MyBatis——第一个程序

MyBatis1:初识

MyBatis第一个程序

流程：搭建环境–》导入MyBatis–》编写代码–》测试

1、创建一张User表。
关键字id、username、pwd

2、导入相关jar包

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.23</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/log4j/log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.10</version>
        </dependency>
    </dependencies>

3、编写MyBatis核心配置文件

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?userSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF8&amp;serverTimezone=GMT"/>
                <property name="username" value="root"/>
                <property name="password" value="Su190419.."/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

4、编写工具类

public class MyBatiUtil {
    private static SqlSessionFactory sqlSessionFactory;
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }

    static{
        String resource = "mybatis-config.xml";
        try {
            InputStream resourceAsStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

5、实体类

package com.pp.pojo;
@Data
public class User {
    private int id;
    private String name;
    private String pwd;
}

6、编写Mapper（DAO）接口类

public interface UserDao {

    List<User> getUserLike(String value);
    List<User> getUserList();
    User getUserById(int id);
    int addUser(User user);
    int updateUser(User user);
    int deleteUser(int id);

}

7、编写Mapper.xml配置文件
namespace十分重要，不能写错

<?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.pp.dao.UserDao">
    <select id="getUserLike" resultType="com.pp.pojo.User">
        select * from mybatis.user where name like #{value}
    </select>
</mapper>

8、编写测试类

• Junit包测试

public class MyTest {
   @Test
   public void selectUser() {
       SqlSession session = MybatisUtils.getSession();
       //方法一:
       //List<User> users = session.selectList("com.kuang.mapper.UserMapper.selectUser");
       //方法二:
       UserMapper mapper = session.getMapper(UserMapper.class);
       List<User> users = mapper.selectUser();

       for (User user: users){
           System.out.println(user);
      }
       session.close();
  }
}

9、db.properties

driver = com.mysql.cj.jdbc.Driver
url = jdbc:mysql://localhost:3306/mybatis?userSSL=true&useUnicode=true&characterEncoding=UTF8&serverTimezone=GMT
username = root
password = Su190419..

10、log4j.properties

#将等级为DEBUG的日志信息输出到console和file这两个目的地，console和file的定义在下面的代码
log4j.rootLogger = DEBUG,console ,file

#控制台输出的相关设置
log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.Threshold = DEBUG
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern =  [%c]-%m%n

#文件输出的相关设置
log4j.appender.file = org.apache.log4j.RollingFileAppender
log4j.appender.file.File = ./log/pp.log
log4j.appender.file.MaxFileSize = 10mb
log4j.appender.file.Threshold = DEBUG
log4j.appender.file.layout = org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern = [%p][%d{yy-MM-dd}][%c]%m%n

#日志输出级别
log4j.logger.org.mybatis=DEBUG
log4j.logger.java.sql=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.ResultSet=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG