elasticsearch系列七：ES Java客户端-Elasticsearch Java client（ES Client 简介、Java REST Client、Java Client、S...

一、ES Client 简介

1. ES是一个服务，采用C/S结构

2. 回顾 ES的架构

3. ES支持的客户端连接方式

3.1 REST API ，端口 9200

　　这种连接方式对应于架构图中的RESTful style API这一层，这种客户端的连接方式是RESTful风格的，使用http的方式进行连接

3.2 Transport 连接端口 9300

这种连接方式对应于架构图中的Transport这一层，这种客户端连接方式是直接连接ES的节点，使用TCP的方式进行连接

4. ES提供了多种编程语言客户端

官网可以了解详情：

https://www.elastic.co/guide/en/elasticsearch/client/index.html

二、Java REST Client介绍

1. ES提供了两个JAVA REST client 版本

Java Low Level REST Client: 低级别的REST客户端，通过http与集群交互，用户需自己编组请求JSON串，及解析响应JSON串。兼容所有ES版本。
Java High Level REST Client: 高级别的REST客户端，基于低级别的REST客户端，增加了编组请求JSON串、解析响应JSON串等相关api。使用的版本需要保持和ES服务端的版本一致，否则会有版本问题。

2. Java Low Level REST Client 说明

特点，maven 引入、使用介绍： https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-low.html

API doc ：https://artifacts.elastic.co/javadoc/org/elasticsearch/client/elasticsearch-rest-client/6.2.4/index.html.

3. Java High Level REST Client 说明

从6.0.0开始加入的，目的是以java面向对象的方式来进行请求、响应处理。
每个API 支持同步/异步两种方式，同步方法直接返回一个结果对象。异步的方法以async为后缀，通过listener参数来通知结果。
高级java REST 客户端依赖Elasticsearch core project

兼容性说明：

依赖 java1.8 和 Elasticsearch core project
请使用与服务端ES版本一致的客户端版本

4. Java High Level REST Client maven 集成

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-high-level-client</artifactId>
    <version>6.2.4</version>
</dependency>

5. Java High Level REST Client 初始化

RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(
                new HttpHost("localhost", 9200, "http"),
                new HttpHost("localhost", 9201, "http")));

给定集群的多个节点地址，将客户端负载均衡地向这个节点地址集发请求

Client 不再使用了，记得关闭它：

client.close();

API及用法示例，请参考：

https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-supported-apis.html

三、Java High Level REST Client 使用示例

准备：

编写示例之前首先在maven工程里面引入和ES服务端版本一样的Java客户端

<dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>elasticsearch-rest-high-level-client</artifactId>
        <version>6.2.4</version>
     </dependency>

给定集群的多个节点地址，将客户端负载均衡地向这个节点地址集发请求：

InitDemo.java

package com.study.es_hrset_client;

import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;

/**
 * 
 * @Description: 获取Java High Level REST Client客户端
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class InitDemo {

    public static RestHighLevelClient getClient() {

        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http"),
                        new HttpHost("localhost", 9201, "http")));

        return client;
    }
}

注意使用ES的客户端时类比之前我们在Kibana进行的ES的相关操作，这样使用起来更加有效果

1. Create index 创建索引

CreateIndexDemo.java

package com.study.es_hrset_client;

import java.io.IOException;

import org.elasticsearch.action.admin.indices.alias.Alias;
import org.elasticsearch.action.admin.indices.create.CreateIndexRequest;
import org.elasticsearch.action.admin.indices.create.CreateIndexResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.xcontent.XContentType;

/**
 * 
 * @Description: 创建索引
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class CreateIndexDemo {

    public static void main(String[] args) {
        try (RestHighLevelClient client = InitDemo.getClient();) {

            // 1、创建 创建索引request 参数：索引名mess
            CreateIndexRequest request = new CreateIndexRequest("mess");

            // 2、设置索引的settings
            request.settings(Settings.builder().put("index.number_of_shards", 3) // 分片数
                    .put("index.number_of_replicas", 2) // 副本数
                    .put("analysis.analyzer.default.tokenizer", "ik_smart") // 默认分词器
            );

            // 3、设置索引的mappings
            request.mapping("_doc",
                    "  {\n" +
                    "    \"_doc\": {\n" +
                    "      \"properties\": {\n" +
                    "        \"message\": {\n" +
                    "          \"type\": \"text\"\n" +
                    "        }\n" +
                    "      }\n" +
                    "    }\n" +
                    "  }",
                    XContentType.JSON);

            // 4、 设置索引的别名
            request.alias(new Alias("mmm"));

            // 5、 发送请求
            // 5.1 同步方式发送请求
            CreateIndexResponse createIndexResponse = client.indices()
                    .create(request);

