mget(可以通过索引、类型、或ID一次得到同一索引或不同索引库里的文档集合) & mapping

使用multi get API可以通过索引名、类型名、文档id一次得到一个文档集合，文档可以来自同一个索引库，也可以来自不同索引库。示例如下:

MultiGetResponse multiGetItemResponses = client.prepareMultiGet()    .add("twitter", "tweet", "1")    //注释1                                .add("twitter", "tweet", "2", "3", "4")     //注释2                 .add("another", "type", "foo")          //注释3                       .get();for (MultiGetItemResponse itemResponse : multiGetItemResponses) {       //注释4    GetResponse response = itemResponse.getResponse();    if (response.isExists()) {                   //注释5                       String json = response.getSourceAsString();    //注释6                     }}
1
2
3
4
5
6
7
8
9
10
11
12
13

注释1: 通过单一的ID获取一个文档. 
注释2：传入多个id，从相同的索引名/类型名中获取多个文档. 
注释3：可以同时获取不同索引中的文档. 
注释4：遍历结果集. 
注释5：检验文档是否存在. 
注释6：获取文档源.

一、获取索引的所有mapping

通过java客户端获取mapping：

package elasticsearch.in.action.client;import java.net.InetAddress;import java.net.UnknownHostException;import org.elasticsearch.client.transport.TransportClient;import org.elasticsearch.cluster.metadata.MappingMetaData;import org.elasticsearch.common.collect.ImmutableOpenMap;import org.elasticsearch.common.settings.Settings;import org.elasticsearch.common.transport.InetSocketTransportAddress;public class TransClient {    public static String clusterName = "elasticsearch";// 集群名称    public static String serverIP = "127.0.0.1";// 服务器IP    public static void main(String[] args) {        System.out.println(getMapping("news", "sportnews"));    }    public static String getMapping(String indexname, String typename) {        Settings settings = Settings.settingsBuilder().put("cluster.name", clusterName).build();        String mapping="";        try {            TransportClient client = TransportClient.builder().settings(settings).build()                    .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName(serverIP), 9300));            ImmutableOpenMap<String, MappingMetaData> mappings = client.admin().cluster().prepareState().execute()                    .actionGet().getState().getMetaData().getIndices().get(indexname).getMappings();            mapping = mappings.get(typename).source().toString();            client.close();        } catch (UnknownHostException e) {            e.printStackTrace();        }        return mapping;    }}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39

二、获取所有的type以及每个type的mapping

mapping信息都是ImmutableOpenMap

for (ObjectObjectCursor<String, MappingMetaData> cursor : mappings) {            System.out.println(cursor.key); // 索引下的每个type            System.out.println(cursor.value.getSourceAsMap()); // 每个type的mapping}