# 背景

# 什么是統(tǒng)一異常處理

# 目標(biāo)

# 統(tǒng)一異常處理實(shí)戰(zhàn)

用 Assert(斷言) 替換 throw exception

@Test    public void test1() {        ...        User user = userDao.selectById(userId);        Assert.notNull(user, "用戶(hù)不存在.");        ...    }
    @Test    public void test2() {        // 另一種寫(xiě)法        User user = userDao.selectById(userId);        if (user == null) {            throw new IllegalArgumentException("用戶(hù)不存在.");        }    }

public abstract class Assert {    public Assert() {    }
    public static void notNull(@Nullable Object object, String message) {        if (object == null) {            throw new IllegalArgumentException(message);        }    }}

Assertpublic interface Assert {    /**     * 創(chuàng)建異常     * @param args     * @return     */    BaseException newException(Object... args);
    /**     * 創(chuàng)建異常     * @param t     * @param args     * @return     */    BaseException newException(Throwable t, Object... args);
    /**     * 
斷言對(duì)象obj非空。如果對(duì)象obj為空，則拋出異常     *     * @param obj 待判斷對(duì)象     */    default void assertNotNull(Object obj) {        if (obj == null) {            throw newException(obj);        }    }
    /**     * 
斷言對(duì)象obj非空。如果對(duì)象obj為空，則拋出異常     * 
異常信息message支持傳遞參數(shù)方式，避免在判斷之前進(jìn)行字符串拼接操作     *     * @param obj 待判斷對(duì)象     * @param args message占位符對(duì)應(yīng)的參數(shù)列表     */    default void assertNotNull(Object obj, Object... args) {        if (obj == null) {            throw newException(args);        }    }}

善解人意的Enum

public interface IResponseEnum {    int getCode();    String getMessage();}/** * 
業(yè)務(wù)異常 * 
業(yè)務(wù)處理時(shí)，出現(xiàn)異常，可以拋出該異常 */public class BusinessException extends  BaseException {
    private static final long serialVersionUID = 1L;
    public BusinessException(IResponseEnum responseEnum, Object[] args, String message) {        super(responseEnum, args, message);    }
    public BusinessException(IResponseEnum responseEnum, Object[] args, String message, Throwable cause) {        super(responseEnum, args, message, cause);    }}public interface BusinessExceptionAssert extends IResponseEnum, Assert {
    @Override    default BaseException newException(Object... args) {        String msg = MessageFormat.format(this.getMessage(), args);
        return new BusinessException(this, args, msg);    }
    @Override    default BaseException newException(Throwable t, Object... args) {        String msg = MessageFormat.format(this.getMessage(), args);
        return new BusinessException(this, args, msg, t);    }
}@Getter@AllArgsConstructorpublic enum ResponseEnum implements BusinessExceptionAssert {
    /**     * Bad licence type     */    BAD_LICENCE_TYPE(7001, "Bad licence type."),    /**     * Licence not found     */    LICENCE_NOT_FOUND(7002, "Licence not found.")    ;
    /**     * 返回碼     */    private int code;    /**     * 返回消息     */    private String message;}

/**     * 校驗(yàn){@link Licence}存在     * @param licence     */    private void checkNotNull(Licence licence) {        ResponseEnum.LICENCE_NOT_FOUND.assertNotNull(licence);    }

private void checkNotNull(Licence licence) {        if (licence == null) {            throw new LicenceNotFoundException();            // 或者這樣            throw new BusinessException(7001, "Bad licence type.");        }    }

注：上面舉的例子是針對(duì)特定的業(yè)務(wù)，而有部分異常情況是通用的，比如：服務(wù)器繁忙、網(wǎng)絡(luò)異常、服務(wù)器異常、參數(shù)校驗(yàn)異常、404等，所以有CommonResponseEnum、ArgumentResponseEnum、ServletResponseEnum，其中 ServletResponseEnum 會(huì)在后文詳細(xì)說(shuō)明。

定義統(tǒng)一異常處理器類(lèi)

