MyBatis 入门01

最新推荐文章于 2024-10-11 20:45:34 发布

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最新推荐文章于 2024-10-11 20:45:34 发布

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分类专栏： mybstis

本文链接：https://blog.youkuaiyun.com/u012948731/article/details/48996345

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这篇博客介绍了MyBatis入门的四个步骤：准备必要的jar包，创建数据库，配置conf.xml文件，建立实体类并编写sql映射文件及测试代码，重点讲解了如何在MyBatis中执行SQL查询。

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第一步准备jar包：
log4j-1.2.16.jar
mybatis-3.1.1.jar
mysql-connector-java-5.1.7-bin.jar.

第二步：创建数据库：

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for users
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of users
-- ----------------------------
INSERT INTO `users` VALUES ('1', 'tom', '20');
INSERT INTO `users` VALUES ('2', 'jack', '29');

第三步添加配置文件conf.xml:

<?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>
    <!-- 配置实体类的别名 -->
    <typeAliases>
        <!-- <typeAlias type="com.atguigu.day03_mybaits.test1.User" alias="_User"/> -->
        <package name="com.atguigu.day03_mybaits.bean"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>
</configuration>

第四步建造实体类：

public class User {
//shift+alt+s
    private int id;
    private String name;
    private int age;

    public User(int id, String name, int age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }
    public User() {
        super();
    }
    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 "User [id=" + id + ", name=" + name + ", age=" + age + "]";
    }


}

2.5. 定义操作users表的sql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 namespace="com.atguigu.mybatis_test.test1.userMapper"> 
    <select id="getUser" parameterType="int" 
        resultType="com.atguigu.mybatis_test.test1.User">
        select * from users where id=#{id}
    </select>
</mapper>

2.6. 在conf.xml文件中注册userMapper.xml文件

<mappers>
    <mapper resource="com/atguigu/mybatis_test/test1/userMapper.xml"/>
</mappers>

2.7. 编写测试代码：执行定义的select语句

public class Test {

    public static void main(String[] args) throws IOException {
        String resource = "conf.xml"; 
        InputStream is = Test.class.getClassLoader().getResourceAsStream(resource);

        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);

        SqlSession session = factory.openSession();

        String statement = "com.atguigu.day03_mybaits.test1.userMapper.getUser";

        User user = session.selectOne(statement, 2);
        System.out.println(user);
    }
}