Java日记——使用强大的Elastisearch搜索引擎

梦里梦外; 2023-10-14 16:34 5阅读 0赞

**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>
                
                <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();
            }
        }