mybatis环境配置与入门例子

1、jar包的导入

• mybatis需要jar包：mybatis-3.4.6.jar
• mysql驱动jar包：mysql-connector-java-5.1.34.-bin.jar
• 日志记录jar包：log4j-1.2.17.jar

2、创建数据库并创建表（mysql）

• 注意数据库表字段命名的规范

3、添加日志配置文件（log4j.properties）

# Configure logging for testing: optionally with log file
log4j.rootLogger=WARN, stdout
# log4j.rootLogger=WARN, stdout, logfile

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n

log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/spring.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

4、添加mybatis配置文件(mybatis.cfg.xml)

除数据库驱动，url，用户名，密码用自己实际的参数，其他的默认就可以

<configuration>
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC" />
                <dataSource type="POOLED">
                    <!--数据库驱动-->
                    <property name="driver" value="com.mysql.jdbc.Driver" />
                    <!--数据库url-->
                    <property name="url"
                        value="jdbc:mysql://localhost:3306/mybatis"></property>
                    <!--数据库用户名-->
                    <property name="username" value="root" />
                    <!--数据库密码-->
                    <property name="password" value="root" />
                </dataSource>
            </environment>
        </environments>
    </configuration>

5、创建与数据库中表相关的实体类（POJO类）

• 注意使用驼峰命名法

6、创建操作数据库的接口方法

    package cn.wfq.mybatis.mapper;

    import java.util.List;

    import cn.wfq.mybatis.model.User;

    public interface UserMapper {
    /**
     * 保存一条用户数据
     * @param user
     */
    public void saveUser(User user);
    
    /**
     * 通过用户id获取一条记录
     * @param id
     * @return
     */
    public User getOneUserById(int id);
    
    /**
     * 修改用户数据
     * @param user
     */
    public void updateUser(User user);
    
    /**
     * 根据id删除用户数据
     * @param id
     */
    public void deleteUser(int id);
    
    /**
     * 获取所有用户数据
     * @return
     */
    public List<User> getAllUser();
}

7、添加操作数据表user的映射文件（userMapper.xml），并在mybatis.cfg.xml中注册

1、添加操作数据表user的映射文件（userMapper.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>标签用来使该xml文件与接口对应，'namespace'属性的参数应该是与xml文件相对应的接口的类路径，本例中就是我们第5步所写的'userMapper'接口-->
<mapper namespace="cn.wfq.mybatis.mapper.UserMapper">

    <!--insert、select、update、delete四个标签即代表这增删改查，这里就不解释了 -->
    
    <!--4个标签中的id值要与接口的方法名一一对应，这样执行方法时，就会执行与方法名相同的id中的sql语句,在标签中写入sql语句 -->
    <!--#{}这个符号表示要传入的参数，在`{}`中填入参数名 -->
    <insert id="saveUser" useGeneratedKeys="true" keyProperty="id">
        insert into user(name,age,reg_date) values
        (#{name},#{age},#{regDate})
    </insert>
    <!--resutlType这个属性的参数是返回值类型的全类名 -->
    <select id="getOneUserById" resultType="cn.wfq.mybatis.model.User">
        select * from user where id = #{id}
    </select>
    <select id="getAllUser" resultType="cn.wfq.mybatis.model.User">
        select * from user
    </select>
    <update id="updateUser">
        update user set
        name=#{name},age=#{age},reg_date=#{regDate} where id=#{id}
    </update>
    <delete id="deleteUser">
        delete from user where id = #{id}
    </delete>
</mapper>

2、在mybatis.cfg.xml中注册userMapper.xml

<mappers>
        <!-- 告知映射文件方式1，一个一个的配置 
        <mapper resource="cn/wfq/mybatis/mapper/UserMapper.xml" /> -->
        <!-- 告知映射文件方式2，自动扫描包内的Mapper接口与配置文件 -->
        <package name="cn/wfq/mybatis/mapper" />
    </mappers>

8、编写junit测试类

package cn.wfq.mybatis.test;



import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

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.jupiter.api.Test;

import cn.wfq.mybatis.mapper.UserMapper;
import cn.wfq.mybatis.model.User;

class UserTest {

    /**
     *  插入数据库测设
     * @throws IOException
     */
    @Test
    void testInsertUser() throws IOException {
        
        //获取配置文件 mybatis.cfg.xml 的输入流
        InputStream inputStream = Resources.getResourceAsStream("mybatis.cfg.xml");
        
        //构建 sqlSessionFactory 实例
        SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream);
        
        //获取操作数据库的会话
        SqlSession session = sqlSessionFactory.openSession();
        
        UserMapper userMapper = session.getMapper(UserMapper.class);
        User user = new User("晓东",18,new Date());
        
        try {
            userMapper.saveUser(user);
            System.out.println(user.toString());
            session.commit();
        }finally {
            session.close();
        }   
    }
    
    /**
     * 根据id获取一条数据测试
     * @throws IOException
     */
    @Test
    void testGetOneUserById() throws IOException {
        
        InputStream inputStream = Resources.getResourceAsStream("mybatis.cfg.xml");
        SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
        
        UserMapper userMapper = session.getMapper(UserMapper.class);
        User user = new User();
        
        try {
            user = userMapper.getOneUserById(10004);
            System.out.println(user.toString());
            session.commit();
        }finally {
            session.close();
        }   
    }
    
    /**
     * 获取所有数据
     * @throws IOException
     */
    @Test
    void testGetAllUser() throws IOException {
        
        InputStream inputStream = Resources.getResourceAsStream("mybatis.cfg.xml");
        SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
        
        UserMapper userMapper = session.getMapper(UserMapper.class);
        List<User> list = new ArrayList<User>();
        
        try {
            list = userMapper.getAllUser();
            for (User user : list) {
                System.out.println(user.toString());
            }
            session.commit();
        }finally {
            session.close();
        }   
    }
    
    /**
     * 修改数据
     * @throws IOException
     */
    @Test
    void testUpdateUser() throws IOException {
        
        InputStream inputStream = Resources.getResourceAsStream("mybatis.cfg.xml");
        SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
        
        UserMapper userMapper = session.getMapper(UserMapper.class);
        User user = new User("晓东",10,new Date());
        user.setId(10003);
        try {
            userMapper.updateUser(user);
            System.out.println(user.toString());
            session.commit();
        }finally {
            session.close();
        }   
    }
    
    /**
     * 删除数据
     * @throws IOException
     */
    @Test
    void testDeleteUser() throws IOException {
        
        InputStream inputStream = Resources.getResourceAsStream("mybatis.cfg.xml");
        SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
        
        UserMapper userMapper = session.getMapper(UserMapper.class);;
        try {
            userMapper.deleteUser(10003);
            session.commit();
        }finally {
            session.close();
        }   
    }
}