2.2.4 매개변수를 넘겨받는 방법

@PathVariable 을 사용하면 됩니다. 

package com.example.demo.controller;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;



@RestController
@RequestMapping("test") //resource
public class TestController {
	
	@GetMapping("/{id}")
	public String testControllerWithPathVariables(@PathVariable(required = false) int id)
	{
		return "Hello World! id : " +id;
	}

}

=> required가 false이므로 굳이 값을 쓰지 않아도 정상적으로 출력됩니다. (물론 id의 값은 안나오겠지만요) 

=> 책은 이렇게 써있는데 왜 제가 쓰면 에러가 날까요? 

---

@RequestParam을 사용하면 됩니다. 

-?id={id}와 같이 매개변수로 넘어오는 값을 변수로 받을 수 있습니다. 

 

package com.example.demo.controller;

import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;



@RestController
@RequestMapping("test") //resource
public class TestController {
	
	@GetMapping("/testRequestParam")
	public String testControllerRequestParama(@RequestParam(required = false) int id)
	{
		return "Hello World! id : " +id;
	}

}

 

 

---

@RequestBody을 사용하면 됩니다. 

-반환하고자 하는 리소스가 복잡할 때 사용합니다. EX) JSON

package com.example.demo.controller;

import com.example.demo.dto.ResponseDTO;
import com.example.demo.dto.TestRequestBodyDTO;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.ArrayList;
import java.util.List;

@RestController
@RequestMapping("test") //resource
public class TestController {
	
	@GetMapping("/testRequestBody")
	public String testControllerRequestBody(@RequestBody TestRequestBodyDTO TestRequestBodyDTO)
	{
		return "Hello World! id " +TestRequestBodyDTO.getId() + " Message : "+ TestRequestBodyDTO.getMessage();
	}

}

package com.example.demo.dto;

import lombok.Data;

@Data
public class TestRequestBodyDTO {
	private int id; 
	private String message;
	
}

 

 

 

---

@RestController :  @Controller + @ResponseBody 

package com.example.demo.controller;

import com.example.demo.dto.ResponseDTO;
import com.example.demo.dto.TestRequestBodyDTO;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.ArrayList;
import java.util.List;

@RestController
@RequestMapping("test") //resource
public class TestController {
	
	@GetMapping("/testResponseBody")
	public ResponseDTO<String> testControllerResponseBody(@RequestBody TestRequestBodyDTO TestRequestBodyDTO)
	{
		List<String> list = new ArrayList<>();
		list.add("Hello World! I'm a ResponseDTO");
		ResponseDTO<String> response = ResponseDTO.<String>builder().data(list).build();
		return response;
	}

}

 

---

@ResponseEntity 

- HTTP 응답의 바디뿐만 아니라 여러 다른 매개변수들, 예를 들어 status나 header를 조작하고 싶을 때 사용합니다. 

package com.example.demo.controller;

import com.example.demo.dto.ResponseDTO;
import com.example.demo.dto.TestRequestBodyDTO;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.ArrayList;
import java.util.List;

@RestController
@RequestMapping("test") //resource
public class TestController {
	
	@GetMapping("/testResponseEntity")
	public ResponseEntity<?> testControllerResponseEntity()
	{
		List<String> list = new ArrayList<>();
		list.add("Hello World! I'm a ResponseEntity & you got 400");
		ResponseDTO<String> response = ResponseDTO.<String>builder().data(list).build();
		//http status를 400으로 설정
	return ResponseEntity.badRequest().body(response);
	}

}

 

=> responseDTO를 리턴한것과 비교했을 때 BODY에는 아무런 차이가 없다. 단지 헤더와 HTTP Status를 조작할 수 있다는 점만이 다르다. 

 

 

---

package com.example.demo.controller;

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

@RestController
@RequestMapping("todo")
public class TodoController {
	//testTodo메서드 작성하기 
}