Spring 異常處理

控制器測試

仍是上次數據不能爲空的問題，寫到了C層測試。

先寫一行測試代碼，先期待一個200，可是咱們是知道的，由於沒有學科類別，這確定會拋出異常，咱們就是想看看Spring捕獲這個異常以後給出的反饋是什麼狀態碼。

@Test
public void saveTest() throws Exception {
    logger.debug("基礎測試數據準備");
    MeasurementUnitCategory measurementUnitCategory = new MeasurementUnitCategory();
    String json = JSON.toJSONString(measurementUnitCategory);

    this.mockMvc.perform(post(baseUrl)
                        .header(xAuthKey, xAuthToken)
                        .contentType(MediaType.APPLICATION_JSON_UTF8)
                        .content(json))
                .andExpect(status().isOk());
}

測試一下，果真，控制檯報錯。

異常拋出

可是看一下報錯信息，發現並非咱們期待的一個錯誤的狀態碼，而是200。同時下面還有異常拋出。

這說明Spring爲咱們拋出了這個DataIntegrityViolationException異常，可是卻沒有幫咱們處理，這就須要咱們手動處理而後返回給前臺狀態碼。

MockHttpServletResponse:
           Status = 200
    Error message = null
          Headers = {X-Content-Type-Options=[nosniff], X-XSS-Protection=[1; mode=block], Cache-Control=[no-cache, no-store, max-age=0, must-revalidate], Pragma=[no-cache], Expires=[0], X-Application-Context=[application:-1], Content-Type=[application/json;charset=UTF-8], x-auth-token=[1b2b8d9f-3457-4277-879e-2ada48e3599e]}
     Content type = application/json;charset=UTF-8
             Body = {"id":8,"name":"","username":"usersdfdfwef23dfvdfwewef","mobile":"","pinyin":null,"createTime":1528338758059,"updateTime":1528338758059,"status":0,"department":{"id":1,"name":"內蒙古自治區管理部門","code":"","postalCode":"","address":"","legalName":"","legalPhone":"","registrantName":"","registrantPhone":"","registrantTel":null,"registrantMail":"","phone":"","pinyin":"neimengguzishiquguanglibumeng","registerDate":null,"createTime":1528338752423,"updateTime":1528338752423,"status":null,"createUser":null,"departmentType":{"id":1,"name":"管理部門","pinyin":"guanlibumen","createTime":1528338751963,"updateTime":1528338751963,"createUser":null},"district":{"id":1,"districtType":{"id":1,"name":"省","pinyin":"sheng"},"name":"內蒙古自治區","createUser":null,"pinyin":"neimengguzizhiqu","createTime":null,"updateTime":null},"checkAbility":false,"outOfRange":null,"standard":false},"roles":[],"createUser":null,"updateUser":null}
    Forwarded URL = null
   Redirected URL = null
          Cookies = []

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement
Caused by: org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement
Caused by: org.hibernate.exception.ConstraintViolationException: could not execute statement
Caused by: org.h2.jdbc.JdbcSQLException: NULL not allowed for column "DISCIPLINE_ID"; SQL statement:
insert into measurement_unit_category (id, discipline_id, is_asc) values (null, ?, ?) [23502-194]

全局異常處理

理論上咱們全部的異常都是由M層拋出，直接捕獲或全局異常處理，是不會將異常拋給控制器的。

因此，咱們須要全局異常處理，M層拋出異常，直接處理，返回xx狀態碼，而不將異常拋給控制器。

@RestController     // 以rest形式返回異常信息
@ControllerAdvice   // 全局異常處理器
public class GlobalExceptionHandler {

    private final static Logger logger = LoggerFactory.getLogger(GlobalExceptionHandler.class.getName());

    /**
     * 手動捕獲數據衝突異常，經測試，該異常系由Spring拋出，但未捕獲
     * @return HttpStatus.CONFLICT
     * 衝突錯誤，409
     * 參考：
     * https://stackoverflow.com/questions/37248719/couldnt-catch-dataintegrityviolationexception-with-spring-data-rest
     */
    @ExceptionHandler(value = DataIntegrityViolationException.class)
    public ResponseEntity<JsonErrorResult> dataIntegrityViolationException(HttpServletRequest httpServletRequest, Exception exception) {
        logger.error("---數據不合法：---Host {} invokes url {} ERROR: {}", httpServletRequest.getRemoteHost(), httpServletRequest.getRequestURL(), exception.getMessage());
        return new ResponseEntity<>(new JsonErrorResult(httpServletRequest, exception), HttpStatus.CONFLICT);
    }
}

我這裏對狀態碼也不是很熟悉，去StackOverflow上看到一個老哥是和我遇到了同樣的問題，他解決的方案是捕獲異常返回409(衝突)，參考原文。

異常捕獲後，修改測試，期待狀態碼爲409，Conflict。

@Test
public void saveTest() throws Exception {
    logger.debug("基礎測試數據準備");
    MeasurementUnitCategory measurementUnitCategory = new MeasurementUnitCategory();
    String json = JSON.toJSONString(measurementUnitCategory);

    logger.debug("無學科的計量單位類別保存，期待409，衝突狀態碼");
    this.mockMvc.perform(post(baseUrl)
                        .header(xAuthKey, xAuthToken)
                        .contentType(MediaType.APPLICATION_JSON_UTF8)
                        .content(json))
                .andExpect(status().isConflict());
}

從新運行單元測試，經過。