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以下是一个简单的Maven工程和Spring demo案例，演示如何使用Java调用Elasticsearch。
配置Maven依赖
在pom.xml文件中添加以下依赖：
org.elasticsearch elasticsearch 6.5.4 org.elasticsearch.client transport
6.5.4 org.elasticsearch.client rest 6.5.4
创建Elasticsearch连接
创建一个Elasticsearch连接配置类，用于连接Elasticsearch集群。示例代码如下：
@Configuration
public class ElasticsearchConfig {
private static final String HOST = "localhost"; private static final int PORT
= 9300; @Bean public RestHighLevelClient restHighLevelClient() {
RestClientBuilder builder = RestClient.builder(new HttpHost(HOST, PORT));
RestHighLevelClient client = new RestHighLevelClient(builder); return client; }
}
创建Elasticsearch操作类
创建一个Elasticsearch操作类，用于执行Elasticsearch的操作。示例代码如下：
@Component public class ElasticsearchService { private RestHighLevelClient
client; @Autowired public ElasticsearchService(RestHighLevelClient client) {
this.client = client; } public void createIndex(String indexName) throws
IOException { CreateIndexRequest request = new CreateIndexRequest(indexName);
client.indices().create(request, RequestOptions.DEFAULT); } public void
deleteIndex(String indexName) throws IOException { DeleteIndexRequest request =
new DeleteIndexRequest(indexName); client.indices().delete(request,
RequestOptions.DEFAULT); } public void insert(String indexName, String id,
String jsonString) throws IOException { IndexRequest request = new
IndexRequest(indexName); request.id(id); request.source(jsonString,
XContentType.JSON); IndexResponse response = client.index(request,
RequestOptions.DEFAULT); } public void update(String indexName, String id,
String jsonString) throws IOException { UpdateRequest request = new
UpdateRequest(indexName, id); request.doc(jsonString, XContentType.JSON);
UpdateResponse response = client.update(request, RequestOptions.DEFAULT); }
public void delete(String indexName, String id) throws IOException {
DeleteRequest request = new DeleteRequest(indexName, id); DeleteResponse
response = client.delete(request, RequestOptions.DEFAULT); } public SearchHits
search(String indexName, QueryBuilder queryBuilder) throws IOException {
SearchRequest searchRequest = new SearchRequest(indexName); SearchSourceBuilder
searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(queryBuilder);
searchRequest.source(searchSourceBuilder); SearchResponse response =
client.search(searchRequest, RequestOptions.DEFAULT); SearchHits hits =
response.getHits(); return hits; } } 4. 创建Spring Boot控制器 创建一个Spring
Boot控制器，在其中调用Elasticsearch操作类执行Elasticsearch操作。示例代码如下： @RestController public
class ElasticsearchController { @Autowired private ElasticsearchService
elasticsearchService; @GetMapping("/createIndex") public String createIndex()
throws IOException { elasticsearchService.createIndex("my_index"); return
"Index created successfully"; } @GetMapping("/deleteIndex") public String
deleteIndex() throws IOException {
elasticsearchService.deleteIndex("my_index"); return "Index deleted
successfully"; } @PostMapping("/insert") public String insert() throws
IOException { String jsonString = "{\"title\":\"Java
Programming\",\"author\":\"John Doe\"}";
elasticsearchService.insert("my_index", "1", jsonString); return "Document
inserted successfully"; } @PostMapping("/update") public String update() throws
IOException { String jsonString = "{\"title\":\"Java
Programming\",\"author\":\"Jane Doe\"}";
elasticsearchService.update("my_index", "1", jsonString); return "Document
updated successfully"; } @GetMapping("/delete") public String delete() throws
IOException { elasticsearchService.delete("my_index", "1"); return "Document
deleted successfully"; } @GetMapping("/search") public SearchHits search()
throws IOException { QueryBuilder queryBuilder =
QueryBuilders.matchQuery("title", "Java"); SearchHits hits =
elasticsearchService.search("my_index", queryBuilder); return hits; } }
以上代码演示了如何创建Elasticsearch连接、执行Elasticsearch
操作，以及在Spring Boot控制器中调用Elasticsearch操作类执行操作。
测试
运行Spring Boot应用程序，并访问以下URL以执行相应的操作：
/createIndex：创建名为“my_index”的索引。
/deleteIndex：删除名为“my_index”的索引。
/insert：向名为“my_index”的索引插入一条文档。
/update：更新名为“my_index”的索引中的文档。
/delete：从名为“my_index”的索引中删除文档。
/search：从名为“my_index”的索引中搜索匹配“Java”的文档。
可以使用Postman或类似的工具进行测试。
以上就是一个基本的Maven工程和Spring
demo案例，演示了如何使用Java调用Elasticsearch。这只是一个简单的示例，实际应用中可能需要更复杂和细致的实现。