注解实现嵌套动态SQL

Mapper, 在接口和接口的方法上加上相应的注解

import org.apache.ibatis.annotations.SelectProvider;
import org.mybatis.spring.annotation.MapperScan;
import yycg.base.domain.vo.SysuserCustom;
import yycg.base.domain.vo.SysuserQueryVo;
import yycg.base.mapper.sql.SysuserCustomSql;

import java.util.List;

/**
 * Created with IDEA
 * author:bigStone
 * Date:2019/5/2
 **/
@MapperScan
public interface SysuserMapperCustom {

    @SelectProvider(type = SysuserCustomSql.class, method = "findSysuserCustomList")
    List findSysuserCustomList(SysuserQueryVo sysuserQueryVo) throws Exception;

}

生成动态SQL的类

import org.apache.ibatis.jdbc.SQL;
import yycg.base.domain.vo.SysuserQueryVo;

/**
 * 多表嵌套查询
 * Created with IDEA
 * author:bigStone
 * Date:2019/5/2
 **/
public class SysuserCustomSql {

    public String findSysuserCustomList(SysuserQueryVo sysuserQueryVo) {

        SQL sql1 = new SQL();
        sql1.SELECT("SYSUSER.id, SYSUSER.userid,SYSUSER.username," +
                " SYSUSER.groupid, SYSUSER.sysid, sysuser.USERSTATE, " +
                "decode(SYSUSER.Groupid, '1', " +
                "(select mc from userjd where id = sysuser.sysid), '2', " +
                "(select mc from userjd where id = sysuser.sysid), '3', " +
                "(select mc from useryy where id = sysuser.sysid), '4'," +
                "(select mc from usergys where id = sysuser.sysid)) sysmc");
        sql1.FROM("sysuser");

        SQL sql2 = new SQL() {{
            SELECT("SYSUSER2.*");
            //把sql1的查询语句作为sql2的查询对象，别名为SYSUSER2
            FROM("(" + sql1.toString() + ") SYSUSER2");
            if (sysuserQueryVo.getSysuserCustom() != null) {
                if (sysuserQueryVo.getSysuserCustom().getUserid() != null && sysuserQueryVo.getSysuserCustom().getUserid() != "") {
                    WHERE("SYSUSER2.userid = #{sysuserCustom.userid}");
                }
                if (sysuserQueryVo.getSysuserCustom().getUsername() != null && sysuserQueryVo.getSysuserCustom().getUsername() != "") {
                    WHERE("SYSUSER2.username = #{sysuserCustom.username}");
                }
                if (sysuserQueryVo.getSysuserCustom().getGroupid() != null && sysuserQueryVo.getSysuserCustom().getGroupid() != "") {
                    WHERE("SYSUSER2.groupid = #{sysuserCustom.groupid}");
                }
                if (sysuserQueryVo.getSysuserCustom().getSysmc() != null && sysuserQueryVo.getSysuserCustom().getSysmc() != "") {
                    WHERE("SYSUSER2.sysmc like '%' || #{sysuserCustom.sysmc} || '%' ");
                }
            }
        }};

        SQL sql3 = new SQL() {{
            SELECT("page_1.*, rownum page_num");
            //把sql2的查询语句作为sql3的查询对象，并给别名page_1
            FROM("(" + sql2.toString() + ") page_1");
            if (sysuserQueryVo.getPageBean() != null) {
                WHERE("rownum <= #{pageBean.endIndex}");
            }
        }};

        SQL sql4 = new SQL() {{
            SELECT("page_2.*");
            //把sql3的查询语句作为sql4的查询对象， 并给别名page_2
            FROM("(" + sql3.toString() + ") page_2");
            if (sysuserQueryVo.getPageBean() != null) {
                WHERE("page_2.page_num >= #{pageBean.startIndex}");
            }
        }};
        return sql4.toString();
    }
}

参数为自定义查询类

/**
 *自定义查询类，包含分页信息和实体类信息
 * Created with IDEA
 * author:bigStone
 * Date:2019/5/2
 **/
public class SysuserQueryVo  {
	//自定义PageBean类，包含分页的相关信息
    private PageBean pageBean;
	//用于映射查询结果的实体类
    private SysuserCustom sysuserCustom;

    public PageBean getPageBean() {
        return pageBean;
    }

    public void setPageBean(PageBean pageBean) {
        this.pageBean = pageBean;
    }

    public SysuserCustom getSysuserCustom() {
        return sysuserCustom;
    }

    public void setSysuserCustom(SysuserCustom sysuserCustom) {
        this.sysuserCustom = sysuserCustom;
    }
}

  虽然一个sql调了大半天，但还是有收获的，主要是当时思路不够清晰，传参的时候比较头痛，后来把每个查询都分离出来，再再原来的基础上一步一步嵌套，还是比较简单的，虽然费了老大事，但感觉还是比配置文件好用。

  传参问题： 如果传递的是一个对象，直接  #{属性} 即可取值， 如果对象属性依然是包装类，可以用 #{属性.下一级属性} 来取值。