            // 6、处理响应
            boolean acknowledged = createIndexResponse.isAcknowledged();
            boolean shardsAcknowledged = createIndexResponse
                    .isShardsAcknowledged();
            System.out.println("acknowledged = " + acknowledged);
            System.out.println("shardsAcknowledged = " + shardsAcknowledged);

            // 5.1 异步方式发送请求
            /*ActionListener<CreateIndexResponse> listener = new ActionListener<CreateIndexResponse>() {
                @Override
                public void onResponse(
                        CreateIndexResponse createIndexResponse) {
                    // 6、处理响应
                    boolean acknowledged = createIndexResponse.isAcknowledged();
                    boolean shardsAcknowledged = createIndexResponse
                            .isShardsAcknowledged();
                    System.out.println("acknowledged = " + acknowledged);
                    System.out.println(
                            "shardsAcknowledged = " + shardsAcknowledged);
                }

                @Override
                public void onFailure(Exception e) {
                    System.out.println("创建索引异常：" + e.getMessage());
                }
            };

            client.indices().createAsync(request, listener);
            */
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

运行结果：

acknowledged = true
shardsAcknowledged = true

2. index document

索引文档，即往索引里面放入文档数据.类似于数据库里面向表里面插入一行数据，一行数据就是一个文档

IndexDocumentDemo.java

package com.study.es_hrset_client;

import java.io.IOException;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.action.DocWriteResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.support.replication.ReplicationResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.rest.RestStatus;

/**
 * 
 * @Description: 索引文档，即往索引里面放入文档数据.类似于数据库里面向表里面插入一行数据，一行数据就是一个文档
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class IndexDocumentDemo {
    
    private static Logger logger = LogManager.getRootLogger();  

    public static void main(String[] args) {
        try (RestHighLevelClient client = InitDemo.getClient();) {
            // 1、创建索引请求
            IndexRequest request = new IndexRequest(
                    "mess",   //索引
                    "_doc",     // mapping type
                    "1");     //文档id  
            
            // 2、准备文档数据
            // 方式一：直接给JSON串
            String jsonString = "{" +
                    "\"user\":\"kimchy\"," +
                    "\"postDate\":\"2013-01-30\"," +
                    "\"message\":\"trying out Elasticsearch\"" +
                    "}";
            request.source(jsonString, XContentType.JSON); 
            
            // 方式二：以map对象来表示文档
            /*
            Map<String, Object> jsonMap = new HashMap<>();
            jsonMap.put("user", "kimchy");
            jsonMap.put("postDate", new Date());
            jsonMap.put("message", "trying out Elasticsearch");
            request.source(jsonMap); 
            */
            
            // 方式三：用XContentBuilder来构建文档
            /*
            XContentBuilder builder = XContentFactory.jsonBuilder();
            builder.startObject();
            {
                builder.field("user", "kimchy");
                builder.field("postDate", new Date());
                builder.field("message", "trying out Elasticsearch");
            }
            builder.endObject();
            request.source(builder); 
            */
            
            // 方式四：直接用key-value对给出
            /*
            request.source("user", "kimchy",
                            "postDate", new Date(),
                            "message", "trying out Elasticsearch");
            */
            
            //3、其他的一些可选设置
            /*
            request.routing("routing");  //设置routing值
            request.timeout(TimeValue.timeValueSeconds(1));  //设置主分片等待时长
            request.setRefreshPolicy("wait_for");  //设置重刷新策略
            request.version(2);  //设置版本号
            request.opType(DocWriteRequest.OpType.CREATE);  //操作类别  
            */
            
            //4、发送请求
            IndexResponse indexResponse = null;
            try {
                // 同步方式
                indexResponse = client.index(request);            
            } catch(ElasticsearchException e) {
                // 捕获，并处理异常
                //判断是否版本冲突、create但文档已存在冲突
                if (e.status() == RestStatus.CONFLICT) {
                    logger.error("冲突了，请在此写冲突处理逻辑！\n" + e.getDetailedMessage());
                }
                
                logger.error("索引异常", e);
            }
            
            //5、处理响应
            if(indexResponse != null) {
                String index = indexResponse.getIndex();
                String type = indexResponse.getType();
                String id = indexResponse.getId();
                long version = indexResponse.getVersion();
                if (indexResponse.getResult() == DocWriteResponse.Result.CREATED) {
                    System.out.println("新增文档成功，处理逻辑代码写到这里。");
                } else if (indexResponse.getResult() == DocWriteResponse.Result.UPDATED) {
                    System.out.println("修改文档成功，处理逻辑代码写到这里。");
                }
                // 分片处理信息
                ReplicationResponse.ShardInfo shardInfo = indexResponse.getShardInfo();
                if (shardInfo.getTotal() != shardInfo.getSuccessful()) {
                    
