【跨域】springboot 解决前后端跨域

Cors协议

H5中的新特性：Cross-Origin Resource Sharing（跨域资源共享）。通过它，我们的开发者（主要指后端开发者）可以决定资源是否能被跨域访问。

cors是一个w3c标准，它允许浏览器（目前ie8以下还不能被支持）像我们不同源的服务器发出xmlHttpRequest请求，我们可以继续使用ajax进行请求访问。

具体关于cors协议的文章 ，可以参考http://www.ruanyifeng.com/blog/2016/04/cors.html 这篇文章，讲的相当不错。

一.CORS 

方式一：CORS全局配置-实现WebMvcConfigurer

package com.hzl.admin.api.config;

import org.springframework.boot.web.servlet.FilterRegistrationBean;
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.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class CorsConfig {

    @Bean
    public FilterRegistrationBean corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        CorsConfiguration config = new CorsConfiguration();
        config.setAllowCredentials(true);
        config.addAllowedOrigin("*");
        config.addAllowedHeader("*");
        config.addAllowedMethod("OPTIONS");
        config.addAllowedMethod("HEAD");
        config.addAllowedMethod("GET");
        config.addAllowedMethod("PUT");
        config.addAllowedMethod("POST");
        config.addAllowedMethod("DELETE");
        config.addAllowedMethod("PATCH");
        source.registerCorsConfiguration("/**", config);
        final FilterRegistrationBean bean = new FilterRegistrationBean(new CorsFilter(source));
        bean.setOrder(0);
        return bean;
    }

    @Bean
    public WebMvcConfigurer mvcConfigurer() {
        return new WebMvcConfigurerAdapter() {
            @Override
            public void addCorsMappings(CorsRegistry registry) {
                registry.addMapping("/**").allowedMethods("GET", "PUT", "POST", "GET", "OPTIONS");
            }
        };
    }
}

方式二：Filter过滤器实现

@Component
public class CorsFilter implements Filter {
 
    final static org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(CorsFilter.class);
 
 
 
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
 
        HttpServletRequest reqs = (HttpServletRequest) req;
 
        response.setHeader("Access-Control-Allow-Origin","*");
        // response.setHeader("Access-Control-Allow-Origin","单个地址");
        // response.setHeader("Access-Control-Allow-Origin",reqs.getHeader("Origin"));
        response.setHeader("Access-Control-Allow-Credentials", "true");
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "x-requested-with");
        chain.doFilter(req, res);
    }
    public void init(FilterConfig filterConfig) {}
    public void destroy() {}
}

方式三：@CrossOrigin

@RequestMapping("/demo2")
@RestController
@CrossOrigin("https://blog.youkuaiyun.com") // 只有指定域名可以访问该类下所有接口
public class CorsTest2Controller {
    @GetMapping("/sayHello")
    public String sayHello() {
        return "hello world --- 2";
    }
}