初始SBT，搭建scala环境采坑

SBT版本： 1.3.4

Scala版本：2.12.10

操作系统： Windows

分别下载SBT的Scala进行安装。

安装完SBT到D:\sbt目录后，配置D:\sbt\conf下的repo.properties和sbtconfig.txt

repo.properties的内容如下

[repositories]
local
aliyun-central: https://maven.aliyun.com/repository/central
aliyun-public: https://maven.aliyun.com/repository/public
jcenter: https://jcenter.bintray.com/
repo1: https://repo1.maven.org/maven2/
store_2: http://repo2.maven.org/maven2/
aliyun-releases: https://maven.aliyun.com/repository/releases
aliyun-apache-snapshots: https://maven.aliyun.com/repository/apache-snapshots
aliyun-google: https://maven.aliyun.com/repository/google
aliyun-jcenter: https://maven.aliyun.com/repository/jcenter
aliyun-spring: https://maven.aliyun.com/repository/spring
aliyun-spring-plugin: https://maven.aliyun.com/repository/spring-plugin
sbt-plugin: http://repo.scala-sbt.org/scalasbt/sbt-plugin-releases/
sonatype: http://oss.sonatype.org/content/repositories/snapshots  
typesafe: http://repo.typesafe.com/typesafe/ivy-releases/, [organization]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext], bootOnly
typesafe2: http://repo.typesafe.com/typesafe/releases/
atlassian: https://packages.atlassian.com/content/repositories/atlassian-public/
spring-plugin: https://repo.spring.io/plugins-release/
hortonworks: https://repo.hortonworks.com/content/repositories/releases/

Repostory的url来源于maven仓库， 冒号前面的名字自己起，如阿里的仓库。 sbt找一个jar，会逐个遍历仓库，直到找到为止，所以要把常用的下载速度快的放在前面。

sbtconfig.txt的内容如下：

# sbt configuration file for Windows

# Set the java args

#-mem 1024 was added in sbt.bat as default

-Xms1024m
-Xmx1024m
-Xss4M
-XX:ReservedCodeCacheSize=128m

# Set the extra sbt options

-Dsbt.log.format=true
-Dsbt.boot.directory=D:/sbt/boot/
-Dsbt.global.base=D:/sbt/.sbt
-Dsbt.ivy.home=D:/sbt/.ivy2
-Dsbt.repository.config=D:/sbt/conf/repo.properties
-Dsbt.override.build.repos=true

第一次执行sbt命令的时候（如sbt new scala/hello-world.g8），会下载一堆堆的依赖，慢。

可以参考 GETTING STARTED WITH SCALA AND SBT ON THE COMMAND LINE

日志文件是 D:\sbt\boot\update.log

下载的各依赖包会放在 D:\sbt\.ivy2\cache目录下。如果下载依赖包的时候挂住了，Ctrl C结束命令，再重新执行命令

如果遇到了下面的错误

[error] java.lang.NoClassDefFoundError: okio/Source
[error] Use 'last' for the full log.

或者

[error] java.lang.NoClassDefFoundError: kotlin/TypeCastException
[error] Use 'last' for the full log.
Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore?

去maven下载相应的jar包放在D:\sbt\boot\scala-2.12.10\org.scala-sbt\sbt\1.3.4目录下

在maven上搜okio和kotlin， 要下载的jar包是okio-2.4.1.jar和kotlin-stdlib-1.3.61.jar

在IDEA里面使用sbt创建scala项目，会dump project structure from sbt很久，key跟踪D:\sbt\boot\update.log看看是不是下载jar包的问题。

如果在Idea里使用sbt建立或导入项目也报NoClassDefFoundError错误，可以把D:\sbt\boot\scala-2.12.10\org.scala-sbt\sbt\1.3.4下jar包作为一个library导入到工程目录下。