                }
                // 如果有分片副本失败，可以获得失败原因信息
                if (shardInfo.getFailed() > 0) {
                    for (ReplicationResponse.ShardInfo.Failure failure : shardInfo.getFailures()) {
                        String reason = failure.reason(); 
                        System.out.println("副本失败原因：" + reason);
                    }
                }
            }
            
            
            //异步方式发送索引请求
            /*ActionListener<IndexResponse> listener = new ActionListener<IndexResponse>() {
                @Override
                public void onResponse(IndexResponse indexResponse) {
                    
                }

                @Override
                public void onFailure(Exception e) {
                    
                }
            };
            client.indexAsync(request, listener);
            */
            
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

运行结果：

新增文档成功，处理逻辑代码写到这里。

3. get document

获取文档数据

GetDocumentDemo.java

package com.study.es_hrset_client;

import java.io.IOException;
import java.util.Map;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.Strings;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.search.fetch.subphase.FetchSourceContext;

/**
 * 
 * @Description: 获取文档数据
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class GetDocumentDemo {
    
    private static Logger logger = LogManager.getRootLogger();  

    public static void main(String[] args) {
        try (RestHighLevelClient client = InitDemo.getClient();) {
            // 1、创建获取文档请求
            GetRequest request = new GetRequest(
                    "mess",   //索引
                    "_doc",     // mapping type
                    "1");     //文档id  
            
            // 2、可选的设置
            //request.routing("routing");
            //request.version(2);
            
            //request.fetchSourceContext(new FetchSourceContext(false)); //是否获取_source字段
            //选择返回的字段
            String[] includes = new String[]{"message", "*Date"};
            String[] excludes = Strings.EMPTY_ARRAY;
            FetchSourceContext fetchSourceContext = new FetchSourceContext(true, includes, excludes);
            request.fetchSourceContext(fetchSourceContext); 
            
            //也可写成这样
            /*String[] includes = Strings.EMPTY_ARRAY;
            String[] excludes = new String[]{"message"};
            FetchSourceContext fetchSourceContext = new FetchSourceContext(true, includes, excludes);
            request.fetchSourceContext(fetchSourceContext);*/
            
            
            // 取stored字段
            /*request.storedFields("message"); 
            GetResponse getResponse = client.get(request);
            String message = getResponse.getField("message").getValue();*/
            
            
            //3、发送请求        
            GetResponse getResponse = null;
            try {
                // 同步请求
                getResponse = client.get(request);
            } catch (ElasticsearchException e) {
                if (e.status() == RestStatus.NOT_FOUND) {
                    logger.error("没有找到该id的文档" );
                }
                if (e.status() == RestStatus.CONFLICT) {
                    logger.error("获取时版本冲突了，请在此写冲突处理逻辑！" );
                }
                logger.error("获取文档异常", e);
            }
            
            //4、处理响应
            if(getResponse != null) {
                String index = getResponse.getIndex();
                String type = getResponse.getType();
                String id = getResponse.getId();
                if (getResponse.isExists()) { // 文档存在
                    long version = getResponse.getVersion();
                    String sourceAsString = getResponse.getSourceAsString(); //结果取成 String       
                    Map<String, Object> sourceAsMap = getResponse.getSourceAsMap();  // 结果取成Map
                    byte[] sourceAsBytes = getResponse.getSourceAsBytes();    //结果取成字节数组
                    
                    logger.info("index:" + index + "  type:" + type + "  id:" + id);
                    logger.info(sourceAsString);
                    
                } else {
                    logger.error("没有找到该id的文档" );
                }
            }
            
            
            //异步方式发送获取文档请求
            /*
            ActionListener<GetResponse> listener = new ActionListener<GetResponse>() {
                @Override
                public void onResponse(GetResponse getResponse) {
                    
                }
            
                @Override
                public void onFailure(Exception e) {
                    
                }
            };
            client.getAsync(request, listener);
            */
            
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

4. Bulk

批量索引文档，即批量往索引里面放入文档数据.类似于数据库里面批量向表里面插入多行数据，一行数据就是一个文档

BulkDemo.java

package com.study.es_hrset_client;

import java.io.IOException;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.DocWriteRequest;
import org.elasticsearch.action.DocWriteResponse;
import org.elasticsearch.action.bulk.BulkItemResponse;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.delete.DeleteResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.update.UpdateResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.xcontent.XContentType;

