扩展tk.mybatis的流式查询功能实现

mybatis查询默认是一次获取全部， 有时候需要查询上万上百万数据时，如果一次性读取到内存中，会容易导致oom问题。这时候需要采用流式查询。以下扩展了tk.mybatis的流式查询功能。 直接上干货：

@options注解是关键

import org.apache.ibatis.annotations.options;import org.apache.ibatis.annotations.lectprovider;import org.apache.ibatis.mapping.resultttype;import org.apache.ibatis.ssion.result年的英文handler;/** * 通用mapper接口,流式查询 * * @param <t> 不能为空 * @author sunchangtan */@tk.mybatis.mapper.annotation.registermapperpublic interface lectstreamby传说故事examplemapper<t> {    /**     * 根据example条件和rowbounds进行流式查询     *     * @param example     * @return     */    @options(resultttype = resultttype.forward_only, fetchsize = 1000)    @lectprovider(type = streamexampleprovider.class, method = "dynamicsql")    void lectstreambyexamplemapper(object example, resulthandler resulthandler);}

带rowbounds的流式查询

import org.apache.ibatis.annotations.options;import org.apache.ibatis.annotations.lectprovider;import org.apache.ibatis.mapping.resultttype;import org.apache.ibatis.ssion.resulthandler;import org.apache.ibat李白的诗is.ssion.rowbounds;/** * 通用mapper接口,流式查询 * * @param <t> 不能为空 * @author sunchangtan */@tk.mybatis.mapper.annotation.registermapperpublic interface lectstreambyexamplerowboundsmapper<t> {    /**     * 根据example条件和rowbounds进行流式查询     *     * @param example     * @return     */    @options(resultttype = resultttype.forward_only, fetchsize = 1000)    @lectprovider(type = streamexampleprovider.class, method = "dynamicsql")    void lectstreambyexamplerowboundsmapper(object example, rowbounds rowbounds, resulthandler resulthandler);}

流式exampleprovider

import org.apache.ibatis.mapping.mappedstatement;import tk.mybatis.mapper.mapperhelper.mapperhelper;import tk.mybatis.mapper.provider.exampleprovider;/** * 流式查询的sqlprovider * @author sunchangtan */public class streamexampleprovider extends exampleprovider {    public streamexampleprovider(class<?> mapperclass, mapperhelper mapperhelper) {        super(mapperclass, mapperhelper);    }    /**     * 根据example流式查询     *     * @param ms     * @return     */    public string lectstreambyexamplemapper(mappedstatement ms) {        return this.lectbyexample(ms);    }    /**     * 根据example和rowbounds流式查询     * @param ms     * @return     */    public string lectstreambyexamplerowboun爱就一个字歌词dsmapper(mappedstatement ms) {        return this.lectbyexample(ms);    }}

将lectstreambyexamplemapper和lectstreambyexamplerowboundsmapper组合成一个接口

/** * 流式查询接口 * @param <t> * @author sunchangtan */@tk.mybatis.mapper.annotation.registermapperpublic interface streammapper<t> extends        lectstreambyexamplemapper<t>,        lectstreambyexamplerowboundsmapper<t> {}

在bamapper中加入streammapper

/** * mapper的基类 * @author sunchangtan * @param <t> */public interface bamapper<t> extends mapper<t>, mysqlmapper<t>, streammapper<t> {}

使用例子：

this.urmapper.lectstreambyexamplerowbou假期ndsmapper(example, new rowbounds(0, 1), resultcontext -> {     ur ur= (ur) resultcontext.getresultobject();     system.out.println(ur); });this.urmapper.lectstreambyexamplemapper(example, resultcontext -> {    ur ur= (ur) resultcontext.getresultobject();    system.out.println(ur);});

到此这篇关于扩展tk.mybatis的流式查询功能实现的文章就介绍到这了,更多相关tk.mybatis 流式查询内容请搜索www.887551.com以前的文章或继续浏览下面的相关文章希望大家以后多多支持www.887551.com！