Elasticsearch自定义插件

来源：互联网发布：python 对象编辑：程序博客网时间：2024/06/05 08:14

检索引擎Elasticsearch支持插件模式，有些时候你可能需要安装一些插件，甚至自己开发插件，这里就提供一个开始ES插件开发示例，ES版本为2.2.0。

自定义插件类继承org.elasticsearch.plugins.Plugin

HelloWorldPlugin：

package org.elasticsearch.plugin.helloworld;import java.util.Collection;  import java.util.Collections;    import org.elasticsearch.common.inject.Module;  import org.elasticsearch.plugins.Plugin;    public class HelloWorldPlugin extends Plugin {      @Override      public String name() {          return "hello-world";      }      @Override      public String description() {          return "hello-world";      }      @Override      public Collection<Module> nodeModules() {          //加入自定义处理模块          return Collections.<Module> singletonList(new HelloWorldModule());      }    }

HelloWorldModule：

package org.elasticsearch.plugin.helloworld;import org.elasticsearch.common.inject.AbstractModule;  import org.elasticsearch.rest.action.helloworld.HelloWorldAction;      public class HelloWorldModule extends AbstractModule {        @Override      protected void configure() {          bind(HelloWorldAction.class).asEagerSingleton();      }  }

HelloWorldAction：

package org.elasticsearch.rest.action.helloworld;import static org.elasticsearch.rest.RestRequest.Method.GET;  import java.io.IOException;    import org.elasticsearch.action.ActionListener;  import org.elasticsearch.action.get.GetRequest;  import org.elasticsearch.action.get.GetResponse;  import org.elasticsearch.client.Client;  import org.elasticsearch.common.inject.Inject;  import org.elasticsearch.common.io.stream.BytesStreamOutput;  import org.elasticsearch.common.settings.Settings;  import org.elasticsearch.common.xcontent.XContentBuilder;  import org.elasticsearch.common.xcontent.XContentBuilderString;  import org.elasticsearch.common.xcontent.XContentFactory;  import org.elasticsearch.common.xcontent.XContentType;  import org.elasticsearch.index.get.GetField;  import org.elasticsearch.rest.BaseRestHandler;  import org.elasticsearch.rest.BytesRestResponse;  import org.elasticsearch.rest.RestChannel;  import org.elasticsearch.rest.RestController;  import org.elasticsearch.rest.RestRequest;  import org.elasticsearch.rest.RestStatus;    public class HelloWorldAction extends BaseRestHandler {        public static String INDEX = "example";      public static String TYPE = "person";        @Inject      public HelloWorldAction(Settings settings, Client client,              RestController controller) {          super(settings, controller, client);            // Define REST endpoints          controller.registerHandler(GET, "/_hello/", this);          controller.registerHandler(GET, "/_hello/{name}", this);      }      public static XContentBuilder restContentBuilder(RestRequest request)              throws IOException {          XContentType contentType = XContentType                  .fromRestContentType(request.header("Content-Type"));          if (contentType == null) {              // try and guess it from the body, if exists              if (request.hasContent()) {                  contentType = XContentFactory.xContentType(request.content());              }          }          if (contentType == null) {              // default to JSON              contentType = XContentType.JSON;          }          BytesStreamOutput out = new BytesStreamOutput();          XContentBuilder builder = new XContentBuilder(                  XContentFactory.xContent(contentType), out);            if (request.paramAsBoolean("pretty", false)) {              builder.prettyPrint();          }          String casing = request.param("case");          if (casing != null && "camelCase".equals(casing)) {              builder.fieldCaseConversion(                      XContentBuilder.FieldCaseConversion.CAMELCASE);          } else {              builder.fieldCaseConversion(                      XContentBuilder.FieldCaseConversion.NONE);          }          return builder;      }        @Override      protected void handleRequest(final RestRequest request,              final RestChannel channel, Client client) throws Exception {          logger.info("HelloWorldAction.handleRequest called");            final String name = request.hasParam("name")                  ? request.param("name")                  : "world";          logger.info("name={}", name);          final GetRequest getRequest = new GetRequest(INDEX, TYPE, name);          getRequest.operationThreaded(true);            String[] fields = {"msg"};          getRequest.fields(fields);            client.get(getRequest, new ActionListener<GetResponse>() {              @Override              public void onResponse(GetResponse response) {                    try {                      XContentBuilder builder = restContentBuilder(request);                      GetField field = response.getField("msg");                      String greeting = (field != null)                              ? (String) field.getValues().get(0)                              : "Sorry, do I know you?";                      builder.startObject()                              .field(new XContentBuilderString("hello"), name)                              .field(new XContentBuilderString("greeting"),                                      greeting)                              .endObject();                        if (!response.isExists()) {                          channel.sendResponse(new BytesRestResponse(                                  RestStatus.NOT_FOUND, builder));                      } else {                          channel.sendResponse(                                  new BytesRestResponse(RestStatus.OK, builder));                      }                  } catch (Exception e) {                      onFailure(e);                  }              }                @Override              public void onFailure(Throwable e) {                  try {                      channel.sendResponse(                              new BytesRestResponse(channel, RestStatus.OK, e));                  } catch (IOException e1) {                      logger.error("Failed to send failure response", e1);                  }              }          });        }  }

