : pulseAngle : " + angle;

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

9. Call a macro on the server

  - HTTP POST /macros/(macro)/(args)

왜냐하면 URL이 /macros로 시작하기 때문이다. 기존의 GpioController는 REST API URL이 /GPIO로 시작하였기 때문에 사용할 수 없고, 새로운 MacroController를 사용한다.

package com.talanton.rest.controller;

import org.springframework.http.HttpStatus;

import org.springframework.http.ResponseEntity;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

@RestController

@RequestMapping("/macros")

public class MacroController {

@RequestMapping(value="/{macro}/{args}", method=RequestMethod.POST)

public ResponseEntity<String> macroFunction(@PathVariable("macro") String macro, @PathVariable("args") String args) {

ResponseEntity<String> entity = null;

String result = "macroFunction : " + macro + ", " + args;

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

}

10. Get full GPIO state/configuration

  - HTTP GET /*

    /* 라는 URL을 처리하기 위하여 새로운 RestController StateController를 정의한다.

package com.talanton.rest.controller;

import org.springframework.http.HttpStatus;

import org.springframework.http.ResponseEntity;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

@RestController

@RequestMapping("")

public class StateController {

@RequestMapping(value="*", method=RequestMethod.GET)

public ResponseEntity<String> gpioState() {

ResponseEntity<String> entity = null;

String result = "getState";

entity = new ResponseEntity<String>(result, HttpStatus.OK);

return entity;

}

}

이제는 Webiopi에서 제공하는 REST API에 대한 처리 함수와 입력 파라미터 파싱을 완료하였다. 이후 실제 라즈베리파이에 적용하여 기능을 개발하는 것이 필요하다.