Eclipse中使用Mybatis

1、用maven方便导包，所以先建立一个maven项目或maven module。
 在pom.xml中进行依赖导入，我这里要用到的有mybatis、lombok、junit、mysql-jdbc-connector这些。（junit和mysql的包之前固定放在tomcat的lib里了所以下边没写）

  <dependencies>
	<dependency>
	    <groupId>org.mybatis</groupId>
	    <artifactId>mybatis</artifactId>
	    <version>3.4.6</version>
	</dependency>
	<dependency>
	    <groupId>org.projectlombok</groupId>
	    <artifactId>lombok</artifactId>
	    <version>1.18.12</version>
	    <scope>provided</scope>
	</dependency>
  </dependencies>

2、在/src/main/resources/这里建立mybatis-config.xml文件，配置数据库环境。

<?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>
	<environments default="mybatis1">
		<environment id="mybatis1">
			<transactionManager type="JDBC"></transactionManager>
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver"/>
				<property name="url" value="jdbc:mysql://localhost:3306/mydatabase01?characterEncoding=utf-8&amp;useSSL=true"/>
				<property name="username" value="root"/>
				<property name="password" value="root"/>
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="UserMapper.xml"/>
	</mappers>
</configuration>

3、mybatis的数据库操作都基于sqlSession，先获取sqlSession。

SqlSessionFactoryBuilder()根据配置文件建立SqlSessionFactory，
SqlSessionFactory.openSession()可以获得SqlSession。

package com.mybatis1.utils;

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 Mybatis1Utils {
	private static SqlSessionFactory sqlSessionFactory=null;
	static {
		try {
			String url = "mybatis-config.xml";
			InputStream stream = Resources.getResourceAsStream(url);
			sqlSessionFactory = new SqlSessionFactoryBuilder().build(stream);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static SqlSession getSqlSession() {
		return sqlSessionFactory.openSession();
	}
}

4、建立数据库、定义实体类：

package com.mybatis1.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
	private int id;
	private String name;
	private String address;
}

5、建立一个Mapper，声明需要的实体类操作。其实就是一个DAO接口。

package com.mybatis1.dao;
import java.util.List;

import com.mybatis1.pojo.*;

public interface UserMapper {
	User getUserById(int id);
	List<User> getAllUsers();
	void insertUser(User user);
	void updateUser(User user);
	void deleteUser(int id);
}

6、编写实现这个Mapper对应的配置文件。当调用UserMapper中的抽象方法时，会根据映射关系在下面的配置文件中找到对应的sql。

<!DOCTYPE mapper
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mybatis1.dao.UserMapper">
	<select id="getUserById" parameterType="int" resultType="com.mybatis1.pojo.User">
		select * from jdbc3 where id=#{id}
	</select>
	<select id="getAllUsers" resultType="com.mybatis1.pojo.User">
		select * from jdbc3
	</select>
	<insert id="insertUser" parameterType="com.mybatis1.pojo.User">
		insert into jdbc3 values(#{id},#{name},#{address})
	</insert>
	<update id="updateUser" parameterType="com.mybatis1.pojo.User">
		update jdbc3 set name=#{name},address=#{address} where id=#{id}
	</update>
	<delete id="deleteUser" parameterType="int">
		delete from jdbc3 where id=#{id}
	</delete>
</mapper>

7、测试一下吧。

package com.mybatis1.pojo;

import java.util.List;

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

import com.mybatis1.dao.UserMapper;
import com.mybatis1.utils.Mybatis1Utils;

public class Mybatis1Test {
//	@Test
	public void test1() {
		SqlSession sqlSession = Mybatis1Utils.getSqlSession();
		UserMapper mapper = sqlSession.getMapper(UserMapper.class);
		User user = mapper.getUserById(3);
		System.out.println(user.toString());
		sqlSession.close();
	}
	public void test2() {
		SqlSession sqlSession = Mybatis1Utils.getSqlSession();
		UserMapper mapper = sqlSession.getMapper(UserMapper.class);
		List<User> users = mapper.getAllUsers();
		for(User user:users)
			System.out.println(user.toString());
		sqlSession.close();
	}
	public void test3() {
		SqlSession sqlSession = Mybatis1Utils.getSqlSession();
		UserMapper mapper = sqlSession.getMapper(UserMapper.class);
		User user=new User(5,"great","Mars");
		mapper.insertUser(user);
		sqlSession.commit();
		sqlSession.close();
	}
	public void test4() {
		SqlSession sqlSession = Mybatis1Utils.getSqlSession();
		UserMapper mapper = sqlSession.getMapper(UserMapper.class);
		User user=new User(5,"greatly","Mars");
		mapper.updateUser(user);
		sqlSession.commit();
		sqlSession.close();
	}
	@Test
	public void test5() {
		SqlSession sqlSession = Mybatis1Utils.getSqlSession();
		UserMapper mapper = sqlSession.getMapper(UserMapper.class);
		mapper.deleteUser(5);
		sqlSession.commit();
		sqlSession.close();
	}
}

 CURD都正常实现。