Spring boot跨域设置实例详解

定义：跨域是指从一个域名的网页去请求另一个域名的资源

1.原由

公司内部有多个不同的子域，比如一个是location.company.com ,而应用是放在app.company.com , 这时想从 app.company.com去访问 location.company.com 的资源就属于跨域

本人是springboot菜鸟，但是做测试框架后端需要使用Springboot和前端对接，出现跨域问题，需要设置后端Response的Header.走了不少坑，在这总结一下以备以后使用

2.使用场景

浏览器默认不允许跨域访问，包括我们平时ajax也是限制跨域访问的。

产生跨域访问的情况主要是因为请求的发起者与请求的接受者1、域名不同；2、端口号不同

如果一个网页可以随意地访问另外一个网站的资源，那么就有可能在客户完全不知情的情况下出现安全问题

3.解决方案

通过设置Access-Control-Allow-Origin来实现跨域访问

4.具体解决

刚开始使用http://www.jianshu.com/p/f2060a6d6e3b设置，但是由于我们使用的spring版本的问题，CorsConfiguration类需要4.2.7版本。和我们使用的spring里面版本不一致，导致版本冲突或者各种问题

@Configuration
public class CorsConfig {
  private CorsConfiguration buildConfig() {
    CorsConfiguration corsConfiguration = new CorsConfiguration();
    corsConfiguration.addAllowedOrigin("*"); // 1
    corsConfiguration.addAllowedHeader("*"); // 2
    corsConfiguration.addAllowedMethod("*"); // 3
    return corsConfiguration;
  }

  @Bean
  public CorsFilter corsFilter() {
    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
    source.registerCorsConfiguration("/**", buildConfig()); // 4
    return new CorsFilter(source);
  }
}

后来改为Filter方式

@Component
public class CorsFilter implements Filter {
  final static org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(CorsFilter.class);

  public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
    HttpServletResponse response = (HttpServletResponse) res;
    HttpServletRequest reqs = (HttpServletRequest) req;
    response.setHeader("Access-Control-Allow-Origin","*");
    response.setHeader("Access-Control-Allow-Credentials", "true");
    response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
    response.setHeader("Access-Control-Max-Age", "3600");
    response.setHeader("Access-Control-Allow-Headers", "x-requested-with");
    chain.doFilter(req, res);
  }
  public void init(FilterConfig filterConfig) {}
  public void destroy() {}
}

后来改为Filter方式

@Component
public class CorsFilter implements Filter {
  final static org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(CorsFilter.class);
  public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
    HttpServletResponse response = (HttpServletResponse) res;
    HttpServletRequest reqs = (HttpServletRequest) req;
    response.setHeader("Access-Control-Allow-Origin","*");
    response.setHeader("Access-Control-Allow-Credentials", "true");
    response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
    response.setHeader("Access-Control-Max-Age", "3600");
    response.setHeader("Access-Control-Allow-Headers", "x-requested-with");
    chain.doFilter(req, res);
  }
  public void init(FilterConfig filterConfig) {}
  public void destroy() {}
}

网上很多资料都是教按以上方法设置，但是我这里就是设置不成功的。出现下面问题

<span style="color:#ff0000;">Fetch API cannot load https://atfcapi.alpha.elenet.me/atfcapi/project/mainPageList. The value of the 'Access-Control-Allow-Origin' </span>

<span style="color:#ff0000;">header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. Origin 'https://atfcapi-test.faas.elenet.me' is therefore not allowed access.</span>

目前为止，不知道为什么这样配置不可以，然后改为设置单个域名，如下显示

response.setHeader("Access-Control-Allow-Origin", "https://atfcapi-test.faas.elenet.me");

这样设置就成功了，但是我们有好几个环境，同一套代码，写死一个域名并解决不了问题，
按照很多网络文章中所说，设置多个域名如下：

response.setHeader("Access-Control-Allow-Origin", "https://atfcapi-test.faas.elenet.me,https://atfcapi-test-beta.faas.elenet.me");

但是设置完以后，并不好用，出现如下错误信息：

<span style="color:#ff6666;">Fetch API cannot load https://atfcapi.alpha.elenet.me/atfcapi/project/getProjects. The 'Access-Control-Allow-Origin' header contains multiple values </span>

<span style="color:#ff6666;">'https://atfcapi-test.faas.elenet.me,https://atfcapi-test-beta.faas.elenet.me', but only one is allowed. Origin 'https://atfcapi-test.faas.elenet.me' is therefore not allowed access. Have the server send the header with a valid value, or, if an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.</span>

设置为以下方式也还是错误：

response.setHeader("Access-Control-Allow-Origin", "https://atfcapi-test.faas.elenet.me"); 
    response.setHeader("Access-Control-Allow-Origin", "https://atfcapi-test-beta.faas.elenet.me");

最后采用了一种和设置为* 的方式一样的办法，代码如下：

@Component
public class CorsFilter implements Filter {
  final static org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(CorsFilter.class);
  public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
    HttpServletResponse response = (HttpServletResponse) res;
    HttpServletRequest reqs = (HttpServletRequest) req;
    response.setHeader("Access-Control-Allow-Origin",reqs.getHeader("Origin"));
    response.setHeader("Access-Control-Allow-Credentials", "true");
    response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
    response.setHeader("Access-Control-Max-Age", "3600");
    response.setHeader("Access-Control-Allow-Headers", "x-requested-with");
    chain.doFilter(req, res);
  }
  public void init(FilterConfig filterConfig) {}
  public void destroy() {}
}

从request 中的header中获取Origin，来做配置，最终成功并满足需求。
其实有些东西还是一知半解，但是起码曲线救国也是一种解决方法。

总结

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