Elasticsearch Java REST高级客户端-DocumentApi

你的名字 2021-12-03 11:53 366阅读 0赞

# Elasticsearch Java REST高级客户端-DocumentApi #

版本：Elasticsearch 7.2.0

当你把Elasticsearch升级到7后会发现TransportClient这个客户端已过时，而且PreBuiltTransportClient这个已被删除，那么现在有如何使用java 客户端？Elasticsearch官方建议使用REST高级客户端RestHighLevelClient。话不多说，直接看例子：

1.  创建客户端、及关闭
2.  插入一条数据（如果存在则更新） index()
3.  获取一个文档 get()
4.  文档是否存在 exists()
5.  删除文档 delete()
6.  更新 update()
7.  批量更新 bulk()
8.  批量查询 multiGet()
9.  异步操作
10. maven配置

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[https://www.cbedai.net/u014646662][Link 1]

## 1.创建客户端、及关闭 ##

/**
    	 * 获取客户端
    	 * 
    	 * @return
    	 */
    	private static RestHighLevelClient getClient() {
    		RestHighLevelClient client = new RestHighLevelClient(
    				RestClient.builder(
    						new HttpHost("node01", 9200, "http"), 
    						new HttpHost("node02", 9200, "http"),
    						new HttpHost("node03", 9200, "http")));
    		return client;
    	}
    
    
    /**
    	 * 关闭客户端
    	 * 
    	 * @param client
    	 */
    	private static void close(RestHighLevelClient client) {
    		try {
    			client.close();
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}

## 2.插入一条数据（如果存在则更新） index() ##

/**
    	 * 插入一条数据（如果存在则更新）
    	 */
    	public static void index() {
    		RestHighLevelClient client = getClient();
    
    		Map<String, Object> jsonMap = new HashMap<>();
    		jsonMap.put("user", "kimchy");
    		jsonMap.put("postDate", new Date());
    		jsonMap.put("message", "trying out Elasticsearch");
    		IndexRequest request = new IndexRequest("user").id("1").source(jsonMap);
    
    		IndexResponse response = null;
    		try {
    			response = client.index(request, RequestOptions.DEFAULT);
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    
    		String index = response.getIndex();
    		String id = response.getId();
    		System.out.println(index + "---" + id);
    
    		close(client);
    	}

## 3.获取一个文档 get() ##

/**
    	 * 获取一个文档
    	 */
    	public static void get() {
    		RestHighLevelClient client = getClient();
    		GetRequest getRequest = new GetRequest("user", "1");
    		try {
    			GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT);
    			String index = getResponse.getIndex();
    			String id = getResponse.getId();
    			if (getResponse.isExists()) {
    				long version = getResponse.getVersion();
    				String sourceAsString = getResponse.getSourceAsString();
    				Map<String, Object> sourceAsMap = getResponse.getSourceAsMap();
    				byte[] sourceAsBytes = getResponse.getSourceAsBytes();
    
    				System.out.println("索引：" + index + "，ID：" + id + "版本：" + version);
    				System.out.println(sourceAsString);
    				System.out.println(sourceAsMap);
    				System.out.println(sourceAsBytes.toString());
    			} else {
    				System.out.println("未查到结果");
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    		close(client);
    	}

## 4.文档是否存在 exists() ##

/**
    	 * 文档是否存在
    	 */
    	public static void exists() {
    		RestHighLevelClient client = getClient();
    		GetRequest getRequest = new GetRequest("user", "1");
    		// 禁止获取_source
    		getRequest.fetchSourceContext(new FetchSourceContext(false));
    		// 禁止获取存储字段
    		getRequest.storedFields("_none_");
    		try {
    			boolean exists = client.exists(getRequest, RequestOptions.DEFAULT);
    			System.out.println(getRequest.index() + "---" + getRequest.id() + "---文档是否存在：" + exists);
    		} catch (IOException e) {
    			// TODO 自动生成的 catch 块
    			e.printStackTrace();
    		}
    		close(client);
    	}

