如何使用spring-boot 写出简洁而优雅的restful 接口_小言_互联网的博客

如何使用spring-boot 写出简洁而优雅的restful 接口

2020-04-11 09:49 256人阅读评论(0)

写一个Restful接口很简单，但是要写出一个健壮而优雅的接口并不容易，通常一个接口包含输入请求参数、输出响应消息及接口中的异常输出。通过对输入请求参数在入口处统一校验，可以及早发现数据的问题，规范统一的响应输出和异常信息使你的Restful接口变得更优雅。
一、使用validation对输入参数进行校验
如果接口的输入信息不在入口处进行校验，我们就需要在业务层写上很多的判断逻辑，比如下面这种写法：

@Override
	public void addMovie(Movie movie) {
		if (StringUtils.isEmpty(movie.getName())) {
			throw new BusinessException("电影名称不能为空");
		}
		if (movie.getDuration() == null) {
			throw new BusinessException("电影时长不能为空");
		}
		if (StringUtils.isEmpty(movie.getDescription())){
			throw new BusinessException("电影描述不能为空");
		}
		if (CollectionUtils.isEmpty(movie.getActors())) {
			throw new BusinessException("演员不能为空");
		}
		//业务代码
		
	}

从上面的代码可以看出业务代码还没有开始写，已经写了一堆的逻辑判断，看起来很不优雅，使用java和spring 的validation可以让我们只关注业务逻辑二不用去担心数据是否规范的问题。

在maven的pom文件中引入validation

<dependency>
   <groupId>javax.validation</groupId>
   <artifactId>validation-api</artifactId>
   <version>${validation-api.version}</version>
</dependency>

编写 entity类
使用@NotEmpty和@NotNull等注解标注需要进行校验的字段

@Getter
@Setter
public class Movie {
	private String id;
	@NotEmpty(message = "Movie name cannot be empty")
	private String name;
	@NotNull(message = "电影时长不能为空")
	private Integer duration;
	@NotNull(message = "演员不能为空")
	@NotEmpty(message = "演员不能为空")
	private List<@Valid Actor> actors;
	@NotEmpty(message = "电影描述不能为空")
	private String description;
}

3.编写controller
controller上需要加上@Validated注解标注，在接口中需要校验的参数前面加上@Valid 注解，Movie前面的@Valid表示实体Movie会使用validation进行校验

@Validated
@RestController
@RequestMapping(value = "/movies")
public class MovieController {
	@PostMapping
	public ResponseResult addMovie(@RequestBody  @Valid Movie movie) {
		movieService.addMovie(movie);
		System.out.println("test");
		System.out.println(movie);
		return ResponseResult.success();
	}
}
4.编写业务代码

```java
@Override
	public void addMovie(Movie movie) {
		//业务代码
		movieDao.save(movie);
	}

二、使用统一的输出格式
1.定义响应消息体ResponseResult
code响应状态码，message 状态码描述，data响应的数据
```java
@Getter
@Setter
public class ResponseResult<T> {
	/**
	 * 状态码
	 */
	int code;
	/**
	 * 状态码描述
	 */
	String message;
	/**
	 * 返回的数据
	 */
	T data;

	private ResponseResult() {
		this(200,"success");
	}

	private ResponseResult(int code,String message) {
		this.code=code;
		this.message=message;
	}

	private ResponseResult(ResponseMessage responseMessage) {
		this.code= responseMessage.getCode();
		this.message= responseMessage.getMessage();
	}

	private ResponseResult(int code,String message,T data) {
		this.code=code;
		this.message=message;
		this.data=data;
	}

	private ResponseResult (ResponseMessage responseMessage, T data) {
		this.code= responseMessage.getCode();
		this.message= responseMessage.getMessage();
		this.data=data;
	}

	public static ResponseResult success() {
		return new ResponseResult();
	}

	public static <T> ResponseResult success(T data) {
		return success(ResponseMessage.SUCCESS.getCode(),"success",data);
	}

	public static ResponseResult success(int code,String message) {
		return success(code,message,null);
	}
	
	public static ResponseResult success(ResponseMessage responseMessage) {
		return success(responseMessage.getCode(),responseMessage.getMessage(),null);
	}

