SpringMVC對出參和入參有非常友好的拓展支持,方便你對數據的輸入和輸出有更大的執行權，我們如何通過SpringMVC定義的結果做一系列處理呢？
入參
RequestBodyAdvice : 針對所有以@RequestBody的參數做處理
參考案例: JsonViewRequestBodyAdvice
public class JsonViewRequestBodyAdvice extends RequestBodyAdviceAdapter { /** * 這裡是一個前置攔截匹配操作,其實就是告訴你滿足為true的才會執行下面的beforeBodyRead方法,這裡可以定義自己業務相關的攔截匹配* @param methodParameter * @param targetType * @param converterType * @return */ @Override public boolean supports(MethodParameter methodParameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) { return (AbstractJackson2HttpMessageConverter.class.isAssignableFrom(converterType) && methodParameter.getParameterAnnotation(JsonView.class) != null); } // 這裡就是具體的前置操作了... 下面的例子就是查找這個入參方法是否有@JsonView修飾@Override public HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter methodParameter, Type targetType, Class<? extends HttpMessageConverter<?>> selectedConverterType) throws IOException { JsonView annotation = methodParameter.getParameterAnnotation(JsonView.class); Class<?>[] classes = annotation.value(); if (classes.length != 1) { throw new IllegalArgumentException( "@JsonView only supported for request body advice with exactly 1 class argument: " + methodParameter); } return new MappingJacksonInputMessage(inputMessage.getBody(), inputMessage.getHeaders(), classes[0]); }}出參
ResponseBodyAdvice: 針對所有以@ResponseBody的參數做處理
參考案例:
@ControllerAdvicepublic class LogResponseBodyAdvice implements ResponseBodyAdvice { /** * * @param returnType * @param converterType * @return */ @Override public boolean supports(MethodParameter returnType, Class converterType) { return true; } @Override public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) { // 做任何事情body 就是返回的結果對象,沒有處理之前return body; }}注意事項
自定義的處理對像類上必須得加上@ControllerAdvice註解!
為什麼?
源碼中RequestMappingHandlerAdapter類在執行initControllerAdviceCache()做初始化的時候會執行一個
List<ControllerAdviceBean> beans = ControllerAdviceBean.findAnnotatedBeans(getApplicationContext());AnnotationAwareOrderComparator.sort(beans);
而ControllerAdviceBean.findAnnotatedBeans方法會查找類上有ControllerAdvice註解的類才會加入到處理當中..
public static List<ControllerAdviceBean> findAnnotatedBeans(ApplicationContext applicationContext) { List<ControllerAdviceBean> beans = new ArrayList<ControllerAdviceBean>(); for (String name : BeanFactoryUtils.beanNamesForTypeIncludingAncestors(applicationContext, Object.class)) { if (applicationContext.findAnnotationOnBean(name, ControllerAdvice.class) != null) { beans.add(new ControllerAdviceBean(name, applicationContext)); } } return beans; }所以大家可以根據自己的需要,定義結果的入參和出參結果做一些特殊處理.....
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。