使用JAVA语言，写一个elastic案例

好的，我可以为您提供一个简单的Java程序，用于在Elasticsearch中创建索引并执行一些基本操作：

首先，您需要确保已经安装了Elasticsearch并启动了它。然后，您需要添加以下依赖项到您的Maven项目中：

<dependency>
    <groupId>org.elasticsearch</groupId>
    <artifactId>elasticsearch</artifactId>
    <version>7.10.1</version>
</dependency>

接下来，您可以使用以下代码来创建一个索引并添加一些文档：

import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;
import org.elasticsearch.search.sort.SortOrder;
import org.elasticsearch.search.suggest.SuggestBuilder;
import org.elasticsearch.search.suggest.completion.CompletionSuggestionBuilder;
import org.elasticsearch.search.suggest.term.TermSuggestionBuilder;
import org.elasticsearch.search.suggest.term.TermSuggestion;

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

public class ElasticExample {
    private RestHighLevelClient client;

    public ElasticExample() {
        // 初始化客户端
        // 填写Elasticsearch的地址和端口号
        client = new RestHighLevelClient(
            RestClient.builder(
                new HttpHost("localhost", 9200, "http")
            )
        );
    }

    public void createIndex() throws IOException {
        // 创建一个索引
        String indexName = "books";
        CreateIndexRequest request = new CreateIndexRequest(indexName);
        client.indices().create(request, RequestOptions.DEFAULT);
        
        // 创建一些文档
        IndexRequest request1 = new IndexRequest(indexName);
        Map<String, Object> book1 = new HashMap<>();
        book1.put("title", "Java入门");
        book1.put("author", "张三");
        book1.put("price", 45.0);
        request1.id("1");
        request1.source(book1);
        client.index(request1, RequestOptions.DEFAULT);

        IndexRequest request2 = new IndexRequest(indexName);
        Map<String, Object> book2 = new HashMap<>();
        book2.put("title", "Python编程");
        book2.put("author", "李四");
        book2.put("price", 60.0);
        request2.id("2");
        request2.source(book2);
        client.index(request2, RequestOptions.DEFAULT);
    }

    public void search() throws IOException {
        // 查询
        String indexName = "books";
        SearchRequest request = new SearchRequest(indexName);
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        sourceBuilder.query(QueryBuilders.matchQuery("title", "Java"));
        sourceBuilder.from(0);
        sourceBuilder.size(10);
        sourceBuilder.sort("price", SortOrder.ASC);
        HighlightBuilder highlightBuilder = new HighlightBuilder();
        highlightBuilder.field("title");
        highlightBuilder.preTags("<em>");
        highlightBuilder.postTags("</em>");
        sourceBuilder.highlighter(highlightBuilder);
        SuggestBuilder suggestBuilder = new SuggestBuilder();
        CompletionSuggestionBuilder completionSuggestionBuilder = new CompletionSuggestionBuilder("suggest");
        completionSuggestionBuilder.text("J");
        suggestBuilder.addSuggestion("suggest", completionSuggestionBuilder);
        TermSuggestionBuilder termSuggestionBuilder = new TermSuggestionBuilder("suggest");
        termSuggestionBuilder.text("Java");
        suggestBuilder.addSuggestion("suggest", termSuggestionBuilder);
        request.source(sourceBuilder);
        request.suggest(suggestBuilder);
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);
        SearchHits hits = response.getHits();
        for (SearchHit hit : hits) {
            String id = hit.getId();
            String title = hit.getSourceAsMap().get("title").toString();
            String author = hit.getSourceAsMap().get("author").toString();
            double price = Double.parseDouble(hit.getSourceAsMap().get("price").toString());
            Map<String, HighlightField> highlightFields = hit.getHighlightFields();
            HighlightField titleField = highlightFields.get("title");
            String highlightTitle = titleField.fragments()[0].toString();
            System.out.println("id: " + id + ", title: " + highlightTitle + ", author: " + author + ", price: " + price);
        }
        Suggest suggest = response.getSuggest();
        CompletionSuggestion completionSuggestion = suggest.getSuggestion("suggest");
        for (CompletionSuggestion.Entry entry : completionSuggestion.getEntries()) {
            for (CompletionSuggestion.Entry.Option option : entry.getOptions()) {
                System.out.println("Suggestion: " + option.getText().toString());
            }
        }
        TermSuggestion termSuggestion = suggest.getSuggestion("suggest");
        for (TermSuggestion.Entry entry : termSuggestion.getEntries()) {
            for (TermSuggestion.Entry.Option option : entry) {
                System.out.println("Suggestion: " + option.getText().toString());
            }
        }
    }

    public static void main(String[] args) throws IOException {
        ElasticExample example = new ElasticExample();
        example.createIndex();
        example.search();
    }
}

这个程序创建了一个名为“books”的索引，并向其中添加了两个文档。然后，它执行了一个查询，返回了所有标题包含“Java”的文档，并对标题进行了高亮显示。此外，它还展示了如何使用自动完成功能和建议功能来提供搜索建议。

请注意，这只是一个简单的示例程序，您需要根据自己的需求进行修改和扩展。