Elasticsearch Java客户端

在Elasticsearch中，为java提供了2种客户端，一种是REST风格的客户端，另一种是Java API的客户端。

REST客户端：

　　Elasticsearch提供了2种REST客户端，一种是低级客户端，一种是高级客户端。
　　　　Java Low Level REST Client：官方提供的低级客户端。该客户端通过http来连接Elasticsearch集群。用户在使用该客户端时需要将请求数据手动拼接成Elasticsearch所需JSON格式进行发送，收到响应时同样也需要将返回的JSON数据手动封装成对象。虽然麻烦，不过该客户端兼容所有的Elasticsearch版本。
　　　　Java High Level REST Client：官方提供的高级客户端。该客户端基于低级客户端实现，它提供了很多便捷的API来解决低级客户端需要手动转换数据格式的问题。
　　1.构造数据

　　　　POST /haoke/house/_bulk

{"index":{"_index":"haoke","_type":"house"}}
{"id":"1001","title":"整租 · 南丹大楼 1居室 7500","price":"7500"}
{"index":{"_index":"haoke","_type":"house"}}
{"id":"1002","title":"陆家嘴板块，精装设计一室一厅，可拎包入住诚意租。","price":"8500"}
{"index":{"_index":"haoke","_type":"house"}}
{"id":"1003","title":"整租 · 健安坊 1居室 4050","price":"7500"}
{"index":{"_index":"haoke","_type":"house"}}
{"id":"1004","title":"整租 · 中凯城市之光+视野开阔+景色秀丽+拎包入住","price":"6500"}
{"index":{"_index":"haoke","_type":"house"}}
{"id":"1005","title":"整租 · 南京西路品质小区 21213三轨交汇 配套齐* 拎包入住","price":"6000"}
{"index":{"_index":"haoke","_type":"house"}}
{"id":"1006","title":"祥康里 简约风格 *南户型 拎包入住 看房随时","price":"7000"}

　　2.REST低级客户端

　　　　创建工程，引入依赖：

<dependencies>
        <!-- elasticsearch rest客户端 -->
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-client</artifactId>
            <version>6.5.4</version>
        </dependency>
        <!-- json格式化工具 -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.4</version>
        </dependency>
        <!-- 单元测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

　　　　编写测试用例：

public class ESRestTest {

    private static final ObjectMapper MAPPER = new ObjectMapper();
    private RestClient restClient;

    @Before
    public void init() {
        RestClientBuilder restClientBuilder = RestClient.builder(
                new HttpHost("192.168.43.182", 9200, "http"),
                new HttpHost("192.168.43.182", 9201, "http"),
                new HttpHost("192.168.43.182", 9202, "http"));
        restClientBuilder.setFailureListener(new RestClient.FailureListener() {
            @Override
            public void onFailure(Node node) {
                System.out.println("出错了 -> " + node);
            }
        });
        this.restClient = restClientBuilder.build();
    }

    @After
    public void after() throws IOException {
        restClient.close();
    }

    // 查询集群状态
    @Test
    public void testGetInfo() throws IOException {
        Request request = new Request("GET", "/_cluster/state");
        request.addParameter("pretty", "true"); // 格式化json数据
        Response response = this.restClient.performRequest(request);
        System.out.println(response.getStatusLine()); // 状态行
        System.out.println(EntityUtils.toString(response.getEntity())); // 响应体
    }

    // 新增数据
    @Test
    public void testCreateData() throws IOException {
        Request request = new Request("POST", "/haoke/house");
        Map<String, Object> data = new HashMap<>();
        data.put("id", "2001");
        data.put("title", "张江高科");
        data.put("price", "3500");
        request.setJsonEntity(MAPPER.writeValueAsString(data));
        Response response = this.restClient.performRequest(request);
        System.out.println(response.getStatusLine());
        System.out.println(EntityUtils.toString(response.getEntity()));
    }

    // 根据id查询数据
    @Test
    public void testQueryData() throws IOException {
        Request request = new Request("GET", "/haoke/house/at6XFXEBO18vQ71rkF2P");
        Response response = this.restClient.performRequest(request);
        System.out.println(response.getStatusLine());
        System.out.println(EntityUtils.toString(response.getEntity()));
    }

    // 搜索数据
    @Test
    public void testSearchData() throws IOException {
        Request request = new Request("POST", "/haoke/house/_search");
        String searchJson = "{"query": {"match": {"title": "拎包入住"}}}";
        request.setJsonEntity(searchJson);
        request.addParameter("pretty", "true");
        Response response = this.restClient.performRequest(request);
        System.out.println(response.getStatusLine());
        System.out.println(EntityUtils.toString(response.getEntity()));
    }
}

　　　　从使用中，可以看出，基本和我们使用RESTful api使用几乎是一致的。

　　3.REST高级客户端

　　　　引入依赖：

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-high-level-client</artifactId>
    <version>6.5.4</version>
</dependency>

　　　　编写测试用例：

public class RestHighLevelTest {

    private RestHighLevelClient client;

