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技术栈版本：
spring boot 2.0.2
遇到事儿了
近来做业务需求，前端同学fe将userId和userName放到request header中了。
后端api接口要想使用userId和userName，每个接口都要从header中获取。
试想一下，如果你有十个接口，那么每个接口都要写一遍
Object.setUserId(request.getHeader("userId"))
正如下面代码段
@RestController@Validated@RequestMapping("/template")public class TemplateController { // 一个feign client @Autowired TemplateClient templateClient @PostMapping(value = "/create", produces = MediaType.APPLICATION_JSON_VALUE) public ResultVO create(@RequestBody @Valid TemplateParam param, HttpServletRequest request) { // 每个接口都要写一遍setXXX()方法 param.setUserId(request.getHeader("userId")); param.setUserName(request.getHeader("userName")); return templateClient.createTemplate(param).toResultVO(); }} @Datapublic class TemplateParam{ private Long templateId; private Long userId; private String userName;}
解决办法
大家都知道的两大利器，
tomcat的Filter和spring的Intercepter(具体为HandlerIntercepter)
实现原理
具体方法为定义一个Filter实现类和一个HandlerIntercepter的实现类。再定义一个HttpServletRequest实现类，其作用分别为
Filter实现类：UserInfoFilter
创建一个入口，在这个入口中定义一个机会：将我们自定义的CustomHttpServletRequestWrapper代替HttpServletRequest随着请求传递下去
HttpServletRequest实现类：customHttpServletRequestWrapper
因为HttpServletRequest对象的body数据只能get，不能set，即不能再次赋值。
而我们的需求是需要给HttpServletRequest赋值，所以需要定义一个HttpServletRequest实现类：customHttpServletRequestWrapper，这个实现类可以被赋值来满足我们的需求。
HandlerIntercepter的实现类：CustomInterceptor
拦截请求，获取接口方法相关信息(方法名，参数，返回值等)。从而实现统一的给request body动态赋值
实现思路如上所述，具体的实现代码如下
代码实现
声明基础bean: UserInfoParam
UserInfoParam：定义了包含userId,userName的实体bean,要想将用户信息注入进入，需要入参对象XXXParam继承UserInfoParam，拦截器中只处理@Requestbody中实现了UserInfoParam类的bean。
如上文controller中create方法的入参：TemplateParam，继承UserInfoParam
@Datapublic class TemplateParam extends UserInfoParam{ private Long templateId; // private Long userId; // private String userName;}@Datapublic class UserInfoParam {// 用户idprivate Long userId;// 用户名称private String userName;}
定义Filter实现类: UserInfoFilter
@Slf4jpublic class UserInfoFilter implements Filter { @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { CustomHttpServletRequestWrapper customHttpServletRequestWrapper = null; try { HttpServletRequest req = (HttpServletRequest)request; customHttpServletRequestWrapper = new CustomHttpServletRequestWrapper(req); }catch (Exception e){ log.warn("customHttpServletRequestWrapper Error:", e); } chain.doFilter((Objects.isNull(customHttpServletRequestWrapper) ? request : customHttpServletRequestWrapper), response); }}
HttpServletRequest实现类：CustomHttpServletRequestWrapper
public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper { // 保存request body的数据 private String body; // 解析request的inputStream(即body)数据，转成字符串 public CustomHttpServletRequestWrapper(HttpServletRequest request) { super(request); StringBuilder stringBuilder = new StringBuilder(); BufferedReader bufferedReader = null; InputStream inputStream = null; try { inputStream = request.getInputStream(); if (inputStream != null) { bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); char[] charBuffer = new char[128]; int bytesRead = -1; while ((bytesRead = bufferedReader.read(charBuffer)) > 0) { stringBuilder.append(charBuffer, 0, bytesRead); } } else { stringBuilder.append(""); } } catch (IOException ex) { } finally { if (inputStream != null) { try { inputStream.close(); } catch (IOException e) { e.printStackTrace(); } } if (bufferedReader != null) { try { bufferedReader.close(); } catch (IOException e) { e.printStackTrace(); } } } body = stringBuilder.toString(); } @Override public ServletInputStream getInputStream() throws IOException { final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes()); ServletInputStream servletInputStream = new ServletInputStream() { @Override public boolean isFinished() { return false; } @Override public boolean isReady() { return false; } @Override public void setReadListener(ReadListener readListener) { } @Override public int read() throws IOException { return byteArrayInputStream.read(); } }; return servletInputStream; } @Override public BufferedReader getReader() throws IOException { return new BufferedReader(new InputStreamReader(this.getInputStream())); } public String getBody() { return this.body; } // 赋值给body字段 public void setBody(String body) { this.body = body; }}
HandlerIntercepter的实现类：CustomInterceptor
@Slf4jpublic class CustomInterceptor implements HandlerInterceptor { @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { if (!(handler instanceof HandlerMethod)) { return true; } HandlerMethod handlerMethod = (HandlerMethod)handler; pushUserInfo2Body(request, handlerMethod); return true; } private void pushUserInfo2Body(HttpServletRequest request, HandlerMethod handlerMethod) { try{ String userId = request.getHeader("userId"); String userName = request.getHeader("userName"); MethodParameter[] methodParameters = handlerMethod.getMethodParameters(); if(ArrayUtils.isEmpty(methodParameters)) { return; } for (MethodParameter methodParameter : methodParameters) { Class clazz = methodParameter.getParameterType(); if(ClassUtils.isAssignable(UserInfoParam.class, clazz)){ if(request instanceof CustomHttpServletRequestWrapper){ CustomHttpServletRequestWrapper requestWrapper = (CustomHttpServletRequestWrapper)request; String body = requestWrapper.getBody(); JSONObject param = JSONObject.parseObject(body); param.put("userId", userId); param.put("userName", Objects.isNull(userName) ? null : URLDecoder.decode(userName, "UTF-8")); requestWrapper.setBody(JSON.toJSONString(param)); } } } }catch (Exception e){ log.warn("fill userInfo to request body Error ", e); } }
定义Configuration class，增加拦截器和过滤器的配置
WebMvcConfigurer子类：CustomWebMvcConfigurer
@Configurationpublic class CustomWebMvcConfigurer implements WebMvcConfigurer { @Override public void addInterceptors(InterceptorRegistry registry) { CustomInterceptor customInterceptor= new CustomInterceptor(); registry.addInterceptor(customInterceptor); } @Bean public FilterRegistrationBean servletRegistrationBean() { UserInfoFilter userInfoFilter = new UserInfoFilter(); FilterRegistrationBean<UserInfoFilter> bean = new FilterRegistrationBean<>(); bean.setFilter(userInfoFilter); bean.setName("userInfoFilter"); bean.addUrlPatterns("/*"); bean.setOrder(Ordered.LOWEST_PRECEDENCE); return bean; }}
到此，实现功能的代码撸完了。启动spring boot App，就可以curl访问restful接口了
http访问
curl -X POST \ http://localhost:8080/template/create -H 'Content-Type: application/json' -H 'username: tiankong天空' -H 'userId: 11' -d '{ "templateId": 1000}
效果
可以看到TemplateController.create(…)打出的信息，userId和username的值正是header中传的值
toDo
剩下的就看你的了，以上为个人经验，希望能给大家一个参考，也希望大家多多支持。
生活不要太劳累，弄得自己很疲惫，快乐幸福多体会，
