[开发测试]Mybatis之入门案例

一、目录结构

classes是项目的根路径，编译后会将com包及其子包，resources的子包放放到classes中，其中需要注意的是java目录下的xml不会被编译到classes中，所以要在resources中建一个结构相同的mapper包。

二、在pom文件中导入依赖的坐标

	<!--mybatis的jar包-->
	<dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.1</version>
    </dependency>
    <!--数据库连接的jar包-->
    <!--mysql8的driver和url有变化注意看dbconfig.properties-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.13</version>
    </dependency>
    <dependency>
    <!--测试依赖的jar包-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
    <!--log4j依赖的jar包-->
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>1.2.17</version>
    </dependency>

三、实体类

public class Website {
    private int id;
    private String name;
    private String url;
    private int age;
    private String country;
    private Date createtime;

  //省略setting和getting,alt+ins可快速添加
}

四、mapper接口

/**
 * @Author: 蔡里都傻
 * @DateTime: 2022/2/19 20:44
 */
public interface WebsiteMapper {
     int addWebsite(Website website);
     Website selectAllWebsite();
}

五、映射文件

和mapper接口同名

<?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.cailibin.mapper.WebsiteMapper">
    <!-- 添加一个网站 -->
    <insert id="addWebsite" parameterType="com.cailibin.pojo.Website">
        insert into website
        (name,url,age,country)
        values(#{name},#{url},#{age},#{country})
    </insert>
    <!-- 查询所有网站信息 -->
    <select id="selectAllWebsite" resultType="com.cailibin.pojo.Website">
        select * from website
    </select>
</mapper>

六、mybatis配置文件

<?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>
    <properties resource="dbconfig.properties"/>
    <settings>
        <setting name="logImpl" value="LOG4J" />
    </settings>

    <!-- 配置mybatis运行环境 -->
    <environments default="development">
        <environment id="development">
            <!-- 使用JDBC的事务管理 -->
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <!-- MySQL数据库驱动 -->
               <property name="driver" value="${jdbc.driver}"/>
                <!-- 连接数据库的URL -->
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
        </environment>
    </environments>
    <!-- 将mapper文件加入到配置文件中 -->
    <mappers>
        <mapper resource="com/cailibin/mapper/WebsiteMapper.xml" />
    </mappers>
</configuration>

七、dbconfig.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis?&useSSL=false&serverTimezone=UTC
jdbc.password=root
jdbc.username=root

八、dao

/**
 * @Author: 蔡里都傻
 * @DateTime: 2022/2/19 22:04
 */
public class WebsiteDao {
    private SqlSessionFactory sqlSessionFactory;

    public WebsiteDao(String configPath) throws IOException {
        InputStream inputStream = Resources.getResourceAsStream(configPath);
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }

    public List<Website> findAll() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<Website> studentList = sqlSession.selectList("com.cailibin.mapper" +
                ".WebsiteMapper." +
                "selectAllWebsite");
        sqlSession.close();
        return studentList;
    }

    public int addWebsite(Website website) {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        int rowsAffected = sqlSession.insert("com.cailibin.mapper.WebsiteMapper" +
                ".addWebsite", website);
        sqlSession.commit();
        sqlSession.close();
        return rowsAffected;
    }

}

九、logej.properties

# Global logging configuration
log4j.rootLogger=ERROR,stdout
# MyBatis logging configuration...
log4j.logger.com.cailibin=DEBUG
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

十、测试

/**
 * Unit test for simple App.
 */
public class AppTest {
   private WebsiteDao websiteDao;
   @Before
   public void init() throws IOException {
      websiteDao = new WebsiteDao("mybatis-config.xml");
   }

   @Test
   public void insertTest() {
      Website website = new Website();
      website.setName("编程帮");
      website.setUrl("https://www.biancheng.net/");
      website.setAge(21);
      website.setCountry("CN");
      websiteDao.addWebsite(website);
   }
   @Test
   public void findAllTest() {
      List<Website> all = websiteDao.findAll();
      all.forEach(System.out::println);
   }

}