Mybatis简介与第一个程序

1.什么是Mybatis

    mybatis是对jdbc的封装

   将sql语句放入到映射文件中(xml)

   自动将输入参数映射到sql语句的动态参数上

   自动将sql语句执行结果映射为java对象

2.入门示例

1.新建java Project项目

2.新建lib包添加jar上图

3.编写日志文件（log4j.properties）

# Global logging configuration
log4j.rootLogger=info, stdout
# 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

4.配置数据库连接（db.properties）

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

5.创建数据库与表

CREATE DATABASE mybatis
CREATE TABLE `user` (
  `user_age` int(11) DEFAULT NULL,
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) DEFAULT NULL,
  `password` varchar(255) DEFAULT NULL,
  `addess` varchar(255) DEFAULT NULL,
  `state` tinyint(1) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT;

-- ----------------------------
-- Records of user
-- ----------------------------

INSERT INTO `user` VALUES ('25', '4', '王五', '123', '河南许昌', '0');
INSERT INTO `user` VALUES ('13', '14', '张三', '123', '河南', '0');

6.建立pojo下User类

package com.linxin.mybatis.pojo;

public class User {
	private Integer id;
	private String username;
	private String password;
	private String addess;
	private Integer age;
	private Boolean state;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public String getAddess() {
		return addess;
	}
	public void setAddess(String addess) {
		this.addess = addess;
	}
	
	public Boolean getState() {
		return state;
	}
	public void setState(Boolean state) {
		this.state = state;
	}
	@Override
	public String toString() {
		return "User [id=" + id + ", username=" + username + ", password=" + password + ", addess=" + addess
				+ ", age=" + age + ", state=" + state + "]";
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	} 
	
}

7.新建接口UserMapper.java与配置UserMapper.xml

package com.linxin.mybatis.mapper;

import com.linxin.mybatis.pojo.User;

public interface UserMapper {
	//查询
	User selectUser(Integer id);

}

<?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="com.linxin.mybatis.mapper.UserMapper">
	<!--parameterType:参数    ，resultType：类型-->
	<select id="selectUser" parameterType="int" resultType="com.linxin.mybatis.pojo.User">
		select * from user where id =#{id}
	</select>
</mapper>

8.编写mybatis-cnfig.xml配置文件

<?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>
	<!-- 引入数据库连接配置 -->
	<properties resource="db.properties"></properties>
	<!-- 定义别名 -->
	<typeAliases>
		<typeAlias type="com.linxin.mybatis.pojo.User" alias="User"/>
	</typeAliases>
	<!-- 引入数据源 -->
	<environments default="development">
		<environment id="development">
			<!-- 事务管理 -->
			<transactionManager type="JDBC"></transactionManager>
			<dataSource type="POOLED">
				<property name="driver" value="${jdbc.driver}"/>
				<property name="url" value="${jdbc.url}"/>
				<property name="username" value="${jdbc.username}"/>
				<property name="password" value="${jdbc.password}"/>
			</dataSource>
		</environment>
	</environments>
	
	<!-- 定义映射文件 -->
	<mappers>
		<!-- 方式一 
		<mapper resource="com/linixn/mybatis/mapper/UserMapper.xml"/>
		-->
		<!-- 方式二 使用包-->
		<package name="com.linxin.mybatis.mapper"/>
	</mappers>
</configuration>

9.编写工具类util （单例模式）

package com.linxin.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 sqlSessionFactory =null;
	static {
		try {
			InputStream in=Resources.getResourceAsStream("mybatis-config.xml");
			sqlSessionFactory=new SqlSessionFactoryBuilder().build(in);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	public static SqlSession getSqlSession() {
		return sqlSessionFactory.openSession();
	}

}

10.测试类

package com.linxin.mysbatis.mapper;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import com.linxin.mybatis.mapper.UserMapper;
import com.linxin.mybatis.pojo.User;
import com.linxin.mybatis.util.MybatisUtil;

public class UserMapperTest {
	@Test
	public  void UserMapper() {
		SqlSession session =MybatisUtil.getSqlSession();
		UserMapper userMapper=session.getMapper(UserMapper.class);
		User user= userMapper.selectUser(1);
		session.close();
		System.out.println(user);
	}
}

11.完成（Junit test)