Apache Solr Search Server: Solr-j
Packages 
Package Description
org.apache.solr.client.solrj
Primary APIs for communicating with a Solr Server from a Java client.
org.apache.solr.client.solrj.beans
Annotation based mapping of client objects to Solr documents.
org.apache.solr.client.solrj.cloud
Common classes for SolrCloud.
org.apache.solr.client.solrj.embedded
SolrJ client implementations for embedded solr access.
org.apache.solr.client.solrj.impl
Concrete implementations of client API classes.
org.apache.solr.client.solrj.request
Convenience classes for dealing with various types of Solr requests.
org.apache.solr.client.solrj.request.beans
Annotated Data objects used in V2 Requests
org.apache.solr.client.solrj.request.json
Allows sending of requests using Solr's JSON query/faceting API
org.apache.solr.client.solrj.request.schema
Convenience classes for making Schema API requests.
org.apache.solr.client.solrj.response
Convenience classes for dealing with various types of Solr responses.
org.apache.solr.client.solrj.response.json
Allows parsing of JSON query/faceting API responses
org.apache.solr.client.solrj.response.schema
Convenience classes for dealing with Schema API responses.
org.apache.solr.client.solrj.routing
Classes to handle query routing preferences
org.apache.solr.client.solrj.util
Utilities for Solr client applications.
org.apache.solr.cluster.api
API interfaces for core SolrCloud classes
org.apache.solr.common
Common classes reused on both clients & server for dealing with documents to be indexed and result documents.
org.apache.solr.common.annotation
Annotations mapping to Jackson
org.apache.solr.common.cloud
Common Solr Cloud and ZooKeeper related classes reused on both clients & server.
org.apache.solr.common.luke
Common constants used by the LukeRequestHandler.
org.apache.solr.common.params
Parameter constants and enumerations.
org.apache.solr.common.util
Common utility classes reused on both clients & server.