java如何在过滤器中为http请求加请求头header_Java

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<string,string> map=new hashmap<>();
        map.put("userid",userid);
        addheader(request,map);
        return true;
    }

    private void addheader(httpservletrequest request, map<string, string> headermap) {
        if (headermap==null||headermap.isempty()){
            return;
        }

        class<? extends httpservletrequest> 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<string,string> 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<userdo> 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);
    }