com.github.aly8246.collectionutil.core.PageInterface Maven / Gradle / Ivy
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Collection Util is a mybatis plug-in designed to solve the problem of N + 1 in mysql. When you use
Mysql to query linked tables and pages, there will be n + 1 problem. This plug-in can help you!
package com.github.aly8246.collectionutil.core;
import com.github.aly8246.collectionutil.core.impl.MysqlPageImpl;
import com.github.aly8246.collectionutil.main.CollectionInterceptor;
import com.github.aly8246.collectionutil.model.Index;
import com.github.aly8246.collectionutil.model.Limit;
import com.github.aly8246.collectionutil.model.Page;
import org.apache.ibatis.cache.CacheKey;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import java.sql.SQLException;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
/**
* 核心接口
*
* 为数据库方言提供sql字段解析，查询数量sql拼接和动态LIMIT核心算法实现
*
*
* @author 南有乔木
* @version v.1.0.2
* @see MysqlPageImpl
* @see CollectionInterceptor
*/
public interface PageInterface {
/**
* 获取id结果集
*
* @param ms MappedStatement
* @param executor 执行器
* @param parameter 参数
* @param boundSql 原始sql
* @param rowBounds 原始分页
* @param resultHandler 返回结果处理器
* @return id结果集
* @author 南有乔木
*/
List getIndexList(MappedStatement ms, Executor executor,
Object parameter, BoundSql boundSql,
RowBounds rowBounds, ResultHandler resultHandler) throws SQLException;
/**
* 根据分页包装结果来查询真正分页需要的数据
*
* @param ms MappedStatement
* @param executor 执行器
* @param parameter 参数
* @param boundSql 原始sql
* @param rowBounds 原始分页
* @param resultHandler 返回结果处理器
* @param cacheKey 缓存
* @param limit 分页包装结果
* @return 查询结果数据
* @author 南有乔木
*/
List query(MappedStatement ms, Executor executor,
Object parameter, BoundSql boundSql,
RowBounds rowBounds, ResultHandler resultHandler,
CacheKey cacheKey, Limit limit) throws SQLException;
/**
* 根据分页条件和查询结果集来计算limit
*
* @param indexList id结果集
* @param page 分页对象
* @return 分页包装结果
* @author 南有乔木
*/
Limit Limit(List indexList, Page page);
/**
* 根据分页条件和查询结果集来计算limit
*
* @param indexList id结果集
* @return id结果集(已初始化)
* @author 南有乔木
*/
static List init(List indexList) {
//第一个index的开始一定为0，结束为0到total
//第二个index的开始为上一个index的end，结束为total+自己的start
Iterator iterator = indexList.iterator();
Index temp = new Index();
while (iterator.hasNext()) {
Index next = iterator.next();
Index pre = temp;
if (next.getIndex() == 1) {
next.setStart(0);
next.setEnd(next.getTotal());
} else {
next.setStart(pre.getEnd());
next.setEnd(next.getStart() + next.getTotal());
}
temp = next;
}
return indexList;
}
/**
* 根据分页条件和查询结果集来计算limit
*
* @param indexList id结果集
* @param page 分页对象
* @return 分页包装结果
* @author 南有乔木
*/
static Limit getLimit(List indexList, Page page) {
if (page.getPage() == 0) page.setPage(1);
if (page.getPageSize() == 0) page.setPage(10);
//TODO 是否开启分页数据保护 还是返回空
//if (page.getPage() > indexList.size()) page.setPage(indexList.size());
if (page.getPage() > indexList.size()) return null;
if (page.getPageSize() == 1) {
Index index = indexList.get(page.getPage() - 1);
return new Limit(index.getStart(), index.getTotal());
} else {
int end = (page.getPage() * page.getPageSize());
int start = end - page.getPageSize();
List tempList = IntStream
.range(start, end)
.filter(i -> i < indexList.size())
.mapToObj(indexList::get)
.collect(Collectors.toList());
//limit等于list里第一个数据的开始到最后一个数据的结束
if (tempList.size() == 1)
return new Limit(tempList.get(0).getStart(), tempList.get(0).getTotal());
else if (tempList.size() > 1) {
return new Limit(tempList.get(0).getStart(), tempList.stream().mapToInt(Index::getTotal).sum());
}
}
//无分页数据
return null;
}
}