相关疑难解决方法(0)

我看到以下错误:

Origin http://localhost:8080 is not allowed by Access-Control-Allow-Origin

使用此代码:

var http = new getXMLHttpRequestObject();
var url = "http://gdata.youtube.com/action/GetUploadToken";
var sendXML = '<?xml version="1.0"?><entry xmlns="http://www.w3.org/2005/Atom"'+
    'xmlns:media="http://search.yahoo.com/mrss/'+
    'xmlns:yt="http://gdata.youtube.com/schemas/2007">'+
    '<media:group><media:title type="plain">My First API</media:title>'+
    '<media:description type="plain">First API</media:description>'+
    '<media:category scheme="http://gdata.youtube.com/schemas/2007/categories.cat">People</media:category>'+
    '<media:keywords>first, api</media:keywords></media:group></entry>';
http.open("POST", url, true);
http.setRequestHeader("Authorization", "AuthSub token=" + AccessToken);
http.setRequestHeader("X-GData-Key", "key="+ dev_key);
http.setRequestHeader("Content-Type", "application/atom+xml; charset=UTF-8");

http.onreadystatechange = function() {
    if(http.readyState == 4) {
        alert(http.responseXML);
    }
}
http.send(sendXML);

是什么导致这种情况,我该如何解决？

我在 servlet doPost 方法中使用此标头方法来启用 CORS。虽然我在获取 api 时在我的 Reactjs 应用程序中遇到 CORS 错误。这里出现reactjs错误（错误：已被CORS策略阻止：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。如果不透明的响应为您提供服务如果需要，请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，我添加了下面给出的一堆代码。如何更改多个客户端的参数值而不是tomcat 中的固定 URL（如http://localhost:3000 ）？

<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> …