What are the ways springboot solves cross-domain issues?

What is cross-domain

Cross-domain: refers to the fact that the browser cannot execute scripts from other websites. It is caused by the browser's same-origin policy, which is a security restriction imposed by the browser on JavaScript.
For example: If page a wants to obtain the resources of page b, if the protocols, domain names, ports, and subdomain names of pages a and b are different, the access actions performed will be cross-domain, and the browser
For security reasons, cross-domain access is generally restricted, that is, cross-domain resource requests are not allowed. Note: Cross-domain access restrictions are actually browser restrictions. It is important to understand this

Same origin policy: It means that the protocol, domain name, and port must be the same. Any difference among them will cause cross-domain problems;

springboot solves cross-domain problems Several ways

Method 1. SpringBoot annotation @CrossOrigin

Add the @CrossOrigin annotation directly to the Controller method or class. SpringMVC uses @CrossOrigin usage scenarios that require jdk1.8 Spring4.2

@GetMapping("/hello")
@CrossOrigin
public String hello() {
        return "hello:" + simpleDateFormat.format(new Date());
}

Method 2: Use CorsFilter

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;
@Configuration
public class ConfigConfiguration {
    @Bean
    public CorsFilter CorsFilter() {
        CorsConfiguration corsConfiguration = new CorsConfiguration();
        corsConfiguration.addAllowedOriginPattern("*");
        corsConfiguration.addAllowedHeader("*");
        corsConfiguration.addAllowedMethod("*");
        corsConfiguration.setAllowCredentials(true);
        UrlBasedCorsConfigurationSource ub = new UrlBasedCorsConfigurationSource();
        ub.registerCorsConfiguration("/**", corsConfiguration);
        return new CorsFilter(ub);
    }
}

Method 3: Custom filter (web filter) method

@Component
public class CustomFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletResponse res = (HttpServletResponse) servletResponse;
        // 设置允许Cookie
        res.addHeader("Access-Control-Allow-Credentials", "true");
        // 允许http://www.xxx.com域（自行设置，这里只做示例）发起跨域请求
        res.addHeader("Access-Control-Allow-Origin", "*");
        // 设置允许跨域请求的方法
        res.addHeader("Access-Control-Allow-Methods", "GET, POST, DELETE, PUT");
        // 允许跨域请求包含content-type
        res.addHeader("Access-Control-Allow-Headers", "Content-Type,X-CAF-Authorization-Token,sessionToken,X-TOKEN");
        if (((HttpServletRequest) servletRequest).getMethod().equals("OPTIONS")) {
            servletResponse.getWriter().println("ok");
            return;
        }
        filterChain.doFilter(servletRequest, servletResponse);
    }
}

Method 4: Implement the addCorsMappings method in WebMvcConfigurer

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Component
public class MyWebMvcConfigurer implements WebMvcConfigurer {
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")  // 匹配所有的路径
                .allowCredentials(true) // 设置允许凭证
                .allowedHeaders("*")   // 设置请求头
                .allowedMethods("GET", "POST", "PUT", "DELETE") // 设置允许的方式
                .allowedOriginPatterns("*");
    }
}

Method 5: Use nginx as a dynamic proxy

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