第一个mybatis实例总结

第一个mybatis程序，查找所有总结

第一步：mybatis环境搭建(依赖添加)

设置打包方式（pom.xml）：

<packaging>jar</packaging>

添加依赖（pom.xml）：

 <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.19</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>
    </dependencies>

添加log4j配置文件：在main的resources下添加log4j.properties文件

log4j.rootCategory=ERROR,stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %t %c{2}:%L -%m%n

log4j.category.org.springframework.beans.factory=ERROR

配置连接池以及mysql(SqlMapConfig.xml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>
<!--    配置环境-->
    <environments default="mysql">
<!--        配置mysql的环境-->
        <environment id="mysql">
<!--            配置事务-->
            <transactionManager type="JDBC"></transactionManager>
<!--                配置连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatislearn?serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="op097916"/>
            </dataSource>
        </environment>
    </environments>
<!--    配置映射文件的位置-->
    <mappers>
        <mapper resource="chen/dao/IUserDao.xml"></mapper>
    </mappers>
</configuration>

第二步：编写映射文件（IUserDao.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 namespace="chen.dao.IUserDao">
    <!--    配置查询所有-->
    <select id="findAll" resultType="chen.domain.User">
        select * from user;
    </select>
</mapper>

第三步：编写pojo类（domain里面的User）:

package chen.domain;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable {
    private Integer id;
    private String username;
    private Date birthday;
    private String sex;
    private String address;

    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 Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", birthday=" + birthday +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

第四步：编写用户持久层接口（IUserdao）

package chen.dao;

import chen.domain.User;

import java.util.List;

/**
 * 用户的持久层接口
 */
public interface IUserDao {
    /**
     * 查询所有用户
     * @return
     */
    List<User> findAll();
}

第五步：添加测试类测试查询结果(test类)

package chen;

import chen.dao.IUserDao;
import chen.domain.User;
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.Test;

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

/**
 * 测试mybatis的crud操作
 */
public class test {
    /**
     * 查询所有
     */
    @Test
    public void testFindAll() throws IOException {
        //读取配置文件，生成字节输入流
        InputStream in= Resources.getResourceAsStream("SqlMapConfig.xml");
        //获取sqlsessionfactory对象
        SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(in);
        //获取sqlsession对象
        SqlSession session=factory.openSession();
        //获取dao的代理对象
        IUserDao userDao=session.getMapper(IUserDao.class);
        //执行查询所有方法
        List<User> users=userDao.findAll();
        for (User u:users) {
            System.out.println(u);
        }
        //关闭资源
        session.close();
        in.close();
    }
}

文件结构