请帮我写一个 java 连接 ELASTICSEARCH的示例，包含增删改查

好的，以下是一个简单的 Java 连接 Elasticsearch 并进行增删改查的示例代码：

import org.elasticsearch.action.delete.DeleteRequest;
import org.elasticsearch.action.delete.DeleteResponse;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.update.UpdateRequest;
import org.elasticsearch.action.update.UpdateResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
import org.elasticsearch.search.sort.SortOrder;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class ElasticsearchDemo {
    private RestHighLevelClient client;

    public ElasticsearchDemo() {
        // TODO 连接 Elasticsearch 的代码
    }

    // 新增文档
    public void addDocument(String index, String type, String id, Map<String, Object> source) throws IOException {
        IndexRequest request = new IndexRequest(index, type, id)
                .source(source);
        IndexResponse response = client.index(request);
        System.out.println(response);
    }

    // 新增文档（使用 XContentBuilder）
    public void addDocument(String index, String type, String id, XContentBuilder builder) throws IOException {
        IndexRequest request = new IndexRequest(index, type, id)
                .source(builder);
        IndexResponse response = client.index(request);
        System.out.println(response);
    }

    // 修改文档
    public void updateDocument(String index, String type, String id, Map<String, Object> source) throws IOException {
        UpdateRequest request = new UpdateRequest(index, type, id)
                .doc(source);
        UpdateResponse response = client.update(request);
        System.out.println(response);
    }

    // 修改文档（使用 XContentBuilder）
    public void updateDocument(String index, String type, String id, XContentBuilder builder) throws IOException {
        UpdateRequest request = new UpdateRequest(index, type, id)
                .doc(builder);
        UpdateResponse response = client.update(request);
        System.out.println(response);
    }

    // 删除文档
    public void deleteDocument(String index, String type, String id) throws IOException {
        DeleteRequest request = new DeleteRequest(index, type, id);
        DeleteResponse response = client.delete(request);
        System.out.println(response);
    }

    // 查询文档
    public void getDocument(String index, String type, String id) throws IOException {
        GetRequest request = new GetRequest(index, type, id);
        GetResponse response = client.get(request);
        System.out.println(response);
    }

    // 复合查询
    public void searchDocuments(String index) throws IOException {
        SearchSourceBuilder builder = new SearchSourceBuilder();
        builder.query(QueryBuilders.matchQuery("name", "john"))
                .from(0)
                .size(5)
                .sort("age", SortOrder.DESC)
                .fetchSource(new String[] {"name", "age"}, null);
        SearchResponse response = client.search(new SearchRequest(index)
                .source(builder));
        System.out.println(response);
    }

    public static void main(String[] args) throws IOException {
        ElasticsearchDemo demo = new ElasticsearchDemo();
        Map<String, Object> source = new HashMap<>();
        source.put("name", "john");
        source.put("age", 20);
        demo.addDocument("test", "user", "1", source);
        demo.getDocument("test", "user", "1");
        demo.updateDocument("test", "user", "1", XContentFactory.jsonBuilder()
                .startObject()
                .field("name", "tom")
                .endObject());
        demo.deleteDocument("test", "user", "1");
        demo.searchDocuments("test");
    }
}

请注意，这只是一个简单的示例，实际使用时需要根据具体场景进行修改和完善。