解决Spring Boot跨域问题（配置JAVA类）

什么是跨域问题

跨域问题指的是不同端口之间，使用 ajax 无法相互调用的问题。跨域问题本质是浏览器的一种保护机制，它是为了保证用户的安全，防止恶意网站窃取数据。比如前端用的端口号为8081，后端用的端口号为8080，后端想接收前端发送的数据就会出现跨域问题。

如图所示：

提供两个配置类

这里我前端的端口采用的为8081，后端为8080。

1.在后端文件创建一个软件包（这里为config）

2.在config里面创建一个JAVA类（这里为CrosConfig）

3.在该JAVA类里面保存并执行下面的配置类

第一个

java 复制代码

package com.kob.backend.config;

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;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;


@Configuration
public class CorsConfig{
    @Bean
    public CorsFilter corsFilter() {
        final UrlBasedCorsConfigurationSource urlBasedCorsConfigurationSource = new UrlBasedCorsConfigurationSource();
        final CorsConfiguration corsConfiguration = new CorsConfiguration();
        /*是否允许请求带有验证信息*/
        corsConfiguration.setAllowCredentials(true);
        /*允许访问的客户端域名*/
        corsConfiguration.addAllowedOriginPattern("*");
        /*允许服务端访问的客户端请求头*/
        corsConfiguration.addAllowedHeader("*");
        /*允许访问的方法名,GET POST等*/
        corsConfiguration.addAllowedMethod("*");
        urlBasedCorsConfigurationSource.registerCorsConfiguration("/**", corsConfiguration);
        return new CorsFilter(urlBasedCorsConfigurationSource);
    }

}

第二个

java 复制代码

package com.kob.backend.config;

import org.springframework.context.annotation.Configuration;

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

@Configuration
public class CorsConfig implements Filter {
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
        HttpServletRequest request = (HttpServletRequest) req;

        String origin = request.getHeader("Origin");
        if(origin!=null) {
            response.setHeader("Access-Control-Allow-Origin", origin);
        }

        String headers = request.getHeader("Access-Control-Request-Headers");
        if(headers!=null) {
            response.setHeader("Access-Control-Allow-Headers", headers);
            response.setHeader("Access-Control-Expose-Headers", headers);
        }

        response.setHeader("Access-Control-Allow-Methods", "*");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Credentials", "true");

        chain.doFilter(request, response);
    }

    @Override
    public void init(FilterConfig filterConfig) {

    }

    @Override
    public void destroy() {
    }
}