Spring中ResponseBodyAdvice的使用详解

目录

• 1 ResponseBodyAdvice的简介
• 2 ResponseBodyAdvice的使用
• 1 准备一个SpringBoot项目环境
• 3 添加一个返回包装类
• 4 添加控制类
• 5 接口测试

ResponseBodyAdvice可以在注解@ResponseBody将返回值处理成相应格式之前操作返回值。实现这个接口即可完成相应操作。可用于对response 数据的一些统一封装或者加密等操作

1 ResponseBodyAdvice的简介

ResponseBodyAdvice接口和之前记录的RequestBodyAdvice接口类似, RequestBodyAdvice是请求到Controller之前拦截,做相应的处理操作, 而ResponseBodyAdvice是对Controller返回的{@code @ResponseBody}or a {@code ResponseEntity} 后,{@code HttpMessageConverter} 类型转换之前拦截, 进行相应的处理操作后,再将结果返回给客户端.

ResponseBodyAdvice的源代码:

/**   数据的处理顺序向下
 * Allows customizing the response after the execution of an {@code @ResponseBody}
 * or a {@code ResponseEntity} controller method but before the body is written
 * with an {@code HttpMessageConverter}.
 *
 * 
Implementations may be registered directly with
 * {@code RequestMappingHandlerAdapter} and {@code ExceptionHandlerExceptionResolver}
 * or more likely annotated with {@code @ControllerAdvice} in which case they
 * will be auto-detected by both.
 *
 * @author Rossen Stoyanchev
 * @since 4.1
 * @param  the body type
 */
public interface ResponseBodyAdvice {

	/**
	 * Whether this component supports the given controller method return type
	 * and the selected {@code HttpMessageConverter} type.
	 * @param returnType the return type   方法返回的类型
	 * @param converterType the selected converter type   参数类型装换
	 * @return {@code true} if {@link #beforeBodyWrite} should be invoked;
	 * {@code false} otherwise
	 * 返回 true 则下面 beforeBodyWrite方法被调用, 否则就不调用下述方法
	 */
	boolean supports(MethodParameter returnType, Class> converterType);

	/**
	 * Invoked after an {@code HttpMessageConverter} is selected and just before
	 * its write method is invoked.
	 * @param body the body to be written
	 * @param returnType the return type of the controller method
	 * @param selectedContentType the content type selected through content negotiation
	 * @param selectedConverterType the converter type selected to write to the response
	 * @param request the current request
	 * @param response the current response
	 * @return the body that was passed in or a modified (possibly new) instance
	 */
	@Nullable
	T beforeBodyWrite(@Nullable T body, MethodParameter returnType, MediaType selectedContentType,
			Class> selectedConverterType,
			ServerHttpRequest request, ServerHttpResponse response);

}

说明:

• supports方法: 判断是否要执行beforeBodyWrite方法,true为执行,false不执行. 通过该方法可以选择哪些类或那些方法的response要进行处理, 其他的不进行处理.
• beforeBodyWrite方法: 对response方法进行具体操作处理

{@code @ResponseBody} 返回响应体, 例如List集合

{@code ResponseEntity} 返回响应实体对象,例如User对象

2 ResponseBodyAdvice的使用

1 准备一个SpringBoot项目环境

2 添加一个响应拦截类

@ControllerAdvice
public class BaseResponseBodyAdvice implements ResponseBodyAdvice