springboot整合Filter实现前后端分离，解决CORS跨域问题

1.没有使用前端框架的，可以使用一下代码测试

(function loadXMLDoc() {
    
    
                var xmlhttp;
                xmlhttp = new XMLHttpRequest();
                            xmlhttp.onreadystatecatechange = function() {
    
    
                }
                            xmlhttp.open("post", "http://www.tangshuaicn.top:81/commondity/initSelectCommondity", true);
                            xmlhttp.withCredentials = true;
                            xmlhttp.send();
            })()

提示跨域异常

解决方法

@Component
@WebFilter(filterName = "loginFilter",urlPatterns = "/*")
public class CorsFilter extends GenericFilterBean{
    
    

	@Override
	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
			throws IOException, ServletException {
    
    
		System.out.println("=====================================过滤器aaaaaaaa");
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) res;
		response.setHeader("Access-Control-Allow-Origin", "*");
		response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE, PUT, GET");
		response.setHeader("Access-Control-Max-Age", "3600");
		response.setHeader("Access-Control-Allow-Headers", "x-requested-with");
		chain.doFilter(req, res);
	}

}

这里我踩了两个坑，
1.过滤器类上没有使用@Component注解，导致一直不进过滤器。
2.之前直接实现Filter接口，在本地测试没问题，发布到服务器所有Controller接口访问变成404，然后使用继承这个最高级过滤器GenericFilterBean发布到服务器完美解决跨域问题。