我有这个枚举:
public enum SortEnum { asc, desc; }
我想用作rest请求的参数:
@RequestMapping(value = "/events", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE) public List<Event> getEvents(@RequestParam(name = "sort", required = false) SortEnum sort) {
当我发送这些请求时,它工作正常
/events /events?sort=asc /events?sort=desc
但是当我发送:
/events?sort=somethingElse 我在控制台中收到500条响应和以下消息:
2019-09-29 17:20:51.600 DEBUG 5104 --- [ XNIO-2 task-6] com.myApp.aop.logging.LoggingAspect : Enter: com.myApp.web.rest.errors.ExceptionTranslator.processRuntimeException() with argument[s] = [org.springframework.web.method.annotation.MethodArgumentTypeMismatchException: Failed to convert value of type [java.lang.String] to required type [com.myApp.common.SortEnum]; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.RequestParam com.myApp.common.SortEnum] for value 'somethingElse'; nested exception is java.lang.IllegalArgumentException: No enum constant com.myApp.common.SortEnum.somethingElse] 2019-09-29 17:20:51.600 DEBUG 5104 --- [ XNIO-2 task-6] com.myApp.aop.logging.LoggingAspect : Exit: com.myApp.web.rest.errors.ExceptionTranslator.processRuntimeException() with result = <500 Internal Server Error,com.myApp.web.rest.errors.ErrorVM@1e3343c9,{}> 2019-09-29 17:20:51.601 WARN 5104 --- [ XNIO-2 task-6] .m.m.a.ExceptionHandlerExceptionResolver : Resolved exception caused by Handler execution: org.springframework.web.method.annotation.MethodArgumentTypeMismatchException: Failed to convert value of type [java.lang.String] to required type [com.myApp.common.SortEnum]; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.RequestParam com.myApp.common.SortEnum] for value 'somethingElse'; nested exception is java.lang.IllegalArgumentException: No enum constant com.myApp.common.SortEnum.somethingElse
有没有一种方法可以防止spring抛出这些异常并将enum设置为null?
编辑
Strelok接受的答案有效。但是,我决定处理MethodArgumentTypeMismatchException。
@ControllerAdvice public class ExceptionTranslator { @ExceptionHandler(MethodArgumentTypeMismatchException.class) @ResponseBody public ResponseEntity<Object> handleMethodArgumentTypeMismatchException(MethodArgumentTypeMismatchException e) { Class<?> type = e.getRequiredType(); String message; if(type.isEnum()){ message = "The parameter " + e.getName() + " must have a value among : " + StringUtils.join(type.getEnumConstants(), ", "); } else{ message = "The parameter " + e.getName() + " must be of type " + type.getTypeName(); } return buildResponse(HttpStatus.UNPROCESSABLE_ENTITY, message); }
你可以创建一个自定义转换器,该转换器将null在提供无效值时返回而不是异常。
null
像这样:
@Configuration public class MyConfig extends WebMvcConfigurationSupport { @Override public FormattingConversionService mvcConversionService() { FormattingConversionService f = super.mvcConversionService(); f.addConverter(new MyCustomEnumConverter()); return f; } }
一个简单的转换器可能看起来像这样:
public class MyCustomEnumConverter implements Converter<String, SortEnum> { @Override public SortEnum convert(String source) { try { return SortEnum.valueOf(source); } catch(Exception e) { return null; // or SortEnum.asc } } }