	public static <T> ResponseResult success(ResponseMessage responseMessage,T data) {
		return success(responseMessage.getCode(),responseMessage.getMessage(),data);
	}

	public static <T> ResponseResult success(int code,String message,T data) {
		return new ResponseResult(code,message,data);
	}

	public static ResponseResult fail() {
		return fail(ResponseMessage.FAIL.getCode(),ResponseMessage.FAIL.getMessage());
	}

	public static ResponseResult fail(int code,String message) {
		return fail(code,message,null);
	}

	public static ResponseResult fail(ResponseMessage responseMessage) {
		return fail(responseMessage.getCode(),responseMessage.getMessage(),null);
	}

	public static <T> ResponseResult fail(ResponseMessage responseMessage, T data) {
		return fail(responseMessage.getCode(),responseMessage.getMessage(),data);
	}

	public static <T> ResponseResult fail(int code,String message,T data) {
		return new ResponseResult(code,message,data);
	}

}

2.定义状态码枚举

@Getter
public enum StatusCode {
	/**
	 * 操作成功
	 */
	SUCCESS(200,"success"),
	/**
	 * 新增成功
	 */
	ADD_SUCCESS(204,"success"),
	/**
	 * 操作失败
	 */
	FAIL(-1,"fail"),
	/**
	 * 资源不存在
	 */
	NOT_FOUND(404,"resource not found"),
	/**
	 * 没有权限访问
	 */
	NOT_AUTH(401,"没有权限访问"),
	/**
	 * 未知错误
	 */
	ERROR(500,"未知错误");
	private int code;
	private String message;

	private StatusCode(int code, String message) {
	    this.code=code;
	    this.message=message;
	}
}

三、使用@ControllerAdvice拦截异常，统一输出异常信息
1.自定义异常类BusinessException

@Getter
public class BusinessException extends RuntimeException {
	private String message;
	private Throwable throwable;
	public BusinessException(String message) {
		this(message,null);
	}

	public BusinessException(String message,Throwable throwable) {
		super(message,throwable);
	}
}

2.定义异常拦截类
程序中抛出的所有异常都会被拦截然后统一输出，避免输出不友好的异常提示信息。

@RestControllerAdvice
@ControllerAdvice
public class GlobalExceptionHandler {
	/**
	* 
	*/
	@ExceptionHandler(Exception.class)
	public ResponseResult handleException(Exception e) {
		ResponseResult result=ResponseResult.fail(500,e.getMessage());
		return result;
	}
	/**
	* 拦截业务异常
	*/
	@ExceptionHandler(BusinessException.class)
	public ResponseResult handleBusinessException(BusinessException e) {
		return ResponseResult.fail(500,e.getMessage());
	}
	
	/**
	* 拦截参数校验异常
	*/
	@ExceptionHandler(MethodArgumentNotValidException.class)
	public ResponseResult handleMethodArgumentNotValidException(MethodArgumentNotValidException methodArgumentNotValidException) {
		StringBuilder errorMessage=new StringBuilder();
		List<ObjectError> objectErrors=methodArgumentNotValidException.getBindingResult().getAllErrors();
		if (!CollectionUtils.isEmpty(objectErrors)) {
			for (int i = 0; i < objectErrors.size(); i++) {
				if (i == 0) {
					errorMessage.append(objectErrors.get(i).getDefaultMessage());
				} else {
					errorMessage.append(",");
					errorMessage.append(objectErrors.get(i).getDefaultMessage());
				}
			}
		}else {
			errorMessage.append("MethodArgumentNotValidException occured.");
		}
		return ResponseResult.fail(400,errorMessage.toString());
	}
    
    /**
    * 拦截自定义约束异常
    */
	@ExceptionHandler(ConstraintViolationException.class)
	public ResponseResult handle(ConstraintViolationException constraintViolationException) {
		Set<ConstraintViolation<?>> violations = constraintViolationException.getConstraintViolations();
		String errorMessage = "";
		if (!violations.isEmpty()) {
			StringBuilder builder = new StringBuilder();
			violations.forEach(violation -> builder.append(" " + violation.getMessage()));
			errorMessage = builder.toString();
		} else {
			errorMessage = "ConstraintViolationException occured.";
		}
		return ResponseResult.fail(400,errorMessage);
	}
	}