myBatis的基本操作（持续更新中。。。）

1. 简介

mybatis是一款优秀的持久层框架，用来简化JDBC开发

持久层：负责将数据保存到数据库的那一层代码

2. 简单使用

依赖

<dependencies>  <dependency>            <groupId>org.mybatis</groupId>  <artifactId>mybatis</artifactId>  <version>3.5.14</version>  </dependency><!--        mysql的驱动-->  <dependency>  <groupId>mysql</groupId>  <artifactId>mysql-connector-java</artifactId>  <version>5.1.26</version>  </dependency>        <dependency>            <groupId>junit</groupId>  <artifactId>junit</artifactId>  <scope>test</scope>  <version>4.13.2</version>  </dependency>    </dependencies>

<?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>  <environments default="development">  <environment id="development">  <transactionManager type="JDBC"/>  <dataSource type="POOLED">  <property name="driver" value="com.mysql.jdbc.Driver"/>  <property name="url" value="${url}"/>  <property name="username" value="${username}"/>  <property name="password" value="${password}"/>  </dataSource>        </environment>    </environments>    <mappers>        <mapper resource="org/mybatis/example/BlogMapper.xml"/>  </mappers></configuration>

Userx

package com.yxz.pojo;  import java.util.Date;  public class Userx {  private Integer id;  private String username;  private Date birthday;  private Character sex;  private String address;  public Integer getId() {  return id;  }  public void setId(Integer id) {  this.id = id;  }  public String getUsername() {  return username;  }  public void setUsername(String username) {  this.username = username;  }  public Date getBirthday() {  return birthday;  }  public void setBirthday(Date birthday) {  this.birthday = birthday;  }  public Character getSex() {  return sex;  }  public void setSex(Character sex) {  this.sex = sex;  }  public String getAddress() {  return address;  }  public void setAddress(String address) {  this.address = address;  }  @Override  public String toString() {  return "Userx{" +  "id=" + id +  ", username='" + username + '\'' +  ", birthday=" + birthday +  ", sex=" + sex +  ", address='" + address + '\'' +  '}';  }  
}

UserMapper.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">  
<mapper namespace="test">  <select id="selectAll" resultType="com.yxz.pojo.Userx">  select * from userx;  </select>  
</mapper>

进行测试：

package com.yxz;  import com.yxz.pojo.Userx;  
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.InputStream;  
import java.util.List;  public class MybatisDemo {  public static void main(String[] args) throws IOException {  // 1. 加载mybatis的核心配置文件，获取SqlSessionFactory  String resource = "mybatis-config.xml";  InputStream inputStream = Resources.getResourceAsStream(resource);  SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);  // 2. 获取对应的SqlSession对象，用它执行sql  SqlSession sqlSession = sqlSessionFactory.openSession();  // 3. 执行sql  List<Userx> userxs =  sqlSession.selectList("test.selectAll");  System.out.println(userxs);  sqlSession.close();  }  
}

建好数据库

目录：

3. 代理开发

创建一个接口，作为代理

package com.yxz.dao;  import com.yxz.pojo.Userx;  import java.util.List;  public interface UserMapper {  List<Userx> selectAll();  
}

命名空间修改：

<?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="com.yxz.dao.UserMapper">  <select id="selectAll" resultType="com.yxz.pojo.Userx">  select * from userx;  </select>  
</mapper>

进行测试

package com.yxz;  import com.yxz.dao.UserMapper;  
import com.yxz.pojo.Userx;  
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.InputStream;  
import java.util.List;  public class MybatisDemo {  public static void main(String[] args) throws IOException {  // 1. 加载mybatis的核心配置文件，获取SqlSessionFactory  String resource = "mybatis-config.xml";  InputStream inputStream = Resources.getResourceAsStream(resource);  SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);  // 2. 获取对应的SqlSession对象，用它执行sql  SqlSession sqlSession = sqlSessionFactory.openSession();  // 3. 执行sql  
//        List<Userx> userxs =  sqlSession.selectList("test.selectAll");  UserMapper userMapper = sqlSession.getMapper(UserMapper.class);  List<Userx> userxs =  userMapper.selectAll();  System.out.println(userxs);  sqlSession.close();  }  
}

4. 小技巧

起别名

<typeAliases>  <package name="com.yxz.pojo"/>  
</typeAliases>

<select id="selectAll" resultType="userx">  select  <include refid="brand_column"/>  from userx;  
</select>  
<sql id="brand_column">  id,username, birthday, sex, address  
</sql>

<select id="selectById" parameterType="int" resultType="userx">  select  <include refid="brand_column"/>  from userx where id  <![CDATA[        <     ]]>     #{id};</select>

5. 动态查询

choose when otherwise
set if

delete from user where id 
in(<foreach collction="ids" item="id" separator=",">#{id} </foreach>) ;

6. 注解（待更新）

@Select
@Insert
@Update
@Delete

底部