4.Improve SqlSession

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工具类: SqlSessionUtil

SqlSessionUtil

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import java.io.IOException;
import java.io.InputStream;

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

public class SqlSessionUtil {

	private static ThreadLocal<SqlSession> local = new ThreadLocal<SqlSession>();
	private static SqlSessionFactory sf = null;
	
	static {
		InputStream inputStream = null;
		
		try {
			inputStream = Resources.getResourceAsStream("mybatis.xml");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		sf = new SqlSessionFactoryBuilder().build(inputStream);
	}
	
	public static SqlSession getSession() {
		SqlSession session = local.get();
		if(session == null) {
			session = sf.openSession();
			local.set(session);
		}
		return session; 
	}
	
	public static void close(SqlSession session) {
		if(session != null) {
			session.close();
			local.remove();
		}
	}
}

类: StudentDaoImpl

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import java.io.IOException;
import java.io.InputStream;

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

public class StudentDaoImpl implements StudentDao{

	@Override
	public void insertStudent(Student student) {
		SqlSession session=SqlSessionUtil.getSession();
		session.insert("insertStudent", student);
		session.commit();
		SqlSessionUtil.close(session);
	}

}

添加属性文件: jdbc.properties

jdbc.properties

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

mybatis.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">
<configuration>
	<!-- 引入属性文件 -->
	<properties resource="jdbc.properties"></properties>

	<environments default="mysql">
		<environment id="mysql">
			...
		</environment>
	</environments>
	<mappers>
		<mapper resource="com/node/dao/StudentDao.xml"/>
	</mappers>
</configuration>

使用日志文件输出SQL语句

log4j.properties

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#
#    Copyright 2009-2016 the original author or authors.
#
#    Licensed under the Apache License, Version 2.0 (the "License");
#    you may not use this file except in compliance with the License.
#    You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS,
#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#    See the License for the specific language governing permissions and
#    limitations under the License.
#

### Global logging configuration
log4j.rootLogger=ERROR, stdout
### 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

log4j.logger.test=trace,console

log4j.logger.[namespace]=trace,console

StudentDao.xml

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<?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="test">
	...
</mapper>