/**
 * 
 * @Description: 批量索引文档，即批量往索引里面放入文档数据.类似于数据库里面批量向表里面插入多行数据，一行数据就是一个文档
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class BulkDemo {
    
    private static Logger logger = LogManager.getRootLogger();  

    public static void main(String[] args) {
        try (RestHighLevelClient client = InitDemo.getClient();) {
            
            // 1、创建批量操作请求
            BulkRequest request = new BulkRequest(); 
            request.add(new IndexRequest("mess", "_doc", "1")  
                    .source(XContentType.JSON,"field", "foo"));
            request.add(new IndexRequest("mess", "_doc", "2")  
                    .source(XContentType.JSON,"field", "bar"));
            request.add(new IndexRequest("mess", "_doc", "3")  
                    .source(XContentType.JSON,"field", "baz"));
            
            /*
            request.add(new DeleteRequest("mess", "_doc", "3")); 
            request.add(new UpdateRequest("mess", "_doc", "2") 
                    .doc(XContentType.JSON,"other", "test"));
            request.add(new IndexRequest("mess", "_doc", "4")  
                    .source(XContentType.JSON,"field", "baz"));
            */
            
            // 2、可选的设置
            /*
            request.timeout("2m");
            request.setRefreshPolicy("wait_for");  
            request.waitForActiveShards(2);
            */
            
            
            //3、发送请求        
        
            // 同步请求
            BulkResponse bulkResponse = client.bulk(request);
            
            
            //4、处理响应
            if(bulkResponse != null) {
                for (BulkItemResponse bulkItemResponse : bulkResponse) { 
                    DocWriteResponse itemResponse = bulkItemResponse.getResponse(); 

                    if (bulkItemResponse.getOpType() == DocWriteRequest.OpType.INDEX
                            || bulkItemResponse.getOpType() == DocWriteRequest.OpType.CREATE) { 
                        IndexResponse indexResponse = (IndexResponse) itemResponse;
                        //TODO 新增成功的处理

                    } else if (bulkItemResponse.getOpType() == DocWriteRequest.OpType.UPDATE) { 
                        UpdateResponse updateResponse = (UpdateResponse) itemResponse;
                       //TODO 修改成功的处理

                    } else if (bulkItemResponse.getOpType() == DocWriteRequest.OpType.DELETE) { 
                        DeleteResponse deleteResponse = (DeleteResponse) itemResponse;
                        //TODO 删除成功的处理
                    }
                }
            }
            
            
            //异步方式发送批量操作请求
            /*
            ActionListener<BulkResponse> listener = new ActionListener<BulkResponse>() {
                @Override
                public void onResponse(BulkResponse bulkResponse) {
                    
                }
            
                @Override
                public void onFailure(Exception e) {
                    
                }
            };
            client.bulkAsync(request, listener);
            */
            
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

5. search

搜索数据

SearchDemo.java

package com.study.es_hrset_client;

import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.action.search.ShardSearchFailure;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import org.elasticsearch.search.suggest.Suggest;
import org.elasticsearch.search.suggest.term.TermSuggestion;

/**
 * 
 * @Description: 搜索数据
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class SearchDemo {
    
    private static Logger logger = LogManager.getRootLogger();  

    public static void main(String[] args) {
        try (RestHighLevelClient client = InitDemo.getClient();) {
            
            // 1、创建search请求
            //SearchRequest searchRequest = new SearchRequest();
            SearchRequest searchRequest = new SearchRequest("bank"); 
            searchRequest.types("_doc");
            
            // 2、用SearchSourceBuilder来构造查询请求体 ,请仔细查看它的方法，构造各种查询的方法都在这。
            SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); 
            
            //构造QueryBuilder
            /*QueryBuilder matchQueryBuilder = QueryBuilders.matchQuery("user", "kimchy")
                    .fuzziness(Fuzziness.AUTO)
                    .prefixLength(3)
                    .maxExpansions(10);
            sourceBuilder.query(matchQueryBuilder);*/
            
            sourceBuilder.query(QueryBuilders.termQuery("age", 24)); 
            sourceBuilder.from(0); 
            sourceBuilder.size(10); 
            sourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS)); 
            
            //是否返回_source字段
            //sourceBuilder.fetchSource(false);
            
            //设置返回哪些字段
            /*String[] includeFields = new String[] {"title", "user", "innerObject.*"};
            String[] excludeFields = new String[] {"_type"};
            sourceBuilder.fetchSource(includeFields, excludeFields);*/
            
            //指定排序
            //sourceBuilder.sort(new ScoreSortBuilder().order(SortOrder.DESC)); 
            //sourceBuilder.sort(new FieldSortBuilder("_uid").order(SortOrder.ASC));
            
