java rest client初始化和搜索查询--es_java方式执行es查询语句

初始化：

RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(
                new HttpHost("localhost", 9200, "http"),
                new HttpHost("localhost", 9201, "http")));

The high-level client 是比low-level更进一层的封装，两者性能相差不大。

highlevel兼容性更好，API丰富，适合于高并发场景，且highlvel的内部基于low level（维护连接池和启动线程），所以hghlevel要正确的关闭才会把内部的lowlevelclient一起关闭，

关闭方式：

client.close();

搜索查询search API

//创建搜索请求
SearchRequest searchRequest = new SearchRequest(); 
//将查询设置和参数添加到searchsourcebuilder
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder(); 
//将match_all添加到ssb
searchSourceBuilder.query(QueryBuilders.matchAllQuery()); 
//最后将查询的结构添加到查询请求中
searchRequest.source(searchSourceBuilder); 
 
 
单个查询示例：
 
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); 
sourceBuilder.query(QueryBuilders.termQuery("user", "kimchy")); 
sourceBuilder.from(0); 
sourceBuilder.size(5); 
sourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS)); 
 
SearchRequest searchRequest = new SearchRequest();
searchRequest.indices("posts");
searchRequest.source(sourceBuilder);
 

同步获取返回值，会可能会引发IO错误，需要捕捉错误信息

//同步执行，获取返回值
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

异步获取返回值，不会阻塞和立马返回。一旦执行完成，会调用ActionListener，成功调用onResponse，失败调用onFailure

client.searchAsync(searchRequest, RequestOptions.DEFAULT, listener);
 
 
通用的listener：
ActionListener<SearchResponse> listener = new ActionListener<SearchResponse>() {
    @Override
    public void onResponse(SearchResponse searchResponse) {
        
    }
 
    @Override
    public void onFailure(Exception e) {
        
    }
};

返回值接收 SearchResponse

        //获取返回值的状态码
         RestStatus status = searchResponse.status();
        //查询所用时间
        TimeValue took = searchResponse.getTook();
        //执行时间或请求是提前终止还是超时：
        Boolean terminatedEarly = searchResponse.isTerminatedEarly();
        boolean timedOut = searchResponse.isTimedOut();