ElasticSearch索引不起作用/可靠

Question

我正在围绕ElasticSearch的管理客户端编写一个简单的Java包装器。为了测试它，我有一个主要方法，该方法首先检查索引是否存在（IndicesExistsRequest），如果存在则将其删除（DeleteIndexRequest），然后再次创建索引。请参见下面的代码。但是我一直得到IndexAlreadyExistsException。

顺便说一句，我正在尝试为您从命令提示符启动的节点获取客户端（只需键入“elasticsearch”）。我已经在nodeBuilder的流畅接口上尝试了每种方法的组合，但是我似乎一无所获。

public static void main(String[] args) {
    ElasticSearchJavaClient esjc = new ElasticSearchJavaClient("nda");
    if (esjc.indexExists()) {
        esjc.deleteIndex();
    }
    esjc.createIndex();
    URL url = SchemaCreator.class.getResource("/elasticsearch/specimen.type.json");
    String mappings = FileUtil.getContents(url);
    esjc.createType("specimen", mappings);
}

final Client esClient;
final IndicesAdminClient adminClient;
final String indexName;

public ElasticSearchJavaClient(String indexName) {
    this.indexName = indexName;
    esClient = nodeBuilder().clusterName("elasticsearch").client(true).node().client();
    adminClient = esClient.admin().indices();
}

public boolean deleteIndex() {
    logger.info("Deleting index " + indexName);
    DeleteIndexRequest request = new DeleteIndexRequest(indexName);
    try {
        DeleteIndexResponse response = adminClient.delete(request).actionGet();
        if (!response.isAcknowledged()) {
            throw new Exception("Failed to delete index " + indexName);
        }
        logger.info("Index deleted");
        return true;
    } catch (IndexMissingException e) {
        logger.info("No such index: " + indexName);
        return false;
    }
}

public boolean indexExists() {
    logger.info(String.format("Verifying existence of index \"%s\"", indexName));
    IndicesExistsRequest request = new IndicesExistsRequest(indexName);
    IndicesExistsResponse response = adminClient.exists(request).actionGet();
    if (response.isExists()) {
        logger.info("Index exists");
        return true;
    }
    logger.info("No such index");
    return false;
}

public void createIndex() {
    logger.info("Creating index " + indexName);
    CreateIndexRequest request = new CreateIndexRequest(indexName);
    IndicesAdminClient iac = esClient.admin().indices();
    CreateIndexResponse response = iac.create(request).actionGet();
    if (!response.isAcknowledged()) {
        throw new Exception("Failed to delete index " + indexName);
    }
    logger.info("Index created");
}

Answer 1

好，我想出了一个解决方案。由于Java客户端的调用是异步完成的，因此您必须使用带有操作侦听器的变体。解决方案仍然有些人为的：

// Inner class because it's just used to be thrown out of
// the action listener implementation to signal that the
// index exists
private class ExistsException extends RuntimeException {
}

public boolean exists() {
    logger.info(String.format("Verifying existence of index \"%s\"", indexName));
    IndicesExistsRequest request = new IndicesExistsRequest(indexName);
    try {
        adminClient.exists(request, new ActionListener<IndicesExistsResponse>() {
            public void onResponse(IndicesExistsResponse response) {
                if (response.isExists()) {
                    throw new ExistsException();
                }
            }
            public void onFailure(Throwable e) {
                ExceptionUtil.smash(e);
            }
        });
    }
    catch (ExistsException e) {
        return true;
    }
    return false;
}