            // 设置返回 profile 
            //sourceBuilder.profile(true);
            
            //将请求体加入到请求中
            searchRequest.source(sourceBuilder);
            
            // 可选的设置
            //searchRequest.routing("routing");
            
            // 高亮设置
            /*
            HighlightBuilder highlightBuilder = new HighlightBuilder(); 
            HighlightBuilder.Field highlightTitle =
                    new HighlightBuilder.Field("title"); 
            highlightTitle.highlighterType("unified");  
            highlightBuilder.field(highlightTitle);  
            HighlightBuilder.Field highlightUser = new HighlightBuilder.Field("user");
            highlightBuilder.field(highlightUser);
            sourceBuilder.highlighter(highlightBuilder);*/
            
            
            //加入聚合
            /*TermsAggregationBuilder aggregation = AggregationBuilders.terms("by_company")
                    .field("company.keyword");
            aggregation.subAggregation(AggregationBuilders.avg("average_age")
                    .field("age"));
            sourceBuilder.aggregation(aggregation);*/
            
            //做查询建议
            /*SuggestionBuilder termSuggestionBuilder =
                    SuggestBuilders.termSuggestion("user").text("kmichy"); 
                SuggestBuilder suggestBuilder = new SuggestBuilder();
                suggestBuilder.addSuggestion("suggest_user", termSuggestionBuilder); 
            sourceBuilder.suggest(suggestBuilder);*/
            
            //3、发送请求        
            SearchResponse searchResponse = client.search(searchRequest);
            
            
            //4、处理响应
            //搜索结果状态信息
            RestStatus status = searchResponse.status();
            TimeValue took = searchResponse.getTook();
            Boolean terminatedEarly = searchResponse.isTerminatedEarly();
            boolean timedOut = searchResponse.isTimedOut();
            
            //分片搜索情况
            int totalShards = searchResponse.getTotalShards();
            int successfulShards = searchResponse.getSuccessfulShards();
            int failedShards = searchResponse.getFailedShards();
            for (ShardSearchFailure failure : searchResponse.getShardFailures()) {
                // failures should be handled here
            }
            
            //处理搜索命中文档结果
            SearchHits hits = searchResponse.getHits();
            
            long totalHits = hits.getTotalHits();
            float maxScore = hits.getMaxScore();
            
            SearchHit[] searchHits = hits.getHits();
            for (SearchHit hit : searchHits) {
                // do something with the SearchHit
                
                String index = hit.getIndex();
                String type = hit.getType();
                String id = hit.getId();
                float score = hit.getScore();
                
                //取_source字段值
                String sourceAsString = hit.getSourceAsString(); //取成json串
                Map<String, Object> sourceAsMap = hit.getSourceAsMap(); // 取成map对象
                //从map中取字段值
                /*
                String documentTitle = (String) sourceAsMap.get("title"); 
                List<Object> users = (List<Object>) sourceAsMap.get("user");
                Map<String, Object> innerObject = (Map<String, Object>) sourceAsMap.get("innerObject");
                */
                logger.info("index:" + index + "  type:" + type + "  id:" + id);
                logger.info(sourceAsString);
                
                //取高亮结果
                /*Map<String, HighlightField> highlightFields = hit.getHighlightFields();
                HighlightField highlight = highlightFields.get("title"); 
                Text[] fragments = highlight.fragments();  
                String fragmentString = fragments[0].string();*/
            }
            
            // 获取聚合结果
            /*
            Aggregations aggregations = searchResponse.getAggregations();
            Terms byCompanyAggregation = aggregations.get("by_company"); 
            Bucket elasticBucket = byCompanyAggregation.getBucketByKey("Elastic"); 
            Avg averageAge = elasticBucket.getAggregations().get("average_age"); 
            double avg = averageAge.getValue();
            */
            
            // 获取建议结果
            /*Suggest suggest = searchResponse.getSuggest(); 
            TermSuggestion termSuggestion = suggest.getSuggestion("suggest_user"); 
            for (TermSuggestion.Entry entry : termSuggestion.getEntries()) { 
                for (TermSuggestion.Entry.Option option : entry) { 
                    String suggestText = option.getText().string();
                }
            }
            */
            
            //异步方式发送获查询请求
            /*
            ActionListener<SearchResponse> listener = new ActionListener<SearchResponse>() {
                @Override
                public void onResponse(SearchResponse getResponse) {
                    //结果获取
                }
            
                @Override
                public void onFailure(Exception e) {
                    //失败处理
                }
            };
            client.searchAsync(searchRequest, listener); 
            */
            
