15.MyBatis配置文件1

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添加日志文件log4j.properties

添加log4j日志文件，可以打印mybatis实际执行的sql语句，方便代码调试

新建日志文件log4j.properties

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# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# MyBatis logging configuration...
log4j.logger.org.mybatis.example.BlogMapper=TRACE
# 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

在mybatis.cfg.xml添加log4j的配置

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<?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">
  
<!-- MyBatis的整体配置 -->
<configuration>
	
    <!-- mybatis.cfg.xml配置文件的<configuration>节点的子节点是有顺序要求的 -->
	<!-- 
	The content of element type "configuration" must match 
 		"(properties?,settings?,typeAliases?,typeHandlers?,
 		objectFactory?,objectWrapperFactory?,reflectorFactory?,
 		plugins?,environments?,databaseIdProvider?,mappers?)".
 		
		<properties></properties>
		<typeAliases></typeAliases>
		<plugins></plugins>
		<environments></environments>
		<mappers></mappers>
	 -->
	
	<settings>
		<!-- 让log4j去记录sql日志，打印mybatis执行的sql语句 -->
		<setting name="logImpl" value="LOG4J"/>
		<!-- https://mybatis.org/mybatis-3/zh/configuration.html#properties -->
	</settings>

	<!-- 数据源环境配置，default默认数据源的id -->
	<environments default="mysql_test">
		
		<!-- mysql 测试数据库 -->
		<environment id="mysql_test">
			
			<!-- mybatis的事务管理器 -->
			<transactionManager type="JDBC"></transactionManager>
			
			<!-- 配置数据库连接池 -->
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver"/>
				<property name="url" value="jdbc:mysql://localhost:3306/mybatis_test"/>
				<property name="username" value="root"/>
				<property name="password" value="123456"/>
			</dataSource>
		</environment>
		
		<!-- mysql 生产数据库 -->
		<!-- <environment id="mysql_prod"></environment> -->
		
		<!-- oracle 数据库 -->
		<!-- <environment id="oracle"></environment> -->
		
	</environments>
	
	<!-- 配置Mapper.xml文件 -->
	<mappers>
		<mapper resource="com/course/mapper/UserMapper.xml" />
	</mappers>
</configuration>
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DEBUG [main] - Opening JDBC Connection
Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
DEBUG [main] - Created connection 2059461664.
DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@7ac0e420]
DEBUG [main] - ==>  Preparing: select * from user 
DEBUG [main] - ==> Parameters: 
DEBUG [main] - <==      Total: 10
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@7ac0e420]
DEBUG [main] - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@7ac0e420]
DEBUG [main] - Returned connection 2059461664 to pool.

添加工具类

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package com.course.util;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MyBatisUtil {

	private static InputStream inputStream = MyBatisUtil.class.getResourceAsStream("/mybatis.cfg.xml");
	
	private static SqlSessionFactoryBuilder sessionFactoryBuilder = new SqlSessionFactoryBuilder();
	
	private static SqlSessionFactory sqlSessionFactory = sessionFactoryBuilder.build(inputStream);
	
	public static SqlSession openSqlSession() {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		return sqlSession;
	}
	
	public static void closeSqlSession(SqlSession sqlSession) {
		sqlSession.commit();
		sqlSession.close();
	}	
}

或者

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package com.course.util;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MyBatisUtil2 {
	
	private static SqlSessionFactory sqlSessionFactory = null;

	static {
		InputStream inputStream = MyBatisUtil2.class.getResourceAsStream("/mybatis.cfg.xml");
		SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
		sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
	}
	
	public static SqlSession openSqlSession() {
		SqlSession sqlSession = sqlSessionFactory.openSession();
		return sqlSession;
	}
	
	public static void closeSqlSession(SqlSession sqlSession) {
		sqlSession.commit();
		sqlSession.close();
	}	
}

接口的实现类

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package com.course.dao.impl;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import com.course.dao.UserDao;
import com.course.util.MyBatisUtil;
import com.course.util.MyBatisUtil2;
import com.course.vo.User;

public class UserDaoImpl implements UserDao {

	@Override
	public void addUser(User user) {
		// 1.得到sqlSession
		SqlSession sqlSession = MyBatisUtil.openSqlSession();
		// 2.进行CRUD 
		/**
		 * 参数1: 对应的是UserMapper.xml里面<insert>节点的命名空间+id属性值
		 * 参数2: UserMapper.xml里面<insert id="参数1">的parameterType属性对应的类型的对象
		 */
		sqlSession.insert("com.course.dao.abc.UserDao.addUserXml", user);
		// 3.提交事务，关闭session
		MyBatisUtil.closeSqlSession(sqlSession);

