SpringBoot 2.1版本升级导致跨域设置失效问题修复

1. 问题

最近需要对SpringBoot的依赖进行版本升级，在使用过程中，发现原先的跨域设置失效问题。

原跨域设置代码：

    @Bean
    public CorsFilter corsFilter() {
        CorsConfiguration config = new CorsConfiguration();
        config.addAllowedOrigin("*");
        config.setAllowCredentials(true);
        config.addAllowedMethod("*");
        config.addAllowedHeader("*");

        UrlBasedCorsConfigurationSource configSource = new UrlBasedCorsConfigurationSource();
        configSource.registerCorsConfiguration("/**", config);
        return new CorsFilter(configSource);
    }

2. 解决方案

网上查询资料，得知SpringBoot在升级至SpringBoot 2.4版本之后，不支持通过addAllowedOrigin方式设置通配符“*”，推荐使用setAllowedOriginPatterns设置通配符"*"。

可通过SpringBoot的异常信息，追溯其具体变更，具体如下所示：

	/**
	 * Validate that when {@link #setAllowCredentials allowCredentials} is {@code true},
	 * {@link #setAllowedOrigins allowedOrigins} does not contain the special
	 * value {@code "*"} since in that case the "Access-Control-Allow-Origin"
	 * cannot be set to {@code "*"}.
	 * @throws IllegalArgumentException if the validation fails
	 * @since 5.3
	 */
	public void validateAllowCredentials() {
		if (this.allowCredentials == Boolean.TRUE &&
				this.allowedOrigins != null && this.allowedOrigins.contains(ALL)) {

			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.");
		}
	}

修改后的代码如下所示（经测试能正常工作）：

    @Bean
    public CorsFilter corsFilter() {
        CorsConfiguration config = new CorsConfiguration();
        config.setAllowedOriginPatterns(Collections.singletonList("*"));
        config.setAllowCredentials(true);
        config.addAllowedMethod("*");
        config.addAllowedHeader("*");

        UrlBasedCorsConfigurationSource configSource = new UrlBasedCorsConfigurationSource();
        configSource.registerCorsConfiguration("/**", config);
        return new CorsFilter(configSource);
    }