【MyBtis】各种查询功能
目录
【MyBtis】配置和映射
11.1 示例:实现表数据的增、删、改、查
1.创建工程mybatis_DML demo
2.创建数据库操作的工具类：DBOperatorMgr.java
3.创建映射接口
4.创建XML映射文件
5.测试
【MyBtis】配置和映射
MyBatis 的真正强大之外在于它的映射语句，这也是它的魅力所在。由于它的异常强大，映射器的XML文件就显得相对简单。如果将其与具有相同功能的 JDBC 代码进行对比，会立即发现其省掉了将近 95% 的代码。MyBatis 就是针对 SQL 构建的并且比普通的方法效果更好。
（1）实现表数据的增、删、改、查；
（2）MyBatis主配置文件；
（3）XML映射文件；
（4）高级结果映射。
11.1 示例:实现表数据的增、删、改、查
1.创建工程mybatis_DML demo
在 idea 中创建 Maven Project，如图11-1所示，“GroupID“ 选项中输入 “com.mialab” ，在 “ArtifactId” 选项输入“student”最终完成的 student 工程目录和 student 初始表数据如图11-1和图11-2所示。
图11-1 mybatisDML_demo 工程目录结构
图11-2student表中的数据
2.创建数据库操作的工具类：DBOperatorMgr.java
在MyBatis 使用中，如果每个方法执行时都需要读取配置文件，并根据配置文件的信息构建SqlSessionFactory对象，然后创建SqlSession 对象，这会导致类大量的重复代码。为了简化开发，需要将重复代码封装到一个工具类中。如下：
public class DBOperatorMgr {static Logger logger = Logger.getLogger(DBOperatorMgr.class.getName());private static DBOperatorMgr dbMgr;private SqlSessionFactory sqlSessionFactory;private DBOperatorMgr() {String resource = "mybatis-config.xml";InputStream inputStream;try {inputStream = Resources.getResourceAsStream(resource);sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);} catch (Exception e) {logger.error(e.toString());}}public static DBOperatorMgr getInstance() {if (dbMgr == null) {dbMgr = new DBOperatorMgr();}return dbMgr;}public SqlSessionFactory getSqlSessionFactory() {return sqlSessionFactory;}
}3.创建映射接口
public interface StudentMapper {public Student getStudent(String sno);public int addStudent(Student student);public List<Student> getSudentAll();public int updateStudent(Student student);public int deleteStudent(String sno);
}4.创建XML映射文件
在包com.mialab.mybatis_DML_demomapper 中创建 StudentMapper.xml文件。
<mapper namespace="com.mialab.mybatis_DML_demo.mapper.StudentMapper"><select id="getStudent" resultType="com.mialab.mybatis_DML_demo.domain.Student">select * from student wheresno = #{sno}</select><insert id="addStudent" parameterType="student">insert intostudent(sno,name,sex,age,dept_no)values(#{sno},#{name},#{sex},#{age},#{dept_no})</insert><resultMap id="studentResultMap" type="student"><id property="sno" column="sno" /><result property="name" column="name" /><result property="sex" column="sex" /><result property="age" column="age" /><result property="dept_no" column="dept_no" /></resultMap><select id="getSudentAll" resultMap="studentResultMap">select * from student</select><update id="updateStudent" parameterType="student">update student set name= #{name}, sex = #{sex}, age = #{age}, dept_no = #{dept_no}where sno =#{sno}</update><delete id="deleteStudent" parameterType="String">delete from studentwhere sno = #{sno}</delete></mapper>5.测试
如图11-1所示，在src/main/java 中创建 Package“com.mialab.mybatis_DML demo.main”。在此包中创建测试类DML_Mainjava，主要代码：
public class DML_Main { public static void main(String[] args) {//testInsert();//testSelectAll();testSelect("20171509");//testUpdate();
// testDelete("20171622");} private static void testDelete(String sno) {Logger log = Logger.getLogger(DML_Main.class);SqlSession session = null;try {session = DBOperatorMgr.getInstance().getSqlSessionFactory().openSession();StudentMapper mapper = session.getMapper(StudentMapper.class); mapper.deleteStudent(sno); session.commit();} catch(Exception ex) {session.rollback();ex.printStackTrace();} finally {if (session != null) {session.close();}} }private static void testSelectAll() {Logger log = Logger.getLogger(DML_Main.class);SqlSession session = null;try {session = DBOperatorMgr.getInstance().getSqlSessionFactory().openSession();StudentMapper mapper = session.getMapper(StudentMapper.class);List<Student> stu_list = mapper.getSudentAll();for(Student stu:stu_list) {//System.out.println(stu);log.info(stu);}} finally {if (session != null) {session.close();}}}private static void testInsert() {Logger log = Logger.getLogger(DML_Main.class);SqlSession session = null;try {session = DBOperatorMgr.getInstance().getSqlSessionFactory().openSession();StudentMapper mapper = session.getMapper(StudentMapper.class);Student student = new Student();student.setSno("20171622");student.setName("李白");student.setAge(88);student.setSex("男");student.setDept_no("2609");log.info(student);mapper.addStudent(student);session.commit();} catch(Exception ex) {session.rollback();ex.printStackTrace();} finally {if (session != null) {session.close();}}}private static void testSelect(String sno) {Logger log = Logger.getLogger(DML_Main.class);SqlSession session = null;try {session = DBOperatorMgr.getInstance().getSqlSessionFactory().openSession();StudentMapper mapper = session.getMapper(StudentMapper.class);Student student = mapper.getStudent(sno);//System.out.println(student);log.info(student);} finally {if (session != null) {session.close();}} }private static void testUpdate() {Logger log = Logger.getLogger(DML_Main.class);SqlSession session = null;try {session = DBOperatorMgr.getInstance().getSqlSessionFactory().openSession();StudentMapper mapper = session.getMapper(StudentMapper.class);Student student = new Student();student.setSno("20171622");student.setName("苏东坡");student.setAge(68);student.setSex("女");student.setDept_no("2612");log.info(student);mapper.updateStudent(student);session.commit();} catch(Exception ex) {session.rollback();ex.printStackTrace();} finally {if (session != null) {session.close();}}}
}
先测试 testSelectA11() 方法。如图 11-1 所示，右击comm.ialab.mybatis _DML_demo.main包中的DML_Main.java，在弹出的快捷菜单中选择“Run DML_Main.java”选项，在控制台中可以得到以下的结果：
INFO [main] - Student [sno=20171508, name=李勇, sex=男, age=20, dept_no=2601]INFO [main] - Student [sno=20171509, name=刘娟, sex=女, age=19, dept_no=2602]INFO [main] - Student [sno=20171622, name=李白, sex=男, age=88, dept_no=2609]可分别对增、删、改、查的方法testInsert()、testUpdate()等进行测试。