加入log4j日志功能
- 加入依赖
<!-- log4j日志 -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
加入log4j的配置文件
log4j的配置文件名为log4j.xml，存放的位置是src/main/resources目录下
日志的级别：FATAL(致命)>ERROR(错误)>WARN(警告)>INFO(信息)>DEBUG(调试) 从左到右打印的内容越来越详细
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
<appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
<param name="Encoding" value="UTF-8" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" />
</layout>
</appender>
<logger name="java.sql">
<level value="debug" />
</logger>
<logger name="org.apache.ibatis">
<level value="info" />
</logger>
<root>
<level value="debug" />
<appender-ref ref="STDOUT" />
</root>
</log4j:configuration>
MyBatis的增删改查
- 添加
<!--int insertUser();-->
<insert id="insertUser">
insert into t_user values(null,'admin','123456',23,'男','12345@qq.com')
</insert>
删除
<!--int deleteUser();-->
<delete id="deleteUser">
delete from t_user where id = 6
</delete>
修改
<!--int updateUser();-->
<update id="updateUser">
update t_user set username = '张三' where id = 5
</update>
查询一个实体类对象
<!--User getUserById();-->
<select id="getUserById" resultType="com.atguigu.mybatis.bean.User">
select * from t_user where id = 2
</select>
查询集合
<!--List<User> getUserList();-->
<select id="getUserList" resultType="com.atguigu.mybatis.bean.User">
select * from t_user
</select>
注意：
- 查询的标签select必须设置属性resultType或resultMap，用于设置实体类和数据库表的映射关系
resultType：自动映射，用于属性名和表中字段名一致的情况
resultMap：自定义映射，用于一对多或多对一或字段名和属性名不一致的情况
当查询的数据为多条时，不能使用实体类作为返回值，只能使用集合，否则会抛出异常TooManyResultsException；但是若查询的数据只有一条，可以使用实体类或集合作为返回值
测试类
juit测试类
import com.atguigu.mybatis.mapper.userMapper;
import com.atguigu.mybatis.pojo.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.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class MyBatisTest {
/**
* 往t_user表中插入数据
* @return 1
* @throws IOException
*/
@Test
public void testInsertUser() throws IOException {
//读取MyBatis的核心配置文件
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
//获取SqlSessionFactoryBuilder对象
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
//通过核心配置文件所对应的字节输入流创建工厂类SqlSessionFactory，生产SqlSession对象
SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
//获取sqlSession，此时通过SqlSession对象所操作的sql都必须手动提交或回滚事务
//SqlSession sqlSession = sqlSessionFactory.openSession();
//创建SqlSession对象，此时通过SqlSession对象所操作的sql都会自动提交
SqlSession sqlSession = sqlSessionFactory.openSession(true);
//通过代理模式创建UserMapper接口的代理实现类对象
userMapper userMapper = sqlSession.getMapper(userMapper.class);
//调用UserMapper接口中的方法，就可以根据UserMapper的全类名匹配元素文件，通过调用的方法名匹配映射文件中的SQL标签，并执行标签中的SQL语句
int result = userMapper.insertUser();
//提交事务
//sqlSession.commit();
System.out.println("result:" + result);
}
/**
* 往t_user表中更新数据
* @throws IOException
*/
@Test
public void testUpdateUser() throws IOException {
InputStream resourceAsStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
SqlSessionFactory build = sqlSessionFactoryBuilder.build(resourceAsStream);
SqlSession sqlSession = build.openSession(true);
userMapper mapper = sqlSession.getMapper(userMapper.class);
mapper.updateUser();
System.out.println("1111");
}
/**
* 删除t_user表中的数据
* @throws IOException
*/
@Test
public void testDeleteUser() throws IOException {
InputStream resourceAsStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
SqlSessionFactory build = sqlSessionFactoryBuilder.build(resourceAsStream);
SqlSession sqlSession = build.openSession(true);
userMapper mapper = sqlSession.getMapper(userMapper.class);
mapper.deleteUser();
}
/**
* 通过id来查询t_user表格
* @throws IOException
*/
@Test
public void testGetUserById() throws IOException {
InputStream resourceAsStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
SqlSessionFactory build = sqlSessionFactoryBuilder.build(resourceAsStream);
SqlSession sqlSession = build.openSession(true);
userMapper mapper = sqlSession.getMapper(userMapper.class);
user userById = mapper.getUserById();
System.out.println(userById.toString());
}
/**
* 查询t_user表中所有的数据
* @throws IOException
*/
@Test
public void TestGetAllUser() throws IOException {
InputStream resourceAsStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
SqlSessionFactory build = sqlSessionFactoryBuilder.build(resourceAsStream);
SqlSession sqlSession = build.openSession(true);
userMapper mapper = sqlSession.getMapper(userMapper.class);
List<user> allUser = mapper.getAllUser();
allUser.forEach(user -> System.out.println(user.toString()));
}
}
