1. MyBaits基本概念：略
2. 案例：需求：建立数据库查询，一对一
3.开发步骤：
4.代码
(1).加包
(2). 建立数据库和表
CREATE TABLE teacher( t_id INT PRIMARY KEY AUTO_INCREMENT, t_name VARCHAR(20) ); CREATE TABLE class( c_id INT PRIMARY KEY AUTO_INCREMENT, c_name VARCHAR(20), teacher_id INT ); ALTER TABLE class ADD CONSTRAINT fk_teacher_id FOREIGN KEY (teacher_id) REFERENCES teacher(t_id); INSERT INTO teacher(t_name) VALUES(‘LS1‘); INSERT INTO teacher(t_name) VALUES(‘LS2‘); INSERT INTO class(c_name, teacher_id) VALUES(‘bj_a‘, 1); INSERT INTO class(c_name, teacher_id) VALUES(‘bj_b‘, 2);
(3). 定义实体类
package com.atguigu.mybatis.domain; /** * @author hp * */ public class Classes { private int id; private String name; private Teacher teacher; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Teacher getTeacher() { return teacher; } public void setTeacher(Teacher teacher) { this.teacher = teacher; } public Classes(int id, String name, Teacher teacher) { super(); this.id = id; this.name = name; this.teacher = teacher; } public Classes() { } @Override public String toString() { return "Classes [id=" + id + ", name=" + name + ", teacher=" + teacher + "]"; } }
package com.atguigu.mybatis.domain; /** * @author hp * */ public class Teacher { private int id; private String name; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Teacher(int id, String name) { super(); this.id = id; this.name = name; } public Teacher() { } @Override public String toString() { return "Teacher [id=" + id + ", name=" + name + "]"; } }
(4). 编写db.properties,将数据库信息写入其中；
username=root password=lfdy jdbcUrl=jdbc:mysql://localhost:3306/mybatis1 driverClass=com.mysql.jdbc.Driver
编写MyBatis的配置文件conf.xml文件，引入db.properties；
1 <!-- 加载db.properties--> 2 <properties resource="db.properties"></properties>
3 <!-- 配置连接数据库信息 --> 4 <environments default="development"> 5 <environment id="development"> 6 <transactionManager type="JDBC" /> 7 <dataSource type="POOLED"> 8 <property name="driver" value="${driverClass}"/> 9 <property name="url" value="${url}"/> 10 <property name="username" value="${username}"/> 11 <property name="password" value="${password}"/> 12 </dataSource> 13 </environment> 14 </environments>
引入别名
<!-- 加入别名 -->
<typeAliases>
<package name="com.atguigu.mybatis.domain"/>
</typeAliases>
(5).定义sql映射文件***Mapper.xml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"> <!-- 编写对应的CRUD --> <mapper namespace="com.atguigu.mybatis.mapper.ClassMapper"> <!-- 方式一： 嵌套结果，使用嵌套结果来处理重复的联合结果的子集 --> <select id="getClass" parameterType="int" resultMap="ClassResultMap"> select * from class c,teacher t where c.teacher_id=t.t_id and c.c_id=#{id} </select> <resultMap type="Classes" id="ClassResultMap"> <id property="id" column="c_id"/> <result property="name" column="c_name"/> <association property="teacher" javaType="Teacher"> <id property="id" column="t_id"/> <result property="name" column="t_name"/> </association> </resultMap>
<!-- 方式二：嵌套查询，使用另一个SQL语句来返回预期的复杂类型 -->
<select id="getClass2" parameterType="int" resultMap="ClassResultMap2">
select * from class where c_id = #{id}
</select>
<select id="getTeacher2" parameterType="int" resultType="Teacher">
select t_id id,t_name name from teacher where t_id = #{id}
</select>
<resultMap type="Classes" id="ClassResultMap2">
<id property="id" column="c_id"/>
<result property="name" column="c_name"/>
<association property="teacher" column="teacher_id" select="getTeacher2">
</association>
</resultMap>
</mapper>
(6). 将***Mapper.xml文件注册到conf.xml文件中
<!-- 注册sql映射的mapper文件 --> <mappers> <mapper resource="com/atguigu/mybatis/mapper/ClassMapper.xml" /> </mappers>
(7). 编写MyBaitsUtils工具
package com.atguigu.mybatis.test;
import java.io.InputStream;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class MyBatisUtils {
public static SqlSessionFactory getFactory(){
String resource = "conf.xml";
InputStream is = MyBatisUtils.class.getClassLoader().getResourceAsStream(resource);
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
return factory;
}
}
(8).测试
package com.atguigu.mybatis.test; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import com.atguigu.mybatis.domain.Classes; /** * @author hp * */ public class MyBatisTest { public static void main(String[] args) { SqlSessionFactory sessionFactory = MyBatisUtils.getFactory(); SqlSession session = sessionFactory.openSession(); String statement = "com.atguigu.mybatis.mapper.ClassMapper.getClass"; Classes c = session.selectOne(statement, 1); System.out.println(c); session.close(); } }
原文：http://www.cnblogs.com/lfdingye/p/6443375.html