response.addHeader("Access-Control-Allow-Origin", "*"); 


    

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正确的做法：

1. 创建一个 Filter 类

/**
 * 使用Filter的方式解决跨域问题
 */ public class CorsFilter implements Filter { private static final List<String> ALLOW_ORIGINS = Config.getListString("allowOrigins", ","); private static final String REQUEST_OPTIONS = "OPTIONS"; @Override public void init(FilterConfig filterConfig) throws ServletException {
    } @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        String orgHeader = request.getHeader(HttpHeaders.ORIGIN); if (orgHeader != null && ALLOW_ORIGINS.contains(orgHeader)) { // 允许的跨域的域名 response.addHeader("Access-Control-Allow-Origin", orgHeader); // 允许携带 cookies 等认证信息 response.addHeader("Access-Control-Allow-Credentials", "true"); // 允许跨域的方法 response.addHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE, PATCH, PUT, HEAD"); // 允许跨域请求携带的请求头 response.addHeader("Access-Control-Allow-Headers", "Content-Type, Content-Length, Authorization, Accept, X-Requested-With"); // 返回结果可以用于缓存的最长时间，单位是秒。-1表示禁用 response.addHeader("Access-Control-Max-Age", "3600"); // 跨域预检请求，直接返回 if (REQUEST_OPTIONS.equalsIgnoreCase(request.getMethod())) { return;
            }
        }
        filterChain.doFilter(request, response);
    } @Override public void destroy() {

    }
} 


    

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2. 在 web.xml 的最前面注册这个 Filter

<filter> <filter-name>corsfilter</filter-name> <filter-class>com.bj58.crm.plus.filter.CorsFilter</filter-class> </filter> <filter-mapping> <filter-name>corsfilter</filter-name> <url-pattern>/*</url-pattern> <dispatcher>REQUEST</dispatcher> </filter-mapping> 


    

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前端使用 axios 可以先进行封装

http-util.js

let axios = require("axios"); let qs = require("qs");
axios.defaults.withCredentials = true;
axios.defaults.headers.post["Content-Type"] = "application/x-www-form-urlencoded"; function post(url, param) { return axios.post(url, qs.stringify(param))
} function get(url, param) { axios.get(url, {params: param})
}

export default {
  get,
  post
};