Java中的跨域请求怎么利用CORS实现

...
@WebFilter(filterName = "corsFilter", urlPatterns = "/*",
    initParams = {@WebInitParam(name = "allowOrigin", value = "*"),
        @WebInitParam(name = "allowMethods", value = "GET,POST,PUT,DELETE,OPTIONS"),
        @WebInitParam(name = "allowCredentials", value = "true"),
        @WebInitParam(name = "allowHeaders", value = "Content-Type,X-Token")})
public class CorsFilter implements Filter {

  private String allowOrigin;
  private String allowMethods;
  private String allowCredentials;
  private String allowHeaders;
  private String exposeHeaders;

  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
    allowOrigin = filterConfig.getInitParameter("allowOrigin");
    allowMethods = filterConfig.getInitParameter("allowMethods");
    allowCredentials = filterConfig.getInitParameter("allowCredentials");
    allowHeaders = filterConfig.getInitParameter("allowHeaders");
    exposeHeaders = filterConfig.getInitParameter("exposeHeaders");
  }

  @Override
  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    HttpServletRequest request = (HttpServletRequest) servletRequest;
    HttpServletResponse response = (HttpServletResponse) servletResponse;
    if (!StringUtils.isEmpty(allowOrigin)) {
      if(allowOrigin.equals("*")){
        response.setHeader("Access-Control-Allow-Origin", allowOrigin);
      }else{
        List<String> allowOriginList = Arrays.asList(allowOrigin.split(","));
        if (allowOriginList != null && allowOriginList.size() > 0) {
          String currentOrigin = request.getHeader("Origin");
          if (allowOriginList.contains(currentOrigin)) {
            response.setHeader("Access-Control-Allow-Origin", currentOrigin);
          }
        }
      }
    }
    if (!StringUtils.isEmpty(allowMethods)) {
      response.setHeader("Access-Control-Allow-Methods", allowMethods);
    }
    if (!StringUtils.isEmpty(allowCredentials)) {
      response.setHeader("Access-Control-Allow-Credentials", allowCredentials);
    }
    if (!StringUtils.isEmpty(allowHeaders)) {
      response.setHeader("Access-Control-Allow-Headers", allowHeaders);
    }
    if (!StringUtils.isEmpty(exposeHeaders)) {
      response.setHeader("Access-Control-Expose-Headers", exposeHeaders);
    }
    filterChain.doFilter(servletRequest, servletResponse);
  }

  @Override
  public void destroy() {

  }
}