0 概述

本文主要闡述 ElasticSearch 5.4 客戶端模式進行開發的時候出現的問題~依賴 maven pom

        <!-- ES -->
        <dependency>
            <groupId>org.elasticsearch</groupId>
            <artifactId>elasticsearch</artifactId>
            <version>5.4.0</version>
        </dependency
 
>

        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>transport</artifactId>
            <version>5.4.0</version>
        </dependency>

1 常見問題以及處理

1.1 jdk版本問題

出現unsorportedClassVersion等類似問題。由於elasticsearch 5.0 以及以後版本 使用了java lambda表示式等相JDK相關特性，因此jdk 版本必須是1.8 以上版本（含1.8）。

1.2 出現log4j相關異常

    at org.elasticsearch.common.logging.Loggers.getLogger(Loggers.java:105)
    at org.elasticsearch.common.logging.Loggers.getLogger(Loggers.java:72)
    at org.elasticsearch.common.component.AbstractComponent.<init>(AbstractComponent.java:37)
    at org.elasticsearch.plugins
 
.PluginsService.<init>(PluginsService.java:110)
    at org.elasticsearch.client.transport.TransportClient.newPluginService(TransportClient.java:92)
    at org.elasticsearch.client.transport.TransportClient.buildTemplate(TransportClient.java:117)
    at org.elasticsearch.client.transport.TransportClient.<init>(TransportClient.java:241)
    at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:92)
    at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:81)
    at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:71)
    at com.hsc.study.ESClient.<init>(ESClient.java:21)
    at com.hsc.study.ESClient.main(ESClient.java:26)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

專案中缺少log4j2 依賴，這個是es5.4 強依賴~
解決辦法：新增如下依賴

       <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
            <version>2.6.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.6.2</version>
        </dependency>

1.3 修改配置中叢集名字後啟動失敗

Exception in thread "main" ElasticsearchParseException[malformed, expected settings to start with 'object', instead was [VALUE_STRING]]
    at org.elasticsearch.common.settings.loader.XContentSettingsLoader.load(XContentSettingsLoader.java:73)
    at org.elasticsearch.common.settings.loader.XContentSettingsLoader.load(XContentSettingsLoader.java:52)
    at org.elasticsearch.common.settings.loader.YamlSettingsLoader.load(YamlSettingsLoader.java:50)
    at org.elasticsearch.common.settings.Settings$Builder.loadFromStream(Settings.java:925)
    at org.elasticsearch.common.settings.Settings$Builder.loadFromPath(Settings.java:914)
    at org.elasticsearch.node.internal.InternalSettingsPreparer.prepareEnvironment(InternalSettingsPreparer.java:102)
    at org.elasticsearch.bootstrap.Bootstrap.initialEnvironment(Bootstrap.java:257)
    at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:297)
    at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:121)
    at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:112)
    at org.elasticsearch.cli.SettingCommand.execute(SettingCommand.java:54)
    at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:122)
    at org.elasticsearch.cli.Command.main(Command.java:88)
    at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:89)
    at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:82)

yml的配置檔案中冒號後邊要跟有 一個空格，不要出現tab符,如下：
cluster.name: test