java - 在 servlet 中启用 CORS

Question

我在我的 servlet doPost 方法中使用了这个头方法来启用 CORS。尽管在获取 api 时我的 reactjs 应用程序中出现 CORS 错误。 reactjs 错误在这里(错误: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” header 。如果不透明的响应为您提供需要，将请求的模式设置为“no-cors”以在禁用 CORS 的情况下获取资源。)

    response.addHeader("Access-Control-Allow-Origin", "*");
    response.addHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, HEAD");
    response.addHeader("Access-Control-Allow-Headers", "X-PINGOTHER, Origin, X-Requested-With, Content-Type, Accept");
    response.addHeader("Access-Control-Max-Age", "1728000");

在 tomcat web.xml 中，我用下面给出的一堆代码添加了它。如何在 tomcat 中更改多个客户端的参数值而不是像( http://localhost:3000 )这样的固定 URL？

<filter>
<filter-name>CorsFilter</filter-name>
<filter-class>org.apache.catalina.filters.CorsFilter</filter-class>
<init-param>
<param-name>cors.allowed.origins</param-name>
<param-value>http://localhost:3000</param-value>
  **(How I can change param-value for multiple client instead of fixed URL)**
</init-param>
<init-param>
<param-name>cors.allowed.methods</param-name>
<param-value>GET,POST,HEAD,OPTIONS,PUT</param-value>
  </init-param>
    <init-param>
     <param-name>cors.allowed.headers</param-name>
     <param-value>Content-Type,X-Requested-With,accept,Origin,Access- 
      Control-Request-Method,Access-Control-Request-Headers</param-value>
  </init-param>
  <init-param>
      <param-name>cors.exposed.headers</param-name>
      <param-value>Access-Control-Allow-Origin,Access-Control-Allow- 
         Credentials</param-value>
  </init-param>
  <init-param>
     <param-name>cors.support.credentials</param-name>
     <param-value>true</param-value>
  </init-param>
  <init-param>
  <param-name>cors.preflight.maxage</param-name>
  <param-value>1800</param-value>
  </init-param>
  </filter>
  <filter-mapping>
  <filter-name>CorsFilter</filter-name>
  <url-pattern>/*</url-pattern>
  </filter-mapping>

Answer 1

它因不同的前端应用程序和后端而异......
对于 Emberjs，在相应的 doGet 或 doPost 方法中添加这一行。

> response.addHeader("Access-Control-Allow-Origin", "http://localhost:4200");

(或者)

> response.addHeader("Access-Control-Allow-Origin", "*"); (for all hosts)

对于 Tomcat 的 web.xml 配置，请遵循我在下面提到的这些步骤!..

https://tomcat.apache.org/tomcat-7.0-doc/config/filter.html#:~:text=The%20filter%20class%20name%20for%20the%20CORS%20Filter%20is%20org,catalina.

For multiple clients URL just place all URL's by separating a comma's

<filter>
  <filter-name>CorsFilter</filter-name>
  <filter-class>org.apache.catalina.filters.CorsFilter</filter-class>
  <init-param>
    <param-name>cors.allowed.origins</param-name>
    <param-value> http://localhost:4200, http://localhost:3000 </param-value>
  </init-param>
</filter>