封裝自定義異常

• 才開通博客沒幾天，不知道寫什麼東西，就把最近在項目中做的東西分享一下，開通博客也可以監督一下自己，技術的路很遙遠，希望能通過寫博客來讓自己走的更遠。

• 一般在web項目中都需要定義一個全局異常來處理一些業務方面的異常，下麵是自定義異常的一些代碼。

1.自定義一個異常，然後繼承RuntimeException

/**
 * @author zhuwenwen
 * @date 2018/8/16 20:18
 */
@Getter
public class CustomException extends RuntimeException {
    /**
     * 異常編碼
     */
    private Integer code;

    /**
     * 附加數據
     */
    private Object data;

    public CustomException(String errorMsg) {

        super(errorMsg);
        this.code= CustomEnum.ERROR.getCode();
    }

    public CustomException(String errorMsg, Integer code) {
        super(errorMsg);
        this.code = code;
    }

    public CustomException(Integer code, String errorMsg, Throwable errorCourse) {
        super(errorMsg,errorCourse);
        this.code = code;
    }

    public CustomException(String message, Integer code, Object data) {
        super(message);
        this.code = code;
        this.data = data;
    }

}

2.定義一個全局異常處理的類

/**
 * 處理全局異常
 *
 * @author zhuwenwen
 * @date 2018/8/17 9:31
 */
@RestControllerAdvice
public class CustomExceptionHandler extends ResponseEntityExceptionHandler implements CustomExceptionHanlerTrit {


    private Logger logger=LoggerFactory.getLogger(CustomExceptionHandler.class);
    /**
     *
     * @see ResponseEntityExceptionHandler#handleExceptionInternal
     */
    @Override
    protected ResponseEntity<Object> handleExceptionInternal(Exception ex, Object body, HttpHeaders headers, HttpStatus status,WebRequest webRequest) {
        logger.warn("{}", ex.getMessage());

        return handleException(CustomEnum.FAILURE_HTTP.getCode() + status.value(), ex.getMessage(), null);
    }

    /**
     * 處理ServletException
     *
     * @param ex      異常
     * @return        異常處理結果
     */
    @ExceptionHandler(value = {ServletException.class})
    protected final ResponseEntity<Object> handleServletException(ServletException ex) {
        logger.error("{}", ex);

        return handleException(CustomEnum.FAILURE_SERVLET.getCode(), ex.getMessage(), null);
    }

    /**
     * 處理SQLException
     *
     * @param ex      異常
     * @return        異常處理結果
     */
    @ExceptionHandler(value = {SQLException.class})
    protected final ResponseEntity<Object> handleSQLException(SQLException ex) {
        logger.error("{}", ex);

        return handleException(CustomEnum.FAILURE_DB.getCode(), ex.getMessage(), null);
    }

    /**
     * 處理ConstraintViolationException
     *
     * @param ex      異常
     * @return        異常處理結果
     */
    @ExceptionHandler(value = {ConstraintViolationException.class})
    protected final ResponseEntity<Object> handleConstraintViolationException(ConstraintViolationException ex) {
        logger.error("{}", ex);

        String message = ex.getMessage();
        if (ex.getConstraintViolations() != null && !ex.getConstraintViolations().isEmpty()) {
            message = ex.getConstraintViolations().stream().findFirst().isPresent()
                    ? ex.getConstraintViolations().stream().findFirst().get().getMessage() : null;
        }

        return handleException(CustomEnum.FAILURE_VALIDATION.getCode(), message, null);
    }

    /**
     * 處理MorphedException
     *
     * @param ex      異常
     * @return        異常處理結果
     */
    @ExceptionHandler(value = {CustomException.class})
    protected final ResponseEntity<Object> handleMorphedException(CustomException ex) {
        logger.info("{}", ex);

        return handleException(ex.getCode(), ex.getMessage(),ex.getData());
    }

    /**
     * 處理RuntimeException
     *
     * @param ex      異常
     * @return        異常處理結果
     */
    @ExceptionHandler(value = {RuntimeException.class})
    protected final ResponseEntity<Object> handleRuntimeException(RuntimeException ex) {
        logger.error("{}", ex);

        return handleException(CustomEnum.FAILURE_UNKNOWN.getCode(), ex.getMessage(), null);
    }

}

3.封裝成一個組件，可以打成jar包，供多個項目使用,那麼可以自定義一個註解，然後在啟動類上加上這個註解，即可使用。下麵是一個簡單的demo

/**
 * @author zhuwenwen
 * @date 2018/8/17 11:02
 */

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(CustomExceptionHandler.class)
@Documented
public @interface EnableCustomException {
    /**
     * 是否開啟
     * @return
     */
    boolean enabled() default true;


}

/**
 * @author zhuwenwen
 * @date 2018/8/17 14:47
 */
public class CustomImportBeanDefination implements ImportBeanDefinitionRegistrar {
    @Override
    public void registerBeanDefinitions(AnnotationMetadata annotationMetadata, BeanDefinitionRegistry beanDefinitionRegistry) {
        //是否含有@EnableCustomException註解
        if (annotationMetadata.isAnnotated(EnableCustomException.class.getName())){
            //獲取該註解上面的所有屬性，然後封裝成一個map
            MultiValueMap<String, Object> attributes = annotationMetadata.getAllAnnotationAttributes(EnableCustomException.class.getName());
            if(attributes.get(EnableCustomExceptionCode.ENABLED).equals(Boolean.TRUE)){
                BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.rootBeanDefinition(CustomExceptionHandler.class);
                beanDefinitionRegistry.registerBeanDefinition(CustomExceptionHandler.class.getName(),beanDefinitionBuilder.getBeanDefinition());
            }
        }
    }
}