SpringBoot 2.4.0跨域问题

当我们沿用之前的跨域配置

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("*")
                .allowedMethods("*")
                .maxAge(3600)
                .allowCredentials(true);
    }
}

前端请求就会报错

java.lang.IllegalArgumentException: When allowCredentials is true, allowedOrigins cannot contain the special value "*"since that cannot be set on the "Access-Control-Allow-Origin" response header. To allow credentials to a set of origins, list them explicitly or consider using "allowedOriginPatterns" instead.
at org.springframework.web.cors.CorsConfiguration.validateAllowCredentials(CorsConfiguration.java:457)
at org.springframework.web.servlet.handler.AbstractHandlerMapping.getHandler(AbstractHandlerMapping.java:520)
at org.springframework.web.servlet.DispatcherServlet.getHandler(DispatcherServlet.java:1255)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1037)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:961)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doOptions(FrameworkServlet.java:945)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:103)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:103)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:712)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:461)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:384)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312)
at org.apache.catalina.core.StandardHostValve.custom(StandardHostValve.java:398)
at org.apache.catalina.core.StandardHostValve.status(StandardHostValve.java:257)
at org.apache.catalina.core.StandardHostValve.throwable(StandardHostValve.java:352)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:177)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)

而提示的意思是：当设置allowCredentials为true，allowedOrigins的值不能为特殊符号 *，因为在响应头里不能设置"Access-Control-Allow-Origin" 的值为*。解决办法有两个

1. 显式的列出allowedOrigins具体值

2. 使用allowedOriginPatterns替代allowedOrigins

    public void validateAllowCredentials() {
        if (this.allowCredentials == Boolean.TRUE && this.allowedOrigins != null && this.allowedOrigins.contains("*")) {
            throw new IllegalArgumentException("When allowCredentials is true, allowedOrigins cannot contain the special value "*"since that cannot be set on the "Access-Control-Allow-Origin" response header. To allow credentials to a set of origins, list them explicitly or consider using "allowedOriginPatterns" instead.");
        }
    }

解决

package com.pixelcat.pixelcat.web.config;

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("/**")
                .allowedOriginPatterns("*") // SpringBoot2.4.0 [allowedOriginPatterns]代替[allowedOrigins]
                .allowedMethods("*")
                .maxAge(3600)
                .allowCredentials(true);
    }
}