restHighLevelClient获取一个索引的全部数据

使用Elasticsearch的Java REST客户端restHighLevelClient获取一个索引的全部数据可以通过以下步骤实现：

1. 创建restHighLevelClient客户端实例：

RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(new HttpHost("localhost", 9200, "http")));

2. 构建一个SearchRequest对象，设置索引名称和查询条件：

SearchRequest searchRequest = new SearchRequest("index_name");
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(QueryBuilders.matchAllQuery());
searchRequest.source(searchSourceBuilder);

3. 执行查询并处理结果：

SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
SearchHits hits = searchResponse.getHits();
for (SearchHit hit : hits.getHits()) {
    Map<String, Object> sourceAsMap = hit.getSourceAsMap();
    // 处理每个文档的数据
}

完整代码示例：

RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(new HttpHost("localhost", 9200, "http")));

SearchRequest searchRequest = new SearchRequest("index_name");
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(QueryBuilders.matchAllQuery());
searchRequest.source(searchSourceBuilder);

SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
SearchHits hits = searchResponse.getHits();
for (SearchHit hit : hits.getHits()) {
    Map<String, Object> sourceAsMap = hit.getSourceAsMap();
    // 处理每个文档的数据
}

client.close();