问题：

Could not resolve all files for configuration ':classpath'.
   > Could not resolve org.springframework.boot:spring-boot-gradle-plugin:3.1.1.
     Required by:
         project : > org.springframework.boot:org.springframework.boot.gradle.plugin:3.1.1
      > No matching variant of org.springframework.boot:spring-boot-gradle-plugin:3.1.1 was found. The consumer was configured to find a library for use during runtime, compatible with Java 8, packaged as a jar, and its dependencies declared externally, as well as attribute 'org.gradle.plugin.api-version' with value '8.1.1' but:
          - Variant 'apiElements' capability org.springframework.boot:spring-boot-gradle-plugin:3.1.1 declares a library, packaged as a jar, and its dependencies declared externally:
              - Incompatible because this component declares a component for use during compile-time, compatible with Java 17 and the consumer needed a component for use during runtime, compatible with Java 8
              - Other compatible attribute:

解决：

问题是在Gradle构建过程中遇到了解析插件spring-boot-gradle-plugin版本3.1.1失败的问题。错误的原因是插件需要的Java版本是17，而你正在使用的Java版本是8。

解决这个问题的方式是升级Java版本。需要一个与插件兼容的Java版本，这里是Java 17。以下是你可以按照的步骤：

下载并安装Java 17，如果还没有安装的话。可以在Oracle的官方网站上下载。

在系统环境变量中设置JAVA_HOME为新安装的Java 17的路径。

在Gradle构建文件中设置使用的Java版本为17。可以在build.gradle文件中添加以下代码：

java {
    sourceCompatibility = JavaVersion.VERSION_17
    targetCompatibility = JavaVersion.VERSION_17
}