Mybatis

关于Mybatis的简单介绍：myBatis是一个用于作用于数据库的

mybatis的配置说明：
这个项目需要创建的文件：
导入依赖：

 <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
    </dependency>

    <!-- 设置好数据库的引用和mybatis引用，使用的是本地仓库的缓存的包 -->
    <dependency>
      <groupId>com.oracle</groupId>
      <artifactId>ojdbc6</artifactId>
      <version>${ojdbc.version}</version>
    </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>${mybatis.version}</version>
    </dependency>

    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>${lombok.version}</version>
    </dependency>

    <!-- 分页插件导入 -->
    <dependency>
      <groupId>com.github.pagehelper</groupId>
      <artifactId>pagehelper</artifactId>
      <version>4.1.4</version>
    </dependency>

    <!-- 导入jstl的标签依赖包 -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <!-- 导入servlet的依赖包 -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.0.1</version>
      <scope>provided</scope>
    </dependency>
    <!-- 导入servlet.jsp的依赖包 -->
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

配置mysql的全局配置config.xml：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
	<settings>
		<!--是否开启全局二级缓存-->
		<setting name="cacheEnabled" value="true"/>
		<!-- 是否在控制台打印日志 -->
		<setting name="logImpl" value="STDOUT_LOGGING" />
	</settings>
	<!--类的别名配置区域-->

	<!-- 别名 -->
	<typeAliases>
		<typeAlias type="com.sc.pojo.Emp" alias="emp" />
		<typeAlias type="com.sc.pojo.News" alias="news" />
		<typeAlias type="com.sc.pojo.Theme" alias="theme" />
	</typeAliases>

	<!--分页插件-->
	<plugins>
		<plugin interceptor="com.github.pagehelper.PageHelper">
			<property name="dialect" value="oracle"/>
			<property name="offsetAsPageNum" value="false"/>
			<property name="rowBoundsWithCount" value="false"/>
			<property name="pageSizeZero" value="true"/>
			<property name="reasonable" value="false"/>
			<property name="supportMethodsArguments" value="false"/>
			<property name="returnPageInfo" value="none"/>
		</plugin>
	</plugins>

	<!-- 配置默认的数据库连接 -->
	<!-- 配置好数据库的执行引擎以及账号密码 -->
	<environments default="oracledb">
		<!-- 配置数据库连接信息 -->
		<environment id="oracledb">
			<transactionManager type="jdbc"></transactionManager>
			<dataSource type="pooled">
				<property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
				<property name="url" value="jdbc:oracle:thin:@localhost:1521:XE"/>
				<property name="username" value="scott"/>
				<property name="password" value="123"/>
			</dataSource>
		</environment>
		
		<!-- 配置数据库连接信息 -->
		<environment id="mysqldb">
			<transactionManager type="jdbc"></transactionManager>
			<dataSource type="pooled">
				<property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
				<property name="url" value="jdbc:oracle:thin:@localhost:1521:orcl"/>
				<property name="username" value="scott"/>
				<property name="password" value="tiger"/>
			</dataSource>
		</environment>
	</environments>
	<!--配置映射文件-->
	<mappers>
		<mapper resource="mapper/EmpMapper.xml"></mapper>
		<mapper resource="mapper/NewsMapper.xml"></mapper>
		<mapper resource="mapper/ThemeMapper.xml"></mapper>
	</mappers>
</configuration>

关于映射mapper.xml的配置：

<?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">
<!-- 配置好映射数据库中的关系-->
<mapper namespace="com.sc.dao.IEmpDao">
	<cache></cache>     <!--用于加入二级缓存 -->
    <resultMap id="getEmpListMap" type="emp" >
        <id property="no" column="empno" />
        <result column="ename" property="name" />
    </resultMap>
    <select id="getEmpList" resultMap="getEmpListMap">
        select * from emp
    </select>
    <select id="getEmpById" resultMap="getEmpListMap">
        select * from emp where empno=#{no}
    </select>
    <select id="getEmpByIdName" resultMap="getEmpListMap">
        select * from emp where empno=#{id} and ename = #{name}
    </select>
    <insert id="insertEmp">
        insert into emp(empno,ename,job,sal,hiredate)
        values(#{id},#{name},#{job},#{sal},#{time})
    </insert>
    <update id="UpdateEmpById" >
        update emp set ename=#{name} where empno = #{id}
    </update>

