Elastisearch是一个很强大,易用的搜索引擎
在系统上运行Elastisearch只需以下几步

1.下载Elastisearch

wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-5.4.0.zip

2.解压

unzip elasticsearch-5.4.0.zip

3.运行

elasticsearch-5.4.0/bin/elasticsearch

这时有可能会直接被Killed掉，因为内存溢出（OOM），elastisearch占用的内存非常大，所以在内存比较小的服务器上运行要先修改jvm的内存大小

vi elasticsearch-5.4.0/config/jvm.options

将22和23行的栈堆大小改为512M

-Xms512M
-Xmx512M

如果重新启动后还是killed就再改小一点

4.测试是否成功

curl    'http://localhost:9200/?pretty'

你能看到以下返回信息:

{
            "status":   200,
            "name": "Shrunken   Bones",
            "version":  {
                        "number":   "1.4.0",
                        "lucene_version":   "4.10"
            },
            "tagline":  "You    Know,   for Search"
}

则表明启动成功

接下来我们用Java的API来操作Elasticsearch

首先是导入elastisearch和log4j的包

POM

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.jk</groupId>
    <artifactId>ElasticsearchExample</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>transport</artifactId>
            <!--用哪个版本就填什么-->
            <version>5.4.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
            <version>2.7</version>
        </dependency>
    </dependencies>

</project>

以下是常用的几种操作

1.创建client

Client client = null;
        try {
            client = new PreBuiltTransportClient(Settings.EMPTY)
                    .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("localhost"), 9300));
        } catch (Exception e) {
            e.printStackTrace();
        }

2.创建索引

/**
     * 创建索引，有则先删除
     * @param client
     */
    private static void recreateIndex(Client client) {
        if (client.admin().indices().prepareExists(index).execute().actionGet()
                .isExists()) {
            DeleteIndexResponse deleteIndexResponse = client.admin().indices()
                    .delete(new DeleteIndexRequest(index)).actionGet();
            System.out.println("delete index :");
            System.out.println(deleteIndexResponse);
        }

        CreateIndexResponse createIndexResponse = client.admin().indices()
                .prepareCreate(index).execute().actionGet();
        System.out.println("create index :");
        System.out.println(createIndexResponse);
    }

3.插入数据

/**
     * 插入数据
     * @param client
     */
    @SuppressWarnings({"rawtypes", "unchecked"})
    private static void doIndex(final Client client) {
        Map s11 = new LinkedHashMap();
        s11.put("title", "Think in java");
        s11.put("origin", "美国");
        s11.put("description", "初级java开发人员必读的书");
        s11.put("author", "Bruce Eckel");
        s11.put("price", 108);

        Map s12 = new LinkedHashMap();
        s12.put("title", "Head First Java");
        s12.put("origin", "英国");
        s12.put("description", "java入门教材");
        s12.put("author", "Kathy Sierra");
        s12.put("price", 54);

        Map s21 = new LinkedHashMap();
        s21.put("title", "Design Pattern");
        s21.put("origin", "法国");
        s21.put("description", "程序员不得不读的设计模式");
        s21.put("author", "Kathy Sierra");
        s21.put("price", 89);

        Map s22 = new LinkedHashMap();
        s22.put("title", "黑客与画家");
        s22.put("origin", "法国");
        s22.put("description", "读完之后脑洞大开");
        s22.put("author", "Paul Graham");
        s22.put("price", 35);

        BulkResponse bulkResponse = client
                .prepareBulk()
                .add(client.prepareIndex(index, type).setId("11").setSource(s11).setOpType(IndexRequest.OpType.INDEX).request())
                .add(client.prepareIndex(index, type).setId("12").setSource(s12).setOpType(IndexRequest.OpType.INDEX).request())
                .add(client.prepareIndex(index, type).setId("21").setSource(s21).setOpType(IndexRequest.OpType.INDEX).request())
                .add(client.prepareIndex(index, type).setId("22").setSource(s22).setOpType(IndexRequest.OpType.INDEX).request())
                .execute().actionGet();
        if (bulkResponse.hasFailures()) {
            System.err.println("index docs ERROR:" + bulkResponse.buildFailureMessage());
        } else {
            System.out.println("index docs SUCCESS:");
            System.out.println(bulkResponse);
        }
    }