    @Before
    public void init() {
        RestClientBuilder restClientBuilder = RestClient.builder(
                new HttpHost("192.168.43.182", 9200, "http"),
                new HttpHost("192.168.43.182", 9201, "http"),
                new HttpHost("192.168.43.182", 9202, "http"));
        restClientBuilder.setFailureListener(new RestClient.FailureListener() {
            @Override
            public void onFailure(Node node) {
                System.out.println("出错了 -> " + node);
            }
        });
        this.client = new RestHighLevelClient(restClientBuilder);
    }

    @After
    public void after() throws Exception {
        this.client.close();
    }

    /**
     * 新增文档，同步操作
     *
     * @throws Exception
     */
    @Test
    public void testCreate() throws Exception {
        Map<String, Object> data = new HashMap<>();
        data.put("id", "2002");
        data.put("title", "南京西路 拎包入住 一室一厅");
        data.put("price", "4500");
        IndexRequest indexRequest = new IndexRequest("haoke", "house").source(data);
        IndexResponse indexResponse = this.client.index(indexRequest, RequestOptions.DEFAULT);
        System.out.println("id->" + indexResponse.getId());
        System.out.println("index->" + indexResponse.getIndex());
        System.out.println("type->" + indexResponse.getType());
        System.out.println("version->" + indexResponse.getVersion());
        System.out.println("result->" + indexResponse.getResult());
        System.out.println("shardInfo->" + indexResponse.getShardInfo());
    }

    /**
     * 新增文档，异步操作
     *
     * @throws Exception
     */
    @Test
    public void testCreateAsync() throws Exception {
        Map<String, Object> data = new HashMap<>();
        data.put("id", "2003");
        data.put("title", "南京东路 最新房源 二室一厅");
        data.put("price", "5500");
        IndexRequest indexRequest = new IndexRequest("haoke", "house").source(data);
        this.client.indexAsync(indexRequest, RequestOptions.DEFAULT, new
                ActionListener<IndexResponse>() {
                    @Override
                    public void onResponse(IndexResponse indexResponse) {
                        System.out.println("id->" + indexResponse.getId());
                        System.out.println("index->" + indexResponse.getIndex());
                        System.out.println("type->" + indexResponse.getType());
                        System.out.println("version->" + indexResponse.getVersion());
                        System.out.println("result->" + indexResponse.getResult());
                        System.out.println("shardInfo->" + indexResponse.getShardInfo());
                    }

                    @Override
                    public void onFailure(Exception e) {
                        System.out.println(e);
                    }
                });

        System.out.println("ok");
        Thread.sleep(20000);
    }

    /**
     * 根据id查询数据
     *
     * @throws Exception
     */
    @Test
    public void testQuery() throws Exception {
        GetRequest getRequest = new GetRequest("haoke", "house", "bd7GFXEBO18vQ71roF3y");
        // 指定返回的字段
        String[] includes = new String[]{"title", "id"};
        String[] excludes = Strings.EMPTY_ARRAY;
        FetchSourceContext fetchSourceContext = new FetchSourceContext(true, includes, excludes);
        getRequest.fetchSourceContext(fetchSourceContext);
        GetResponse response = this.client.get(getRequest, RequestOptions.DEFAULT);
        System.out.println("数据 -> " + response.getSource());
    }

    /**
     * 判断是否存在
     *
     * @throws Exception
     */
    @Test
    public void testExists() throws Exception {
        GetRequest getRequest = new GetRequest("haoke", "house", "bd7GFXEBO18vQ71roF3y");
        // 不返回的字段
        getRequest.fetchSourceContext(new FetchSourceContext(false));
        boolean exists = this.client.exists(getRequest, RequestOptions.DEFAULT);
        System.out.println("exists -> " + exists);
    }

    /**
     * 删除数据
     *
     * @throws Exception
     */
    @Test
    public void testDelete() throws Exception {
        DeleteRequest deleteRequest = new DeleteRequest("haoke", "house", "bd7GFXEBO18vQ71roF3y");
        DeleteResponse response = this.client.delete(deleteRequest, RequestOptions.DEFAULT);
        System.out.println(response.status());// OK 或者 NOT_FOUND
    }

    /**
     * 更新数据
     *
     * @throws Exception
     */
    @Test
    public void testUpdate() throws Exception {
        UpdateRequest updateRequest = new UpdateRequest("haoke", "house", "at6XFXEBO18vQ71rkF2P");
        Map<String, Object> data = new HashMap<>();
        data.put("title", "张江高科2");
        data.put("price", "5000");
        updateRequest.doc(data);
        UpdateResponse response = this.client.update(updateRequest, RequestOptions.DEFAULT);
        System.out.println("version -> " + response.getVersion());
    }

    /**
     * 全文搜索
     *
     * @throws Exception
     */
    @Test
    public void testSearch() throws Exception {
        SearchRequest searchRequest = new SearchRequest("haoke");
        searchRequest.types("house");

        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        sourceBuilder.query(QueryBuilders.matchQuery("title", "拎包入住"));
        // 设置分页
        sourceBuilder.from(0);
        sourceBuilder.size(5);
        // 设置搜索的超时时间
        sourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS));

        searchRequest.source(sourceBuilder);
        SearchResponse search = this.client.search(searchRequest, RequestOptions.DEFAULT);
        System.out.println("搜索到 " + search.getHits().totalHits + " 条数据.");
        SearchHits hits = search.getHits();
        for (SearchHit hit : hits) {
            System.out.println(hit.getSourceAsString());
        }
    }
}