Question

我正在使用Java EE（JPA）为后端创建RESTful应用程序，并使用Eclipse IDE和前端中的angular6。我目前正在尝试创建CORSfilter。我已经编写了以下两个类，但是当我发送POST请求时收到：
No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4200' is therefore not allowed access.
在浏览器（Chrome）的控制台中。

CrossOriginResourceFilter.java：

package filters;

import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerResponseContext;
import javax.ws.rs.container.ContainerResponseFilter;
import javax.ws.rs.ext.Provider;

@Provider
public class CrossOriginResourceFilter implements ContainerResponseFilter {

    @Override
    public void filter(ContainerRequestContext requestContext, ContainerResponseContext response) {
      response.getHeaders().putSingle("Access-Control-Allow-Origin", "*");
      response.getHeaders().putSingle("Access-Control-Allow-Methods", "OPTIONS, GET, POST, PUT, DELETE");
      response.getHeaders().putSingle("Access-Control-Allow-Headers", "Content-Type");
      response.getHeaders().putSingle("Access-Control-Allow-Headers", "responseType");

    }

}

ApplicationConfig.java

package service;

import java.util.Set;
import javax.ws.rs.core.Application;

@javax.ws.rs.ApplicationPath("linkedInRestfulProject")
public class ApplicationConfig extends Application {

    @Override
    public Set<Class<?>> getClasses() {
      Set<Class<?>> resources = new java.util.HashSet<>();
      addRestResourceClasses(resources);
      return resources;
    }

    private void addRestResourceClasses(Set<Class<?>> resources) {
      resources.add(filters.CrossOriginResourceFilter.class);
      resources.add(service.AdvertismentEndpoint.class);
      resources.add(service.ArticleEndpoint.class);
      resources.add(service.ConnectionRequestEndpoint.class);
      resources.add(service.UserEndpoint.class);
      resources.add(service.ConversationEndpoint.class);
      resources.add(service.MessageEndpoint.class);

    }

}

似乎我的后端无法使用或查看过滤器。
我已经搜索过是否必须创建/更改其他任何内容（例如web.xml），但找不到任何东西。

我还尝试在web.xml中添加以下行，并且得到以下错误（编译后端时）。

<filter>
  <filter-name>CrossOriginResourceFilter</filter-name>
  <filter-class>filters.CrossOriginResourceFilter</filter-class>
</filter>
<filter-mapping>
   <filter-name>CrossOriginResourceFilter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>


SEVERE: Exception starting filter [CrossOriginResourceFilter]
java.lang.ClassCastException: filters.CrossOriginResourceFilter cannot be cast to javax.servlet.Filter
    at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:264)
    at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:108)
    at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4598)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5241)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1421)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1411)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

月食-CORSfilter无法正常运行

0 个答案: