最近在工作中协助研发进行了ES优化，效果还是非常明显的，几乎翻倍。除了通过各种业务接口测试ES性能以外，还可以直接请求ES接口，绕过服务，这样应该数据回更加准确。所以，ES Client学起来。

准备工作

首先，先准备了一个ES服务，这里就不多赘述了，大家自己在尝试的时候一定主意好ES Server和ES Client的版本要一致。 其次，新建项目，添加依赖。

学习资料

搜一下，能搜到很多的ES学习资料，建议先去看看大厂出品的基础知识了解一下ES功能。然后就可以直接看ES的API了。 下面是ES官方的文档地址： https://www.elastic.co/guide/en/elasticsearch/client/java-rest/6.7/java-rest-high-search.html

如果能能查看自己公司项目源码的小伙伴可以多研究研发的代码，能够更好结合业务理解ES API的使用。

ES Client

HTTP请求

这里说一下，很多ES查询功能都是通过HTTP请求完成的，GET请求，body传参，一开始还是比较懵逼的。查了一些资料需要自己实现是个body携带数据的HTTPGET请求，下面是我的实现代码：

package com.funtester.httpclient

import org.apache.http.client.methods.HttpEntityEnclosingRequestBase

import javax.annotation.concurrent.NotThreadSafe

/**
 * HttpGet请求携带body参数
 */
@NotThreadSafe
class HttpGetByBody extends HttpEntityEnclosingRequestBase {

    static final String METHOD_NAME = "GET";

    /**
     * 获取方法（必须重载）
     *
     * @return
     */
    @Override
    String getMethod() {
        return METHOD_NAME;
    }

    /**
     * PS:不能照抄{@link org.apache.http.client.methods.HttpPost}
     * @param uri
     */
    HttpGetByBody(final String uri) {
        this(new URI(uri))
    }

    HttpGetByBody(final URI uri) {
        super();
        setURI(uri);
    }

    HttpGetByBody() {
        super();
    }
}

ES Client

如果使用HTTP接口进行ES操作，需要组合多层级的参数，这个写起来会比较麻烦、可读性也比较差，而且更加容易出错。所以，还是使用ES Client作为操作ES的基础框架。

如果翻看ES Client源码，最终也是通过HttpClient发起HTTP请求的，这中间进行了很多的封装。这里分享一下ES Client的HTTP Client创建代码部分：

    private CloseableHttpAsyncClient createHttpClient() {
        //default timeouts are all infinite
        RequestConfig.Builder requestConfigBuilder = RequestConfig.custom()
                .setConnectTimeout(DEFAULT_CONNECT_TIMEOUT_MILLIS)
                .setSocketTimeout(DEFAULT_SOCKET_TIMEOUT_MILLIS);
        if (requestConfigCallback != null) {
            requestConfigBuilder = requestConfigCallback.customizeRequestConfig(requestConfigBuilder);
        }

        try {
            HttpAsyncClientBuilder httpClientBuilder = HttpAsyncClientBuilder.create().setDefaultRequestConfig(requestConfigBuilder.build())
                //default settings for connection pooling may be too constraining
                .setMaxConnPerRoute(DEFAULT_MAX_CONN_PER_ROUTE).setMaxConnTotal(DEFAULT_MAX_CONN_TOTAL)
                .setSSLContext(SSLContext.getDefault())
                .setTargetAuthenticationStrategy(new PersistentCredentialsAuthenticationStrategy());
            if (httpClientConfigCallback != null) {
                httpClientBuilder = httpClientConfigCallback.customizeHttpClient(httpClientBuilder);
            }

            final HttpAsyncClientBuilder finalBuilder = httpClientBuilder;
            return AccessController.doPrivileged(new PrivilegedAction<CloseableHttpAsyncClient>() {
                @Override
                public CloseableHttpAsyncClient run() {
                    return finalBuilder.build();
                }
            });
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalStateException("could not create the default ssl context", e);
        }
    }

可以看出ES Client用到了HttpClient的异步Client，我猜是用future实现同步返回响应结果，这个没仔细看，有错请指出。这里也回答我的自己的一个疑惑，ES Client是支持并发的。

ES Client 封装

就我自己的观察，ES Client的封装程度非常高，完全可以拿来就用。我担心自己过几天之后就不知道改怎么用这些ES Client 的API了，所以又进行了一次封装，权当是一个学习笔记类。

封装代码有点多，放到了文末。

测试用例

添加数据

这个可以用来跑一部分数据到ES里。

package com.funtest.groovytest

import com.alibaba.fastjson.JSONObject
import com.funtester.es.ESClient
import com.funtester.frame.SourceCode
import com.funtester.frame.execute.FunQpsConcurrent

import java.util.concurrent.atomic.AtomicInteger

class ESC extends SourceCode {

    static void main(String[] args) {
        def client = new ESClient("127.0.0.1", 9200, "http")
        def data = new JSONObject()
        data.name = "FunTester"
        data.age = getRandomInt(100)
        def index = new AtomicInteger(0)
        def test = {
            data.put("time", index.getAndIncrement())
            client.index("fun", "tt", data)
        }
        new FunQpsConcurrent(test, "ES添加数据").start()
    }

}

如果想测试添加、删除功能，只需要把test闭包内容修改即可。

        def test = {
            data.put("time", index.getAndIncrement())
            client.delete("fun", "tt", client.index("fun", "tt", data))
        }

