java后端cors跨域设置白名单

Java后端cors跨域设置白名单可以通过以下步骤实现：
1. 在web.xml文件中添加CorsFilter过滤器。
2. 在CorsFilter过滤器中设置允许跨域的域名白名单，可以使用通配符*表示允许所有域名跨域访问。
3. 在CorsFilter过滤器中设置允许跨域的请求方法，例如GET、POST等。
4. 在CorsFilter过滤器中设置允许跨域的请求头，例如Content-Type、Authorization等。
5. 在CorsFilter过滤器中设置允许跨域的响应头，例如Access-Control-Allow-Origin、Access-Control-Allow-Methods等。

具体实现可以参考以下代码：

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 {
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        HttpServletRequest request = (HttpServletRequest) servletRequest;

        if (StringUtils.isNotBlank(allowOrigin)) {
            response.setHeader("Access-Control-Allow-Origin", allowOrigin);
        }
        if (StringUtils.isNotBlank(allowMethods)) {
            response.setHeader("Access-Control-Allow-Methods", allowMethods);
        }
        if (StringUtils.isNotBlank(allowCredentials)) {
            response.setHeader("Access-Control-Allow-Credentials", allowCredentials);
        }
        if (StringUtils.isNotBlank(allowHeaders)) {
            response.setHeader("Access-Control-Allow-Headers", allowHeaders);
        }
        if (StringUtils.isNotBlank(exposeHeaders)) {
            response.setHeader("Access-Control-Expose-Headers", exposeHeaders);
        }

        filterChain.doFilter(request, response);
    }

    @Override
    public void destroy() {

    }
}