打包后j将jar包上传至${ES_HOME}/plugins/HelloWorld目录下（新建HelloWorld）
HelloWorld目录下新建文件plugin-descriptor.properties，文件内容如下
description=hello for ElasticSearch
version=1.0
name=HelloWorldPlugin
jvm=true
classname=org.elasticsearch.plugin.helloworld.HelloWorldPlugin
java.version=1.7（当时我这里写的是1.7但实际装的是jdk1.8.0_91倒也能正常运行）
elasticsearch.version=2.2.0

重启es，插件便安装成功了。

注意：在编写plugin-descriptor.properties文件的时候每行的后面一定不要有空格，我一开始就是直接粘贴过去的，结果每行末尾都有两个空格，重启es会报下面这个错，耗费了很长时间，这里吐槽一下CSDN，当你在它的文本编辑器中将这个josn复制过去再展示的时候你会发现每行后面自动就会有两个空格，真是坑死我了！

[hadoop@h153 ~]$ ./elasticsearch-2.2.0/bin/elasticsearch[2017-10-12 01:19:08,902][INFO ][node                     ] [node-1] version[2.2.0], pid[8548], build[8ff36d1/2016-01-27T13:32:39Z][2017-10-12 01:19:08,903][INFO ][node                     ] [node-1] initializing ...Exception in thread "main" ElasticsearchException[Could not find plugin class [org.elasticsearch.plugin.helloworld.HelloWorldPlugin]]; nested: ClassNotFoundException[org.elasticsearch.plugin.helloworld.HelloWorldPlugin];Likely root cause: java.lang.ClassNotFoundException: org.elasticsearch.plugin.helloworld.HelloWorldPlugin        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 org.elasticsearch.plugins.PluginsService.loadPluginClass(PluginsService.java:463)        at org.elasticsearch.plugins.PluginsService.loadBundles(PluginsService.java:431)        at org.elasticsearch.plugins.PluginsService.<init>(PluginsService.java:129)        at org.elasticsearch.node.Node.<init>(Node.java:146)        at org.elasticsearch.node.Node.<init>(Node.java:128)        at org.elasticsearch.node.NodeBuilder.build(NodeBuilder.java:145)        at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:178)        at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:285)        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)Refer to the log for complete error details.

下面进行插件的验证：

先创建相应的索引：[hadoop@h153 ~]$ curl -XPOST http://192.168.205.153:9200/example{"acknowledged":true}[hadoop@h153 ~]$ curl -XGET http://192.168.205.153:9200/_hello{"hello":"world","greeting":"Sorry, do I know you?"}[hadoop@h153 ~]$ curl -XGET http://192.168.205.153:9200/_hello/xmine{"hello":"xmine","greeting":"Sorry, do I know you?"}[hadoop@h153 ~]$ curl -XPUT  http://192.168.205.153:9200/example/person/xmine?pretty -d '{"msg":"elasticsearch"}'{  "_index" : "example",  "_type" : "person",  "_id" : "xmine",  "_version" : 1,  "_shards" : {    "total" : 2,    "successful" : 1,    "failed" : 0  },  "created" : true}[hadoop@h153 ~]$ curl -XGET http://192.168.205.153:9200/_hello/xmine{"hello":"xmine","greeting":"elasticsearch"}

补充：为插件添加页面
如果你想为你的插件添加访问页面，则可以在ES_HOME/plugins/HelloWorld目录下创建一个名为"_site"的目录，该目录名称必须为_site，然后将相应的html页面放置进_site目录即可，如果放置了一个名为index.html文件，则可以通过localhost:9200/_plugin/HelloWorld/index.html进行访问。
由于Elasticsearch提供了js客户端API，所以使用html静态页面与js就可以完成相应的功能了。

参考：
http://blog.csdn.net/xtayfjpk/article/details/47005219
http://blog.csdn.net/l253272670/article/details/54141169
https://stackoverflow.com/questions/33538903/elasticsearch-2-0-plugin-installation-info

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