mybatis基础

一、创建maven项目并添加如下依赖

	<dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

二、创建mybatis_study数据库和t_user表用于测试

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for t_user
-- ----------------------------
DROP TABLE IF EXISTS `t_user`;
CREATE TABLE `t_user`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `age` int(11) NULL DEFAULT NULL,
  `address` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 4 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of t_user
-- ----------------------------
INSERT INTO `t_user` VALUES (1, '李洪刚', 20, '江阳区嘉裕花园3栋四楼15#');
INSERT INTO `t_user` VALUES (2, '王云华', 30, '纳溪区大渡镇红鱼村三大队');
INSERT INTO `t_user` VALUES (3, '郑小翠', 21, '江阳区老窖花园2栋五楼15号');

SET FOREIGN_KEY_CHECKS = 1;

三、编写User实体类用于数据封装

package com.dc.domain;

public class User {
     
    private Integer id;
    private String name;
    private Integer age;
    private String address;

    public Integer getId() {
     
        return id;
    }

    public void setId(Integer id) {
     
        this.id = id;
    }

    public String getName() {
     
        return name;
    }

    public void setName(String name) {
     
        this.name = name;
    }

    public Integer getAge() {
     
        return age;
    }

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

    public String getAddress() {
     
        return address;
    }

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

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

四、编写dao层数据访问接口

package com.dc.dao;

import com.dc.domain.User;

import java.util.List;

public interface UserDao {
     
    /**
     * 查询所有
     *
     * @return
     */
    List<User> findAll();

    /**
     * 根据id查询
     *
     * @param id
     * @return
     */
    User findUserById(Integer id);
}

五、resources中创建mysql连接文件jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis_study?characterEncoding=utf8&useSSL=false
jdbc.username=root
jdbc.password=1234

六、resources中创建mybatis主配置文件sqlMapConfig.xml

<configuration>

    <properties resource="jdbc.properties">properties>
    
    <typeAliases>
        <package name="com.dc.domain"/>
    typeAliases>

    
    <environments default="mysql">
        
        <environment id="mysql">
            
            <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>

    <mappers>
        
        <package name="com.dc.dao"/>
    mappers>
configuration>

七、创建UserDao的映射文件

<mapper namespace="com.dc.dao.UserDao">
    <select id="findAll" resultType="user">
        select *
        from t_user
    select>

    <select id="findUserById" resultType="User" parameterType="Integer">
        select *
        from t_user
        where id = #{id}
    select>
mapper>

八、编写测试类进行测试

package com.dc;

import com.dc.dao.UserDao;
import com.dc.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.After;
import org.junit.Before;
import org.junit.Test;

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

public class MybatisTest {
     
    private InputStream in;
    private SqlSession sqlSession;
    private UserDao userDao;

    @Before
    public void init() throws Exception {
     
        // 1、读取配置文件
        in = Resources.getResourceAsStream("sqlMapConfig.xml");
        // 2、创建SqlSessionFactory工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        // 3、根据工厂创建SqlSession对象
        sqlSession = factory.openSession(true);
        // 4、根据SqlSession生产代理对象
        userDao = sqlSession.getMapper(UserDao.class);
    }

    @After
    public void destroy() throws Exception {
     
        sqlSession.close();
        in.close();
    }

    @Test
    public void testFindAll() {
     
        List<User> users = userDao.findAll();
        users.forEach(System.out::println);
    }

    @Test
    public void testFindUserById() {
     
        User user = userDao.findUserById(1);
        System.out.println(user);
    }
}

项目结构：

测试结果：