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ElasticSearch High Level REST API【5】使用模板搜索
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ElasticSearch Rest高级API 提供了多种搜索方式，除了前面讲到的search查询，ElasticSearch 还提供了通过模板搜索查询。我个人比较喜欢这种方式。
我们可以通过脚本预选注册模板，在注册模板时定义一个模板名称。在查询时通过模板名称调用该模板。首先演示下如何注册模板：
public void registTemplate(){
RestClient restClient = elasticClient.getRestClient();
String template = "{\n" +
" \"script\":{\n" +
" \"lang\":\"mustache\",\n" +
" \"source\":{\n" +
" \"query\":{\n" +
" \"match\":{\n" +
" \"{{key}}\":\"{{value}}\"\n" +
" }\n" +
" },\n" +
" \"size\":\"{{size}}\"\n" +
" }\n" +
" }\n" +
"}";
Request scriptRequest1 = new Request("POST", "_scripts/title_search");
scriptRequest1.setJsonEntity(template);
try {
restClient.performRequest(scriptRequest1);
restClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
由于ElasticSearch 6.5版本的高级Rest API中暂时还没有提供用于注册模板的存储脚本，所以本示例中使用的低级REST客户端。本示例中注册了一个名为“title_search”的模板
有了这个模板就可以通过“title_search”去调用，动态的将查询参数添加到模板中去。模板调用示例如下：
public void templateSearch(){
RestHighLevelClient client = elasticClient.getRestHighLevelClient();
try {
SearchTemplateRequest request = new SearchTemplateRequest();
request.setRequest(new SearchRequest("posts"));
request.setScriptType(ScriptType.STORED);
request.setScript("title_search");
Map<String, Object> params = new HashMap<>();
params.put("key", "name");
params.put("value", "福卖福");
params.put("size", 5);
request.setScriptParams(params);
try {
SearchTemplateResponse searchTemplateResponse = client.searchTemplate(request, RequestOptions.DEFAULT);
SearchHit[] hits = searchTemplateResponse.getResponse().getHits().getHits();
for (SearchHit hit : hits) {
System.out.println(hit.getSourceAsString());
}
client.close();
} catch (IOException e) {
e.printStackTrace();
}
} catch (Exception e) {
e.printStackTrace();
}
}
针对每个模板我们执行一次搜索请求，如果我们工作中针对同一模板可能会有不止一次的请求，如果每个请求都去单独执行的话未免有点繁琐。我们可以通过msearchTemplate
来实现一次请求实现多条搜索，示例如下：
public void multiTemplateSearch(){
RestHighLevelClient client = elasticClient.getRestHighLevelClient();
String [] searchTerms = {"周大福", "特博士", "詹姆斯"}; // 要搜索的条件
MultiSearchTemplateRequest multiRequest = new MultiSearchTemplateRequest();
for (String searchTerm : searchTerms) {
SearchTemplateRequest request = new SearchTemplateRequest();
request.setRequest(new SearchRequest("posts")); //指定为posts索引库
request.setScriptType(ScriptType.INLINE);
request.setScript(
"{\n" +
" \"query\":{\n" +
" \"match\":{\n" +
" \"{{key}}\":\"{{value}}\"\n" +
" }\n" +
" },\n" +
" \"size\":\"{{size}}\"\n" +
"}");
Map<String, Object> scriptParams = new HashMap<>();
//向模板中填充对应值
scriptParams.put("key", "name");
scriptParams.put("value", searchTerm);
scriptParams.put("size", 5);
request.setScriptParams(scriptParams);
multiRequest.add(request);
}
//执行查询
try {
MultiSearchTemplateResponse multiResponse = client.msearchTemplate(multiRequest, RequestOptions.DEFAULT);
//返回一组响应 ，每个请求对应一个响应
for (MultiSearchTemplateResponse.Item item : multiResponse.getResponses()) {
if (item.isFailure()) {
String error = item.getFailureMessage(); //搜索请求失败返回错误信息
}else {
SearchTemplateResponse searchTemplateResponse = item.getResponse();
SearchResponse response = searchTemplateResponse.getResponse();
SearchHits hits = response.getHits();
System.out.println("----------");
for (SearchHit hit : hits) {
System.out.println(hit.getSourceAsString());
}
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
执行结果如下
