1、Java High Level REST Client说明
Java High Level REST Client从6.0.0开始加入的，目的是以java面向对象的方式来进行请求、响应处理。每个API支持同步/异步两种方式，同步方法直接返回一个结果对象。异步的方法以async为后缀，通过listener参数来通知结果。高级java REST 客户端依赖Elasticsearch core project
兼容性说明：依赖 java1.8 和 Elasticsearch core project，请使用与服务端ES版本一致的客户端版本。
2、Elasticsearch服务搭建
文章中使用Elasticsearch的6.5.4版本，该版本在windows启动时会出现以下异常
[2019-06-30T12:12:58,471][INFO][o.e.p.PluginsService ] [JP55XpU] noplugins loaded
[2019-06-30T12:13:09,651][INFO][o.e.x.s.a.s.FileRolesStore] [JP55XpU] parsed [0] roles from file[D:\devtools\elasticsearch-6.5.4\config\roles.yml]
[2019-06-30T12:13:10,844][ERROR][o.e.b.Bootstrap ] [JP55XpU] Exception
org.elasticsearch.ElasticsearchException:X-Pack is not supported and Machine Learning is not available for [windows-x86];you can use the other X-Pack features (unsupported) by settingxpack.ml.enabled: false in elasticsearch.yml
atorg.elasticsearch.xpack.ml.MachineLearningFeatureSet.isRunningOnMlPlatform(MachineLearningFeatureSet.java:104)~[?:?]
atorg.elasticsearch.xpack.ml.MachineLearningFeatureSet.isRunningOnMlPlatform(MachineLearningFeatureSet.java:95)~[?:?]关于该异常可以参考如下这两篇文章的其中的任何一种解决方案
将jdk与jre安装成64位：
https://www.cnblogs.com/alvin-niu/p/9747361.html
关闭X-Pack支持：
https://blog.csdn.net/fanrenxiang/article/details/81358332
3、Maven集成Java High LevelREST Client
<dependencies>
<dependency>
<groupId>org.elasticsearch.client</groupId>
<artifactId>elasticsearch-rest-high-level-client</artifactId>
<version>6.5.4</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.12.0</version>
</dependency>
</dependencies>
4、Java High Level REST Client 初始化
public static RestHighLevelClient getClient(){
RestHighLevelClient client = new RestHighLevelClient(
RestClient.builder(
new HttpHost("localhost", 9200, "http")));
return client;
}可以给定集群的多个节点地址，构建RestHighLevelClient对象
public static RestHighLevelClient getClient(){
RestHighLevelClient client = new RestHighLevelClient(
RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9100, "http")));
return client;
}Client 不再使用了，记得关闭它：
client.close();
API及用法示例，可以参考官网API：
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-supported-apis.html
5、Create Index（创建索引）
同步方式创建Index
public static void createIndexSync(){
RestHighLevelClient client=null;
try{
client = getClient();
// 1、创建 创建索引request 参数：索引名java
CreateIndexRequest request = new CreateIndexRequest("java");
// 2、设置索引的settings
request.settings(Settings.builder().put("index.number_of_shards", 3) // 分片数
.put("index.number_of_replicas", 2) // 副本数
);
// 3、设置索引的mappings
request.mapping("_doc",
" {\n" +
" \"_doc\": {\n" +
" \"properties\": {\n" +
" \"message\": {\n" +
" \"type\": \"text\"\n" +
" }\n" +
" }\n" +
" }\n" +
" }",
XContentType.JSON);
// 4、 设置索引的别名
request.alias(new Alias("it"));
RequestOptions requestOptions = RequestOptions.DEFAULT;
// 5、 发送请求
// 5.1 同步方式发送请求
CreateIndexResponse createIndexResponse = client.indices().create(request,requestOptions);
// 6、处理响应
boolean acknowledged = createIndexResponse.isAcknowledged();
boolean shardsAcknowledged = createIndexResponse
.isShardsAcknowledged();
System.out.println("acknowledged = " + acknowledged);
System.out.println("shardsAcknowledged = " + shardsAcknowledged);
} catch (Exception e) {
e.printStackTrace();
}finally {
try{
client.close();
} catch (Exception e) {
}
}
}
异步方式创建Index：
public static void createIndexAsync(){
RestHighLevelClient client=null;
try{
client = getClient();
// 1、创建 创建索引request 参数：索引名java
CreateIndexRequest request = new CreateIndexRequest("python");
// 2、设置索引的settings
request.settings(Settings.builder().put("index.number_of_shards", 3) // 分片数
.put("index.number_of_replicas", 2) // 副本数
);
// 3、设置索引的mappings
request.mapping("_doc",
" {\n" +
" \"_doc\": {\n" +
" \"properties\": {\n" +
" \"message\": {\n" +
" \"type\": \"text\"\n" +
" }\n" +
" }\n" +
" }\n" +
" }",
XContentType.JSON);
// 4、 设置索引的别名
request.alias(new Alias("py"));
RequestOptions requestOptions = RequestOptions.DEFAULT;
// 5、 发送请求
// 5.1 异步方式发送请求
ActionListener<CreateIndexResponse> listener = new ActionListener<CreateIndexResponse>() {
public void onResponse(
CreateIndexResponse createIndexResponse) {
// 6、处理响应
boolean acknowledged = createIndexResponse.isAcknowledged();
boolean shardsAcknowledged = createIndexResponse
.isShardsAcknowledged();
System.out.println("acknowledged = " + acknowledged);
System.out.println(
"shardsAcknowledged = " + shardsAcknowledged);
}
public void onFailure(Exception e) {
System.out.println("创建索引异常：" + e.getMessage());
}
};
client.indices().createAsync(request, RequestOptions.DEFAULT, listener);
} catch (Exception e) {
e.printStackTrace();
}finally {
try{
client.close();
} catch (Exception e) {
}
}
}
