HandlerInterceptor拦截器 postHandle执行addHeader无效，postHandle执行setStatus无效的解决方案-编程知识

问题描述

想在postHandle方法里执行addHeader方法来补充一些Header信息（如分页信息），但是最后执行却未如期显示

拦截器源码

import com.zhangziwa.practisesvr.utils.response.ResponseContext;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.http.HttpHeaders;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;@Component
public class ResponsePostInterceptor implements HandlerInterceptor {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {# 想在postHandle方法里执行addHeader方法来补充一些Header信息HttpHeaders headers = ResponseContext.getHeaders();if (headers != null) {headers.forEach((key, values) -> values.forEach((value) -> {if (!response.getHeaderNames().contains(key)) {response.addHeader(key, value);}}));}if (ResponseContext.getResponseCode() != null) {response.setStatus(ResponseContext.getResponseCode().value());}}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {ResponseContext.clear();}
}

Controller 构造初始的HttpHeaders

    @RequestMapping(value = "/getAllStudents4", method = RequestMethod.GET)public ResponseEntity<List<Student>> getAllStudents4() {System.err.println("***Controller.getAllStudents4***");List<Student> students = userService.listStudents3(1, 5);HttpHeaders httpHeaders = new HttpHeaders();httpHeaders.add("test", "test");return ResponseEntity.ok().headers(httpHeaders).contentType(MediaType.APPLICATION_JSON).body(students);}

postHandle 补充HttpHeaders的代码正常执行

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执行结果却没有补充的HttpHeaders

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原因分析

[Ref] springboot设置返回的response中的header解决办法

解决方案

方案1：`postHandle`追加`HttpHeaders`的逻辑前移到`preHandle`方法

    @Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.err.println("***ResponsePostInterceptor.preHandle***");response.addHeader("test1", "test1");return true;}

验证可行

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弊端

preHandle执行时机是在进入Controller层之前，如果要追加的HttpHeaders是在Controller层里计算得到的，则此方案完全用不上

方案2：使用`ResponseBodyAdvice` + `@ControllerAdvice`

源码：`HandlerInterceptor` 去除补充`HttpHeaders`逻辑

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;@Component
public class ResponsePostInterceptor implements HandlerInterceptor {//在Controller执行之前调用，如果返回false，controller不执行@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.err.println("***ResponsePostInterceptor.preHandle***");return true;}//controller执行之后，且页面渲染之前调用@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.err.println("***ResponsePostInterceptor.postHandle***");}//页面渲染之后调用，一般用于资源清理操作@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.err.println("***ResponsePostInterceptor.afterCompletion***");ResponseContext.clear();}
}

源码：`ResponseBodyAdvice` 补充`HttpHeaders`逻辑

import org.springframework.core.MethodParameter;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;import static java.util.Objects.nonNull;@ControllerAdvice
public class ResponsePostAdvice implements ResponseBodyAdvice {@Overridepublic boolean supports(MethodParameter returnType, Class converterType) {System.err.println("***ResponsePostAdvice.supports***");return true;}@Overridepublic Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class clazz, ServerHttpRequest request, ServerHttpResponse response) {System.err.println("***ResponsePostAdvice.beforeBodyWrite***");HttpHeaders headers = response.getHeaders();// 分页信息添加到ServerHttpResponseHttpHeaders headersContext = ResponseContext.getHeaders();// 实现方式1: 一次性梭哈 重复项新值覆盖旧值
//        if (nonNull(headersContext) && !headersContext.isEmpty()) {
//            headers.addAll(headersContext);
//        }// 实现方式1: 逐个补充 重复项不添加if (nonNull(headersContext) && !headersContext.isEmpty()) {headersContext.forEach((key, values) -> values.forEach((value) -> {headers.addIfAbsent(key, value);}));}// 状态码添加到ServerHttpResponseif (nonNull(ResponseContext.getResponseCode())) {response.setStatusCode(ResponseContext.getResponseCode());}return body;}
}

验证好用

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补充：执行顺序为 ResponseBodyAdvice → HandlerInterceptor

***ResponsePostInterceptor.preHandle***
***Controller.getAllStudents4***
***ResponsePostAdvice.supports***
***ResponsePostAdvice.beforeBodyWrite***
***ResponsePostInterceptor.postHandle***
***ResponsePostInterceptor.afterCompletion***