跨域请求实现

跨域请求问题出现时往往伴随以下报错信息：

...has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

解决问题也很简单，我是基于Java服务器：

@WebFilter("/*")
public class AccessControlAllowOriginFilter implements Filter {
	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Allow-Credentials", "true");
        chain.doFilter(req, response);
    } 
 
   public void init(FilterConfig filterConfig) {
 
   } 
 
   public void destroy() {
 
   } 
}

然后将这个过滤器配置到项目中，上面是用注解进行配置