当用户在搜索框输入字符时,我们应该提示出与该字符有关的搜索项,如图:
这种根据用户输入的字母,提示完整词条的功能,就是自动补全了。
因为需要根据拼音字母来推断,因此要用到拼音分词功能。
1.拼音分词器
要实现根据字母做补全,就必须对文档按照拼音分词。在GitHub
上恰好有elasticsearch
的拼音分词插件。地址:https://github.com/medcl/elasticsearch-analysis-pinyin
安装方式与iK
分词器一样,分三步:
①下载解压
②上传到虚拟机中,elasticsearch
的plugin
目录
③重启elasticsearch
④测试
详细安装步骤可以参考IK
分词器的安装过程。
测试用法如下:
POST /_analyze
{
"text": "我爱北京天安门",
"analyzer": "pinyin"
}
结果:
2.自定义分词器
默认的拼音分词器会将每个汉字单独分为拼音,而我们希望的是每个词条形成一组拼音,需要对拼音分词器做个性化定制,形成自定义分词器。
elasticsearch
中分词器(analyzer
)的组成包含三部分:
character filters
:在tokenizer
之前对文本进行处理。例如删除字符、替换字符tokenizer
:将文本按照一定的规则切割成词条(term
)。例如keyword
,就是不分词;还有ik_smart
tokenizer filter
:将tokenizer
输出的词条做进一步处理。例如大小写转换、同义词处理、拼音处理等
文档分词时会依次由这三部分来处理文档:
声明自定义分词器的语法如下:
PUT /test
{
"settings": {
"analysis": {
"analyzer": { // 自定义分词器
"my_analyzer": { // 分词器名称
"tokenizer": "ik_max_word",
"filter": "py"
}
},
"filter": { // 自定义tokenizer filter
"py": { // 过滤器名称
"type": "pinyin", // 过滤器类型,这里是pinyin
"keep_full_pinyin": false,
"keep_joined_full_pinyin": true,
"keep_original": true,
"limit_first_letter_length": 16,
"remove_duplicated_term": true,
"none_chinese_pinyin_tokenize": false
}
}
}
},
"mappings": {
"properties": {
"name": {
"type": "text",
"analyzer": "my_analyzer",
"search_analyzer": "ik_smart"
}
}
}
}
测试:
总结:
如何使用拼音分词器?
-
①下载
pinyin
分词器 -
②解压并放到
elasticsearch
的plugin
目录 -
③重启即可
如何自定义分词器?
-
①创建索引库时,在
settings
中配置,可以包含三部分 -
②
character filter
-
③
tokenizer
-
④
filter
拼音分词器注意事项?
- 为了避免搜索到同音字,搜索时不要使用拼音分词器
3.自动补全查询
elasticsearch
提供了Completion Suggester查询来实现自动补全功能。这个查询会匹配以用户输入内容开头的词条并返回。为了提高补全查询的效率,对于文档中字段的类型有一些约束:
-
参与补全查询的字段必须是
completion
类型。 -
字段的内容一般是用来补全的多个词条形成的数组。
比如,一个这样的索引库:
// 创建索引库
PUT test
{
"mappings": {
"properties": {
"title":{
"type": "completion"
}
}
}
}
然后插入下面的数据:
// 示例数据
POST test/_doc
{
"title": ["Sony", "WH-1000XM3"]
}
POST test/_doc
{
"title": ["SK-II", "PITERA"]
}
POST test/_doc
{
"title": ["Nintendo", "switch"]
}
查询的DSL
语句如下:
// 自动补全查询
GET /test/_search
{
"suggest": {
"title_suggest": {
"text": "s", // 关键字
"completion": {
"field": "title", // 补全查询的字段
"skip_duplicates": true, // 跳过重复的
"size": 10 // 获取前10条结果
}
}
}
}
4.实现酒店搜索框自动补全
现在,我们的hotel
索引库还没有设置拼音分词器,需要修改索引库中的配置。但是我们知道索引库是无法修改的,只能删除然后重新创建。
另外,我们需要添加一个字段,用来做自动补全,将brand
、suggestion
、city
等都放进去,作为自动补全的提示。
因此,总结一下,我们需要做的事情包括:
-
修改
hotel
索引库结构,设置自定义拼音分词器 -
修改索引库的
name
、all
字段,使用自定义分词器 -
索引库添加一个新字段
suggestion
,类型为completion
类型,使用自定义的分词器 -
给
HotelDoc
类添加suggestion
字段,内容包含brand
、business
-
重新导入数据到
hotel
库
4.1.修改酒店映射结构
代码如下:
// 酒店数据索引库
PUT /hotel
{
"settings": {
"analysis": {
"analyzer": {
"text_anlyzer": {
"tokenizer": "ik_max_word",
"filter": "py"
},
"completion_analyzer": {
"tokenizer": "keyword",
"filter": "py"
}
},
"filter": {
"py": {
"type": "pinyin",
"keep_full_pinyin": false,
"keep_joined_full_pinyin": true,
"keep_original": true,
"limit_first_letter_length": 16,
"remove_duplicated_term": true,
"none_chinese_pinyin_tokenize": false
}
}
}
},
"mappings": {
"properties": {
"id":{
"type": "keyword"
},
"name":{
"type": "text",
"analyzer": "text_anlyzer",
"search_analyzer": "ik_smart",
"copy_to": "all"
},
"address":{
"type": "keyword",
"index": false
},
"price":{
"type": "integer"
},
"score":{
"type": "integer"
},
"brand":{
"type": "keyword",
"copy_to": "all"
},
"city":{
"type": "keyword"
},
"starName":{
"type": "keyword"
},
"business":{
"type": "keyword",
"copy_to": "all"
},
"location":{
"type": "geo_point"
},
"pic":{
"type": "keyword",
"index": false
},
"all":{
"type": "text",
"analyzer": "text_anlyzer",
"search_analyzer": "ik_smart"
},
"suggestion":{
"type": "completion",
"analyzer": "completion_analyzer"
}
}
}
}
4.2.修改HotelDoc
实体
HotelDoc
中要添加一个字段,用来做自动补全,内容可以是酒店品牌、城市、商圈等信息。按照自动补全字段的要求,最好是这些字段的数组。
因此我们在HotelDoc
中添加一个suggestion
字段,类型为List<String>
,然后将brand
、city
、business
