出现错误：“Access-Control-Allow-Origin”标头包含多个值“*、*”，但只允许一个

Question

我试图在我的 Angular 前端和 Java / Spring 中的 REST 端点之间建立连接（我没有开发，也不太了解）。通过 GET，一切正常。通过 POST，我在终端收到消息

已被 CORS 政策阻止：对预检请求的响应未通过访问控制检查：请求的资源上不存在“Access-Control-Allow-Origin”标头。

并且，在开发工具的“网络”选项卡中，OPTIONS 方法出现错误 403

Request Method: OPTIONS
Status Code: 403 
Remote Address: xx.xx.xx.xx:xxxx
Referrer Policy: strict-origin-when-cross-origin

所以，我在互联网上多次搜索后发现了这种情况，原因是 CORS 设置：通常，在这种情况下，OPTIONS 调用在 POST 之前发送；但是，由于 CORS，不允许调用 OPTIONS。所以，我试图在我的控制器上设置这一行

@CrossOrigin(origins = "*", methods = {RequestMethod.OPTIONS, RequestMethod.GET, RequestMethod.POST, RequestMethod.PUT, RequestMethod.DELETE})

这次错误发生了变化

Multiple CORS header 'Access-Control-Allow-Origin' not allowed
But the code I added is the only similar to @CrossOrigin, I dind't found others similar.

所以，根据CORS issue - No 'Access-Control-Allow-Origin' header is present on the requested resource的帖子，我尝试了以下解决方案：

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedMethods("HEAD", "GET", "PUT", "POST", "DELETE", "PATCH");
    }
}

和

@Configuration
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
//        http.csrf().disable();
        http.cors();
    }

    @Bean
    public CorsConfigurationSource corsConfigurationSource() {
        final CorsConfiguration configuration = new CorsConfiguration();
        configuration.setAllowedOrigins(ImmutableList.of("*"));
        configuration.setAllowedMethods(ImmutableList.of("HEAD",
                "GET", "POST", "PUT", "DELETE", "PATCH"));
        // setAllowCredentials(true) is important, otherwise:
        // The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'.
        configuration.setAllowCredentials(true);
        // setAllowedHeaders is important! Without it, OPTIONS preflight request
        // will fail with 403 Invalid CORS request
        configuration.setAllowedHeaders(ImmutableList.of("Authorization", "Cache-Control", "Content-Type"));
        final UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/**", configuration);
        return source;
    }
}

但是这次我在控制台看到的错误变成了

已被 CORS 策略阻止：“Access-Control-Allow-Origin”标头包含多个值“*、*”，但只允许一个。

所以，这是我到达的最后一点。如何解决关于多个值的最后一个错误？每次我处理这个问题时，我都会提前一步，错误会发生变化，但它仍然存在。

Answer 1

只需将其添加到您的 WebSecurityConfigurerAdapter

@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

    
/*@Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedMethods("HEAD", "GET", "PUT", "POST", "DELETE", "PATCH");
    }*/ not needed

@Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // by default uses a Bean by the name of corsConfigurationSource
            .cors(withDefaults())
            ...
    }

    @Bean
    CorsConfigurationSource corsConfigurationSource() {
        CorsConfiguration configuration = new CorsConfiguration();
        configuration.setAllowedOrigins(Arrays.asList("https://localhost:5000"));// if your front end running on localhost:5000
        configuration.setAllowedMethods(Arrays.asList("GET","POST"));
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/**", configuration);
        return source;
    }
}

确保除了上面的代码之外，您没有任何其他过滤器或 cors 注释

Spring CORS section 在 Spring Security 文档中。

如果你没有使用 Spring Security：

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }


    @Bean
    public WebMvcConfigurer corsConfigurer() {
        return new WebMvcConfigurer() {
            @Override
            public void addCorsMappings(CorsRegistry registry) {
                registry
                .addMapping("/**")
                .allowedOrigins("*","http://localhost:5000");// list all domains
            }
        };
    }
}