4.查询所有

    /**
     * 查询所有
     */
    private static void searchAll(Client client) {
        SearchResponse response = client.prepareSearch(index)
                .setQuery(QueryBuilders.matchAllQuery())
                .setExplain(true).execute().actionGet();
        System.out.println("searchAll : ");
        for (SearchHit searchHit : response.getHits()) {
            System.out.println("********");
            System.out.println(searchHit.getSource());
        }
    }

5.关键词查询

    /**
     * 关键词查询
     *
     * @param client
     */
    private static void searchKeyWord(Client client) {
        SearchResponse response = client.prepareSearch(index)
                //查询所有字段匹配关键字
                .setQuery(QueryBuilders.matchQuery("_all", "法国"))
                //设置最小匹配程度
//                .setQuery(QueryBuilders.matchQuery("_all", "法国").minimumShouldMatch("100%"))
                .execute().actionGet();
        System.out.println("searchKeyWord : ");
        System.out.println(response);
    }

6.数值范围过滤

    /**
     * 数值范围过滤
     *
     * @param client
     */
    private static void searchRange(Client client) {
        SearchResponse response = client.prepareSearch(index).
                //大于80，小于100
                setQuery(QueryBuilders.rangeQuery("price").gt(80).lt(100))
                .execute()
                .actionGet();
        System.out.println("searchRange : ");
        System.out.println(response);
    }

7.排序

    /**
     * 排序
     *
     * @param client
     */
    private static void searchOrdered(Client client) {
        SearchResponse response = client.prepareSearch(index)
                .setQuery(QueryBuilders.matchAllQuery())
                //根据价格降序排序
                .addSort(SortBuilders.fieldSort("price")
                        .order(SortOrder.DESC)).execute().actionGet();
        System.out.println("searchOrdered : ");
        System.out.println(response);
    }

8.高亮关键字

/**
     * 高亮关键字
     * @param client
     */
    private static void searchHightlight(Client client) {
        //高亮多个字段
        HighlightBuilder highlightBuilder = new HighlightBuilder();
        highlightBuilder.field("title");
        highlightBuilder.field("description");
        SearchResponse response = client.prepareSearch(index)
                //单条件匹配，高亮时只能高亮该字段
//                .setQuery(QueryBuilders.matchQuery("title", "java"))
                //多条件匹配，高亮时只能高亮多个字段
                .setQuery(QueryBuilders.multiMatchQuery("开发人员必读", "title", "description"))
                .highlighter(highlightBuilder)
                .execute()
                .actionGet();
        System.out.println("searchHightlight : ");
        System.out.println(response);
    }

9.根据id查找

    /**
     * 根据id查找
     * @param client
     */
    private static void findById(final Client client) {
        String id="12";
        GetResponse response = client.prepareGet(index, type, id).get();
        System.out.println("findById");
        System.out.println(response);
    }

10.删除

     /**
     * 删除
     * @param client
     */
    private static void deleteById(Client client) {
        String id="12";
        DeleteResponse response = client.prepareDelete(index, type, id).get();
    }

11.更新

    /**
     * 更新
     * @param client
     */
    private static void updateById(Client client) {
        try {
            String id="11";
            client.prepareUpdate(index, type, id)
                    .setDoc(jsonBuilder()
                            .startObject()
                            .field("title", "白鹿原")
                            .endObject())
                    .get();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

常用的操作就这些,代码上传到https://github.com/jkgeekJack/ElasticsearchExample

建议大家还可以看看Elasticsearch: 权威指南,这里有更详细的介绍