1 MyBatis入门

源码下载地址：http://download.youkuaiyun.com/download/u010349169/7555959

持久化层的工作是什么？
将从数据库中查询得到的数据生成所需要的java对象；将java对象中的数据通过SQL持久化到数据库中

简单的MyBatis实例

1、在pom.xml中添加依赖

例：
<url>http://www.mybatis.org</url>
  <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
        <junit.version>4.11</junit.version>
        <slf4j.version>1.7.5</slf4j.version>
        <log4j.version>1.2.17</log4j.version>
        <mybatis.version>3.2.2</mybatis.version>
        <mysql.version>5.1.21</mysql.version>
        <maven.compiler.plugin>2.3.2</maven.compiler.plugin>
    </properties> 

  <dependencies>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>${mybatis.version}</version>
        </dependency>       
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
  </dependencies>

另外要在src/main/resources下加个 log4j.properties

2、在src/main/resources下创建mybatis-config.xml

首先在src/main/resources下创建数据库连接文件application.properties，内容为：
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=hehe

下面是mybatis-config.xml的内容：

<?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>
      <!--  数据库连接属性文件     -->
      <properties resource="application.properties"/>

      <typeAliases>
        <package name="com.mybatis3.domain"/>
      </typeAliases>

      <environments default="development">
        <environment id="development">
          <transactionManager type="JDBC"/>
          <dataSource type="POOLED">
            <property name="driver" value="${jdbc.driverClassName}"/>
            <property name="url" value="${jdbc.url}"/>
            <property name="username" value="${jdbc.username}"/>
            <property name="password" value="${jdbc.password}"/>
          </dataSource>
        </environment>
      </environments>
      <!-- 映射器   -->
      <mappers>
        <mapper resource="com/mybatis3/mappers/StudentMapper.xml"/>
      </mappers>

</configuration>

3、创建SQL映射器配置文件 StudentMapper.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="com.mybatis3.mappers.StudentMapper">

    <resultMap type="Student" id="StudentResult">
        <id     property="studId" column="stud_id"/>
        <result property="name" column="name"/>
        <result property="email" column="email"/>
        <result property="dob" column="dob"/>
    </resultMap>

    <select id="findAllStudents" resultMap="StudentResult">
        select * from Students
    </select>

    <select id="findStudentById" parameterType="int" resultType="Student">
        select stud_id as studId, name, email, dob from Students where stud_id=#{studId}
    </select>

    <insert id="insertStudent" parameterType="Student">
        INSERT INTO STUDENTS(STUD_ID,NAME,EMAIL,DOB) VALUES(#{studId},#{name},#{email},#{dob})
    </insert>

    <update id="updateStudent" parameterType="Student">
        UPDATE STUDENTS SET NAME=#{name}, EMAIL=#{email}, DOB=#{dob} WHERE STUD_ID=#{studId}
    </update>

</mapper>

4、创建自己的MyBatisSqlSessionFactory.java，里面会用到mybatis-config.xml
5、实体类 Student.java
6、接口 StudentMapper.java ，与上面的StudentMapper.xml对应。

public interface StudentMapper
{

    List<Student> findAllStudents();

    Student findStudentById(Integer id);

    void insertStudent(Student student);

    void updateStudent(Student student);

}

7、StudentService.java
需要用到自己写的MyBatisSqlSessionFactory和StudentMapper，里面方法有：

public List<Student> findAllStudents()
public Student findStudentById(Integer studId)
public void createStudent(Student student)
public void updateStudent(Student student)