Solr 6.0 学习（八） SolrDispatchFilter源码解析及solr扩展

最新推荐文章于 2018-03-02 13:24:34 发布

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最新推荐文章于 2018-03-02 13:24:34 发布 · 4.1k 阅读

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#solr #源码

本文探讨SolrDispatchFilter在Solr 6.0中的作用，它是全局过滤器，负责初始化Solr核心容器并提供全文检索服务。通过分析web.xml配置，我们关注SolrResourceLoader.locateSolrHome()方法。在doFilter过程中，SolrDispatchFilter创建HttpSolrCall实例并执行。后续文章将深入研究HttpSolrCall的细节。

传送门：老版SolrDispatchFilter源码解析

SolrDispatchFilter做了什么

我们发布好我们的solr6.X之后我们可以看到项目下web.xml中一段配置

<!-- Any path (name) registered in solrconfig.xml will be sent to that filter -->
  <filter>
    <filter-name>SolrRequestFilter</filter-name>
    <filter-class>org.apache.solr.servlet.SolrDispatchFilter</filter-class>
    <!--
    Exclude patterns is a list of directories that would be short circuited by the 
    SolrDispatchFilter. It includes all Admin UI related static content.
    NOTE: It is NOT a pattern but only matches the start of the HTTP ServletPath.
    -->

    <init-param>
      <param-name>excludePatterns</param-name>
      <param-value>/css/.+,/js/.+,/img/.+,/tpl/.+</param-value>
    </init-param>

  </filter>

  <filter-mapping>
    <!--
      NOTE: When using multicore, /admin JSP URLs with a core specified
      such as /solr/coreName/admin/stats.jsp get forwarded by a
      RequestDispatcher to /solr/admin/stats.jsp with the specified core
      put into request scope keyed as "org.apache.solr.SolrCore".

      It is unnecessary, and potentially problematic, to have the SolrDispatchFilter
      configured to also filter on forwards.  Do not configure
      this dispatcher as <dispatcher>FORWARD</dispatcher>.
    -->
    <filter-name>SolrRequestFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

我们注意其中org.apache.solr.servlet.SolrDispatchFilter
这个是个全局的过滤器Filter。下面我们来一步步的研究一下其源码主要做了些什么

BaseSolrFilter

package org.apache.solr.servlet;

import javax.servlet.Filter;

abstract class BaseSolrFilter
  implements Filter
{
  static
  {
    CheckLoggingConfiguration.check();
  }
}

CheckLoggingConfiguration

package org.apache.solr.servlet;

import org.slf4j.LoggerFactory;

final class CheckLoggingConfiguration
{
  static void check()
  {
    try
    {
      LoggerFactory.getLogger(CheckLoggingConfiguration.class);
    } catch (NoClassDefFoundError e) {
      throw new NoClassDefFoundError("Failed to initialize Apache Solr: Could not find necessary SLF4j logging jars. If using Jetty, the SLF4j logging jars need to go in the jetty lib/ext directory. For other containers, the corresponding directory should be used. For more information, see: http://wiki.apache.org/solr/SolrLogging");
    }
  }
}

SolrDispatchFilter

package org.apache.solr.servlet;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Properties;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.lang.StringUtils;
import org.apache.http.client.HttpClient;
import org.apache.solr.common.SolrException;
import org.apache.solr.common.SolrEx