    <delete id="delEmpById">
        delete from emp where empno=#{id}
    </delete>

    <!--  动态查询中，大于和小于使用转义字符
          大于：>  &gt;         小于：<    &lt;
          大于等于：>=    &ge;   小于等于：<=   &le;
          模糊查询: 连接字符串使用concat();
    -->
    <select id="getEmpByIdJob" resultMap="getEmpListMap">
        select * from emp where 1=1
        <if test="id &gt; 0">
            and empno = #{id}
        </if>
        <if test="job != null and job != ''">
            and job like concat('%',concat(#{job},'%'))
        </if>
    </select>

    <delete id="delEmpByIds" >
        delete from emp2 where empno in
        <foreach collection="list" open="("
                 close=")" item="empno" separator=",">
            #{empno}
        </foreach>
    </delete>
</mapper>

关于dao的接口的配置：

public interface IEmpDao {
/**
 *这里每一个方法名对应mapper.xml中的id
 */
    List<Emp> getEmpList();  // 获取到所有的信息
    Emp getEmpById(int id);  // 根据ID获取信息
    Emp getEmpByIdName(@Param("id") int id, @Param("name") String name);  // 根据ID和姓名获取对象
    int delEmpById(int id);  //根据id删除对象
    int UpdateEmpById(@Param("id") int id,@Param("name")String name);    // 根据姓名进行更新对象
    int insertEmp(@Param("id") int id, @Param("name") String name, @Param("sal")String sal, @Param("job")String job,
                  @Param("time") Date time);  // 插入信息
    Emp getEmpByIdJob(@Param("id")int id,@Param("job")String job);   // 动态查询
    int delEmpByIds(List<Integer> empnoList);    // 批量删除
}

关于数据库字段与类对应的属性显示：

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.sql.Date;
import java.sql.Timestamp;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Emp {
    private int no;
    private String name;
    private String sal;
    private String job;
    private Date hiredate;
}

关于Mybatis的工厂的打开：

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 java.io.IOException;
import java.io.Reader;

public class SqlSessionUtil {
    static SqlSessionFactory sqlSessionFactory;
    static{
        try {
            Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static SqlSession openSqlSession(){
       return sqlSessionFactory.openSession();
    }
}

关于mybatis的使用，使用了反射：

public class EmpText {
    @Test
    public void test1(){
        SqlSession sqlSession = SqlSessionUtil.openSqlSession();
        IEmpDao empDao = sqlSession.getMapper(IEmpDao.class);
        List<Emp> list = empDao.getEmpList();
        for (Emp emp : list){
            System.out.println(emp);
        }
    }

    @Test
    public void test2(){
        SqlSession sqlSession = SqlSessionUtil.openSqlSession();
        IEmpDao empDao = sqlSession.getMapper(IEmpDao.class);
        Emp emp = empDao.getEmpById(7521);
        System.out.println(emp);
    }

    @Test
    public void test3(){
        SqlSession sqlSession = SqlSessionUtil.openSqlSession();
        IEmpDao empDao = sqlSession.getMapper(IEmpDao.class);
        Emp emp = empDao.getEmpByIdName(7521,"WARD");
        System.out.println(emp);
    }

    @Test
    public void test4(){
        SqlSession sqlSession = SqlSessionUtil.openSqlSession();
        IEmpDao empDao = sqlSession.getMapper(IEmpDao.class);
        int count= empDao.insertEmp(7562,"WARD","75610","SALESMAN",new Date(15));
        sqlSession.commit();
        System.out.println(count);
    }

    @Test
    public void test5(){
        SqlSession sqlSession =  SqlSessionUtil.openSqlSession();
        IEmpDao empDao = sqlSession.getMapper(IEmpDao.class);
        int count = empDao.UpdateEmpById(7562,"jiem");
        System.out.println(count);
    }

    @Test
    public void test6(){
        SqlSession sqlSession = SqlSessionUtil.openSqlSession();
        IEmpDao empDao = sqlSession.getMapper(IEmpDao.class);
        int count = empDao.delEmpById(7562);
        sqlSession.commit();
        System.out.println(count);
    }

    /*动态查询*/
    @Test
    public void test7(){
        SqlSession sqlSession = SqlSessionUtil.openSqlSession();
        IEmpDao empDao = sqlSession.getMapper(IEmpDao.class);
        Emp emp = empDao.getEmpByIdJob(7521,"S");
        System.out.println(emp);
    }

    /*批量删除*/
    @Test
    public void test8(){
        SqlSession sqlSession = SqlSessionUtil.openSqlSession();
        IEmpDao empDao = sqlSession.getMapper(IEmpDao.class);
        List list = new ArrayList();
        list.add(7521);
        list.add(7566);
        int count = empDao.delEmpByIds(list);
        sqlSession.commit();
        System.out.println(count);
    }
}

标签：int,empDao,IEmpDao,sqlSession,emp,Mybatis,id
来源： https://blog.csdn.net/qq_44969215/article/details/111773927