mybatis入门

首先来回顾一下jdbc

@Test
	public void testJdbc(){
		Connection connection=null;
		PreparedStatement prepareStatement=null;
		ResultSet resultSet=null;
		try {
			//加载驱动
			Class.forName("com.mysql.jdbc.Driver");
			
			//建立连接
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/ssm?characterEncoding=utf-8","root", "root");
			
			//创建sql语句并执行
			String sql="select * from user ";
			prepareStatement = connection.prepareStatement(sql);
			//prepareStatement.setString(1, "王五");
			resultSet = prepareStatement.executeQuery();
			
			//返回结果集并处理
			while (resultSet.next()) {
				System.out.println(resultSet.getString("id")+"------>"+resultSet.getString("userName"));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			if(resultSet!=null){
				try {
					resultSet.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
			if(prepareStatement!=null){
				try {
					prepareStatement.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
			if(connection!=null){
				try {
					connection.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
	}

　　

最基础的xml开发

然后再来看看mybatis

建立maven工程

file--new--project---maven--maven project--next

然后在pom中添加依赖

	<dependencies>
		<!-- mybatis依赖 -->
		<dependency>
			<groupId>org.mybatis</groupId>
			<artifactId>mybatis</artifactId>
			<version>3.4.6</version>
		</dependency>
		<!-- mysql依赖 -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.35</version>
		</dependency>

		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.17</version>
		</dependency>


		<!-- 单元测试 -->
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.12</version>
		</dependency>
	</dependencies>

　　

 建立pojo类

public class User {

	private int id;
	private String userId;
	private String userName;
	private String birthday;
	private String gender;
	private String address;
	private String tel;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getUserId() {
		return userId;
	}
	public void setUserId(String userId) {
		this.userId = userId;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getBirthday() {
		return birthday;
	}
	public void setBirthday(String birthday) {
		this.birthday = birthday;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	public String getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	public String getTel() {
		return tel;
	}
	public void setTel(String tel) {
		this.tel = tel;
	}
	@Override
	public String toString() {
		return "User [id=" + id + ", userId=" + userId + ", userName=" + userName + ", birthday=" + birthday
				+ ", gender=" + gender + ", address=" + address + ", tel=" + tel + "]";
	}
	
	

}

　　

dao接口以及实现类daoImpl

public interface UserDao {
	public User findUserById(int id) ;
	public void insertUser(User user) ;
}

　　

public class UserDaoImpl implements UserDao {

	// 注入SqlSessionFactory
	public UserDaoImpl(SqlSessionFactory sqlSessionFactory) {
		this.sqlSessionFactory = sqlSessionFactory;
	}

	private SqlSessionFactory sqlSessionFactory;

	@Override
	public User findUserById(int id)  {
		SqlSession session = sqlSessionFactory.openSession();
		User user = null;
		try {
			// 通过sqlsession调用selectOne方法获取一条结果集
			// 参数1：指定定义的statement的id,参数2：指定向statement中传递的参数
			user = session.selectOne("test.findUserById", id);
			System.out.println(user);

		} finally {
			session.close();
		}
		return user;
	}

	@Override
	public void insertUser(User user)  {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		try {
			sqlSession.insert("insertUser", user);
			sqlSession.commit();
		} finally {
			sqlSession.close();
		}

	}

}

　　

关键是配置文件

全局配置

<?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>
	<!-- 读取properties 配置文件 -->
	<properties resource="properties/db.properties"></properties>

	<!-- 配置数据源 -->
	<environments default="development">
		<environment id="development">
			<!-- 事务管理：采用的是JDBC的事务管理 -->
			<transactionManager type="JDBC" />
			<!-- 配置数据源连接池： POOLED使用的是Mybatis自己的连接池 -->
			<dataSource type="POOLED">
				<property name="driver" value="${db.driver}" />
				<property name="url" value="${db.url}" />
				<property name="username" value="${db.username}" />
				<property name="password" value="${db.password}" />
			</dataSource>
		</environment>
	</environments>

	<!-- 读取mapper映射文件 -->
	<mappers>
		<mapper resource="dao/UserMapper.xml" />
	</mappers>
</configuration>

　　

映射文件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="test">
	<select id="findUserById" parameterType="int"
		resultType="com.kkb.mybatis.dao.po.User">
		SELECT * 
		FROM user
		WHERE id = #{id}
	</select>
	<insert id="insertUser"
		parameterType="com.kkb.mybatis.dao.po.User" useGeneratedKeys="true">
		INSERT
		INTO user (username,gender,birthday,address)
		VALUES (#{userName},#{gender},#{birthday},#{address})
	</insert>
</mapper>

　　

db.properties

db.driver=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/ssm?characterEncoding=utf-8
db.username=root
db.password=root

　　

log4j.properties

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# MyBatis logging configuration...
log4j.logger.com.kkb.mybatis.mapper=DEBUG
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

　　

测试

public class UserDaoTest {

	private SqlSessionFactory sqlSessionFactory;

	@Before
	public void before() {
		try {
			// 指定全局配置文件路径
			String resource = "dao/SqlMapConfig.xml";
			// 加载资源文件（全局配置文件和映射文件）
			InputStream inputStream = Resources.getResourceAsStream(resource);
			// 还有构建者模式，去创建SqlSessionFactory对象
			sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	@Test
	public void testFindUserById() {
		UserDao dao = new UserDaoImpl(sqlSessionFactory);
		User user = dao.findUserById(2);
		System.out.println(user);
	}

	@Test
	public void testInsertUser() {
		UserDao dao = new UserDaoImpl(sqlSessionFactory);
		User user = new User();
		user.setUserName("lucas");
		user.setGender("男");
		user.setAddress("上海");
		// 调用dao的添加用户操作
		dao.insertUser(user);
		// 打印通过主键返回策略生成的ID
		System.out.println(user.getId());
	}

}

　　

控制台信息

DEBUG [main] - Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - Opening JDBC Connection
DEBUG [main] - Created connection 813656972.
DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@307f6b8c]
DEBUG [main] - ==>  Preparing: SELECT * FROM user WHERE id = ? 
DEBUG [main] - ==> Parameters: 2(Integer)
DEBUG [main] - <==      Total: 1
User [id=2, userId=001, userName=王五, birthday=2019-05-17, gender=男, address=上海, tel=110]
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@307f6b8c]
DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@307f6b8c]
DEBUG [main] - Returned connection 813656972 to pool.
User [id=2, userId=001, userName=王五, birthday=2019-05-17, gender=男, address=上海, tel=110]