java.lang.ClassNotFoundException: solr.DataImportHandler

错误信息截图：

2018-08-02 07:56:17.527 INFO  (qtp817348612-15) [   x:mysql2solr] o.a.s.m.r.SolrJmxReporter Closing reporter [org.apache.solr.metrics.reporters.SolrJmxReporter@47d9861c: rootName = null, domain = solr.core.mysql2solr, service url = null, agent id = null] for registry solr.core.mysql2solr / com.codahale.metrics.MetricRegistry@7b867df 
2018-08-02 07:56:17.661 ERROR (qtp817348612-15) [   x:mysql2solr] o.a.s.h.RequestHandlerBase org.apache.solr.common.SolrException: Error CREATEing SolrCore 'mysql2solr': Unable to create core [mysql2solr] Caused by: solr.DataImportHandler 
        at org.apache.solr.core.CoreContainer.create(CoreContainer.java:1084) 
        at org.apache.solr.handler.admin.CoreAdminOperation.lambda$static$0(CoreAdminOperation.java:94) 
        at org.apache.solr.handler.admin.CoreAdminOperation.execute(CoreAdminOperation.java:380) 
        at org.apache.solr.handler.admin.CoreAdminHandler$CallInfo.call(CoreAdminHandler.java:395) 
        at org.apache.solr.handler.admin.CoreAdminHandler.handleRequestBody(CoreAdminHandler.java:180) 
        at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:199) 
        at org.apache.solr.servlet.HttpSolrCall.handleAdmin(HttpSolrCall.java:734) 
        at org.apache.solr.servlet.HttpSolrCall.handleAdminRequest(HttpSolrCall.java:715) 
        at org.apache.solr.servlet.HttpSolrCall.call(HttpSolrCall.java:496) 
        at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:377) 
        at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:323) 
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1634) 
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533) 
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:146) 
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548) 
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) 
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:257) 
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595) 
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255) 
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253) 
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203) 
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473) 
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564) 
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201) 
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155) 
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144) 
        at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:219) 
        at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:126) 
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) 
        at org.eclipse.jetty.rewrite.handler.RewriteHandler.handle(RewriteHandler.java:335) 
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) 
        at org.eclipse.jetty.server.Server.handle(Server.java:531) 
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:352) 
        at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:260) 
        at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:281) 
        at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:102) 
        at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:118) 
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:333) 
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:310) 
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:168) 
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:126) 
        at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:366) 
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:760) 
        at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:678) 
        at java.lang.Thread.run(Thread.java:748) 
Caused by: org.apache.solr.common.SolrException: Unable to create core [mysql2solr] 
        at org.apache.solr.core.CoreContainer.createFromDescriptor(CoreContainer.java:1156) 
        at org.apache.solr.core.CoreContainer.create(CoreContainer.java:1045) 
        ... 44 more 
Caused by: org.apache.solr.common.SolrException: Error loading class 'solr.DataImportHandler' 
        at org.apache.solr.core.SolrCore.<init>(SolrCore.java:1012) 
        at org.apache.solr.core.SolrCore.<init>(SolrCore.java:867) 
        at org.apache.solr.core.CoreContainer.createFromDescriptor(CoreContainer.java:1135) 
        ... 45 more 
Caused by: org.apache.solr.common.SolrException: Error loading class 'solr.DataImportHandler' 
        at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:557) 
        at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:488) 
        at org.apache.solr.core.SolrCore.createInstance(SolrCore.java:790) 
        at org.apache.solr.core.PluginBag.createPlugin(PluginBag.java:141) 
        at org.apache.solr.core.PluginBag.init(PluginBag.java:277) 
        at org.apache.solr.core.RequestHandlers.initHandlersFromConfig(RequestHandlers.java:130) 
        at org.apache.solr.core.SolrCore.<init>(SolrCore.java:970) 
        ... 47 more 
Caused by: java.lang.ClassNotFoundException: solr.DataImportHandler 
        at java.net.URLClassLoader.findClass(URLClassLoader.java:381) 
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424) 
        at java.net.FactoryURLClassLoader.loadClass(URLClassLoader.java:814) 
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357) 
        at java.lang.Class.forName0(Native Method) 
        at java.lang.Class.forName(Class.java:348) 
        at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:541) 
        ... 53 more

原因：因为启动 Jetty 的时候缺少了相关依赖包。

解决办法：将 solr-8.1.0/distdist 目录下的 solr-dataimporthandler-8.1.0.jar 文件复制到 apache-tomcat-8.0.47/webapps/solr/WEB-INF/lib 目录下，然后重启 Solr 即可解决。

solr-8.1.0 ：下载solr-8.1.0源码

apache-tomcat-8.0.47：部署solr 的tomcat 服务器