4_MyBatis传统DAO模式开发

迷南。 2023-09-30 17:18 0阅读 0赞

普通模式,也称为传统DAO模式,就是在传统DAO模式下,定义接口和实现类,如 interface EmpDao class EmpDaoImpl implements EmpDao. 在实现类中,用SQLSession对象调用select insert delete update 等方法实现.目前极为少见.在传统模式下,我们需要知道SqlSession对象 实现CURD和 参数传递的处理

1\_sqlSession查询的三种方式

SqlSession对象本身的API中就有三个查询方法,分别能够实现如下查询方式

1返回单个对象 selectOne

2返回对象List集合 selectList

3返回对象Map集合 selectMap

接下来我们就对这三个方法进行一个快速的学习

![abc2f49fbc6ea895eac651fc67970bb0.png][]

创建Emp实体类

@AllArgsConstructor  
@NoArgsConstructor  
@Data  
public class Emp implements Serializable \{  
private Integer empno;  
private String ename;  
private String job;  
private Integer mgr;  
private Date hiredate;  
private Double sal;  
private Double comm;  
private Integer deptno;  
\}  
准备Mapper映射文件

<?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">  
<mapper namespace="EmpMapper">  
  
<select id="findOne" resultType="emp" >  
select \* from emp where empno = 7499  
</select>  
  
<select id="findAll" resultType="emp">  
select \* from emp  
</select>  
  
<select id="findEmpMap" resultType="map">  
select \* from emp  
</select>  
</mapper>  
sqlMapConfig中导入EmpMapper映射文件

<mappers>  
<mapper resource="com/msb/mapper/DeptMapper.xml"/>  
<mapper resource="com/msb/mapper/EmpMapper.xml"/>  
</mappers>

测试代码

package com.msb.test;  
import com.msb.pojo.Dept;  
import com.msb.pojo.Emp;  
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 org.junit.After;  
import org.junit.Before;  
import org.junit.Test;  
import java.io.IOException;  
import java.io.InputStream;  
import java.util.List;  
import java.util.Map;  
import java.util.Set;  
/\*\*  
\* @Author: Ma HaiYang  
\* @Description: MircoMessage:Mark\_7001  
\*/  
public class Test2 \{  
private SqlSession sqlSession;  
@Before  
public void init()\{  
SqlSessionFactoryBuilder ssfb =new SqlSessionFactoryBuilder();  
InputStream resourceAsStream = null;  
try \{  
resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
SqlSessionFactory factory=ssfb.build(resourceAsStream) ;  
sqlSession=factory.openSession();  
\}  
@Test  
public void testSelectOne()\{  
// 查询单个对象  
System.out.println("sqlSession查询单个对象");  
Emp emp = sqlSession.selectOne("findOne");  
System.out.println(emp);  
\}  
@Test  
public void testSelectList()\{  
// 查询多个对象的List集合  
System.out.println("sqlSession查询对象List集合");  
List<Emp> emps = sqlSession.selectList("EmpMapper.findAll");  
emps.forEach(System.out::println);  
\}  
@Test  
public void testSelectMap()\{  
// 查询多个对象的Map集合  
System.out.println("sqlSession查询对象Map集合");  
Map<Integer, Emp> empMap = sqlSession.selectMap("findEmpMap", "EMPNO");  
Set<Integer> empnos = empMap.keySet();  
for (Integer empno : empnos) \{  
System.out.println(empno+" :" +empMap.get(empno));  
\}  
\}  
@After  
public void release()\{  
// 关闭SQLSession  
sqlSession.close();  
\}  
\}

2\_sqlSession传递参数的三种方式

1 单个基础数据类型作为参数

2 多个基础数据类型的map 集合作为参数

3 引用类型作为参数

Mapper映射文件

<?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">  
<mapper namespace="EmpMapper2">  
  
<select id="findByEmpno" resultType="emp" parameterType="int">  
select \* from emp where empno = \#\{empno\}  
</select>  
  
<select id="findEmpByDeptnoAndSal" resultType="emp" parameterType="map">  
select \* from emp where deptno = \#\{deptno\} and sal >= \#\{sal\}  
</select>  
  
