一 SqlSession使用范围
- SqlSessionFactoryBuilder
- 通过SqlSessionFactoryBuilder创建会话工厂SqlSessionFactory
- 将SqlSessionFactoryBuilder当作一个工具类使用即可，不需要使用单例管理SqlSessionFactoryBuilder。
- 在需要创建SqlSessionFactory时候，只需要new一次SqlSessionFactoryBuilder 即可
- SqlSessionFactory
- 通过SqlSessionFactory创建SqlSession使用单例模式管理SqlSessionFactory(工厂一旦创建，使用一个实例)
- 将来mybatis和spring整合后使用单例模式管理sqlSessionFactory
- SqlSession
- SqlSession是一个面向用户（程序员）的接口
- SqlSession中提供了很多操作数据库的方法，例如：selectOne/selectList
- sqlSession是线程不安全的，在SqlSession实现类中除了有接口中的方法（操作数据库的方法）还有ukulel域属性
- SqlSession最佳应用场合在方法体内，定义成局部变量使用
二 mybatis开发dao方法-原始dao开发方法-程序员需要写dao接口和dao实现类
1 UserDao.java
package dao;
import entity.User;
public interface UserDao {
//根据id查询信息
public User findUserById(int id) throws Exception;
//添加用户信息
public void insertUser(User user) throws Exception;
//删除用户信息
public void deleteUser(int id) throws Exception;
}
2 UserDaoImpl.java
package dao.impl;
import dao.UserDao;
import entity.User;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import java.util.Date;
public class UserDaoImpl implements UserDao {
//需要向dao实现类中注入SqlSessionFactory
//这里通过构造方法注入
private SqlSessionFactory sqlSessionFactory;
public UserDaoImpl(SqlSessionFactory sqlSessionFactory){
this.sqlSessionFactory = sqlSessionFactory;
}
public User findUserById(int id) throws Exception {
SqlSession sqlSession = sqlSessionFactory.openSession();
User user = sqlSession.selectOne("test.findUserById",id);
sqlSession.close();
return user;
}
public void insertUser(User user) throws Exception {
SqlSession sqlSession = sqlSessionFactory.openSession();
sqlSession.insert("test.insertUser",user);
sqlSession.commit();
sqlSession.close();
}
public void deleteUser(int id) throws Exception {
SqlSession sqlSession = sqlSessionFactory.openSession();
sqlSession.delete("test.deleteUser",id);
sqlSession.commit();
sqlSession.close();
}
}
3 UserDaoImplTest.java
import dao.UserDao;
import dao.impl.UserDaoImpl;
import entity.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
public class UserDaoImplTest {
private SqlSessionFactory sqlSessionFactory;
//测试前执行
@Before
public void setUp() throws IOException {
//配置文件
String resource = "SqlMapConfig.xml";
//的到配置文件流
InputStream inputStream = Resources.getResourceAsStream(resource);
//创建会话工厂
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void testFinUserById() throws Exception {
UserDao userDao = new UserDaoImpl(sqlSessionFactory);
User user = userDao.findUserById(1);
System.out.println(user);
}
@Test
public void insertUser() throws Exception{
UserDao userDao = new UserDaoImpl(sqlSessionFactory);
User user1 = new User();
user1.setUsername("王麻子");
user1.setBirthday(new Date());
user1.setSex("女");
user1.setAddress("日本东京");
userDao.insertUser(user1);
}
@Test
public void deleteUser() throws Exception{
UserDao userDao = new UserDaoImpl(sqlSessionFactory);
userDao.deleteUser(13);
}
}
查询测试结果
三 mybatis开发dao方法-mapper代理开发方法-程序员只需要mapper接口（相当于dao接口）
- 程序员不在需要编写dao接口的实现
- 程序员需要编写mapper.xml映射文件，编写时遵循一些开发规范，mybatis可以自动生成mapper接口类代理对象
1 开发规范
（1）在mapper.xml中namespace等于mapper接口地址
（2）mapper.java接口中的方法名和mapper.xml中statement的id一致
（3）mapper.java接口中的方法输入类型和mapper.xml中statement的parameterType指定的类型一致
（4）mapper.java接口中方法返回值类型和mapper.xml中statement的resultType指定的类型一致
2 UserDaoMapper.java
package dao;
import entity.User;
public interface UserDaoMapper {
//根据id查询
public User findUserById(int id) throws Exception;
//插入用户
public void insertUser(User user) throws Exception;
//删除用户
public void deleteUser(int id) throws Exception;
//修改用户信息
public void updateUser(User user) throws Exception;
}
3 userMapper.xml
SELECT LAST_INSERT_ID()
INSERT INTO user (username,birthday,sex,address) VALUES(#{username},#{birthday},#{sex},#{address})
DELETE from user where id = #{id}
UPDATE user SET username = #{username},birthday = #{birthday},sex = #{sex},address = #{address} WHERE id = #{id}
4 UserDaoMapperTest
import dao.UserDaoMapper;
import entity.User;
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 org.junit.Before;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
public class UserDaoMapperTest {
private SqlSessionFactory sqlSessionFactory;
@Before
public void setUp() throws IOException{
String resource = "SqlMapConfig.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void findUserById() throws Exception{
SqlSession sqlSession= sqlSessionFactory.openSession();
//创建UserMapper对象，mybatis自动生成mapper代理对象
UserDaoMapper userDaoMapper = sqlSession.getMapper(UserDaoMapper.class);
//调用usermapper对象
User user = userDaoMapper.findUserById(10);
System.out.println(user);
}
@Test
public void insertUserd() throws Exception{
SqlSession sqlSession= sqlSessionFactory.openSession();
//创建UserMapper对象，mybatis自动生成mapper代理对象
UserDaoMapper userDaoMapper = sqlSession.getMapper(UserDaoMapper.class);
//调用usermapper对象
User user = new User();
user.setUsername("短毛");
user.setBirthday(new Date());
user.setSex("女");
user.setAddress("德国柏林");
userDaoMapper.insertUser(user);
sqlSession.commit();
sqlSession.close();
}
@Test
public void deleteUser() throws Exception {
SqlSession sqlSession = sqlSessionFactory.openSession();
UserDaoMapper userDaoMapper = sqlSession.getMapper(UserDaoMapper.class);
userDaoMapper.deleteUser(13);
sqlSession.commit();
sqlSession.close();
}
@Test
public void updateUser() throws Exception{
SqlSession sqlSession = sqlSessionFactory.openSession();
UserDaoMapper userDaoMapper = sqlSession.getMapper(UserDaoMapper.class);
User user = new User();
user.setId(12);
user.setUsername("短毛");
user.setBirthday(new Date());
user.setSex("女");
user.setAddress("德国柏林");
userDaoMapper.updateUser(user);
sqlSession.commit();
sqlSession.close();
}
}
查询执行结果