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MyBatis01:第一个程序

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MyBatis01:第一个程序

思路流程:搭建环境-->导入Mybatis--->编写代码--->测试

  1. 数据库文件
DROP DATABASE `mybatis`;

CREATE DATABASE `mybatis`;

USE `mybatis`;

DROP TABLE IF EXISTS `user`;

CREATE TABLE `user` (
`id` INT(20) NOT NULL,
`name` VARCHAR(30) DEFAULT NULL,
`pwd` VARCHAR(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;

INSERT  INTO `user`(`id`,`name`,`pwd`) 
VALUES (1,'小明','123456'),
(2,'张三','abcdef'),
(3,'李四','987654');
  1. 新建空白maven项目

    image-20201108114027049

  2. pom.xml中导入jar包

 		<dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
  1. mybatis-config.xml核心配置文件,官网中有头文件

    image-20201108114223607

    <?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"></transactionManager>
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf8"/>
                    <property name="username" value="root"/>
                    <property name="password" value="123456"/>
                </dataSource>
                
            </environment>
        </environments>
        
    </configuration>
    
  2. MybatisUtils工具类,使用SqlSessionFactory创建session,注意import的时候是ibatis包下的类

    image-20201108120447888

    public class MybatisUtils {
        private static SqlSessionFactory sqlSessionFactory;
    
        static {
            try {
                String resource="mybatis-config.xml";
                InputStream inputStream = Resources.getResourceAsStream(resource);
                sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream);
            }catch (IOException e){
                e.printStackTrace();
            }
        }
        //获取sqlession连接
        public static SqlSession getSession(){
            return sqlSessionFactory.openSession();
        }
    }
    
    
  3. 实体类User

image-20201108121312104

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

   //构造,有参,无参
   //set/get
   //toString()
}

  1. UserMapper接口,声明一个查询所有用户的方法

image-20201108121644327

public interface UserMapper {
    List<User> selectUser();
}
  1. UserMapper.xml配置文件写sql,注意namespace
<?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.wgg.dao.UserMapper">
    <select id="selectUser" resultType="com.wgg.pojo.User">
        select * from user
    </select>
</mapper>
  1. mybatis-config.xml中注册UserMapper.xml
    <mappers>
        <mapper resource="com/wgg/dao/UserMapper.xml"/>
    </mappers>
  1. 测试类

image-20201108151634127

public class TestDemo01 {
    @Test
    public void selectUser(){
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        List<User> users = mapper.selectUser();
        for (User user : users) {
            System.out.println(user);
        }
        session.close();
    }
}

运行结果

image-20201108151724110

可能会产生maven静态资源过滤问题,pom.xml中添加

<build>
    <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
    </resources>
</build>

标签:xml,第一个,UserMapper,程序,session,user,mybatis,public,MyBatis01
来源: https://www.cnblogs.com/zhishu/p/13944471.html