【Mybatis】Mybatis开发入门程序

第一步：创建maven工程

在idea中点击File->New->Project ,选择maven工程

第二步：添加依赖包

找到工程中的pom.xml文件，在文pom.xml文件的dependencies节点下添加如下依赖包

	<dependency>
          <groupId>org.mybatis</groupId>
          <artifactId>mybatis</artifactId>
          <version>3.4.6</version>
      </dependency>
      <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>8.0.20</version>
      </dependency>
      <dependency>
          <groupId>log4j</groupId>
          <artifactId>log4j</artifactId>
          <version>1.2.12</version>
      </dependency>

添加完依赖包以后点击maven同步按钮

第三步：创建数据库和实体类

创建数据库

在数据库中创建一个名字为user的，给该表增加3个字段分别是id、name、age

创建实体类和Mapper类

目录结构如下：

实体类User

public class User {
    private int id;
    private String name;
    private int age;

    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 int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "MyUser{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

UserMapper类

public interface UserMapper {
    User slelectUserById(int id);
    List<User> slelectAll();
    void insertUser(User user);
    void updateUser(User user);
    void deleteUser(int userId);
}

第四步：添加Mybatis配置文件

mybatis-config.xml

创建mybatis-config.xml文件，并添加相关数据库连接配置

<?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>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/springtest?characterEncoding=utf-8&amp;serverTimezone=UTC&amp;useSSL=false" />
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="UserMapper.xml"/>
    </mappers>

</configuration>

UserMapper.xml

创建UserMapper.xml映射文件

<?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="com.lucas.mybatis.mapper.UserMapper">
    <select id="slelectUserById" parameterType="Integer"
            resultType="com.lucas.mybatis.model.User">
    select  * from user where id = #{id}
    </select>

    <select id="slelectAll"  resultType="com.lucas.mybatis.model.User">
    select  * from user
    </select>
    <insert id="insertUser" parameterType="com.lucas.mybatis.model.User">
        insert into user (name,age) value (#{name},#{age})
    </insert>
    <update id="updateUser" parameterType="com.lucas.mybatis.model.User">
        update  user set name= #{name},age= #{age} where id = #{id}
    </update>
    <delete id="deleteUser" parameterType="Integer">
        delete from user where id =  #{id}
    </delete>
</mapper>

创建日志配置文件log4j.properties

# 全局配置
log4j.rootLogger=ERROR,stdout
# MyBatis 日志配置
log4j.logger.com.lucas=DEBUG
# 控制台输出配置
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

添加测试代码

public class App {
    private static SqlSessionFactory sqlsessionfactory;

    public static void main(String[] args) {
        InputStream inputstream;

        try {
            //获取Mybatis容器内容
            inputstream = Resources.getResourceAsStream("mybatis-config.xml");
            if (sqlsessionfactory == null) {
                //新建一个factory，作用用来生产sqlSeesion
                sqlsessionfactory = new SqlSessionFactoryBuilder().build(inputstream);
            }
            //使用factory的open方法创建一个sqlSeesion
            SqlSession sqlsession = sqlsessionfactory.openSession();

            // 根据Id查询数据
            User userOne = sqlsession.selectOne("com.lucas.mybatis.mapper.UserMapper.slelectUserById",1);
            System.out.println(userOne);
            System.out.println("------------------------------");

            //增加一条数据
            User userInsert = new User();
            userInsert.setName("张三1");
            userInsert.setAge(20);
            sqlsession.insert("com.lucas.mybatis.mapper.UserMapper.insertUser",userInsert);
            System.out.println("------------------------------");

            //修改一条数据
            User userUpdate = new User();
            userUpdate.setId(2);
            userUpdate.setName("张三2" );
            userUpdate.setAge(30);
            sqlsession.update("com.lucas.mybatis.mapper.UserMapper.updateUser",userUpdate);
            System.out.println("------------------------------");

            //查询所有数据
            List<User> user1All = sqlsession.selectList("com.lucas.mybatis.mapper.UserMapper.slelectAll");
            for (User myUser : user1All) {
                System.out.println(myUser);
            }
            System.out.println("------------------------------");

            //删除数据
            sqlsession.delete("com.lucas.mybatis.mapper.UserMapper.deleteUser",6);
            
            sqlsession.commit(); //提交事务
            sqlsession.close();//关闭连接
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

运行结果如下：