Elasticsearch生成json，创建索引（把数据写入索引中）

ElasticSearch JAVA API官网文档：https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/java-docs-index.html

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\"" +    "}";
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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");
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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 mapperObjectMapper mapper = new ObjectMapper(); // create once, reuse// generate jsonbyte[] json = mapper.writeValueAsBytes(yourbeaninstance);
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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();
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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();
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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();
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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idString _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 updatedboolean created = response.isCreated();
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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  ｝
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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;    }}
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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;    }}
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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();        }    }}
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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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视频教程

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课程地址：http://edu.csdn.net/course/detail/5578