在一个 hoplon 项目中，通过执行：boot development，我得到这些错误：
I/O exception (java.net.SocketException) caught when connecting to the target host: Network is unreachable
Failed to collect dependencies for [#<Dependency org.clojure:clojure:jar:1.6.0 (compile)> #<Dependency tailrecursion:boot.core:jar:2.5.1 (compile)> #<Dependency tailrecursion:boot.task:jar:2.2.4 (compile)> #<Dependency tailrecursion:hoplon:jar:5.10.23
Failed to read artifact descriptor for org.clojure:clojure:jar:1.6.0
↳ Caused by: Could not transfer artifact org.clojure:clojure:pom:1.6.0 from/to http://repo1.maven.org/maven2/ (http://repo1.maven.org/maven2/): Connection to http://repo1.maven.org refused
我已经在我的机器上安装了引导。（Ubuntu 12.04）有什么建议吗？