Java springboot跨域

在Java Spring Boot中解决跨域问题可以通过以下几个步骤实现：

1. 添加CORS配置：在你的Spring Boot应用程序的配置类或者Web配置类中，添加一个CORS配置。你可以使用`@CrossOrigin`注解来实现全局的CORS配置，或者使用`CorsRegistry`来配置CORS规则。例如：

   import org.springframework.context.annotation.Configuration;
   import org.springframework.web.servlet.config.annotation.CorsRegistry;
   import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

   @Configuration
   public class WebConfig implements WebMvcConfigurer {
       @Override
       public void addCorsMappings(CorsRegistry registry) {
           registry.addMapping("/**")
                   .allowedOrigins("http://localhost:8080") // 允许的前端域名
                   .allowedMethods("GET", "POST", "PUT", "DELETE") // 允许的请求方法
                   .allowedHeaders("*") // 允许的请求头
                   .allowCredentials(true); // 是否允许发送 Cookie
       }
   }

2. 配置跨域过滤器：如果你不想使用全局的CORS配置，你可以通过配置一个跨域过滤器来实现。创建一个类实现`javax.servlet.Filter`接口，并在`doFilter`方法中设置响应头信息来允许跨域请求。例如：

   import javax.servlet.Filter;
   import javax.servlet.FilterChain;
   import javax.servlet.ServletException;
   import javax.servlet.ServletRequest;
   import javax.servlet.ServletResponse;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   import java.io.IOException;

   public class CorsFilter implements Filter {
       @Override
       public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
               throws IOException, ServletException {
           HttpServletRequest httpRequest = (HttpServletRequest) request;
           HttpServletResponse httpResponse = (HttpServletResponse) response;

           httpResponse.setHeader("Access-Control-Allow-Origin", "http://localhost:8080");
           httpResponse.setHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE");
           httpResponse.setHeader("Access-Control-Allow-Headers", "*");
           httpResponse.setHeader("Access-Control-Allow-Credentials", "true");

           chain.doFilter(request, response);
       }
   }

3. 注册跨域过滤器：在你的应用程序配置中注册跨域过滤器。例如，在Spring Boot的主类中添加以下代码：

   import org.springframework.boot.SpringApplication;
   import org.springframework.boot.autoconfigure.SpringBootApplication;
   import org.springframework.boot.web.servlet.FilterRegistrationBean;
   import org.springframework.context.annotation.Bean;

   @SpringBootApplication
   public class YourApplication {

       public static void main(String[] args) {
           SpringApplication.run(YourApplication.class, args);
       }

       @Bean
       public FilterRegistrationBean<CorsFilter> corsFilter() {
           FilterRegistrationBean<CorsFilter> registrationBean = new FilterRegistrationBean<>();
           registrationBean.setFilter(new CorsFilter());
           registrationBean.setOrder(0); // 设置过滤器优先级
           return registrationBean;
       }