问题 已被CORS策略阻止 请求的资源上没有 Access-Control-Allow-Origin 标头 跨域请求失败

解决方法 使用过滤器设置Access-Control-Allow-Origin解决跨域请求

第一步  创建过滤器

package com.ljw.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletResponse;public class SimpleCORSFilter implements Filter { Override public void destroy() { } Override public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletResponse response (HttpServletResponse) res; // 指定允许其他域名访问 response.setHeader( Access-Control-Allow-Origin , * // 允许所有 // response.setHeader( Access-Control-Allow-Origin , http://127.0.0.1, http://locahost // 允许白名单IP // 响应类型 response.setHeader( Access-Control-Allow-Methods , POST, GET, OPTIONS, DELETE // 预检请求的结果缓存60分钟 response.setHeader( Access-Control-Max-Age , 3600 // 响应头设置 response.setHeader( Access-Control-Allow-Headers , x-requested-with chain.doFilter(req, res); } Override public void init(FilterConfig arg0) throws ServletException { }}

第二步 web.xml 配置过滤器

 filter filter-name cors /filter-name filter-class com.ljw.filter.SimpleCORSFilter /filter-class /filter filter-mapping filter-name cors /filter-name url-pattern /* /url-pattern /filter-mapping