JS跨域请求外部服务器的资源

 package com.soft.filter;
/**
 * Created by Administrator on 2017/2/6.
 */
import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class CORSFilter implements Filter {
  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
  }
  @Override
  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    HttpServletResponse httpResponse = (HttpServletResponse) servletResponse;
    httpResponse.addHeader("Access-Control-Allow-Origin", "*");
    filterChain.doFilter(servletRequest, servletResponse);
  }
  @Override
  public void destroy() {
  }
}

<filter>
  <filter-name>CorsFilter</filter-name>
  <filter-class>com.omiaozu.manager.filter.CORSFilter</filter-class>
</filter>
<filter-mapping>
  <filter-name>CorsFilter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>