文章目錄
- 建立design-demo項目
- 建立EsController
- 建立EsService
- 建立EsServiceimpl
- 建立EsQueryProcessor
- 建立EsSqlQuery
- 建立EsSqlResult
建立design-demo項目
項目代碼:https://gitee.com/java_wxid/java_wxid/tree/master/demo/design-demo 項目結構如下(示例):
建立EsController
代碼如下(示例):
package com.example.designdemo.controller;
import com.example.designdemo.service.EsService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class EsController {
@Autowired
private EsService esService;
@PostMapping("es")
public Boolean query(@RequestParam String query, Long fetchSize) {
return esService.query(query, fetchSize);
}
}
建立EsService
代碼如下(示例):
package com.example.designdemo.service;
/**
* @author zhiwei Liao
* @Description
* @Date create in 2022/9/12 0012 21:03
*/
public interface EsService {
Boolean query(String query, Long fetchSize);
}
建立EsServiceimpl
代碼如下(示例):
package com.example.designdemo.service.impl;
import com.example.designdemo.esquery.EsQueryProcessor;
import com.example.designdemo.service.EsService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.Map;
import java.util.stream.Stream;
@Service
public class EsServiceimpl implements EsService {
@Autowired
private EsQueryProcessor esQueryProcessor;
public Boolean query(String query, Long fetchSize) {
Stream<Map<String, Object>> mapStream = esQueryProcessor
.scrollEsStream(query, fetchSize);
mapStream.forEach(x -> System.out.println(x));
return true;
}
}
建立EsQueryProcessor
代碼如下(示例):
package com.example.designdemo.esquery;
import org.springframework.stereotype.Component;
import org.springframework.web.client.RestTemplate;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
/**
* @Author: zhiwei Liao
* @Date: 2022/9/29 21:29
* @Description:
*/
@Component
public class EsQueryProcessor {
//1. 我們要用stream 傳回 為了節省記憶體
public Stream<Map<String, Object>> scrollEsStream(String query, Long fetchSize) {
return StreamSupport.stream(Spliterators
.spliteratorUnknownSize(new ScrollIterator(query, fetchSize), 0), false);
}
//2. 我們要 疊代器
private class ScrollIterator implements Iterator<Map<String, Object>> {
private String scrollId;
private List<String> columns;
Iterator<Map<String, Object>> iterator;
RestTemplate restTemplate = new RestTemplate(); // 真是項目中使用resttemplate的時候
//一定是進行過我們的 bean 配置注入的。這裡邊直接用new關鍵字是為了通路我們的es 接口。
//構造函數進行第一次查詢,并且初始化我們後續需要使用的 columns 和 iterator 和 scroll
public ScrollIterator(String query, Long fetchSize) {
EsSqlResult esSqlResult = restTemplate.postForObject("http://localhost:9200/_sql?format=json",
new EsSqlQuery(query, fetchSize), EsSqlResult.class);//第一次通路的結果出來了
this.scrollId = esSqlResult.getCursor();
this.columns = esSqlResult.getColumns()
.stream().map(x->x.get("name"))
.collect(Collectors.toList());
this.iterator = convert(columns, esSqlResult).iterator();
}
// hasNext 根據 是否 scrollId 為null進行後續的 第二次,第三次,,,的通路,直到 scrollId 為null
@Override
public boolean hasNext() {
return iterator.hasNext() || scrollNext();
}
private boolean scrollNext() {
if(iterator == null || this.scrollId == null) {
return false;
}
EsSqlResult esSqlResult = restTemplate.postForObject("http://localhost:9200/_sql?format=json",
new EsSqlQuery(this.scrollId), EsSqlResult.class);//第二次通路的結果出來了
this.scrollId = esSqlResult.getCursor();
this.iterator = convert(columns, esSqlResult).iterator();
return iterator.hasNext();
}
@Override
public Map<String, Object> next() {
return iterator.next();
}
}
//3. 傳回結果傳統一點 List<map>
private List<Map<String, Object>> convert(List<String> columns, EsSqlResult esSqlResult) {
List<Map<String, Object>> results = new ArrayList<>();
for(List<Object> row : esSqlResult.getRows()) {
Map<String, Object> map = new HashMap<>();
for(int i = 0; i < columns.size(); i++) {
map.put(columns.get(i), row.get(i));
}
results.add(map);
}
return results;
}
}
建立EsSqlQuery
package com.example.designdemo.esquery;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
/**
* @Author: zhiwei Liao
* @Date: 2022/9/29 21:29
* @Description:
*/
@JsonIgnoreProperties
public class EsSqlQuery {
private String query;
private Long fetchSize;
private String cursor;
public EsSqlQuery(String cursor) {
this.cursor = cursor;
}
public EsSqlQuery(String query, Long fetchSize) {
this.query = query;
this.fetchSize = fetchSize;
}
public String getQuery() {
return query;
}
public void setQuery(String query) {
this.query = query;
}
public Long getFetchSize() {
return fetchSize;
}
public void setFetchSize(Long fetchSize) {
this.fetchSize = fetchSize;
}
public String getCursor() {
return cursor;
}
public void setCursor(String cursor) {
this.cursor = cursor;
}
}
建立EsSqlResult
package com.example.designdemo.esquery;
import java.util.List;
import java.util.Map;
/**
* @Author: zhiwei Liao
* @Date: 2022/9/29 21:29
* @Description:
*/
public class EsSqlResult {
private List<Map<String, String>> columns;
private List<List<Object>> rows;
private String cursor;
public List<Map<String, String>> getColumns() {
return columns;
}
public void setColumns(List<Map<String, String>> columns) {
this.columns = columns;
}
public List<List<Object>> getRows() {
return rows;
}
public void setRows(List<List<Object>> rows) {
this.rows = rows;
}
public String getCursor() {
return cursor;
}
public void setCursor(String cursor) {
this.cursor = cursor;
}
}