（22）ElasticSearch java項目中聚合運算求最大、最小、平均、求和以及求不同值

　　1、求索引lib3下的age字段的最大值

@Test
    public void testAggMax() throws IOException, InterruptedException, ExecutionException {
        //指定集群
        Settings settings = Settings.builder().put("cluster.name","my-application").build(); 
        //創建客戶端
        TransportClient client = new PreBuiltTransportClient(settings)
                                .addTransportAddress(new TransportAddress(InetAddress.getByName("192.168.43.151"),9300));
        //aggMax是固定寫法，求最大年齡
        AggregationBuilder agg = AggregationBuilders.max("aggMax").field("age");
        //執行查詢
        SearchResponse response = client.prepareSearch("lib3")//索引是lib
                                  .addAggregation(agg)
                                  .get();
        //獲取結果
        Max max = response.getAggregations().get("aggMax");
        //輸出結果
        System.out.println(max.getValue());
        client.close();
   }

　　2、求索引lib3下的age字段的最小值

@Test
    public void testAggMin() throws IOException, InterruptedException, ExecutionException {
        //指定集群
        Settings settings = Settings.builder().put("cluster.name","my-application").build(); 
        //創建客戶端
        TransportClient client = new PreBuiltTransportClient(settings)
                                .addTransportAddress(new TransportAddress(InetAddress.getByName("192.168.43.151"),9300));
        //aggMin是固定寫法，求最小年齡
        AggregationBuilder agg = AggregationBuilders.min("aggMin").field("age");
        //執行查詢
        SearchResponse response = client.prepareSearch("lib3")//索引是lib
                                  .addAggregation(agg)
                                  .get();
        //獲取結果
        Min min = response.getAggregations().get("aggMin");
        //輸出結果
        System.out.println(min.getValue());
        client.close();
   }

　　3、求索引lib3下的age字段的平均值

@Test
    public void testAggAvg() throws IOException, InterruptedException, ExecutionException {
        //指定集群
        Settings settings = Settings.builder().put("cluster.name","my-application").build(); 
        //創建客戶端
        TransportClient client = new PreBuiltTransportClient(settings)
                                .addTransportAddress(new TransportAddress(InetAddress.getByName("192.168.43.151"),9300));
        //aggAvg是固定寫法，求平均年齡
        AggregationBuilder agg = AggregationBuilders.avg("aggAvg").field("age");
        //執行查詢
        SearchResponse response = client.prepareSearch("lib3")//索引是lib
                                  .addAggregation(agg)
                                  .get();
        //獲取結果
        Avg avg = response.getAggregations().get("aggAvg");
        //輸出結果
        System.out.println(avg.getValue());
        client.close();
   }

　　4、求索引lib3下的age字段的和

@Test
    public void testAggSum() throws IOException, InterruptedException, ExecutionException {
        //指定集群
        Settings settings = Settings.builder().put("cluster.name","my-application").build(); 
        //創建客戶端
        TransportClient client = new PreBuiltTransportClient(settings)
                                .addTransportAddress(new TransportAddress(InetAddress.getByName("192.168.43.151"),9300));
        //aggSum是固定寫法，求年齡總和
        AggregationBuilder agg = AggregationBuilders.sum("aggSum").field("age");
        //執行查詢
        SearchResponse response = client.prepareSearch("lib3")//索引是lib
                                  .addAggregation(agg)
                                  .get();
        //獲取結果
        Sum sum = response.getAggregations().get("aggSum");
        //輸出結果
        System.out.println(sum.getValue());
        client.close();
   }

　　5、求索引lib3中age字段有多個不同值

@Test
    public void testAggCardinality() throws IOException, InterruptedException, ExecutionException {
        //指定集群
        Settings settings = Settings.builder().put("cluster.name","my-application").build(); 
        //創建客戶端
        TransportClient client = new PreBuiltTransportClient(settings)
                                .addTransportAddress(new TransportAddress(InetAddress.getByName("192.168.43.151"),9300));
        //aggCardinality是固定寫法，求某字段有多個不同值
        AggregationBuilder agg = AggregationBuilders.cardinality("aggCardinality").field("age");
        //執行查詢
        SearchResponse response = client.prepareSearch("lib3")//索引是lib
                                  .addAggregation(agg)
                                  .get();
        //獲取結果
        Cardinality cardinality = response.getAggregations().get("aggCardinality");
        //輸出結果
        System.out.println(cardinality.getValue());
        client.close();
   }