Mybatis之入门实例

• MyBatis 是什么

        MyBatis是一款一流的支持自定义 SQL、存储过程和高级映射的持久化框架。MyBatis几乎消除了所有的JDBC代码，也基本不需要手工去设置参数和获取检索结果。MyBatis能够使用简单的XML格式或者注解进行来配置，能够映射基本数据元素、Map接口和POJOs（普通java 对象）到数据库中的记录。

• MyBatis 开发配置

    mybatis-3.1.1.jar

    mysql-connector-java-5.0.4-bin.jar

    junit-4.8.1.jar（可选：用于测试）

• MyBatis 入门实例

    第一个MyBatis项目目录：

    开发流程：

    1）在src目录下创建mybatis的配置文件mybatis-config.xml，在该文件中完成和数据库的连接设置操作

<?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>
	<properties resource="jdbc.properties" />
	<typeAliases>
		<typeAlias type="cn.mybatis.model.User" alias="User" />
	</typeAliases>
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				<property name="driver" value="${driver}" />
				<property name="username" value="${username}" />
				<property name="password" value="${password}" />
				<property name="url" value="${url}" />
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="cn/mybatis/model/User.xml" />
	</mappers>
</configuration>

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

    2）创建数据库表并生成相应的实体类

DROP TABLE IF EXISTS `t_user`;
CREATE TABLE `t_user` (
  `id` int(10) NOT NULL auto_increment,
  `name` varchar(20) default NULL COMMENT '姓名',
  `nickname` varchar(20) default NULL COMMENT '昵称',
  `password` varchar(10) default NULL COMMENT '用户密码',
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

package cn.mybatis.model;
public class User {

	private int id;
	private String name;
	private String nickname;
	private String password;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getNickname() {
		return nickname;
	}

	public void setNickname(String nickname) {
		this.nickname = nickname;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", nickname=" + nickname
				+ ", password=" + password + "]";
	}

}

    3）生成实体类的mapper映射xml文件

<?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="cn.mybatis.model.User">

	<insert id="add" parameterType="User">
		insert into t_user
		(name,password,nickname) value
		(#{name},#{password},#{nickname})
	</insert>

	<update id="update" parameterType="User">
		update t_user set
		name=#{name},nickname=#{nickname},password=#{password} where id=#{id}
	</update>

	<delete id="delete" parameterType="int">
		delete from t_user where
		id=#{id}
	</delete>

	<select id="load" parameterType="int" resultType="User">
		select * from t_user where
		id=#{id}
	</select>
	
</mapper>

    4）创建获取SQlSession的Util类

package cn.mybatis.util;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MyBatisUtil {
	
	private static SqlSessionFactory factory;
	
	static {
		try {
			InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
			factory = new SqlSessionFactoryBuilder().build(is);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static SqlSession createSession() {
		return factory.openSession();
	}

	public static void closeSession(SqlSession session) {
		if (session != null)
			session.close();
	}

}

    5）Junit方式测试SqlSession完成对数据库的操作

package cn.mybatis.test;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import cn.mybatis.model.User;
import cn.mybatis.util.MyBatisUtil;

public class MybatisTest01 {

	@Test
	public void testAdd() {
		SqlSession session = null;
		try {
			session = MyBatisUtil.createSession();
			User u = new User();
			u.setName("Tom");
			u.setNickname("Tomy");
			u.setPassword("123");
			session.insert(User.class.getName() + ".add", u);
			session.commit();
		} catch (Exception e) {
			e.printStackTrace();
			session.rollback();
		} finally {
			MyBatisUtil.closeSession(session);
		}
	}

	@Test
	public void testUpdate() {
		SqlSession session = null;
		try {
			session = MyBatisUtil.createSession();
			User u = new User();
			u.setId(1);
			u.setName("Tom");
			u.setNickname("Tomy");
			u.setPassword("123456");
			session.update(User.class.getName() + ".update", u);
			session.commit();
		} catch (Exception e) {
			e.printStackTrace();
			session.rollback();
		} finally {
			MyBatisUtil.closeSession(session);
		}
	}

	@Test
	public void testSelect() {
		SqlSession session = null;
		try {
			session = MyBatisUtil.createSession();
			User u = (User) session.selectOne(User.class.getName() + ".load", 1);
			System.out.println("name: " + u.getName());
		} finally {
			MyBatisUtil.closeSession(session);
		}
	}

	@Test
	public void testDelete() {
		SqlSession session = null;
		try {
			session = MyBatisUtil.createSession();
			session.delete(User.class.getName() + ".delete", 1);
			session.commit();
		} catch (Exception e) {
			e.printStackTrace();
			session.rollback();
		} finally {
			MyBatisUtil.closeSession(session);
		}
	}

}