Elasticsearch Java API简介
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Elasticsearch Java API简介
1、创建项目
创建Maven项目添加依赖，依赖版本与ES服务版本一致：
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.dameng.log</groupId> <artifactId>restLog</artifactId> <packaging>war</packaging> <version>1.0-SNAPSHOT</version> <name>restLog Maven Webapp</name> <url>http://maven.apache.org</url> <repositories> <repository> <id>elasticsearch-releases</id> <url>https://artifacts.elastic.co/maven</url> <releases> <enabled>true</enabled> </releases> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>org.elasticsearch.client</groupId> <artifactId>x-pack-transport</artifactId> <version>5.4.1</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> <version>2.8.2</version> </dependency> </dependencies> <build> <finalName>restLog</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> </build></project> 值得注意的是，如果ES安装了x-pack插件，在链接ES服务时需要使用 PreBuiltXPackTransportClient ，该类在x-pack-transport包中，这个包在Maven的公共库里是没有的，需要添加ES的库。
2、ES基本配置与连接
2.1、基本配置
ES有两种连接方式： Connecting a Client to a Coordinating Only Node 和 Transport Client ，本文使用的是后者，基本配置内容如下：
# Elasticsearch configuration# ES的集群名称cluster.name = elasticsearch# 是否发现集群中的其他节点client.transport.sniff = true# 如果安装的x-pack插件，此处填写ES的用户名和密码xpack.security.user = elastic:changeme# 链接ES节点地址transportAddress = localhost:9300# 默认时区，用于查询时的日期比较default.timeZone = Asia/Shanghai# 默认返回页大小default.size = 100# 默认返回起始位置default.from = 02.2、建立连接
建立client的代码如下：
package com.dameng.es;import org.elasticsearch.client.transport.TransportClient;import org.elasticsearch.common.settings.Settings;import org.elasticsearch.common.transport.InetSocketTransportAddress;import org.elasticsearch.transport.client.PreBuiltTransportClient;import org.elasticsearch.xpack.client.PreBuiltXPackTransportClient;import java.io.IOException;import java.io.InputStream;import java.net.InetAddress;import java.util.*;/** * Created by lion on 2017/7/24. */public class ESUtil { private static volatile TransportClient client = null; private static String timeZone = ""; public static String getDefaultTimeZone() { return timeZone; } public static String getDefaultSize() { try { return ESUtil.getProperties().getProperty("default.size", "100"); } catch (IOException e) { e.printStackTrace(); } return "100"; } public static String getDefaultFrom() { try { return ESUtil.getProperties().getProperty("default.from", "0"); } catch (IOException e) { e.printStackTrace(); } return "0"; } private ESUtil () { } /** * 读取配置文件 * @return * @throws IOException */ private static Properties getProperties() throws IOException { try (InputStream inputStream = ESUtil.class.getClassLoader().getResourceAsStream("ES.properties")) { Properties properties = new Properties(); properties.load(inputStream); return properties; } } /** * 获取ES客户端，单例实现 * @return */ public static TransportClient getClient() throws Exception { if (ESUtil.client == null) { Properties properties = ESUtil.getProperties(); Settings.Builder builder = Settings.builder(); builder.put("cluster.name", properties.getProperty("properties")); builder.put("client.transport.sniff", properties.getProperty("client.transport.sniff")); builder.put("xpack.security.user", properties.getProperty("xpack.security.user")); Settings settings = builder.build(); if (settings.isEmpty()) { throw new Exception("ES设置项未设置."); } if (settings.get("xpack.security.user") == null || settings.get("xpack.security.user").equals("")) { ESUtil.client = new PreBuiltTransportClient(settings); } else { ESUtil.client = new PreBuiltXPackTransportClient(settings); } String transportAddress = properties.getProperty("transportAddress"); if (transportAddress == null || transportAddress.equals("")) { throw new Exception("ES集群地址未设置."); } String[] address = transportAddress.split(","); for (int i = 0; i < address.length; i++) { String hoseName = address[i].split(":")[0]; int port = Integer.parseInt(address[i].split(":")[1]); ESUtil.client.addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName(hoseName), port)); } ESUtil.timeZone = properties.getProperty("default.timeZone", "Asia/Shanghai"); } return ESUtil.client; }}3、API代码事例