下面是搜索功能的性能测试用例：

package com.funtest.groovytest

import com.alibaba.fastjson.JSONObject
import com.funtester.es.ESClient
import com.funtester.frame.SourceCode
import com.funtester.frame.execute.FunQpsConcurrent
import org.elasticsearch.index.query.QueryBuilders

import java.util.concurrent.atomic.AtomicInteger

class ESC extends SourceCode {

    static void main(String[] args) {
        def client = new ESClient("127.0.0.1", 9200, "http")
        def data = new JSONObject()
        data.name = "FunTester"
        data.age = getRandomInt(100)
        def index = new AtomicInteger(0)
        def test = {
            client.search("fun", QueryBuilders.matchQuery("time", getRandomInt(10)))
        }
        new FunQpsConcurrent(test, "ES搜索").start()
    }

}

ES Client API封装类

package com.funtester.es

import com.funtester.frame.SourceCode
import groovy.util.logging.Log4j2
import org.apache.http.HttpHost
import org.elasticsearch.action.delete.DeleteRequest
import org.elasticsearch.action.get.GetRequest
import org.elasticsearch.action.get.GetResponse
import org.elasticsearch.action.index.IndexRequest
import org.elasticsearch.action.index.IndexResponse
import org.elasticsearch.action.search.SearchRequest
import org.elasticsearch.action.search.SearchResponse
import org.elasticsearch.action.search.SearchScrollRequest
import org.elasticsearch.client.RequestOptions
import org.elasticsearch.client.RestClient
import org.elasticsearch.client.RestHighLevelClient
import org.elasticsearch.common.unit.TimeValue
import org.elasticsearch.index.query.QueryBuilder
import org.elasticsearch.search.SearchHits
import org.elasticsearch.search.builder.SearchSourceBuilder
import org.elasticsearch.search.fetch.subphase.FetchSourceContext

import java.util.concurrent.TimeUnit

/**
 * ES客户端API练习类
 */
@Log4j2
class ESClient extends SourceCode {

    String host

    int port

    String scheme

    RestHighLevelClient client

    ESClient(String host, int port = 9200, String scheme = "http") {
        this.host = host
        this.port = port
        this.scheme = scheme
        // 设置验证信息，填写账号及密码
        //        CredentialsProvider credentialsProvider = new BasicCredentialsProvider()
        //        credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("user", "passwd"))
        def builder = RestClient.builder(new HttpHost(host, port, scheme))
        // 设置认证信息
        //        builder.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
        //
        //            @Override
        //            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
        //                return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider)
        //            }
        //        })
        builder.setMaxRetryTimeoutMillis(1000)
        client = new RestHighLevelClient(builder)
    }

    /**
     * 添加数据
     * @param index
     * @param type
     * @param data
     * @return
     */
    def index(String index, type, Map data) {
        IndexRequest indexRequest = new IndexRequest(index, type).source(data)
        IndexResponse indexResponse = client.index(indexRequest, RequestOptions.DEFAULT)
        indexResponse.getId()
    }

    /**
     * 获取数据
     * @param index
     * @param type
     * @param id
     * @return
     */
    def get(String index, type, id) {
        // 查询文档
        GetRequest getRequest = new GetRequest(index, type, id)
        GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT)
        if (getResponse.isExists()) {
            getResponse.getSourceAsString()
        }
    }

    /**
     * 数据是否存在
     * @param index
     * @param type
     * @param id
     * @return
     */
    def exists(String index, type, id) {
        GetRequest getRequest = new GetRequest(index, type, id)
        getRequest.fetchSourceContext(new FetchSourceContext(false))
        getRequest.storedFields("_none_")
        client.exists(getRequest, RequestOptions.DEFAULT)
    }

    /**
     * 删除数据
     * @param index
     * @param type
     * @param id
     * @return
     */
    def delete(String index, type, id) {
        DeleteRequest deleteRequest = new DeleteRequest(index, type, id)
        client.delete(deleteRequest, RequestOptions.DEFAULT)
    }

    /**
     * 搜索数据
     * @param index
     * @param query
     * @param size
     * @return
     */
    def search(String index, QueryBuilder query, int size = 10) {
        SearchRequest searchRequest = new SearchRequest(index)
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder()
        sourceBuilder.query(query)
        sourceBuilder.from(0)
        sourceBuilder.size(size)
        sourceBuilder.timeout(new TimeValue(1, TimeUnit.SECONDS))
        searchRequest.source(sourceBuilder)
       client.search(searchRequest, RequestOptions.DEFAULT)
    }

    /**
     * 滚动搜索
     * @param index
     * @param query
     * @param size
     */
    def searchScroll(String index, QueryBuilder query, int size = 10) {
        SearchRequest searchRequest = new SearchRequest(index)
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder()
        searchSourceBuilder.query(query)
        searchSourceBuilder.size(size)
        searchRequest.source(searchSourceBuilder)
        searchRequest.scroll(TimeValue.timeValueMinutes(1L))
        SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT)
        String scrollId = searchResponse.getScrollId()
        SearchHits hits = searchResponse.getHits()
        def searchHits = hits.getHits()
        while (searchHits != null && searchHits.length > 0) {
            SearchScrollRequest scrollRequest = new SearchScrollRequest(scrollId)
            scrollRequest.scroll(TimeValue.timeValueMinutes(1L))
            searchResponse = client.scroll(scrollRequest, RequestOptions.DEFAULT)
            scrollId = searchResponse.getScrollId()
            searchHits = searchResponse.getHits().getHits()
        }

    }

    def close() {
        client.close()
    }
}