## 5.删除文档 delete() ##

/**
    	 * 删除文档
    	 */
    	public static void delete() {
    		RestHighLevelClient client = getClient();
    		DeleteRequest deleteRequest = new DeleteRequest("user", "1");
    		try {
    			client.delete(deleteRequest, RequestOptions.DEFAULT);
    			System.out.println(deleteRequest.index() + "---" + deleteRequest.id() + ": 文档已删除");
    			exists();
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    		close(client);
    	}

## 6.更新 update() ##

public static void update() {
    		RestHighLevelClient client = getClient();
    		Map<String, Object> jsonMap = new HashMap<>();
    		jsonMap.put("updated", new Date());
    		jsonMap.put("reason", "daily update");
    		UpdateRequest request = new UpdateRequest("user", "2").doc(jsonMap);
    		try {
    			UpdateResponse response = client.update(request, RequestOptions.DEFAULT);
    			System.out.println(response.getIndex() + "---" + response.getId() + "完成更新");
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    		close(client);
    	}

## 7.批量更新 bulk() ##

/**
    	 * 批量更新
    	 */
    	public static void bulk() {
    		RestHighLevelClient client = getClient();
    
    		BulkRequest request = new BulkRequest();
    		request.add(new IndexRequest("user").id("3").source(XContentType.JSON, "field", "foo", "user", "lucky"));
    		request.add(new IndexRequest("user").id("4").source(XContentType.JSON, "field", "bar", "user", "Jon"));
    		request.add(new IndexRequest("user").id("5").source(XContentType.JSON, "field", "baz", "user", "Lucy"));
    		// id为10的不存在
    		request.add(new DeleteRequest("user", "3"));
    		request.add(new UpdateRequest("user", "2").doc(XContentType.JSON, "other", "test"));
    		BulkResponse bulkResponse = null;
    		try {
    			bulkResponse = client.bulk(request, RequestOptions.DEFAULT);
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    		// 获取执行状态
    		System.out.println("批量更新结果状态：" + bulkResponse.status());
    		close(client);
    	}

## 8.批量查询 multiGet() ##

// 批量查询
    	public static void multiGet() {
    		RestHighLevelClient client = getClient();
    
    		MultiGetRequest request = new MultiGetRequest();
    		request.add(new MultiGetRequest.Item("user", "2"));
    		request.add(new MultiGetRequest.Item("user", "4"));
    		request.add(new MultiGetRequest.Item("user", "5"));
    
    		MultiGetResponse mget = null;
    		try {
    			mget = client.mget(request, RequestOptions.DEFAULT);
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    		// 打印查詢結果
    		System.out.println("mget:");
    		mget.forEach(item -> System.out.println(item.getResponse().getSourceAsString()));
    		close(client);
    	}

## 9.异步操作 ##

以上做法均为同步性操作，非异步操作，所以这些操作都是阻塞式操作，知道查到结果为止。对异步操作只列出代码，不做举例

ActionListener<SearchResponse> listener = new ActionListener<SearchResponse>() {
        @Override
        public void onResponse(SearchResponse searchResponse) {
            // 查询成功
        }
    
        @Override
        public void onFailure(Exception e) {
            // 查询失败
        }
    };
    
    client.indexAsync(request, RequestOptions.DEFAULT, listener);

## 10.maven ##

<dependency>
    			<groupId>org.elasticsearch.plugin</groupId>
    			<artifactId>x-pack-sql-jdbc</artifactId>
    			<version>7.2.0</version>
    
    		</dependency>
    
    		<dependency>
    			<groupId>org.elasticsearch.client</groupId>
    			<artifactId>elasticsearch-rest-high-level-client</artifactId>
    			<version>7.2.0</version>
    
    		</dependency>

##      ##

[Link 1]: https://www.cbedai.net/u014646662