3.1、查询
3.1.1、查询全部内容
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.1.2、设置索引
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setIndices("file*").get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.1.3、设置类型
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setIndices("file*").setTypes("BIZZ").get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.1.4、设置翻页
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setFrom(0).setSize(100).get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.1.5、字段过滤
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setQuery(QueryBuilders.termQuery("level", "BIZZ")).get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.1.6、通配符查询
通配符支持 * 和 ? 两个， * 表示任意多个字符， ? 表示单个字符：
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setQuery(QueryBuilders.wildcardQuery("level", "I*")).get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.1.7、多条件查询
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); ExistsQueryBuilder existsQueryBuilder = QueryBuilders.existsQuery("offset"); TermQueryBuilder termQueryBuilder = QueryBuilders.termQuery("level", "BIZZ"); BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery().must(existsQueryBuilder).must(termQueryBuilder); SearchResponse searchResponse = client.prepareSearch().setQuery(boolQueryBuilder).get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.1.8、范围查询
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); ExistsQueryBuilder existsQueryBuilder = QueryBuilders.existsQuery("offset"); RangeQueryBuilder rangeQueryBuilder = QueryBuilders.rangeQuery("offset").gte(0).lt(134166220); BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery().must(existsQueryBuilder).must(rangeQueryBuilder); SearchResponse searchResponse = client.prepareSearch().setQuery(boolQueryBuilder).get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.1.9、时间查询
对于时间范围查询，需要注意时区的问题。ES默认使用的UTC时区，在日起比较时需要设置为当前时区。还有一点需要注意：ES默认的时间格式是ISO8601。
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setQuery(QueryBuilders.rangeQuery("@timestamp").timeZone(ESUtil.getDefaultTimeZone()).gt("2017-07-25T16:30")).get(); SearchHits hits = searchResponse.getHits(); System.out.println(hits.totalHits); if (hits.getTotalHits() > 0) { for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } } } catch (Exception e) { e.printStackTrace(); }}3.2、统计
3.2.1、简单分组统计
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setQuery(QueryBuilders.existsQuery("level")).addAggregation(AggregationBuilders.terms("by_level").field("level")).get(); StringTerms by_level = searchResponse.getAggregations().get("by_level"); List<Terms.Bucket> buckets = by_level.getBuckets(); for (Terms.Bucket bucket : buckets) { System.out.println(bucket.getKey() + ":" + bucket.getDocCount()); } } catch (Exception e) { e.printStackTrace(); }}3.2.2、时间频度统计
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setQuery(QueryBuilders.existsQuery("level")).addAggregation(AggregationBuilders.dateHistogram("by_day").field("@timestamp").dateHistogramInterval(DateHistogramInterval.DAY)).get(); InternalDateHistogram by_day = searchResponse.getAggregations().get("by_day"); List<InternalDateHistogram.Bucket> buckets = by_day.getBuckets(); for (InternalDateHistogram.Bucket bucket : buckets) { DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"); df.setTimeZone(TimeZone.getTimeZone("Asia/shanghai")); System.out.println(new SimpleDateFormat("yyyy-MM-dd").format(df.parse(bucket.getKeyAsString())) + ":" + bucket.getDocCount()); } } catch (Exception e) { e.printStackTrace(); }}3.2.3、多维度分组统计
