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1.class的javabean（此时设置变量students来表示多个学生）
package com.bean;
import java.util.List;
public class Classes {
private Integer id;
private Integer code;
private List<Student> students;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getCode() {
return code;
}
public void setCode(Integer code) {
this.code = code;
}
public List<Student> getStudents() {
return students;
}
public void setStudents(List<Student> students) {
this.students = students;
}
@Override
public String toString() {
return "Classes [id=" + id + ", code=" + code +"]";
}
}
2.
package com.bean;
public class Student {
private Integer id;
private String name;
private Integer age;
private String sex;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
@Override
public String toString() {
return "Student [id=" + id + ", name=" + name + ", age=" + age + ", sex=" + sex + "]";
}
}
3.log4j.properties
# Global logging configuration
log4j.rootLogger=ERROR, stdout
# MyBatis logging configuration...
log4j.logger.com.mapper=DEBUG
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
4.jdbc.properties（对一些变量的设置）
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/mybatis
username=root
password=1234565.mybatis配置文件
<?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">
<!--1.配置环境 ，默认的环境id为mysql-->
<configuration>
<!-- 导入 jdbc.properties 引用里面的值-->
<properties resource="jdbc.properties"/>
<!-- 1.指定mybatis所用日志的具体实现 -->
<settings>
<setting name="logImpl" value="LOG4j"/>
</settings>
<!--2.配置环境 ，默认的环境id为mysql-->
<environments default="mysql">
<!--2.2.配置id为mysql的数据库环境 -->
<environment id="mysql">
<!-- 2.2.1使用JDBC的事务管理 使用了JDBC的提交和回滚设置-->
<transactionManager type="JDBC"></transactionManager>
<!--2.2.2数据库连接池 POOLED是JDBC连接对象的数据源连接池的实现 -->
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<!--3.配置Mapper的位置 -->
<mappers>
<mapper class="com.mapper.ClassesMapper"/>
<mapper resource="com/mapper/StudentMapper.XML"/>
<!-- 使用本地文件 -->
<!-- <mapper url="file:///D:/java/workspaces/mybatis0/src/com/mapper/UserMapper.xml"/> -->
</mappers>
</configuration>
6.数据库操作的类
package com.mapper;
import org.apache.ibatis.annotations.Many;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.ResultMap;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.mapping.FetchType;
import com.bean.Classes;
import com.bean.Student;
public interface ClassesMapper {
@Select("select * from class where id=#{id}")
@Results({
@Result(id=true,property="id",column="id"),
@Result(property="code",column="code"),
@Result(property="students",column="id",
many=@Many(select="com.mapper.StudentMapper.selectStudent",fetchType=FetchType.LAZY))
})
Classes selectStudent(Integer id);
}
7.数据库操作的配置文件
<?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="com.mapper.StudentMapper">
<select id="selectStudent" resultType="com.bean.Student">
select * from student where class_id=#{id}
</select>
</mapper>8.查
package com.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
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.Test;
import com.bean.Classes;
import com.bean.Student;
import com.mapper.ClassesMapper;
public class test {
@Test
public void select() throws IOException
{
InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession session = sessionFactory.openSession();
ClassesMapper userMapper=session.getMapper(ClassesMapper.class);
Classes classes=userMapper.selectStudent(2);
List<Student> students=classes.getStudents();
System.out.println(classes);
students.forEach(student->System.out.println(student));
}
}