前些天发现了一个巨牛的人工智能学习网站,通俗易懂,风趣幽默,忍不住分享一下给大家。点击跳转到教程。
1. 前端 vue 工程 post 请求后端接口,报错:
Request header field Content-Type is not allowed by Access-Control-Allow-Headers
前端请求方式:
this.$ajax({method: "post",url: this.GLOBAL.BASE_URL + "/gentle/first",data: {name: "JY",info: "test"}});
2. 解决:
在过滤器中设置请求头:
resp.setHeader("Access-Control-Allow-Headers", "Content-Type,XFILENAME,XFILECATEGORY,XFILESIZE");
3. 过滤器完整写法:
过滤器用法见另一博文:Springboot 项目中过滤器的使用
package gentle;import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;/*** 改写所有请求头* @author silence* @date 2018/12/11 15:19*/@WebFilter(filterName = "requestFilter",urlPatterns = {"/*"})
public class RequestFilter implements Filter {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {HttpServletResponse response = (HttpServletResponse) servletResponse;HttpServletRequest request = (HttpServletRequest)servletRequest;response.setHeader("Access-Control-Allow-Origin", "*");response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");response.setHeader("Access-Control-Max-Age", "3600");response.setHeader("Access-Control-Allow-Headers", "Content-Type,XFILENAME,XFILECATEGORY,XFILESIZE,x-requested-with,Authorization");response.setHeader("Access-Control-Allow-Credentials", "true");String method = request.getMethod();if(method.equalsIgnoreCase("OPTIONS")){servletResponse.getOutputStream().write("Success".getBytes("utf-8"));}else{filterChain.doFilter(servletRequest, servletResponse);}}@Overridepublic void destroy() {}}
4. 重新请求,访问接口成功 :
这样每次请求都会显示 2 次,第 1 次只返回个 success。第 2 次才是正式访问接口。
至于能不能只请求 1 次,目前我还不知道。
后记:
在网上看到可以在 js 中作如下设置,F12 中只提示一次请求。而且正好是我要的第 2 个请求,就是正式请求。
let headers= new Headers();
headers.set('Content-Type','application/json');
headers.set('Access-Control-Allow-Origin','*');