        } catch (IOException e) {
            logger.error(e);
        }
    }
}

6. highlight 高亮

HighlightDemo.java

package com.study.es_hrset_client;

import java.io.IOException;
import java.util.Map;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.text.Text;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;
import org.elasticsearch.search.fetch.subphase.highlight.HighlightField;

/**
 * 
 * @Description: 高亮
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class HighlightDemo {
    
    private static Logger logger = LogManager.getRootLogger();  

    public static void main(String[] args) {
        try (RestHighLevelClient client = InitDemo.getClient();) {
            
            // 1、创建search请求
            SearchRequest searchRequest = new SearchRequest("hl_test"); 
            
            // 2、用SearchSourceBuilder来构造查询请求体 ,请仔细查看它的方法，构造各种查询的方法都在这。
            SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); 
            
            //构造QueryBuilder
            QueryBuilder matchQueryBuilder = QueryBuilders.matchQuery("title", "lucene solr");
            sourceBuilder.query(matchQueryBuilder);
            
            //分页设置
            /*sourceBuilder.from(0); 
            sourceBuilder.size(5); ;*/ 
            
                    
            // 高亮设置
            HighlightBuilder highlightBuilder = new HighlightBuilder(); 
            highlightBuilder.requireFieldMatch(false).field("title").field("content")
                .preTags("<strong>").postTags("</strong>");
            //不同字段可有不同设置，如不同标签
            /*HighlightBuilder.Field highlightTitle = new HighlightBuilder.Field("title"); 
            highlightTitle.preTags("<strong>").postTags("</strong>");
            highlightBuilder.field(highlightTitle);  
            HighlightBuilder.Field highlightContent = new HighlightBuilder.Field("content");
            highlightContent.preTags("<b>").postTags("</b>");
            highlightBuilder.field(highlightContent).requireFieldMatch(false);*/
            
            sourceBuilder.highlighter(highlightBuilder);
            
            searchRequest.source(sourceBuilder);
            
            //3、发送请求        
            SearchResponse searchResponse = client.search(searchRequest);
            
            
            //4、处理响应
            if(RestStatus.OK.equals(searchResponse.status())) {
                //处理搜索命中文档结果
                SearchHits hits = searchResponse.getHits();
                long totalHits = hits.getTotalHits();
                
                SearchHit[] searchHits = hits.getHits();
                for (SearchHit hit : searchHits) {        
                    String index = hit.getIndex();
                    String type = hit.getType();
                    String id = hit.getId();
                    float score = hit.getScore();
                    
                    //取_source字段值
                    //String sourceAsString = hit.getSourceAsString(); //取成json串
                    Map<String, Object> sourceAsMap = hit.getSourceAsMap(); // 取成map对象
                    //从map中取字段值
                    /*String title = (String) sourceAsMap.get("title"); 
                    String content  = (String) sourceAsMap.get("content"); */
                    logger.info("index:" + index + "  type:" + type + "  id:" + id);
                    logger.info("sourceMap : " +  sourceAsMap);
                    //取高亮结果
                    Map<String, HighlightField> highlightFields = hit.getHighlightFields();
                    HighlightField highlight = highlightFields.get("title"); 
                    if(highlight != null) {
                        Text[] fragments = highlight.fragments();  //多值的字段会有多个值
                        if(fragments != null) {
                            String fragmentString = fragments[0].string();
                            logger.info("title highlight : " +  fragmentString);
                            //可用高亮字符串替换上面sourceAsMap中的对应字段返回到上一级调用
                            //sourceAsMap.put("title", fragmentString);
                        }
                    }
                    
                    highlight = highlightFields.get("content"); 
                    if(highlight != null) {
                        Text[] fragments = highlight.fragments();  //多值的字段会有多个值
                        if(fragments != null) {
                            String fragmentString = fragments[0].string();
                            logger.info("content highlight : " +  fragmentString);
                            //可用高亮字符串替换上面sourceAsMap中的对应字段返回到上一级调用
                            //sourceAsMap.put("content", fragmentString);
                        }
                    }
                }
            }
            
        } catch (IOException e) {
            logger.error(e);
        }
    }
}

7. suggest 查询建议

SuggestDemo.java

package com.study.es_hrset_client;

import java.io.IOException;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import org.elasticsearch.search.suggest.Suggest;
import org.elasticsearch.search.suggest.SuggestBuilder;
import org.elasticsearch.search.suggest.SuggestBuilders;
import org.elasticsearch.search.suggest.SuggestionBuilder;
import org.elasticsearch.search.suggest.completion.CompletionSuggestion;
import org.elasticsearch.search.suggest.term.TermSuggestion;

/**
 * 
 * @Description: 查询建议
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class SuggestDemo {
    
    private static Logger logger = LogManager.getRootLogger();  
    
