Security框架：通过CorsFilter解决前端跨域请求问题

项目情况：

 最近做的pmdb项目是前后端分离的， 由于测试的时候是前端与后端联调，所以出现了跨域请求的问题。浏览器默认会向后端发送一个Options方式的请求，根据后端的响应来判断后端支持哪些请求方式，支持才会真正的发送请求。

CORS介绍：

CORS（Cross-Origin Resource Sharing 跨源资源共享），当一个请求url的协议、域名、端口三者之间任意一与当前页面地址不同即为跨域。

在日常的项目开发时会不可避免的需要进行跨域操作，而在实际进行跨域请求时，经常会遇到类似 No 'Access-Control-Allow-Origin' header is present on the requested resource.这样的报错。

这样的错误，一般是由于CORS跨域验证机制设置不正确导致的。

解决方案：

注释：本项目使用的是SprintBoot+Security+JWT+Swagger

第一步：新建CorsFilter，在过滤器中设置相关请求头

package com.handlecar.basf_pmdb_service.filter;

import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class CorsFilter extends OncePerRequestFilter {

//public class CorsFilter implements Filter {
//    static final String ORIGIN = "Origin";

    protected void doFilterInternal(
            HttpServletRequest request, HttpServletResponse response,
            FilterChain filterChain) throws ServletException, IOException {

//        String origin = request.getHeader(ORIGIN);

        response.setHeader("Access-Control-Allow-Origin", "*");//* or origin as u prefer
        response.setHeader("Access-Control-Allow-Credentials", "true");
        response.setHeader("Access-Control-Allow-Methods", "PUT, POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Max-Age", "3600");
//        response.setHeader("Access-Control-Allow-Headers", "content-type, authorization");
        response.setHeader("Access-Control-Allow-Headers", "Origin, No-Cache, X-Requested-With, If-Modified-Since, Pragma, Last-Modified, Cache-Control, Expires, Content-Type, X-E4M-With, Authorization");
        response.setHeader("XDomainRequestAllowed","1");
        //使前端能够获取到
        response.setHeader("Access-Control-Expose-Headers","download-status,download-filename,download-message");


        if (request.getMethod().equals("OPTIONS"))
//            response.setStatus(HttpServletResponse.SC_OK);
            response.setStatus(HttpServletResponse.SC_NO_CONTENT);
        else
            filterChain.doFilter(request, response);

    }

//    @Override
//    public void doFilter(ServletRequest req, ServletResponse res,
//                         FilterChain chain) throws IOException, ServletException {
//
//        HttpServletResponse response = (HttpServletResponse) res;
//        //测试环境用【*】匹配，上生产环境后需要切换为实际的前端请求地址
//        response.setHeader("Access-Control-Allow-Origin", "*");
//        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
//
//        response.setHeader("Access-Control-Max-Age", "0");
//
//        response.setHeader("Access-Control-Allow-Headers", "Origin, No-Cache, X-Requested-With, If-Modified-Since, Pragma, Last-Modified, Cache-Control, Expires, Content-Type, X-E4M-With, auth");
//
//        response.setHeader("Access-Control-Allow-Credentials", "true");
//
//        response.setHeader("XDomainRequestAllowed","1");
//        chain.doFilter(req, res);
//    }
//
//    @Override
//    public void destroy() {
//    }
//
//    @Override
//    public void init(FilterConfig arg0) throws ServletException {
//    }
}

注释：这里的Access-Control-Expose-Headers的请求头是为了使前端能够获得到后端在response中自定义的header，不设置的话，前端只能看到几个默认显示的header。我这里是在使用response导出Excel的时候将文件名和下载状态信息以自定义请求头的形式放在了response的header里。

第二步：在Security的配置文件中初始化CorsFilter的Bean

 @Bean
    public CorsFilter corsFilter() throws Exception {
        return new CorsFilter();
    }

第三步：在Security的配置文件中添加Filter配置，和映射配置

.antMatchers(HttpMethod.OPTIONS,"/**").permitAll()
                    // 除上面外的所有请求全部需要鉴权认证。 .and() 相当于标示一个标签的结束，之前相当于都是一个标签项下的内容
                .anyRequest().authenticated().and()
                .addFilterBefore(corsFilter(), UsernamePasswordAuthenticationFilter.class)

附：该配置文件

package com.handlecar.basf_pmdb_service.conf;

import com.handlecar.basf_pmdb_service.filter.CorsFilter;
import com.handlecar.basf_pmdb_service.filter.JwtAuthenticationTokenFilter;
import com.handlecar.basf_pmdb_service.security.JwtTokenUtil;
import com.handlecar.basf_pmdb_service.security.CustomAuthenticationProvider;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpMethod;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.config.http.SessionCreationPolicy;
import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;

//import com.allcom.security.JwtTokenUtil;

@Configuration
//@EnableWebSecurity is used to enable Spring Security’s web security support and provide the Spring MVC integration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true)
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {


    private final CustomAuthenticationProvider customAuthenticationProvider;

    @Autowired
    public WebSecurityConfig(CustomAuthenticationProvider customAuthenticationProvider) {
        this.customAuthenticationProvider = customAuthenticationProvider;
    }

    @Override
    protected void configure(AuthenticationManagerBuilder auth) {
        auth.authenticationProvider(customAuthenticationProvider);
    }

    @Bean
    public JwtTokenUtil jwtTokenUtil(){
        return new JwtTokenUtil();
    }

    @Bean
    public CorsFilter corsFilter() throws Exception {
        return new CorsFilter();
    }

    @Bean
    public JwtAuthenticationTokenFilter authenticationTokenFilterBean() {
        return new JwtAuthenticationTokenFilter();
    }

    @Override
    protected void configure(HttpSecurity httpSecurity) throws Exception {
        httpSecurity
                // 由于使用的是JWT，我们这里不需要csrf,不用担心csrf攻击
                .csrf().disable()
                // 基于token，所以不需要session
                .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS).and()

                .authorizeRequests()
                    //.antMatchers(HttpMethod.OPTIONS, "/**").permitAll()

                    // 允许对于网站静态资源的无授权访问
                    .antMatchers(
                        HttpMethod.GET,
                        "/",
                        "/*.html",
                        "/favicon.ico",
                        "/**/*.html",
                        "/**/*.css",
                        "/**/*.js",
                        "/webjars/springfox-swagger-ui/images/**","/swagger-resources/configuration/*","/swagger-resources",//swagger请求
                        "/v2/api-docs"
                    ).permitAll()
                    // 对于获取token的rest api要允许匿名访问
                    .antMatchers("/pmdbservice/auth/**","/pmdbservice/keywords/export3").permitAll()
                    .antMatchers(HttpMethod.OPTIONS,"/**").permitAll()
                    // 除上面外的所有请求全部需要鉴权认证。 .and() 相当于标示一个标签的结束，之前相当于都是一个标签项下的内容
                .anyRequest().authenticated().and()
                .addFilterBefore(corsFilter(), UsernamePasswordAuthenticationFilter.class)
                .addFilterBefore(authenticationTokenFilterBean(), UsernamePasswordAuthenticationFilter.class);

        // 禁用缓存
        httpSecurity.headers().cacheControl();
    }

}