1.运行命令：>rake db:migrate
报错：
ERROR: 'rake/rdoctask' is obsolete and no longer supported. Use 'rdoc/task'
解决方法：rake版本太高，降低版本
gem uninstall rake --version 10.0.4
gem install rake --version 0.8.7
2.The driver encountered an error: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
解决方法：启动mysql
3.rake aborted!
The driver encountered an error: org.jruby.runtime.builtin.IRubyObject.setInstanceVariable(Ljava/lang/String;Lorg/jruby/runtime/builtin/IRubyObject;)Lorg/jruby/runtime/builtin/IRubyObject;
4.Gem 'ruby-debug-ide' isn't installed or its executable script 'rdebug-ide' doesn't exist
解决方法：
gem install ruby-debug-ide --pre
gem install linecache