    //词项建议拼写检查，检查用户的拼写是否错误，如果有错给用户推荐正确的词，appel->apple
    public static void termSuggest() {
        try (RestHighLevelClient client = InitDemo.getClient();) {
            
            // 1、创建search请求
            //SearchRequest searchRequest = new SearchRequest();
            SearchRequest searchRequest = new SearchRequest("mess"); 
            
            // 2、用SearchSourceBuilder来构造查询请求体 ,请仔细查看它的方法，构造各种查询的方法都在这。
            SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); 
             
            sourceBuilder.size(0); 
            
            //做查询建议        
            //词项建议
            SuggestionBuilder termSuggestionBuilder =
                    SuggestBuilders.termSuggestion("user").text("kmichy"); 
            SuggestBuilder suggestBuilder = new SuggestBuilder();
            suggestBuilder.addSuggestion("suggest_user", termSuggestionBuilder);     
            sourceBuilder.suggest(suggestBuilder);
            
            searchRequest.source(sourceBuilder);    
            
            //3、发送请求        
            SearchResponse searchResponse = client.search(searchRequest);
            
            
            //4、处理响应
            //搜索结果状态信息
            if(RestStatus.OK.equals(searchResponse.status())) {
                // 获取建议结果
                Suggest suggest = searchResponse.getSuggest(); 
                TermSuggestion termSuggestion = suggest.getSuggestion("suggest_user"); 
                for (TermSuggestion.Entry entry : termSuggestion.getEntries()) { 
                    logger.info("text: " + entry.getText().string());
                    for (TermSuggestion.Entry.Option option : entry) { 
                        String suggestText = option.getText().string();
                        logger.info("   suggest option : " + suggestText);
                    }
                }
            }
            /*
              "suggest": {
                "my-suggestion": [
                  {
                    "text": "tring",
                    "offset": 0,
                    "length": 5,
                    "options": [
                      {
                        "text": "trying",
                        "score": 0.8,
                        "freq": 1
                      }
                    ]
                  },
                  {
                    "text": "out",
                    "offset": 6,
                    "length": 3,
                    "options": []
                  },
                  {
                    "text": "elasticsearch",
                    "offset": 10,
                    "length": 13,
                    "options": []
                  }
                ]
              }*/

        } catch (IOException e) {
            logger.error(e);
        }
    }
    
    //自动补全，根据用户的输入联想到可能的词或者短语
    public static void completionSuggester() {
        try (RestHighLevelClient client = InitDemo.getClient();) {
            
            // 1、创建search请求
            //SearchRequest searchRequest = new SearchRequest();
            SearchRequest searchRequest = new SearchRequest("music"); 
            
            // 2、用SearchSourceBuilder来构造查询请求体 ,请仔细查看它的方法，构造各种查询的方法都在这。
            SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); 
             
            sourceBuilder.size(0); 
            
            //做查询建议        
            //自动补全
            /*POST music/_search?pretty
                    {
                        "suggest": {
                            "song-suggest" : {
                                "prefix" : "lucene s", 
                                "completion" : { 
                                    "field" : "suggest" ,
                                    "skip_duplicates": true
                                }
                            }
                        }
                    }*/

            SuggestionBuilder termSuggestionBuilder =
                    SuggestBuilders.completionSuggestion("suggest").prefix("lucene s")
                    .skipDuplicates(true); 
            SuggestBuilder suggestBuilder = new SuggestBuilder();
            suggestBuilder.addSuggestion("song-suggest", termSuggestionBuilder);     
            sourceBuilder.suggest(suggestBuilder);
            
            searchRequest.source(sourceBuilder);    
            
            //3、发送请求        
            SearchResponse searchResponse = client.search(searchRequest);
            
            
            //4、处理响应
            //搜索结果状态信息
            if(RestStatus.OK.equals(searchResponse.status())) {
                // 获取建议结果
                Suggest suggest = searchResponse.getSuggest(); 
                CompletionSuggestion termSuggestion = suggest.getSuggestion("song-suggest"); 
                for (CompletionSuggestion.Entry entry : termSuggestion.getEntries()) { 
                    logger.info("text: " + entry.getText().string());
                    for (CompletionSuggestion.Entry.Option option : entry) { 
                        String suggestText = option.getText().string();
                        logger.info("   suggest option : " + suggestText);
                    }
                }
            }

