综合案例
我们之前在做学生管理系统时，使用的是原始JDBC操作数据库的，操作非常麻烦，现在我们使用MyBatis操作数据库，简化Dao的开发。
步骤一：新增MyBatis配置文件 MyBatisConfig.xml
<?xml version="1.0" encoding="UTF-8" ?> <!--MyBatis的DTD约束--> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd"> <!--configuration 核心根标签--> <configuration> <!--引入数据库连接的配置文件--> <properties resource="config.properties"/> <!--配置LOG4J--> <settings> <setting name="logImpl" value="log4j"/> </settings> <!--environments配置数据库环境，环境可以有多个。default属性指定使用的是哪个--> <environments default="mysql"> <!--environment配置数据库环境 id属性唯一标识--> <environment id="mysql"> <!-- transactionManager事务管理。 type属性，采用JDBC默认的事务--> <transactionManager type="JDBC"></transactionManager> <!-- dataSource数据源信息 type属性 连接池--> <dataSource type="POOLED"> <!-- property获取数据库连接的配置信息 --> <property name="driver" value="${driver}" /> <property name="url" value="${url}" /> <property name="username" value="${username}" /> <property name="password" value="${password}" /> </dataSource> </environment> </environments> <!--配置映射关系--> <mappers> <package name="com.itheima"/> </mappers> </configuration>
package com.itheima.dao; import com.itheima.domain.Student; import org.apache.ibatis.annotations.Delete; import org.apache.ibatis.annotations.Insert; import org.apache.ibatis.annotations.Select; import org.apache.ibatis.annotations.Update; import java.util.ArrayList; /* Dao层接口 */ public interface StudentDao { //查询所有学生信息 @Select("SELECT * FROM student") public abstract ArrayList<Student> findAll(); //条件查询，根据id获取学生信息 @Select("SELECT * FROM student WHERE sid=#{sid}") public abstract Student findById(Integer sid); //新增学生信息 @Insert("INSERT INTO student VALUES (#{sid},#{name},#{age},#{birthday})") public abstract int insert(Student stu); //修改学生信息 @Update("UPDATE student SET name=#{name},age=#{age},birthday=#{birthday} WHERE sid=#{sid}") public abstract int update(Student stu); //删除学生信息 @Delete("DELETE FROM student WHERE sid=#{sid}") public abstract int delete(Integer sid); }
package com.itheima.service.impl; import com.itheima.dao.StudentDao; import com.itheima.domain.Student; import com.itheima.service.StudentService; 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 java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.List; /** * 学生的业务层实现类 * @author 黑马程序员 * @Company http://www.itheima.com */ public class StudentServiceImpl implements StudentService { @Override public List<Student> findAll() { ArrayList<Student> list = null; SqlSession sqlSession = null; InputStream is = null; try{ //1.加载核心配置文件 is = Resources.getResourceAsStream("MyBatisConfig.xml"); //2.获取SqlSession工厂对象 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is); //3.通过工厂对象获取SqlSession对象 sqlSession = sqlSessionFactory.openSession(true); //4.获取StudentDao接口的实现类对象 StudentDao mapper = sqlSession.getMapper(StudentDao.class); //5.调用实现类对象的方法，接收结果 list = mapper.findAll(); } catch (Exception e) { e.printStackTrace(); } finally { //6.释放资源 if(sqlSession != null) { sqlSession.close(); } if(is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } //7.返回结果 return list; } @Override public Student findById(Integer sid) { Student stu = null; SqlSession sqlSession = null; InputStream is = null; try{ //1.加载核心配置文件 is = Resources.getResourceAsStream("MyBatisConfig.xml"); //2.获取SqlSession工厂对象 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is); //3.通过工厂对象获取SqlSession对象 sqlSession = sqlSessionFactory.openSession(true); //4.获取StudentDao接口的实现类对象 StudentDao mapper = sqlSession.getMapper(StudentDao.class); //5.调用实现类对象的方法，接收结果 stu = mapper.findById(sid); } catch (Exception e) { e.printStackTrace(); } finally { //6.释放资源 if(sqlSession != null) { sqlSession.close(); } if(is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } //7.返回结果 return stu; } @Override public void save(Student student) { SqlSession sqlSession = null; InputStream is = null; try{ //1.加载核心配置文件 is = Resources.getResourceAsStream("MyBatisConfig.xml"); //2.获取SqlSession工厂对象 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is); //3.通过工厂对象获取SqlSession对象 sqlSession = sqlSessionFactory.openSession(true); //4.获取StudentDao接口的实现类对象 StudentDao mapper = sqlSession.getMapper(StudentDao.class); //5.调用实现类对象的方法，接收结果 mapper.insert(student); } catch (Exception e) { e.printStackTrace(); } finally { //6.释放资源 if(sqlSession != null) { sqlSession.close(); } if(is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } } @Override public void update(Student student) { SqlSession sqlSession = null; InputStream is = null; try{ //1.加载核心配置文件 is = Resources.getResourceAsStream("MyBatisConfig.xml"); //2.获取SqlSession工厂对象 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is); //3.通过工厂对象获取SqlSession对象 sqlSession = sqlSessionFactory.openSession(true); //4.获取StudentDao接口的实现类对象 StudentDao mapper = sqlSession.getMapper(StudentDao.class); //5.调用实现类对象的方法，接收结果 mapper.update(student); } catch (Exception e) { e.printStackTrace(); } finally { //6.释放资源 if(sqlSession != null) { sqlSession.close(); } if(is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } } @Override public void delete(Integer sid) { SqlSession sqlSession = null; InputStream is = null; try{ //1.加载核心配置文件 is = Resources.getResourceAsStream("MyBatisConfig.xml"); //2.获取SqlSession工厂对象 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is); //3.通过工厂对象获取SqlSession对象 sqlSession = sqlSessionFactory.openSession(true); //4.获取StudentDao接口的实现类对象 StudentDao mapper = sqlSession.getMapper(StudentDao.class); //5.调用实现类对象的方法，接收结果 mapper.delete(sid); } catch (Exception e) { e.printStackTrace(); } finally { //6.释放资源 if(sqlSession != null) { sqlSession.close(); } if(is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } } }
