mybatis（二）接口編程 、動態sql 、批量刪除 、動態更新、連表查詢

原理等不在贅述，這里主要通過代碼展現。

在mybatis（一）基礎上，新建一個dao包，並在里面編寫接口，然后再在xml文件中引入接口路徑，其他不變，在運用階段將比原始方法更節約時間，因為不用再去手動的

引用sql,我們只需調用dao層的方法，然后讓dao層的方法去找配置文件，去找sql，sql查詢數據並賦值給對象，或者設置對象參數值在經過sql更新到數據庫，小伙伴們這就是

orm對象關系映射模型！（個人見解，不對之處請指正。）

新增后項目：

一、新建一個com.ckx.dao包，並new一個（interface）DeptDao.java。

DeptDao.java：

package com.ckx.dao;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.ckx.entity.Dept;

public interface DeptDao {
    //通過ID查數據
    public Dept selectDeptById(int deptno);
    //查詢一個結果集
    public List<Dept> selectDeptAll();
    //多條件動態 ，查詢注意@Param的重要性，沒有回報參數not find錯誤
    public List<Dept> selectDeptByMore(@Param("deptno") int deptno,@Param("dname") String dname);
    //根據ID動態修改
    public int updateDeptById(Dept d);
    //批量刪除
    public int deleteDepts(List<Integer> list);
    //新增
    public int insertDept(Dept d); 
    public int insertDept2(Dept d); 
    //多表關聯
    public Dept selectDeptEmps(int t);
    

}

 

二、配置Dept.xml：

<?xml version="1.0" encoding="UTF-8" ?>    
<!DOCTYPE mapper    
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"    
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--接口編程-->
<mapper namespace="com.ckx.dao.DeptDao">

    <resultMap type="Dept" id="DeptList">
        <result column="deptno" property="deptno"/>
        <result column="dname" property="dname"/>
        <result column="loc" property="loc"/>
        <!--        代表集合數據  property：實體bean中的屬性名稱 ofType：數據類型 -->
        <collection property="emps" ofType="Emp">
            <result column="EMPNO" property="empno" />
            <result column="ENAME" property="ename" />
            <result column="JOB" property="job" />
            <result column="MGR" property="mgr" />
            <result column="HIREDATE" property="hiredate" />
            <result column="SAL" property="sal" />
            <result column="COMM" property="comm" />
            <result column="DEPNO" property="depno" />
        </collection>
    </resultMap>
<!--    通過ID查詢-->
    <select id="selectDeptById" parameterType="int" resultType="Dept">
        select * from dept where deptno = #{deptno}
    </select>
<!--    查詢整張表，注意返回參數是一個DeptList集合，這個需要在上面配置-->
    <select id="selectDeptAll"  resultMap="DeptList">
        select * from dept 
    </select>
<!--    多參數動態查詢-->
    <select id="selectDeptByMore"  resultMap="DeptList">
        select * from dept  
        <where>
            <if test="deptno != 0">
                deptno = #{deptno}
            </if>
            <if test="dname != null">
                or dname like #{dname}
            </if>
        </where>
    </select>
<!--    動態更新數據-->
    <update id="updateDeptById"  parameterType="Dept">
        update   
        dept 
        <set>
            <if test="deptno != null">
                 dname = #{dname},
            </if>
            <if test="deptno != null">
                 loc = #{loc}
            </if>
        </set>
        where 
        deptno = #{deptno}
    </update>
<!--    批量刪除-->
    <delete id="deleteDepts" parameterType="list">
        delete from dept where deptno in
        <foreach item="item" index="index" collection="list" open="("
            separator=", " close=") ">
            #{item}
         </foreach>
    </delete>
<!--    新增數據-->
    <insert id="insertDept" parameterType="Dept" >
        insert into dept (deptno,dname,loc) values (#{deptno},#{dname},#{loc})
    </insert>
<!--    連表查詢，注意1、到層返回值為對象類本身 2、查詢返回值為list集合。-->
    <select id="selectDeptEmps" parameterType="int" resultMap="DeptList">
        SELECT d.DNAME,e.*  FROM dept d,emp e WHERE d.DEPTNO=e.DEPNO and d.DEPTNO = #{deptno}
    </select>
    
