如何解决cors java中的预检请求问题

CORS（跨源资源共享）是一种安全机制，用于在Web应用程序中允许或禁止来自不同源的HTTP请求

1. 使用Java Servlet Filter：

创建一个名为CORSFilter.java的新类，并实现javax.servlet.Filter接口。在这个类中，你需要实现以下三个方法：init(), doFilter()和destroy()。

import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.annotation.WebFilter; import javax.servlet.http.HttpServletResponse;  @WebFilter(asyncSupported = true, urlPatterns = { "/*" }) public class CORSFilter implements Filter {      @Override     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)             throws IOException, ServletException {         HttpServletResponse httpResponse = (HttpServletResponse) response;         httpResponse.setHeader("Access-Control-Allow-Origin", "*");         httpResponse.setHeader("Access-Control-Allow-Methods", "POST, GET, PUT, OPTIONS, DELETE");         httpResponse.setHeader("Access-Control-Max-Age", "3600");         httpResponse.setHeader("Access-Control-Allow-Headers", "Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With");         chain.doFilter(request, response);     }      @Override     public void init(FilterConfig filterConfig) throws ServletException {     }      @Override     public void destroy() {     } } 

2. 配置Spring Boot：

如果你使用的是Spring Boot，可以通过添加@Bean到你的主应用程序类中来配置CORS。例如：

import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.Bean; import org.springframework.web.servlet.config.annotation.CorsRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;  @SpringBootApplication public class Application {      public static void main(String[] args) {         SpringApplication.run(Application.class, args);     }      @Bean     public WebMvcConfigurer corsConfigurer() {         return new WebMvcConfigurer() {             @Override             public void addCorsMappings(CorsRegistry registry) {                 registry.addMapping("/**")                         .allowedOrigins("*")                         .allowedMethods("GET", "POST", "PUT", "DELETE", "OPTIONS")                         .allowedHeaders("*")                         .maxAge(3600);             }         };     } } 

3. 配置JAX-RS：

如果你使用的是JAX-RS（Jersey），可以通过创建一个名为CORSFilter.java的新类，并实现ContainerResponseFilter接口来配置CORS。例如：

import javax.ws.rs.container.ContainerRequestContext; import javax.ws.rs.container.ContainerResponseContext; import javax.ws.rs.container.ContainerResponseFilter; import javax.ws.rs.core.MultivaluedMap; import java.io.IOException;  public class CORSFilter implements ContainerResponseFilter {      @Override     public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext)             throws IOException {         MultivaluedMap<String, Object> headers = responseContext.getHeaders();         headers.add("Access-Control-Allow-Origin", "*");         headers.add("Access-Control-Allow-Methods", "GET, POST, DELETE, PUT, OPTIONS");         headers.add("Access-Control-Allow-Headers", "Content-Type, Authorization, X-Requested-With");     } } 

然后，确保在你的应用程序中注册此过滤器。例如，在Application类中添加以下代码：

import org.glassfish.jersey.server.ResourceConfig;  public class Application extends ResourceConfig {     public Application() {         packages("your.package.name");         register(CORSFilter.class);     } } 

这些方法应该能帮助你解决Java中的CORS预检请求问题。根据你的项目需求和架构选择合适的方法进行配置。