@Slf4j@Component@ControllerAdvice@ConditionalOnWebApplication@ConditionalOnMissingBean(UnifiedExceptionHandler.class)public class UnifiedExceptionHandler {    /**     * 生產(chǎn)環(huán)境     */    private final static String ENV_PROD = "prod";
    @Autowired    private UnifiedMessageSource unifiedMessageSource;
    /**     * 當(dāng)前環(huán)境     */    @Value("${spring.profiles.active}")    private String profile;
    /**     * 獲取國(guó)際化消息     *     * @param e 異常     * @return     */    public String getMessage(BaseException e) {        String code = "response." + e.getResponseEnum().toString();        String message = unifiedMessageSource.getMessage(code, e.getArgs());
        if (message == null || message.isEmpty()) {            return e.getMessage();        }
        return message;    }
    /**     * 業(yè)務(wù)異常     *     * @param e 異常     * @return 異常結(jié)果     */    @ExceptionHandler(value = BusinessException.class)    @ResponseBody    public ErrorResponse handleBusinessException(BaseException e) {        log.error(e.getMessage(), e);
        return new ErrorResponse(e.getResponseEnum().getCode(), getMessage(e));    }
    /**     * 自定義異常     *     * @param e 異常     * @return 異常結(jié)果     */    @ExceptionHandler(value = BaseException.class)    @ResponseBody    public ErrorResponse handleBaseException(BaseException e) {        log.error(e.getMessage(), e);
        return new ErrorResponse(e.getResponseEnum().getCode(), getMessage(e));    }
    /**     * Controller上一層相關(guān)異常     *     * @param e 異常     * @return 異常結(jié)果     */    @ExceptionHandler({            NoHandlerFoundException.class,            HttpRequestMethodNotSupportedException.class,            HttpMediaTypeNotSupportedException.class,            MissingPathVariableException.class,            MissingServletRequestParameterException.class,            TypeMismatchException.class,            HttpMessageNotReadableException.class,            HttpMessageNotWritableException.class,            // BindException.class,            // MethodArgumentNotValidException.class            HttpMediaTypeNotAcceptableException.class,            ServletRequestBindingException.class,            ConversionNotSupportedException.class,            MissingServletRequestPartException.class,            AsyncRequestTimeoutException.class    })    @ResponseBody    public ErrorResponse handleServletException(Exception e) {        log.error(e.getMessage(), e);        int code = CommonResponseEnum.SERVER_ERROR.getCode();        try {            ServletResponseEnum servletExceptionEnum = ServletResponseEnum.valueOf(e.getClass().getSimpleName());            code = servletExceptionEnum.getCode();        } catch (IllegalArgumentException e1) {            log.error("class [{}] not defined in enum {}", e.getClass().getName(), ServletResponseEnum.class.getName());        }
        if (ENV_PROD.equals(profile)) {            // 當(dāng)為生產(chǎn)環(huán)境, 不適合把具體的異常信息展示給用戶(hù), 比如404.            code = CommonResponseEnum.SERVER_ERROR.getCode();            BaseException baseException = new BaseException(CommonResponseEnum.SERVER_ERROR);            String message = getMessage(baseException);            return new ErrorResponse(code, message);        }
        return new ErrorResponse(code, e.getMessage());    }

