# Elastic App Search 後端連接

Elastic App Search 後端連接有兩種方式，一種是透過ELK的Elastic 去取得 Elastic App
的資料，第二種是直接用Java 打API的方式，去取得 Elastic App Search 的資料

---

## 一、透過ELK查詢 Elastic App Search

1. 取得Elastic App Search 的 index，可以從Kibana取得所有的Elastic 列表，GET
`_cat/indices?v&index=*engine*`

2. 回傳的結果

| health | status | index | uuid | pri | rep | docs.count | docs.deleted | store.size | pri.store.size |
| -------- | -------- | -------- |-------- |-------- |-------- |-------- |-------- |-------- |-------- |
|green|open|.ent-search-engine-documents-hktv|N3UnO9mkRYS94RJnxUi23w|2|1|100|0|1.9mb|993.9kb|

3. 會有多個 index，可以用docs.count 來判斷，Elastic App Search 的 index

4. 使用之前的遠端連結範例

[遠端連接](https://hackmd.io/@ElasticNote/rkx8e42H_)

    public static void main(String[] args ) throws IOException {

        //  建立連線端 這裡的是ELK的使用者名稱密碼與Host
        String username = "yourname";
        String password = "yourpassword";
        String host = "yourHost";

        int port = 9243;
        int nextPort = 9244;
        String protocol = "https";

        final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(
                AuthScope.ANY,
                new UsernamePasswordCredentials(username, password));

        RestClientBuilder Builder = RestClient.builder(
                new HttpHost(host, port, protocol),
                new HttpHost(host, nextPort, protocol))
                .setHttpClientConfigCallback((h) -> h.setDefaultCredentialsProvider(credentialsProvider));


        try (RestHighLevelClient client = new RestHighLevelClient(Builder)) {
            //搜尋的Key與一般搜尋ELK不同，可能會因版本差異而改變
            QueryBuilder matchQueryBuilder = QueryBuilders.matchQuery("name_zh$string", "貓砂").fuzziness(Fuzziness.AUTO);;


            SearchSourceBuilder searchBuilder = SearchSourceBuilder.searchSource().query(matchQueryBuilder).size(50);

            //  index 的名稱
            SearchRequest request = new SearchRequest(".yourIndex").source(searchBuilder);

            SearchHits hits = client.search(request, RequestOptions.DEFAULT).getHits();


            //  逐筆取資料
            for(SearchHit hit : hits) {
                Map<String, Object> sourceAsMap = hit.getSourceAsMap();

                String name_zh = (String) sourceAsMap.get("name_zh$string");
                String selling_price = (String) sourceAsMap.get("selling_price$string");

                System.out.println(String.format("NameZH:%s selling_price:%s ",name_zh, selling_price));
            }
        }catch (IOException ignored) {}
    }