跨域问题：Access-Control-Allow-Origin

博客来源：

项目合作的时候，出现跨域访问，虽然种种迹象表明、跨域不安全、对于合作项目，来说跨域也不是不可

解决办法：【项目完结后将跨域取消即可】

修改跨域问题在Java后端解决

web.xml中

  <filter>
    <filter-name>crossDomain</filter-name>
    <filter-class>online.wenmeng.filter.crossDomain</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

crossDomain 复制这个类，放到你的项目中【要与上面过滤器中class对应】

package online.wenmeng.filter;

import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Descrintion: 解决跨域问题的过滤器
 * @version: 1.0
 */
public class crossDomain implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        // 将ServletResponse转换为HttpServletResponse
        HttpServletResponse httpResponse = (HttpServletResponse) res;
        httpResponse.setHeader("Access-Control-Allow-Origin", "*");
        httpResponse.setContentType("application/json;charset=UTF-8");
        httpResponse.setHeader("Access-Control-Allow-Methods", "GET, HEAD, POST, PUT, DELETE, OPTIONS, PATCH");
        httpResponse.setHeader("Access-Control-Max-Age", "3600");
        httpResponse.setHeader("Access-Control-Allow-Headers", "Content-Type,Access-Token");
        // 如果要把Cookie发到服务器，需要指定Access-Control-Allow-Credentials字段为true
        httpResponse.setHeader("Access-Control-Allow-Credentials", "true");
        httpResponse.setHeader("Access-Control-Expose-Headers", "*");
        chain.doFilter(req, res);
    }

    @Override
    public void destroy() {

    }
}