下载已经打包的gem包
1:下载logstash-input-jdbc-4.1.3.gem包
wget https://rubygems.org/downloads/logstash-input-jdbc-4.1.3.gem
2:安装gem包
进入logstash安装目录，执行
bin/logstash-plugin install /your path/logstash-input-jdbc-4.1.3.gem
出现下面语句即安装成功：
Validating logstash-input-jdbc-4.1.3.gem
Installing logstash-input-jdbc
Installation successful
