下载地址
https://github.com/spring-projects/spring-boot/tags
找到V2.2.9
编译
解压文件，进入文件spring-boot-2.2.9RELEASE，执行命令
mvn clean install -DskipTests -Pfast
编译构建如果发生如下异常：
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.6.0:exec (gradle) on project spring-boot-gradle-plugin: Command execution failed.: Process exited with an error: 1 (Exit value: 1) -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn <args> -rf :spring-boot-gradle-plugin
则执行命令：
mvn clean -rf :spring-boot-gradle-plugin
发生构建成功过了
然后使用idea到如spring-boot-2.2.9.RELEASE即可