    /**     * 參數(shù)綁定異常     *     * @param e 異常     * @return 異常結(jié)果     */    @ExceptionHandler(value = BindException.class)    @ResponseBody    public ErrorResponse handleBindException(BindException e) {        log.error("參數(shù)綁定校驗(yàn)異常", e);
        return wrapperBindingResult(e.getBindingResult());    }
    /**     * 參數(shù)校驗(yàn)異常，將校驗(yàn)失敗的所有異常組合成一條錯(cuò)誤信息     *     * @param e 異常     * @return 異常結(jié)果     */    @ExceptionHandler(value = MethodArgumentNotValidException.class)    @ResponseBody    public ErrorResponse handleValidException(MethodArgumentNotValidException e) {        log.error("參數(shù)綁定校驗(yàn)異常", e);
        return wrapperBindingResult(e.getBindingResult());    }
    /**     * 包裝綁定異常結(jié)果     *     * @param bindingResult 綁定結(jié)果     * @return 異常結(jié)果     */    private ErrorResponse wrapperBindingResult(BindingResult bindingResult) {        StringBuilder msg = new StringBuilder();
        for (ObjectError error : bindingResult.getAllErrors()) {            msg.append(", ");            if (error instanceof FieldError) {                msg.append(((FieldError) error).getField()).append(": ");            }            msg.append(error.getDefaultMessage() == null ? "" : error.getDefaultMessage());
        }
        return new ErrorResponse(ArgumentResponseEnum.VALID_ERROR.getCode(), msg.substring(2));    }
    /**     * 未定義異常     *     * @param e 異常     * @return 異常結(jié)果     */    @ExceptionHandler(value = Exception.class)    @ResponseBody    public ErrorResponse handleException(Exception e) {        log.error(e.getMessage(), e);
        if (ENV_PROD.equals(profile)) {            // 當(dāng)為生產(chǎn)環(huán)境, 不適合把具體的異常信息展示給用戶(hù), 比如數(shù)據(jù)庫(kù)異常信息.            int code = CommonResponseEnum.SERVER_ERROR.getCode();            BaseException baseException = new BaseException(CommonResponseEnum.SERVER_ERROR);            String message = getMessage(baseException);            return new ErrorResponse(code, message);????????}        return new ErrorResponse(CommonResponseEnum.SERVER_ERROR.getCode(), e.getMessage());????}}

• 進(jìn)入Controller前的異常: handleServletException、handleBindException、handleValidException
• 自定義異常: handleBusinessException、handleBaseException
• 未知異常: handleException

# 異常處理器說(shuō)明

handleServletException

handleBindException

handleValidException

handleBusinessException、handleBaseException

handleException

注：上面的handleServletException、handleException 這兩個(gè)處理器，返回的異常信息，不同環(huán)境返回的可能不一樣，以為這些異常信息都是框架自帶的異常信息，一般都是英文的，不太好直接展示給用戶(hù)看，所以統(tǒng)一返回SERVER_ERROR代表的異常信息。

# 異于常人的404

spring.mvc.throw-exception-if-no-handler-found=truespring.resources.add-mappings=false

# 統(tǒng)一返回結(jié)果

# 驗(yàn)證統(tǒng)一異常處理

# 主要代碼

@Servicepublic class LicenceService extends ServiceImpl<LicenceMapper, Licence> {
    @Autowired    private OrganizationClient organizationClient;
    /**     * 查詢(xún){@link Licence} 詳情     * @param licenceId     * @return     */    public LicenceDTO queryDetail(Long licenceId) {        Licence licence = this.getById(licenceId);        checkNotNull(licence);
        OrganizationDTO org = ClientUtil.execute(() -> organizationClient.getOrganization(licence.getOrganizationId()));        return toLicenceDTO(licence, org);    }
    /**     * 分頁(yè)獲取     * @param licenceParam 分頁(yè)查詢(xún)參數(shù)     * @return     */    public QueryData getLicences(LicenceParam licenceParam) {        String licenceType = licenceParam.getLicenceType();        LicenceTypeEnum licenceTypeEnum = LicenceTypeEnum.parseOfNullable(licenceType);        // 斷言, 非空        ResponseEnum.BAD_LICENCE_TYPE.assertNotNull(licenceTypeEnum);
        LambdaQueryWrapper wrapper = new LambdaQueryWrapper<>();        wrapper.eq(Licence::getLicenceType, licenceType);        IPage page = this.page(new QueryPage<>(licenceParam), wrapper);        return new QueryData<>(page, this::toSimpleLicenceDTO);    }
    /**     * 新增{@link Licence}     * @param request 請(qǐng)求體     * @return     */    @Transactional(rollbackFor = Throwable.class)    public LicenceAddRespData addLicence(LicenceAddRequest request) {        Licence licence = new Licence();        licence.setOrganizationId(request.getOrganizationId());        licence.setLicenceType(request.getLicenceType());        licence.setProductName(request.getProductName());        licence.setLicenceMax(request.getLicenceMax());        licence.setLicenceAllocated(request.getLicenceAllocated());        licence.setComment(request.getComment());        this.save(licence);
        return new LicenceAddRespData(licence.getLicenceId());    }
    /**     * entity -> simple dto     * @param licence {@link Licence} entity     * @return {@link SimpleLicenceDTO}     */    private SimpleLicenceDTO toSimpleLicenceDTO(Licence licence) {        // 省略    }
    /**     * entity -> dto     * @param licence {@link Licence} entity     * @param org {@link OrganizationDTO}     * @return {@link LicenceDTO}     */    private LicenceDTO toLicenceDTO(Licence licence, OrganizationDTO org) {        // 省略    }
    /**     * 校驗(yàn){@link Licence}存在     * @param licence     */    private void checkNotNull(Licence licence) {        ResponseEnum.LICENCE_NOT_FOUND.assertNotNull(licence);    }
}