	}

	@Override
	public void updateUser(User user) {
		// 1.得到sqlSession
		SqlSession sqlSession = MyBatisUtil.openSqlSession();
		// 2.进行CRUD 
		sqlSession.update("com.course.dao.abc.UserDao.updateUser", user);
		// 3.提交事务，关闭session
		MyBatisUtil.closeSqlSession(sqlSession);

	}

	@Override
	public void deleteUser(Integer id) {
		// 1.得到sqlSession
		SqlSession sqlSession = MyBatisUtil.openSqlSession();
		// 2.进行CRUD 
		sqlSession.delete("com.course.dao.abc.UserDao.deleteUser", id);
		// 3.提交事务，关闭session
		MyBatisUtil.closeSqlSession(sqlSession);

	}

	@Override
	public User getUserById(Integer id) {
		// 1.得到sqlSession
		SqlSession sqlSession = MyBatisUtil.openSqlSession();
		// 2.进行CRUD 
		User user = sqlSession.selectOne("com.course.dao.abc.UserDao.getUserById", id);
		// 3.提交事务，关闭session
		MyBatisUtil.closeSqlSession(sqlSession);
		
		return user;
	}

	@Override
	public List<User> getAllUser() {
		// 1.得到sqlSession
		SqlSession sqlSession = MyBatisUtil2.openSqlSession();
		// 2.进行CRUD 
		List<User> userList = sqlSession.selectList("com.course.dao.abc.UserDao.getAllUser");
		// 3.提交事务，关闭session
		MyBatisUtil2.closeSqlSession(sqlSession);
		
		return userList;
	}
}

mybatis.cfg.xml配置文件详解

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<?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">
  
<!-- MyBatis的整体配置 -->
<configuration>
	
	<settings>
		<!-- 让log4j去记录sql日志，打印mybatis执行的sql语句 -->
		<setting name="logImpl" value="LOG4J"/>
		<!-- https://mybatis.org/mybatis-3/zh/configuration.html#properties -->
	</settings>

	<!-- 数据源环境配置，default默认数据源的id -->
    <!-- 数据源环境配置  default默认数据源的ID
		environments 指mybatis可以配置多个环境，default指向默认的环境
		每个SqlSessionFactory对应一个环境environment
		 -->
	<environments default="mysql_test">
		
        <!-- 环境 
	        可以配置多个数据源  但是能使用一个
	    -->
		<!-- mysql 测试数据库 -->
		<environment id="mysql_test">
			
			<!-- mybatis的事务管理器 -->
            <!-- 配置mybatis的事务管理器
			type 的配置 
				JDBC【建议】 – 这个配置直接使用JDBC 的提交和回滚功能。它依赖于从数据源获得连接来管理
					事务的生命周期。
				MANAGED – 这个配置基本上什么都不做。它从不提交或者回滚一个连接的事务。而是让
					容器（例如：Spring 或者J2EE 应用服务器）来管理事务的生命周期
			-->
			<transactionManager type="JDBC"></transactionManager>
			
			<!-- 配置数据库连接池 -->
            <!-- 这个环境里面的数据源
			type：POOLED【建议】
					 这个数据源的实现缓存了JDBC 连接对象，用于避免每次创建新的数据库连接时都初始
					化和进行认证，加快程序响应。并发WEB 应用通常通过这种做法来获得快速响应。
				 UNPOOLED:每次连接数据库时都创建新的连接【不推荐】
				 JNDI:使用外部的数据源 如tomcat可以配置数据源在这里使用
			 -->
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver"/>
				<property name="url" value="jdbc:mysql://localhost:3306/mybatis_test"/>
				<property name="username" value="root"/>
				<property name="password" value="123456"/>
			</dataSource>
		</environment>
		
		<!-- mysql 生产数据库 -->
		<!-- <environment id="mysql_prod"></environment> -->
		
		<!-- oracle 数据库 -->
		<!-- <environment id="oracle"></environment> -->
		
	</environments>
	
	<!-- 配置Mapper.xml文件 -->
	<mappers>
		<mapper resource="com/course/mapper/UserMapper.xml" />
	</mappers>

</configuration>

引入db.properties

新建db.properties

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driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis_test
username=root
password=123456

修改mybatis.cfg.xml

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<?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">
  
<!-- MyBatis的整体配置 -->
<configuration>
	
	<properties resource="db.properties"></properties>
	
	...
	
</configuration>