ElasticSearch JAVA API

一、生成JSON

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创建索引的第一步是要把对象转换为JSON字符串.官网给出了四种创建JSON文档的方法：

1.1手写方式生成

String json = "{" +
        "\"user\":\"kimchy\"," +
        "\"postDate\":\"2013-01-30\"," +
        "\"message\":\"trying out Elasticsearch\"" +
    "}";

手写方式很简单，但是要注意日期格式：Date Formate

1.2使用集合

集合是key:value数据类型，可以代表json结构.

Map<String, Object> json = new HashMap<String, Object>();
json.put("user","kimchy");
json.put("postDate","2013-01-30");
json.put("message","trying out Elasticsearch");

1.3使用JACKSON序列化

ElasticSearch已经使用了jackson，可以直接使用它把javabean转为json.

// instance a json mapper
ObjectMapper mapper = new ObjectMapper(); // create once, reuse

// generate json
byte[] json = mapper.writeValueAsBytes(yourbeaninstance);

1.4使用ElasticSearch 帮助类

import static org.elasticsearch.common.xcontent.XContentFactory.*;

XContentBuilder builder = jsonBuilder()
    .startObject()
        .field("user", "kimchy")
        .field("postDate", new Date())
        .field("message", "trying out Elasticsearch")
    .endObject()

 String json = builder.string();

二、创建索引

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下面的例子把json文档写入所以，索引库名为twitter、类型为tweet,id为1：

import static org.elasticsearch.common.xcontent.XContentFactory.*;

IndexResponse response = client.prepareIndex("twitter", "tweet", "1")
        .setSource(jsonBuilder()
                    .startObject()
                        .field("user", "kimchy")
                        .field("postDate", new Date())
                        .field("message", "trying out Elasticsearch")
                    .endObject()
                  )
        .get();

也可以直接传人JSON字符串：

String json = "{" +
        "\"user\":\"kimchy\"," +
        "\"postDate\":\"2013-01-30\"," +
        "\"message\":\"trying out Elasticsearch\"" +
    "}";

IndexResponse response = client.prepareIndex("twitter", "tweet")
        .setSource(json)
        .get();

可以调用response对象的方法获取返回信息：

// 索引名称
String _index = response.getIndex();
// 类型名称
String _type = response.getType();
// 文档id
String _id = response.getId();
// 版本(if it's the first time you index this document, you will get: 1)
long _version = response.getVersion();
// 是否被创建is true if the document is a new one, false if it has been updated
boolean created = response.isCreated();

更简单的可以直接System.out.println(response)查看返回信息.

三、java实现

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新建一个java项目，导入elasticsearch-2.3.3/lib目录下的jar文件.新建一个Blog类：

public class Blog {
    private Integer id;
    private String title;
    private String posttime;
    private String content;

    public Blog() {
    }

    public Blog(Integer id, String title, String posttime, String content) {
        this.id = id;
        this.title = title;
        this.posttime = posttime;
        this.content = content;
    }
  //setter and getter  
｝

创建java实体类转json工具类：

import java.io.IOException;

import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentFactory;

public class JsonUtil {

    // Java实体对象转json对象
    public static String model2Json(Blog blog) {
        String jsonData = null;
        try {
            XContentBuilder jsonBuild = XContentFactory.jsonBuilder();
            jsonBuild.startObject().field("id", blog.getId()).field("title", blog.getTitle())
                    .field("posttime", blog.getPosttime()).field("content",blog.getContent()).endObject();

            jsonData = jsonBuild.string();
            //System.out.println(jsonData);

        } catch (IOException e) {
            e.printStackTrace();
        }

        return jsonData;
    }

}

添加数据，返回一个list：

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class DataFactory {
    public static DataFactory dataFactory = new DataFactory();

    private DataFactory() {
    }

    public DataFactory getInstance() {
        return dataFactory;
    }

    public static List<String> getInitJsonData() {
        List<String> list = new ArrayList<String>();
        String data1 = JsonUtil.model2Json(new Blog(1, "git简介", "2016-06-19", "SVN与Git最主要的区别..."));
        String data2 = JsonUtil.model2Json(new Blog(2, "Java中泛型的介绍与简单使用", "2016-06-19", "学习目标 掌握泛型的产生意义..."));
        String data3 = JsonUtil.model2Json(new Blog(3, "SQL基本操作", "2016-06-19", "基本操作：CRUD ..."));
        String data4 = JsonUtil.model2Json(new Blog(4, "Hibernate框架基础", "2016-06-19", "Hibernate框架基础..."));
        String data5 = JsonUtil.model2Json(new Blog(5, "Shell基本知识", "2016-06-19", "Shell是什么..."));
        list.add(data1);
        list.add(data2);
        list.add(data3);
        list.add(data4);
        list.add(data5);
        return list;
    }

}

创建索引、添加数据：

import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Date;
import java.util.List;

import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.client.Client;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.common.transport.InetSocketTransportAddress;
import org.elasticsearch.common.xcontent.XContentBuilder;

import static org.elasticsearch.common.xcontent.XContentFactory.*;

public class ElasticSearchHandler {
    public static void main(String[] args) {
        try {
            /* 创建客户端 */
            // client startup
            Client client = TransportClient.builder().build()
                    .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("127.0.0.1"), 9300));

            List<String> jsonData = DataFactory.getInitJsonData();

            for (int i = 0; i < jsonData.size(); i++) {
                IndexResponse response = client.prepareIndex("blog", "article").setSource(jsonData.get(i)).get();
                if (response.isCreated()) {
                   System.out.println("创建成功!");
                }
            }
            client.close();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}

查看插入的数据：

2016.12.12 日更新

使用5.X版本的移步到这里：Elasticsearch 5.0下Java API使用指南

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