springboot&ajax&has been blocked by CORS policy: No 'Access-Control-Allow-Origin

ajax+springboot解决跨域问题，以下报的错误就是html跨域的问题

Access to XMLHttpRequest at 'http://localhost:8080/user/login1' from origin 'http://localhost:59033' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

springboot解决跨域的问题的两种方法

前端测试代码：

    
    




    

        
用户名：
        
密　码：
        
 
    

第一种：写一个class，配置的class

package com.example.demo;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;


/**
 * Author:Yangjingcheng
 * Date:2018/
 */
@Configuration
public class CorsConfig {
    private CorsConfiguration buildConfig() {
        CorsConfiguration corsConfiguration = new CorsConfiguration();
        corsConfiguration.addAllowedOrigin("*");
        corsConfiguration.addAllowedHeader("*");
        corsConfiguration.addAllowedMethod("*");
        return corsConfiguration;
    }

    @Bean
    public CorsFilter corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        // 配置所有请求
        source.registerCorsConfiguration("/**", buildConfig());
        return new CorsFilter(source);
    }
}

第二种，在你要访问的Controller的方法上面加上注解

@CrossOrigin

例子：

package com.example.demo;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.ModelAndView;
import java.util.ArrayList;
import java.util.List;

@Controller
public class TestController {


    @CrossOrigin
    @RequestMapping("/user/login1")
    @ResponseBody
    public List userLogin(User user) {
        System.out.println(user);
        ArrayList users = new ArrayList<>();
        for (int i = 0; i < 3; i++) {
            users.add(user);
        }
        return users;
    }
}

这样的话就会解决前端接收不到返回值得情况了