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setQuery(QueryBuilders.existsQuery("level")).addAggregation( AggregationBuilders.dateHistogram("by_day").field("@timestamp").dateHistogramInterval(DateHistogramInterval.DAY).subAggregation( AggregationBuilders.terms("by_level").field("level") ) ).get(); InternalDateHistogram by_day = searchResponse.getAggregations().get("by_day"); List<InternalDateHistogram.Bucket> buckets = by_day.getBuckets(); for (InternalDateHistogram.Bucket bucket : buckets) { DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"); df.setTimeZone(TimeZone.getTimeZone("Asia/shanghai")); System.out.println(new SimpleDateFormat("yyyy-MM-dd").format(df.parse(bucket.getKeyAsString())) + ":" + bucket.getDocCount()); InternalTerms by_level = bucket.getAggregations().get("by_level"); List<Terms.Bucket> buckets_level = by_level.getBuckets(); for (Terms.Bucket bucket_level : buckets_level) { System.out.println("\t" + bucket_level.getKey() + ":" + bucket_level.getDocCount()); } } } catch (Exception e) { e.printStackTrace(); }}3.2.4、聚合函数
public static void main(String[] args) { try { TransportClient client = ESUtil.getClient(); SearchResponse searchResponse = client.prepareSearch().setQuery(QueryBuilders.existsQuery("offset")).addAggregation( AggregationBuilders.dateHistogram("by_day").field("@timestamp").dateHistogramInterval(DateHistogramInterval.DAY).subAggregation( AggregationBuilders.max("max_offset").field("offset") ) ).get(); InternalDateHistogram by_day = searchResponse.getAggregations().get("by_day"); List<InternalDateHistogram.Bucket> buckets = by_day.getBuckets(); for (InternalDateHistogram.Bucket bucket : buckets) { DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"); df.setTimeZone(TimeZone.getTimeZone("Asia/shanghai")); System.out.println(new SimpleDateFormat("yyyy-MM-dd").format(df.parse(bucket.getKeyAsString())) + ":" + bucket.getDocCount()); InternalMax max_offset = bucket.getAggregations().get("max_offset"); System.out.println("\t" + max_offset.getName() + ":" + max_offset.getValue()); } } catch (Exception e) { e.printStackTrace(); }}4、注意事项
- x-pack插件需要用到x-pack-transport依赖，x-pack并非开源（收费）软件，该依赖在Maven公共库中没有；
- 日起过滤时注意时区设置；
5、参考资料：
- 官方文档：https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/index.html
- ES 2.3.3 JAVA api说明文档：https://www.blog-china.cn/template/documentHtml/1484101683485.html#title_9
- ES java api 基本搜索部分详解：http://blog.csdn.net/molong1208/article/details/50512149
6、补充：将任意Aggregations转换为JSON的例子
以下代码算是一个思路，将多层嵌套的统计结果转换成json格式的字符串，调用方法类似这样："{\"result\": [" + this.analysisAggregations(searchResponse.getAggregations()) + "]}";
private String analysisAggregations (Aggregations aggregations) { StringBuffer sb = new StringBuffer(); for (Aggregation aggregation : aggregations.asList()) { if (aggregation instanceof StringTerms) { for (Terms.Bucket bucket : ((StringTerms) aggregation).getBuckets()) { String result = analysisAggregations(bucket.getAggregations()); if (result == null || result.equals("")) { result = String.valueOf(bucket.getDocCount()); } if (result.indexOf(",") != -1) { sb.append(",{\"").append(bucket.getKeyAsString()).append("\":[").append(result).append("]}"); } else { sb.append(",{\"").append(bucket.getKeyAsString()).append("\":").append(result).append("}"); } } } if (aggregation instanceof InternalDateHistogram) { for (InternalDateHistogram.Bucket bucket : ((InternalDateHistogram) aggregation).getBuckets()) { String result = analysisAggregations(bucket.getAggregations()); if (result == null || result.equals("")) { result = String.valueOf(bucket.getDocCount()); } if (result.indexOf(",") != -1) { sb.append(",{\"").append(bucket.getKeyAsString()).append("\":[").append(result).append("]}"); } else { sb.append(",{\"").append(bucket.getKeyAsString()).append("\":").append(result).append("}"); } } } if (aggregation instanceof InternalNumericMetricsAggregation.SingleValue) { sb.append(",{\"").append(aggregation.getName()).append("\":\"").append(((InternalNumericMetricsAggregation.SingleValue) aggregation).getValueAsString()).append("\"}"); } } if (sb.length() == 0) { return ""; } return sb.substring(1);}阅读全文
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