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今天我们来继续看 ElasticSearch 中的 Java 高级客户端，来看看 RestHighLevelClient 如何操作索引？
索引基本操作：
索引别名管理：
以下是视频笔记：
注意，笔记只是视频内容的一个简要记录，因此笔记内容比较简单，完整的内容可以查看视频。
28.1.2 查询索引是否存在
代码语言：javascript复制public class HighLevelTest3 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
GetIndexRequest blog = new GetIndexRequest("blog2");
boolean exists = client.indices().exists(blog, RequestOptions.DEFAULT);
System.out.println("exists = " exists);
//关闭 client
client.close();
}
}
28.1.3 关闭/打开索引
关闭：
代码语言：javascript复制public class HighLevelTest4 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
CloseIndexRequest blog = new CloseIndexRequest("blog");
CloseIndexResponse close = client.indices().close(blog, RequestOptions.DEFAULT);
List<CloseIndexResponse.IndexResult> indices = close.getIndices();
for (CloseIndexResponse.IndexResult index : indices) {
System.out.println("index.getIndex() = " index.getIndex());
}
//关闭 client
client.close();
}
}
打开：
代码语言：javascript复制public class HighLevelTest4 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
OpenIndexRequest blog = new OpenIndexRequest("blog");
client.indices().open(blog, RequestOptions.DEFAULT);
//关闭 client
client.close();
}
}
28.1.4 索引修改
代码语言：javascript复制public class HighLevelTest5 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
UpdateSettingsRequest request = new UpdateSettingsRequest("blog");
request.settings(Settings.builder().put("index.blocks.write", true).build());
client.indices().putSettings(request, RequestOptions.DEFAULT);
//关闭 client
client.close();
}
}
28.1.5 克隆索引
被克隆的索引需要是只读索引，可以通过 28.1.4 小节中的方式设置索引为只读。
代码语言：javascript复制public class HighLevelTest6 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
ResizeRequest request = new ResizeRequest("blog2", "blog");
client.indices().clone(request, RequestOptions.DEFAULT);
//关闭 client
client.close();
}
}
28.1.6 查看索引
代码语言：javascript复制public class HighLevelTest7 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
GetSettingsRequest request = new GetSettingsRequest().indices("blog");
//设置需要互殴去的具体的参数，不设置则返回所有参数
request.names("index.blocks.write");
GetSettingsResponse response = client.indices().getSettings(request, RequestOptions.DEFAULT);
ImmutableOpenMap<String, Settings> indexToSettings = response.getIndexToSettings();
System.out.println(indexToSettings);
String s = response.getSetting("blog", "index.number_of_replicas");
System.out.println(s);
//关闭 client
client.close();
}
}
28.1.7 Refresh & Flush
Es 底层依赖 Lucene，而 Lucene 中有 reopen 和 commit 两种操作，还有一个特殊的概念叫做 segment。
Es 中，基本的存储单元是 shard，对应到 Lucene 上，就是一个索引，Lucene 中的索引由 segment 组成，每个 segment 相当于 es 中的倒排索引。每个 es 文档创建时，都会写入到一个新的 segment 中，删除文档时，只是从属于它的 segment 处标记为删除，并没有从磁盘中删除。
Lucene 中：
reopen 可以让数据搜索到，但是不保证数据被持久化到磁盘中。
commit 可以让数据持久化。
Es 中：
默认是每秒 refresh 一次（Es 中文档被索引之后，首先添加到内存缓冲区，refresh 操作将内存缓冲区中的数据拷贝到新创建的 segment 中，这里是在内存中操作的）。
flush 将内存中的数据持久化到磁盘中。一般来说，flush 的时间间隔比较久，默认 30 分钟。
代码语言：javascript复制public class HighLevelTest8 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
RefreshRequest request = new RefreshRequest("blog");
client.indices().refresh(request, RequestOptions.DEFAULT);
FlushRequest flushRequest = new FlushRequest("blog");
client.indices().flush(flushRequest, RequestOptions.DEFAULT);
//关闭 client
client.close();
}
}
28.1.9 索引别名
索引的别名类似于 MySQL 中的视图。
28.1.9.1 添加别名
添加一个普通的别名：
代码语言：javascript复制public class HighLevelTest9 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
IndicesAliasesRequest indicesAliasesRequest = new IndicesAliasesRequest();
IndicesAliasesRequest.AliasActions aliasAction = new IndicesAliasesRequest.AliasActions(IndicesAliasesRequest.AliasActions.Type.ADD);
aliasAction.index("books").alias("books_alias");
indicesAliasesRequest.addAliasAction(aliasAction);
client.indices().updateAliases(indicesAliasesRequest, RequestOptions.DEFAULT);
//关闭 client
client.close();
}
}
添加一个带 filter 的别名：
代码语言：javascript复制public class HighLevelTest9 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
IndicesAliasesRequest indicesAliasesRequest = new IndicesAliasesRequest();
IndicesAliasesRequest.AliasActions aliasAction = new IndicesAliasesRequest.AliasActions(IndicesAliasesRequest.AliasActions.Type.ADD);
aliasAction.index("books").alias("books_alias2").filter("{"term": {"name": "java"}}");
indicesAliasesRequest.addAliasAction(aliasAction);
client.indices().updateAliases(indicesAliasesRequest, RequestOptions.DEFAULT);
//关闭 client
client.close();
}
}
现在，books 索引将存在两个别名，其中，books_alias2 自动过滤 name 中含有 java 的文档。
28.1.9.2 删除别名
代码语言：javascript复制public class HighLevelTest9 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
IndicesAliasesRequest indicesAliasesRequest = new IndicesAliasesRequest();
IndicesAliasesRequest.AliasActions aliasAction = new IndicesAliasesRequest.AliasActions(IndicesAliasesRequest.AliasActions.Type.REMOVE);
aliasAction.index("books").alias("books_alias");
indicesAliasesRequest.addAliasAction(aliasAction);
client.indices().updateAliases(indicesAliasesRequest, RequestOptions.DEFAULT);
//关闭 client
client.close();
}
}
第二种移除方式：
代码语言：javascript复制public class HighLevelTest9 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
DeleteAliasRequest deleteAliasRequest = new DeleteAliasRequest("books", "books_alias2");
client.indices().deleteAlias(deleteAliasRequest, RequestOptions.DEFAULT);
//关闭 client
client.close();
}
}
28.1.9.3 判断别名是否存在
代码语言：javascript复制public class HighLevelTest9 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
GetAliasesRequest books_alias = new GetAliasesRequest("books_alias");
//指定查看某一个索引的别名，不指定，则会搜索所有的别名
books_alias.indices("books");
boolean b = client.indices().existsAlias(books_alias, RequestOptions.DEFAULT);
System.out.println(b);
//关闭 client
client.close();
}
}
28.1.9.4 获取别名
代码语言：javascript复制public class HighLevelTest9 {
public static void main(String[] args) throws IOException {
RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http"),
new HttpHost("localhost", 9202, "http")
));
GetAliasesRequest books_alias = new GetAliasesRequest("books_alias");
//指定查看某一个索引的别名，不指定，则会搜索所有的别名
books_alias.indices("books");
GetAliasesResponse response = client.indices().getAlias(books_alias, RequestOptions.DEFAULT);
Map<String, Set<AliasMetadata>> aliases = response.getAliases();
System.out.println("aliases = " aliases);
//关闭 client
client.close();
}
}
