ElasticSearch JAVA API

一、生成JSON

建立索引的第一步是要把物件轉換為JSON字串.官網給出了四種建立JSON文件的方法：

1.1手寫方式生成

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

手寫方式很簡單，但是要注意日期格式：Date Formate

1.2使用集合

集合是key:value資料型別，可以代表json結構.

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已經使用了jackson，可以直接使用它把javabean轉為json.

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

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

1.4使用ElasticSearch 幫助類

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、建立索引

下面的例子把json文件寫入所以，索引庫名為twitter、型別為tweet,id為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();

也可以直接傳人JSON字串：

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

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

可以呼叫response物件的方法獲取返回資訊：

// 索引名稱
String _index = response.getIndex();
// 型別名稱
String _type = response.getType();
// 文件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();
// 是否被建立is true if the document is a new one, false if it has been updated
boolean created = response.isCreated();

更簡單的可以直接System.out.println(response)檢視返回資訊.

三、java實現

新建一個java專案，匯入elasticsearch-2.3.3/lib目錄下的jar檔案.新建一個Blog類：

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  
｝

建立java實體類轉json工具類：

import java.io.IOException;

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

public class JsonUtil {

    // Java實體物件轉json物件
    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;
    }

}

新增資料，返回一個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簡介", "2016-06-19", "SVN與Git最主要的區別..."));
        String data2 = JsonUtil.model2Json(new Blog(2, "Java中泛型的介紹與簡單使用", "2016-06-19", "學習目標 掌握泛型的產生意義..."));
        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框架基礎", "2016-06-19", "Hibernate框架基礎..."));
        String data5 = JsonUtil.model2Json(new Blog(5, "Shell基本知識", "2016-06-19", "Shell是什麼..."));
        list.add(data1);
        list.add(data2);
        list.add(data3);
        list.add(data4);
        list.add(data5);
        return list;
    }

}

建立索引、新增資料：

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 {
            /* 建立客戶端 */
            // 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("建立成功!");
                }
            }
            client.close();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}

檢視插入的資料： 

2016.12.12 日更新