<select id="findEmpByDeptnoAndSal2" resultType="emp" parameterType="emp">  
select \* from emp where deptno = \#\{deptno\} and sal >= \#\{sal\}  
</select>  
</mapper>  
测试代码

package com.msb.test;  
import com.msb.pojo.Emp;  
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 org.junit.After;  
import org.junit.Before;  
import org.junit.Test;  
import java.io.IOException;  
import java.io.InputStream;  
import java.util.HashMap;  
import java.util.List;  
import java.util.Map;  
import java.util.Set;  
/\*\*  
\* @Author: Ma HaiYang  
\* @Description: MircoMessage:Mark\_7001  
\*/  
public class Test3 \{  
private SqlSession sqlSession;  
@Before  
public void init()\{  
SqlSessionFactoryBuilder ssfb =new SqlSessionFactoryBuilder();  
InputStream resourceAsStream = null;  
try \{  
resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
SqlSessionFactory factory=ssfb.build(resourceAsStream) ;  
sqlSession=factory.openSession();  
\}  
@Test  
public void testSingleArg()\{  
// 测试单个基本数据类型作为参数  
Emp emp = sqlSession.selectOne("findByEmpno", 7499);  
System.out.println(emp);  
\}  
@Test  
public void testMapArg()\{  
// 测试Map集合作为参数  
Map<String,Object> args=new HashMap<>();  
args.put("deptno", 20);  
args.put("sal", 3000.0);  
List<Emp> emps = sqlSession.selectList("findEmpByDeptnoAndSal", args);  
emps.forEach(System.out::println);  
\}  
@Test  
public void testEmpArg()\{  
// 测试Map集合作为参数  
Emp arg =new Emp();  
arg.setDeptno(10);  
arg.setSal(2000.0);  
List<Emp> emps = sqlSession.selectList("findEmpByDeptnoAndSal2", arg);  
emps.forEach(System.out::println);  
\}  
@After  
public void release()\{  
// 关闭SQLSession  
sqlSession.close();  
\}  
\}

3\_sqlSession完成DML所有操作

Mapper映射文件

<?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">  
<mapper namespace="EmpMapper3">  
  
  
<insert id="addEmp" parameterType="emp">  
insert into emp values(\#\{empno\},\#\{ename\},\#\{job\},\#\{mgr\},\#\{hiredate\},\#\{sal\},\#\{comm\},\#\{deptno\})  
</insert>  
  
<update id="updateEmp" parameterType="emp">  
update emp set ename = \#\{ename\} where empno=\#\{empno\}  
</update>  
  
<delete id="deleteEmp" parameterType="int">  
delete from emp where empno >= \#\{empno\}  
</delete>  
</mapper>  
测试代码

package com.msb.test;  
import com.msb.pojo.Emp;  
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 org.junit.After;  
import org.junit.Before;  
import org.junit.Test;  
import java.io.IOException;  
import java.io.InputStream;  
import java.util.Date;  
import java.util.HashMap;  
import java.util.List;  
import java.util.Map;  
/\*\*  
\* @Author: Ma HaiYang  
\* @Description: MircoMessage:Mark\_7001  
\*/  
public class Test4 \{  
private SqlSession sqlSession;  
@Before  
public void init()\{  
SqlSessionFactoryBuilder ssfb =new SqlSessionFactoryBuilder();  
InputStream resourceAsStream = null;  
try \{  
resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
SqlSessionFactory factory=ssfb.build(resourceAsStream) ;  
sqlSession=factory.openSession(true);  
\}  
@Test  
public void testInsert()\{  
Emp emp =new Emp(null,"按住啦Baby","SALESMAN",7839,new Date(),3100.0, 200.0,10 );  
int rows = sqlSession.insert("addEmp", emp);  
System.out.println(rows);  
// 手动提交事务  
//sqlSession.commit();  
/\*增删改 要提交事务  
\* sqlSession.commit();手动提交事务  
\* sqlSession=factory.openSession(true); 设置事务自动提交  
\* \*/  
\}  
@Test  
public void testUpdate()\{  
Emp emp =new Emp( );  
emp.setEname("晓明");  
emp.setEmpno(7937);  
int rows = sqlSession.update("updateEmp", emp);  
System.out.println(rows);  
\}  
@Test  
public void testDelete()\{  
int rows = sqlSession.delete("deleteEmp", 7936);  
System.out.println(rows);  
\}  
@After  
public void release()\{  
// 关闭SQLSession  
sqlSession.close();  
\}  
\}

[abc2f49fbc6ea895eac651fc67970bb0.png]: https://img-blog.csdnimg.cn/img_convert/abc2f49fbc6ea895eac651fc67970bb0.png