mybatis入门案例

public class Student {

    private int studentID;
    private String studentName;
    private String studentSex;

    public int getStudentID() {
        return studentID;
    }

    public void setStudentID(int studentID) {
        this.studentID = studentID;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public String getStudentSex() {
        return studentSex;
    }

    public void setStudentSex(String studentSex) {
        this.studentSex = studentSex;
    }
}

<?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" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/test" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!-- 注册studentMapper.xml文件， studentMapper.xml位于com.test.bean这个包下，所以resource写成com/test/bean/studentMapper.xml -->
        <mapper resource="com/test/bean/studentMapper.xml" />
    </mappers>
</configuration>

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=root

<?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>

<!-- 导入db.properties -->
    <properties resource="db.properties"></properties>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!-- 注册studentMapper.xml文件， studentMapper.xml位于com.test.bean这个包下，所以resource写成com/test/bean/studentMapper.xml -->
        <mapper resource="com/test/bean/studentMapper.xml" />
    </mappers>
</configuration>

<?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">
<!-- 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的 -->

<mapper namespace="com.test.bean.studentMapper">
    <!-- 在select标签中编写查询的SQL语句， 设置select标签的id属性为getStudent，id属性值必须是唯一的， 不能够重复 
        使用parameterType属性指明查询时使用的参数类型，resultType属性指明查询返回的结果集类型 resultType="com.test.bean.Student"
        表示将查询结果封装成一个User类的对象返回 
        User类就是users表所对应的实体类 -->
    <!-- 根据id查询得到一个student对象 -->
    <select id="getStudent" parameterType="int" resultType="com.test.bean.Student">
        select *
        from tb_student where studentID=#{id}
    </select>

    <!-- 通过姓名模糊查询，返回结果可能为多个，但是这里的结果类型还是对应一个Java类 -->
    <select id="findStudentByName" parameterType="java.lang.String" resultType="com.test.bean.Student">
        select * from tb_student where studentName like #{value}
    </select>
    
    <!-- 插入一条记录 , 如果tb_student中的主键是自增的，那这里就不用管主键，系统会自动分配-->
    <insert id="insertStudent" parameterType="com.test.bean.Student">
        insert into tb_student (studentName,studentSex) values(#{studentName},#{studentSex})
    </insert>
</mapper>

public class DBTools {
    public static SqlSessionFactory sessionFactory;

    static {
        try {
            // 使用MyBatis提供的Resources类加载mybatis的配置文件
            Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
            // 构建sqlSession的工厂
            sessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    // 创建能执行映射文件中sql的sqlSession
    public static SqlSession getSession() {
        return sessionFactory.openSession();
    }

}

public class StudentDAO {

    // 通过ID查询student
    public void findStudentById(int studentID) {
        SqlSession session = DBTools.getSession();
        /**
         * 映射sql的标识字符串，
         * com.test.bean.studentMapper是studentMapper.xml文件中mapper标签的namespace属性的值，
         * getStudent是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL
         */
        String statement = "com.test.bean.studentMapper.getStudent";// 映射sql的标识字符串
        Student stu1 = session.selectOne(statement, 1);
        System.out.println(stu1.getStudentID() + "\n" + stu1.getStudentName() + "\n" + stu1.getStudentSex());
        session.close();
    }

    // 通过姓名模糊查询
    public void findStudentByName(String studentName) {
        SqlSession session = DBTools.getSession();
        String statement = "com.test.bean.studentMapper.findStudentByName";// 映射sql的标识字符串
        // 这里不能使用selectOne，因为返回的结构可能是多条
        List<Student> list = session.selectList(statement, "%" + studentName + "%");
        System.out.println(list.get(0).getStudentName());
        session.close();
    }

    // 插入一条学生信息
    public void insertStudent(Student student) {
        SqlSession session = DBTools.getSession();
        String statement = "com.test.bean.studentMapper.insertStudent";
        session.insert(statement, student);
        session.commit();
        System.out.println("插入成功");
        session.close();
    }
}