elasticsearch滚动索引java实现

Elasticsearch的滚动索引可以用来遍历大量数据，而不会导致内存溢出或超时。下面是Java代码实现滚动索引的步骤：

1.创建Elasticsearch客户端:

TransportClient client = new PreBuiltTransportClient(Settings.EMPTY)
        .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("localhost"), 9300));

2.定义搜索条件:

SearchRequestBuilder searchRequestBuilder = client.prepareSearch("indexName")
        .setTypes("typeName")
        .setQuery(QueryBuilders.matchAllQuery())
        .setSize(100)
        .setScroll(new TimeValue(60000));

这里设置了每次搜索返回100条记录，并且每次搜索的有效时间为60秒。

3.执行搜索:

SearchResponse searchResponse = searchRequestBuilder.execute().actionGet();

4.处理搜索结果:

while (true) {
    for (SearchHit searchHit : searchResponse.getHits().getHits()) {
        // 处理每个搜索结果
    }
    searchResponse = client.prepareSearchScroll(searchResponse.getScrollId())
            .setScroll(new TimeValue(60000)).execute().actionGet();
    if (searchResponse.getHits().getHits().length == 0) {
        break;
    }
}

通过循环，我们可以遍历所有搜索结果。在每次循环结束后，我们需要使用`prepareSearchScroll`方法获取下一页搜索结果，直到没有更多结果为止。

5.关闭客户端:

client.close();

完整的Java代码示例:

TransportClient client = new PreBuiltTransportClient(Settings.EMPTY)
        .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("localhost"), 9300));

SearchRequestBuilder searchRequestBuilder = client.prepareSearch("indexName")
        .setTypes("typeName")
        .setQuery(QueryBuilders.matchAllQuery())
        .setSize(100)
        .setScroll(new TimeValue(60000));

SearchResponse searchResponse = searchRequestBuilder.execute().actionGet();

while (true) {
    for (SearchHit searchHit : searchResponse.getHits().getHits()) {
        // 处理每个搜索结果
    }
    searchResponse = client.prepareSearchScroll(searchResponse.getScrollId())
            .setScroll(new TimeValue(60000)).execute().actionGet();
    if (searchResponse.getHits().getHits().length == 0) {
        break;
    }
}

client.close();