Elasticsearch 7.3 Java Practice: Index & Document CRUD Fu...

Summary

This article details the complete flow for index and document CRUD operations using Elasticsearch 7.3.0 and RestHighLevelClient.

1. Version Matrix

Component	Version	Note
Elasticsearch Server	7.3.0	Code examples based on this version
Rest High Level Client	7.3.0	Match with server version
Java	17	maven.compiler.source/target=17

2. Maven Dependencies Config

<dependencies>
    <dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>elasticsearch-rest-high-level-client</artifactId>
        <version>7.3.0</version>
    </dependency>
    <dependency>
        <groupId>org.elasticsearch</groupId>
        <artifactId>elasticsearch</artifactId>
        <version>7.3.0</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
</dependencies>

3. Create RestHighLevelClient

RestClientBuilder builder = RestClient.builder(
    new HttpHost("h121.wzk.icu", 9200, "http"),
    new HttpHost("h122.wzk.icu", 9200, "http"),
    new HttpHost("h123.wzk.icu", 9200, "http")
);
RestHighLevelClient client = new RestHighLevelClient(builder);

4. Index Operations

4.1 Create Index (JSON Way)

CreateIndexRequest indexRequest = new CreateIndexRequest("wzk-icu-es-test");
String mapping = "{\"settings\":{},\"mappings\":{\"properties\":{\"description\":{\"type\":\"text\",\"analyzer\":\"ik_max_word\"},\"name\":{\"type\":\"text\"}}}}";
indexRequest.source(mapping, XContentType.JSON);
CreateIndexResponse indexResponse = client.indices().create(indexRequest, RequestOptions.DEFAULT);

4.2 Create Index (Object Way)

CreateIndexRequest createIndexRequest = new CreateIndexRequest("wzk-icu-es-2");
createIndexRequest.settings(Settings.builder()
    .put("index.number_of_shards", 5)
    .put("index.number_of_replicas", 1)
    .build());
XContentBuilder xContentBuilder = XContentFactory.jsonBuilder();
xContentBuilder.startObject();
xContentBuilder.startObject("properties");
xContentBuilder.startObject("description").field("type", "text").field("analyzer", "ik_max_word").endObject();
xContentBuilder.endObject();
xContentBuilder.endObject();
createIndexRequest.mapping(xContentBuilder);

4.3 Delete Index

DeleteIndexRequest deleteRequest = new DeleteIndexRequest("wzk-icu-es-test");
AcknowledgedResponse deleteResponse = client.indices().delete(deleteRequest, RequestOptions.DEFAULT);

5. Document Operations

5.1 Add Document

IndexRequest indexRequest = new IndexRequest("wzk-icu-es-2").id("1");
String str = "{\"name\":\"spark添加文档\",\"description\":\"spark技术栈\",\"studymodel\":\"online\"}";
indexRequest.source(str, XContentType.JSON);
IndexResponse index = client.index(indexRequest, RequestOptions.DEFAULT);

5.2 Query Document

GetRequest getRequest = new GetRequest("wzk-icu-es-2");
getRequest.id("1");
GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT);
Map<String, Object> sourceMap = getResponse.getSourceAsMap();

5.3 Query All Documents

SearchRequest searchRequest = new SearchRequest();
searchRequest.indices("wzk-icu-es-2");
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.matchAllQuery());
searchRequest.source(sourceBuilder);
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
SearchHits hits = searchResponse.getHits();
for (SearchHit sh : hits.getHits()) {
    Map<String, Object> map = sh.getSourceAsMap();
}

6. Error Quick Reference

Symptom	Root Cause	Fix
Connection refused	ES node address config wrong	Check HttpHost address and port
Index already exists	Creating same name index repeatedly	First execute indices().exists check
Mapping parsing exception	JSON structure syntax error	Use online JSON validation tool
Search result empty	Tokenizer config improper	Check analyzer config

7. Summary

This article provides complete CRUD tutorial for Elasticsearch 7.3 Java API, including:

• Maven dependencies config
• RestHighLevelClient initialization
• Index creation and deletion
• Document CRUD
• Common error troubleshooting guide

Suitable for developers who need to maintain ES7 systems for reference and learning.