servlet 前端 java在过滤器中为http请求加请求头header

前言

        现在有一个需求场景：每一个请求我都需要在请求头里面加上token这个请求头，作为一种校验机制，传统的接口可以通过设置一个全局的变量，然后通过页面携带过来（大概就是先将我们的token放在session中，写一个服务用来获取session中的token，然后主页面用 ajax 调用接口，将 token放在隐藏域中，然后将请求头放进来，用 ajax 方法，这里不想细说了），但是有一个情况是通过页面传递的并不一定都会适用所有接口，比如上传和下载的接口有时候请求头里面就没有token 参数，可能是上传和下载是用表单提交的。 这个时候如何将请求头通过后台的方法加进来？ 想到用过滤器，用后台方法强制加入请求头。

我这里加的是将用户唯一标识加在请求头上，并在自己需要的时候自己获取

1.创建拦截器，核心代码为 addHeader方法，将userid添加到请求头中

package com.kaying.luck.interceptor;

import com.kaying.luck.dao.draw.user.UserDao;

import com.kaying.luck.exception.ServiceException;

import com.kaying.luck.pojo.draw.user.dos.UserDO;

import com.kaying.luck.response.enums.ApiResponseCodeEnum;

import com.kaying.luck.utils.applicationContext.MyApplicationContext;

import org.apache.commons.lang3.StringUtils;

import org.apache.tomcat.util.http.MimeHeaders;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Component;

import org.springframework.web.servlet.HandlerInterceptor;

import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.lang.reflect.Field;

import java.util.HashMap;

import java.util.Map;

/**

* @author csp

* @create 2021-11-23 14:54

* @description

*/

@Component

public class BaseInterceptor implements HandlerInterceptor {

@Autowired

private UserDao userDao = MyApplicationContext.getBean(UserDao.class);

@Override

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) throws Exception {

String userId = request.getHeader("userId");

if (StringUtils.isBlank(userId)){

throw new ServiceException(ApiResponseCodeEnum.ERROR_USER_ID, "未查询到用户信息");

}

UserDO userDO = userDao.getUserByUserId(userId);

if (userDO == null) {

userDO = new UserDO();

userDO.setId(null);

userDO.setUserId(userId);

userDO.setUserOrderStatus(0);

userDao.insert(userDO);

}

Map map=new HashMap<>();

map.put("userId",userId);

addHeader(request,map);

return true;

}

private void addHeader(HttpServletRequest request, Map headerMap) {

if (headerMap==null||headerMap.isEmpty()){

return;

}

Class c=request.getClass();

//System.out.println(c.getName());

System.out.println("request实现类="+c.getName());

try{

Field requestField=c.getDeclaredField("request");

requestField.setAccessible(true);

Object o=requestField.get(request);

Field coyoteRequest=o.getClass().getDeclaredField("coyoteRequest");

coyoteRequest.setAccessible(true);

Object o2=coyoteRequest.get(o);

System.out.println("coyoteRequest实现类="+o2.getClass().getName());

Field headers=o2.getClass().getDeclaredField("headers");

headers.setAccessible(true);

MimeHeaders mimeHeaders=(MimeHeaders) headers.get(o2);

for (Map.Entry entry:headerMap.entrySet()){

mimeHeaders.removeHeader(entry.getKey());

mimeHeaders.addValue(entry.getKey()).setString(entry.getValue());

}

}catch (Exception e){

e.printStackTrace();

}

}

@Override

public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse response, Object o, ModelAndView modelAndView) throws Exception {

response.setHeader("Access-Control-Allow-Origin", "*");

response.setHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");

response.setHeader("Access-Control-Max-Age", "3600");

response.setHeader("Access-Control-Allow-Headers", "*");

response.setHeader("Access-Control-Allow-Credentials", "true");

}

@Override

public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {

}

}

2.配置拦截器，拦截器需要配置才能使用

package com.kaying.luck.config.interceptor;

import com.kaying.luck.interceptor.BaseInterceptor;

import org.springframework.context.annotation.Configuration;

import org.springframework.web.servlet.config.annotation.CorsRegistry;

import org.springframework.web.servlet.config.annotation.InterceptorRegistry;

import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**

* 拦截器需要配置才可以使用，也可以在这里注入其他的类

*

* @author yt

* @create 2022/10/17 14:26

*/

@Configuration

public class BaseInterceptorConfig implements WebMvcConfigurer {

@Override

public void addInterceptors(InterceptorRegistry registry) {

// 添加拦截器

registry.addInterceptor(new BaseInterceptor())

//添加拦截路径

.addPathPatterns("/**")

//排除的拦截路径（此路径不拦截）

.excludePathPatterns("/swagger/**","/error","/download/**","/wx/**","/address/**","/management/**","/callback/**",

"/favicon.ico","/swagger2/**", "/swagger*", "/swagger*/**", "/webjars/**", "/doc.html", "/swagger-ui.html", "/swagger-resources/**", "/v2/api-docs**");

}

/**

* 开启跨域

*/

@Override

public void addCorsMappings(CorsRegistry registry) {

// 设置允许跨域的路由

registry.addMapping("/**")

// 设置允许跨域请求的域名

.allowedOriginPatterns("*")

// 是否允许证书（cookies）

.allowCredentials(true)

// 设置允许的方法

.allowedMethods("*")

// 跨域允许时间

.maxAge(3600);

}

}

4.在要拦截的方法接收参数上添加 @RequestHeader注解

@ApiOperation(value = "根据用户UserId查询用户信息")

@GetMapping("get/user")

public ApiResponse getUserByUserId( @RequestHeader("userId") String userId) {

System.out.println("userId = " + userId);

if (StringUtils.isBlank(userId)) {

throw new ServiceException(ApiResponseCodeEnum.FAIL, "获取用户信息失败");

}

UserDO userDO = userLoginService.getUserByUserId(userId);

return ApiResponse.success(userDO);

}

5.测试访问是可以拿到userid的

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