<!--    未完成-->
    <sql id='dept'>TEST_USER</sql>
     <!-- 注意這里需要先查詢自增主鍵值 -->
     <insert id="insertDept2" parameterType="Dept">
         <selectKey keyProperty="deptno" resultType="int" order="BEFORE">
             SELECT LAST_INSERT_deptno()
         </selectKey>
         insert into <include refid="dept" /> (deptno,dname,loc)
             values ( #{deptno},#{dname},#{loc} )
     </insert>



</mapper>

三、測試

DeptTest.java：

package com.ckx.test;

import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

import javax.mail.Session;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.ckx.dao.DeptDao;
import com.ckx.entity.Dept;
import com.ckx.entity.Emp;

public class DeptTest {
    static SqlSessionFactory sessionFactory;
    static Reader reader;
    static SqlSession sqlSession;

    static {
        try {
            reader = Resources.getResourceAsReader("config.xml");
            sessionFactory = new SqlSessionFactoryBuilder().build(reader);
            sqlSession = sessionFactory.openSession();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    
    public void select(){
        DeptDao dao = sqlSession.getMapper(DeptDao.class);
        Dept d =  dao.selectDeptById(10);
        System.out.println(d.getDname());
    }

    public void selectDeptAll(){
        DeptDao dao = sqlSession.getMapper(DeptDao.class);
        List<Dept> list = dao.selectDeptAll();
        
        for (Dept dept : list) {
            String s = dept.getDname();
            System.out.println(s);
        }
        
        Iterator<Dept> ite = list.iterator();
        while (ite.hasNext()) {
            Dept d = ite.next();
            String ss = d.getLoc();
            System.out.println(ss);
        }
        
        for (int i = 0; i < list.size(); i++) {
            Dept d = list.get(i);
            int t = d.getDeptno();
            System.out.println(t);
        }
    }

    public void selectDeptByMore(){
        DeptDao dao = sqlSession.getMapper(DeptDao.class);
        List<Dept> list = dao.selectDeptByMore(20,"A%");
        Iterator<Dept> it = list.iterator();
        while (it.hasNext()) {
            Dept dept = (Dept) it.next();
            String s = dept.getDname();
            System.out.println(s);
        }
    }
    
    public void updateDeptById(){
        DeptDao dao = sqlSession.getMapper(DeptDao.class);
        Dept d = new Dept();
        d.setDeptno(10);
        d.setDname("ASC");
        d.setLoc("desc");
        dao.updateDeptById(d);
        System.out.println(d.getDeptno()+d.getDname()+d.getLoc());
        sqlSession.commit();
    }
    
    public void deleteDepts(){
        DeptDao dao = sqlSession.getMapper(DeptDao.class);
        List<Integer> list = new ArrayList<Integer>();
        list.add(0);
        dao.deleteDepts(list);
    }

    public void insertDept(){
        DeptDao dao = sqlSession.getMapper(DeptDao.class);
        Dept d = new Dept();
        d.setDeptno(10);
        d.setDname("assc");
        d.setLoc("deff");
        dao.insertDept(d);
        sqlSession.commit();
    }
    //多表聯查
    public void selectDeptEmps(){
        DeptDao dao = sqlSession.getMapper(DeptDao.class);
        Dept d = dao.selectDeptEmps(10);
        List<Emp> list = d.getEmps();
        for (Emp emp : list) {
            String s = emp.getEname();
            System.out.println(d.getDname()+"\t"+s);
        }
        
    }
    ;
    //主鍵自增為完成
     public void insertDept2(){
        DeptDao dao = sqlSession.getMapper(DeptDao.class);
        Dept d = new Dept();
        d.setDname("sss");
        d.setLoc("ddd");
        dao.insertDept(d);
        sqlSession.commit();
        System.out.println(d.getDeptno());
    }
    
    public static void main(String[] args) {
        DeptTest dt = new DeptTest();
        dt.selectDeptEmps();
    }
}

以上皆為測試過運行正常的方法，每一個方法的調用只需能改dt后的方法即可。

具體注意說明：