ElasticSearch(三) DocumentAPIS Index API

ElasticSearch 允许将一个JSON字符串作为文档。

生成JSON文档有下面几种方式：

Manually (aka do it yourself) using native byte[] or as a String(自己构造byte[] 或者json串)
Using a Map that will be automatically converted to its JSON equivalent(使用Map自动转换为JSON)
Using a third party library to serialize your beans such as Jackson(将对象用第三方JSON库转换)
Using built-in helpers XContentFactory.jsonBuilder()(用XContentFactory)

实际上每种类型最终都是转化为byte[]，所以XContentFactory.jsonBuilder() 是最高效的办法。

Do It Yourselfedit

Nothing really difficult here but note that you will have to encode dates according to the Date Format.

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

Using Mapedit

Map is a key:values pair collection. It represents a JSON structure:

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

Serialize your beansedit

You can use Jackson to serialize your beans to JSON. Please add Jackson Databind to your project. Then you can use ObjectMapper to serialize your beans:

import com.fasterxml.jackson.databind.*;

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

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

Use Elasticsearch helpersedit

Elasticsearch provides built-in helpers to generate JSON content.

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

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

Index documentedit

The following example indexes a JSON document into an index called twitter, under a type called tweet, with id valued 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();

Note that you can also index your documents as JSON String and that you don’t have to give an ID:

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

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

IndexResponse object will give you a report:

// Index name
String _index = response.getIndex();
// Type name
String _type = response.getType();
// Document ID (generated or not)
String _id = response.getId();
// Version (if it's the first time you index this document, you will get: 1)
long _version = response.getVersion();
// status has stored current instance statement.
RestStatus status = response.status();