等信息放到里面。
代码如下:
package cn.itcast.hotel.pojo;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
@Data
@NoArgsConstructor
public class HotelDoc {
private Long id;
private String name;
private String address;
private Integer price;
private Integer score;
private String brand;
private String city;
private String starName;
private String business;
private String location;
private String pic;
private Object distance;
private Boolean isAD;
private List<String> suggestion;
public HotelDoc(Hotel hotel) {
this.id = hotel.getId();
this.name = hotel.getName();
this.address = hotel.getAddress();
this.price = hotel.getPrice();
this.score = hotel.getScore();
this.brand = hotel.getBrand();
this.city = hotel.getCity();
this.starName = hotel.getStarName();
this.business = hotel.getBusiness();
this.location = hotel.getLatitude() + ", " + hotel.getLongitude();
this.pic = hotel.getPic();
// 组装suggestion
if(this.business.contains("/")){
// business有多个值,需要切割
String[] arr = this.business.split("/");
// 添加元素
this.suggestion = new ArrayList<>();
this.suggestion.add(this.brand);
Collections.addAll(this.suggestion, arr);
}else {
this.suggestion = Arrays.asList(this.brand, this.business);
}
}
}
4.3.重新导入
重新执行之前编写的导入数据功能,可以看到新的酒店数据中包含了suggestion
:
4.4.自动补全查询的JavaAPI
之前自动补全查询的DSL
,而没有对应的JavaAPI
,这里给出一个示例:
@Test
void testSuggest() throws IOException {
// 1.准备Request
SearchRequest request = new SearchRequest("hotel");
// 2.准备DSL
request.source().suggest(new SuggestBuilder().addSuggestion(
"suggestions",
SuggestBuilders.completionSuggestion("suggestion")
.prefix("h")
.skipDuplicates(true)
.size(10)
));
// 3.发送请求
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 4.解析响应
System.out.println("response = " + response);
}
而自动补全的结果也比较特殊,解析的代码如下:
@Test
void testSuggest() throws IOException {
// 1.准备Request
SearchRequest request = new SearchRequest("hotel");
// 2.准备DSL
request.source().suggest(new SuggestBuilder().addSuggestion(
"suggestions",
SuggestBuilders.completionSuggestion("suggestion")
.prefix("h")
.skipDuplicates(true)
.size(10)
));
// 3.发送请求
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 4.解析响应
//System.out.println("response = " + response);
Suggest suggest = response.getSuggest();
// 4.1 根据名称获取补全结果
CompletionSuggestion suggestions = suggest.getSuggestion("suggestions");
// 4.2 获取options并遍历
for (CompletionSuggestion.Entry.Option option : suggestions.getOptions()) {
// 4.3 获取一个option的text,,也就是补全的词条
String string = option.getText().string();
System.out.println(string);
}
}
4.5.实现搜索框自动补全
1)在cn.itcast.hotel.web
包下的HotelController
中添加新接口,接收新的请求:
@GetMapping("suggestion")
public List<String> getSuggestions(@RequestParam("key") String prefix) {
return hotelService.getSuggestions(prefix);
}
2)在cn.itcast.hotel.service
包下的IhotelService
中添加方法:
List<String> getSuggestions(String prefix);
3)在cn.itcast.hotel.service.impl.HotelService
中实现该方法:
@Override
public List<String> getSuggestions(String prefix) {
try {
// 1.准备Request
SearchRequest request = new SearchRequest("hotel");
// 2.准备DSL
request.source().suggest(new SuggestBuilder().addSuggestion(
"suggestions",
SuggestBuilders.completionSuggestion("suggestion")
.prefix(prefix)
.skipDuplicates(true)
.size(10)
));
// 3.发起请求
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 4.解析结果
Suggest suggest = response.getSuggest();
// 4.1.根据补全查询名称,获取补全结果
CompletionSuggestion suggestions = suggest.getSuggestion("suggestions");
// 4.2.获取options
List<CompletionSuggestion.Entry.Option> options = suggestions.getOptions();
// 4.3.遍历
List<String> list = new ArrayList<>(options.size());
for (CompletionSuggestion.Entry.Option option : options) {
String text = option.getText().toString();
list.add(text);
}
return list;
} catch (IOException e) {
throw new RuntimeException(e);
}
}