-- licenceINSERT INTO licence (licence_id, organization_id, licence_type, product_name, licence_max, licence_allocated)VALUES (1, 1, 'user','CustomerPro', 100,5);INSERT INTO licence (licence_id, organization_id, licence_type, product_name, licence_max, licence_allocated)VALUES (2, 1, 'user','suitability-plus', 200,189);INSERT INTO licence (licence_id, organization_id, licence_type, product_name, licence_max, licence_allocated)VALUES (3, 2, 'user','HR-PowerSuite', 100,4);INSERT INTO licence (licence_id, organization_id, licence_type, product_name, licence_max, licence_allocated)VALUES (4, 2, 'core-prod','WildCat Application Gateway', 16,16);
-- organizationsINSERT INTO organization (id, name, contact_name, contact_email, contact_phone)VALUES (1, 'customer-crm-co', 'Mark Balster', '[email protected]', '823-555-1212');INSERT INTO organization (id, name, contact_name, contact_email, contact_phone)VALUES (2, 'HR-PowerSuite', 'Doug Drewry','[email protected]', '920-555-1212');

# 開(kāi)始驗(yàn)證

捕獲自定義異常

捕獲未知異常

# 小結(jié)

# 擴(kuò)展

# 總結(jié)

@Slf4j@RestControllerAdvicepublic class GlobalExceptionHandler {
    /**     * 沒(méi)有登錄     * @param request     * @param response     * @param e     * @return     */    @ExceptionHandler(NoLoginException.class)    public Object noLoginExceptionHandler(HttpServletRequest request,HttpServletResponse response,Exception e){        log.error("[GlobalExceptionHandler][noLoginExceptionHandler] exception",e);        JsonResult jsonResult = new JsonResult();        jsonResult.setCode(JsonResultCode.NO_LOGIN);        jsonResult.setMessage("用戶(hù)登錄失效或者登錄超時(shí),請(qǐng)先登錄");        return jsonResult;    }
    /**     * 業(yè)務(wù)異常     * @param request     * @param response     * @param e     * @return     */    @ExceptionHandler(ServiceException.class)    public Object businessExceptionHandler(HttpServletRequest request,HttpServletResponse response,Exception e){        log.error("[GlobalExceptionHandler][businessExceptionHandler] exception",e);        JsonResult jsonResult = new JsonResult();        jsonResult.setCode(JsonResultCode.FAILURE);        jsonResult.setMessage("業(yè)務(wù)異常,請(qǐng)聯(lián)系管理員");        return jsonResult;    }
    /**     * 全局異常處理     * @param request     * @param response     * @param e     * @return     */    @ExceptionHandler(Exception.class)    public Object exceptionHandler(HttpServletRequest request,HttpServletResponse response,Exception e){        log.error("[GlobalExceptionHandler][exceptionHandler] exception",e);        JsonResult jsonResult = new JsonResult();        jsonResult.setCode(JsonResultCode.FAILURE);        jsonResult.setMessage("系統(tǒng)錯(cuò)誤,請(qǐng)聯(lián)系管理員");        return jsonResult;    }}