跨域一直是个很玄学的问题，SSM的时候又得前后端一起配置，sb的时候又不用。

• 前端
  axios普通get请求

submitForm() {     var v=this;     this.$axios({         method: 'get',         url: api.base_url+'/user/login',     }).then(function(res){         var json = res.data;         console.log(json);         v.$store.commit('ADD_COUNT', json.data.token);         v.$message('登录成功');     }).catch(function(err){         v.$message('密码或用户名错误');     }) }

• 后端
  加一个配置类

package com.zxc.ticketsys.config;  import org.springframework.context.annotation.Configuration; import org.springframework.scheduling.concurrent.ConcurrentTaskExecutor; import org.springframework.web.servlet.config.annotation.AsyncSupportConfigurer; import org.springframework.web.servlet.config.annotation.CorsRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;  import java.util.concurrent.Executors;  /**  * 跨域请求支持  */ @Configuration public class WebConfiguration extends WebMvcConfigurationSupport {      @Override     public void addCorsMappings(CorsRegistry registry) {         registry.addMapping("/**")                 .allowCredentials(true)                 .allowedHeaders("*")                 .allowedMethods("*")                 .allowedOrigins("*");     }      @Override     protected void configureAsyncSupport(AsyncSupportConfigurer configurer){         configurer.setTaskExecutor(new ConcurrentTaskExecutor(Executors.newFixedThreadPool(3)));         configurer.setDefaultTimeout(30000);     } }https://www.cnblogs.com/zxcoder/p/11961069.html