solr 第二章，
下载：http://archive.apache.org/dist/lucene/solr/4.7.0/
目录结构：
|--contrib — 扩展插件
|--dist —jar包（solrJ, solr WAR）
|--example — example server
|--solr — solr home for example server
There is one Solr home directory set per Jetty
server, using Java system property
solr.solr.home.
Solr can host multiple cores
per server, and each core has a separate directory (for example, collection1) containing a core-specific
configuration and index (data) under
Solr home.
solr home 目录结构：
solr home directory ——对应 server 容器
|--core1 directory ——对应core
| |--configuration & index
|--core2 directory ——对应core
|--configuration & index
Each Solr server has one and only one Solr home directory that contains all cores. The global Java system property solr.solr.home sets the location of the Solr home directory.