        } catch (IOException e) {
            logger.error(e);
        }
    }

    public static void main(String[] args) {
        termSuggest();
        
        logger.info("--------------------------------------");
        
        completionSuggester();
    }
}

8. aggregation 聚合分析

AggregationDemo.java

package com.study.es_hrset_client;

import java.io.IOException;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.search.aggregations.AggregationBuilders;
import org.elasticsearch.search.aggregations.Aggregations;
import org.elasticsearch.search.aggregations.BucketOrder;
import org.elasticsearch.search.aggregations.bucket.terms.Terms;
import org.elasticsearch.search.aggregations.bucket.terms.Terms.Bucket;
import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregationBuilder;
import org.elasticsearch.search.aggregations.metrics.avg.Avg;
import org.elasticsearch.search.builder.SearchSourceBuilder;

/**
 * 
 * @Description: 聚合分析
 * @author lgs
 * @date 2018年6月23日
 *
 */
public class AggregationDemo {
    
    private static Logger logger = LogManager.getRootLogger();  

    public static void main(String[] args) {
        try (RestHighLevelClient client = InitDemo.getClient();) {
            
            // 1、创建search请求
            //SearchRequest searchRequest = new SearchRequest();
            SearchRequest searchRequest = new SearchRequest("bank"); 
            
            // 2、用SearchSourceBuilder来构造查询请求体 ,请仔细查看它的方法，构造各种查询的方法都在这。
            SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); 
             
            sourceBuilder.size(0); 

            //加入聚合
            //字段值项分组聚合
            TermsAggregationBuilder aggregation = AggregationBuilders.terms("by_age")
                    .field("age").order(BucketOrder.aggregation("average_balance", true));
            //计算每组的平均balance指标
            aggregation.subAggregation(AggregationBuilders.avg("average_balance")
                    .field("balance"));
            sourceBuilder.aggregation(aggregation);
            
            searchRequest.source(sourceBuilder);
            
            //3、发送请求        
            SearchResponse searchResponse = client.search(searchRequest);
                
            //4、处理响应
            //搜索结果状态信息
            if(RestStatus.OK.equals(searchResponse.status())) {
                // 获取聚合结果
                Aggregations aggregations = searchResponse.getAggregations();
                Terms byAgeAggregation = aggregations.get("by_age"); 
                logger.info("aggregation by_age 结果");
                logger.info("docCountError: " + byAgeAggregation.getDocCountError());
                logger.info("sumOfOtherDocCounts: " + byAgeAggregation.getSumOfOtherDocCounts());
                logger.info("------------------------------------");
                for(Bucket buck : byAgeAggregation.getBuckets()) {
                    logger.info("key: " + buck.getKeyAsNumber());
                    logger.info("docCount: " + buck.getDocCount());
                    logger.info("docCountError: " + buck.getDocCountError());
                    //取子聚合
                    Avg averageBalance = buck.getAggregations().get("average_balance"); 

                    logger.info("average_balance: " + averageBalance.getValue());
                    logger.info("------------------------------------");
                }
                //直接用key 来去分组
                /*Bucket elasticBucket = byCompanyAggregation.getBucketByKey("24"); 
                Avg averageAge = elasticBucket.getAggregations().get("average_age"); 
                double avg = averageAge.getValue();*/
                
            }
            
        } catch (IOException e) {
            logger.error(e);
        }
    }
}

9. 官网资料

各种查询对应的QueryBuilder：

https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-query-builders.html

各种聚合对应的AggregationBuilder：

https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-aggregation-builders.html

四、Java Client

1. Java Client 说明

java client 使用 TransportClient，各种操作本质上都是异步的(可以用 listener，或返回 Future ）。
注意：ES的发展规划中在7.0版本开始将废弃 TransportClient，8.0版本中将完全移除 TransportClient，取而代之的是High Level REST Client。
High Level REST Client 中的操作API和java client 大多是一样的。

2. 官方学习链接

https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/index.html

3. 兼容性说明

请使用与服务端ES版本一致的客户端版本

4. Java Client maven 集成

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>transport</artifactId>
    <version>6.2.4</version>
</dependency>

5. Java Client logger 日志器说明

使用的是 log4j2 日志组件。
如果要使用其他的日志组件，可使用slf4j作桥

6. Init Client

Init Client setting 可用参数说明：

cluster.name
指定集群的名字，如果集群的名字不是默认的elasticsearch，需指定。
client.transport.sniff
设置为true,将自动嗅探整个集群，自动加入集群的节点到连接列表中。
client.transport.ignore_cluster_name
Set to true to ignore cluster name validation of connected nodes. (since 0.19.4)
client.transport.ping_timeout
The time to wait for a ping response from a node. Defaults to 5s.
client.transport.nodes_sampler_interval
How often to sample / ping the nodes listed and connected. Defaults to 5s.

五、Java Client使用示例

注意：TransPort客户端的使用和RESTful风格的使用基本一致，除了获取客户端不一样，还有发送请求有的不一样外

准备：