近期需要在项目中将Elasticsearch查询由Python切换到Java才可以在公司的项目中正常使用,而且项目使用的还是Java7的版本,而默认的Elasticsearch需要Java8的支持,只好降级处理了。
这里我们的demo,使用的Elasticsearch版本是 6.3.1
,对应的Java版本为8,我们使用Jest库来简化操作。
首先使用maven下载对应的依赖库:
<?xml version="1.0"?> <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/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.es</groupId> <artifactId>es</artifactId> <version>1.0</version> <dependencies> <dependency> <groupId>io.searchbox</groupId> <artifactId>jest</artifactId> <version>6.3.1</version> </dependency> </dependencies> </project>
在这个过程中,我们需要配置对应maven源为国内的阿里云,不然其下载速度不堪入目。
我们修改maven配置文件 settings.xml
中mirrors中的节点,添加如下代码:
<mirror> <id>nexus-aliyun</id> <mirrorOf>central</mirrorOf> <name>Nexus aliyun</name> <url>http://maven.aliyun.com/nexus/content/groups/public</url> </mirror>
接着我们下载对应的依赖包:
mvn dependency:copy-dependencies -DoutputDirectory=libs
在这里,我们设置其下载目录为当前目录下libs目录,接着maven就会帮我们自动下载对应的包了。
下面我们开始编写我们的程序,1个非常简单的程序:
import java.io.IOException; import java.util.*; import java.util.Objects; import com.google.gson.GsonBuilder; import io.searchbox.client.*; import io.searchbox.core.*; import io.searchbox.client.config.*; public class ESClient { private static final String ES_HOST = "http://127.0.0.1"; private static final int ES_HTTP_PORT = 9200; private static JestClient client; public static synchronized JestClient getClient(){ if(client==null){ build(); } return client; } public static void close(JestClient client){ if(!Objects.isNull(client)){ try{ client.close(); }catch (Exception e){ e.printStackTrace(); } } } private static void build() { JestClientFactory factory = new JestClientFactory(); //实例化客户端工厂类 factory.setHttpClientConfig(new HttpClientConfig.Builder(ES_HOST+":"+ES_HTTP_PORT) .multiThreaded(true) .defaultMaxTotalConnectionPerRoute(2) .maxTotalConnection(2) //设置总连接数为2个 .connTimeout(10000) //设置连接超时时间 .readTimeout(10000) //设置读取超时时间 .gson(new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create()) //设置JSON日期格式 .build()); client = factory.getObject(); } public static void main(String[] args) throws IOException { JestClient client = getClient(); String query = "{/"query/":{/"match_all/":{}}}"; Search.Builder searchBuilder = new Search.Builder(query).addIndex("demo").addType("person"); SearchResult result = client.execute(searchBuilder.build()); System.out.println(result.toString()); } }
在这里,导入对应的包,主要是下面这3行代码:
import io.searchbox.client.*; import io.searchbox.core.*; import io.searchbox.client.config.*;
在方法build中,我们实例化1个 JestClientFactory
类,之后进行对应的配置,最后通过其工厂类的 getObject
得到对应的客户端对象。
而在main入口中,我们通过 getClient
方法得到对应的实例后,之后构建1个JSON字符串,之后调用 Search.Builder
对JSON字符串进行构建,并添加对应的Index和DocType后,我们通过客户端实例的execute方法来执行,最后通过其查询的结果转换为字符串即可。
其结果如下:
dog@debian:~/es$ javac -classpath ".:libs/*" ESClient.java dog@debian:~/es$ java -classpath ".:libs/*" ESClient SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". SLF4J: Defaulting to no-operation (NOP) logger implementation SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details. Result: {"took":7,"timed_out":false,"_shards":{"total":5,"successful":5,"skipped":0,"failed":0},"hits":{"total":5,"max_score":1.0,"hits":[{"_index":"demo","_type":"person","_id":"1g3l82UB8TY7aIKswO1s","_score":1.0,"_source":{"username":"王五","gender":"男","age":"21","region":"杭州","tags":["吃货","技术大牛"]}},{"_index":"demo","_type":"person","_id":"1A3l82UB8TY7aIKsvu2-","_score":1.0,"_source":{"username":"张三","gender":"男","age":"20","region":"中山","tags":["吃货","宅男"]}},{"_index":"demo","_type":"person","_id":"1Q3l82UB8TY7aIKswO0f","_score":1.0,"_source":{"username":"李四","gender":"男","age":"25","region":"金华","tags":["宅男","技术大牛"]}},{"_index":"demo","_type":"person","_id":"2A3l82UB8TY7aIKswe0G","_score":1.0,"_source":{"username":"熊莎莎","gender":"女","age":"25","region":"河源","tags":["吃货","中二"]}},{"_index":"demo","_type":"person","_id":"1w3l82UB8TY7aIKswO2-","_score":1.0,"_source":{"username":"莫晓佳","gender":"女","age":"23","region":"苏州","tags":["麦霸","吃货"]}}]}}, isSucceeded: true, response code: 200, error message: null
这个过程不得不说还是有点问题的,由于项目比较赶,于是趁早起的时候编写了上述代码,走了不少弯路,还是有不足了。只能等上班再进行完善了。