MyBatis学习练习（1）

della0887

昨天晚上学习了Mybatis文档，今天编写了一个简单练习。
基本目的：利用Mybatis完成对一个表简单的select、insert、update、delete操作。达到熟悉MyBatis基本用法的目的。
用到的jar：MyBatis.jar,数据库驱动.jar（如mysql-connector.jar）

MyBatis的配置文件MyBatisConfig.xml。可以进行数据源和事务管理器的配置，以及其他影响MyBatis执行的变量。

<?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>
<!-- 导入属性文件，采用类路径方式 -->
<properties resource="com/chl/mybatis/properties/config.properties">
</properties>
<!-- 简称  -->
<typeAliases>
<typeAlias alias="User" type="com.chl.mybatis.domain.User"></typeAlias>
</typeAliases>
<!-- 环境设置 -->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
<!-- 可以继续配置environment -->
</environments>
<!-- 导入映射的文件，采用类路径方式 -->
<mappers>
<mapper resource="com/chl/mybatis/data/UserMapper.xml"/>
</mappers>

</configuration>


MyBatis的映射文件UserMapper.xml。文档中评价这个文件时奇迹发生的地方。

<?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.chl.mybatis.data.UserMapper">
<select id="selectUsers" resultType="User">
select username, sex from t_user;
</select>
<insert id="insertUser" parameterType="User">
insert into t_user (username, sex) values (#{userName},#{sex});
</insert>
<update id="updateUser" parameterType="User">
update t_user set username=#{userName}, sex=#{sex} where username=#{userName};
</update>
<delete id="deleteUser" parameterType="User">
delete from t_user where username=#{userName} and sex=#{sex}
</delete>
</mapper>


UserMapper接口文件，该文件与UserMapper.xml有着某些地方一一对应的关系，注意哦。

package com.chl.mybatis.data;
import java.util.List;
import com.chl.mybatis.domain.User;
/**
* @author chl
* 定义User的映射器接口，
* 接口名称与命名空间的名称同，
* 方法名称与映射配置中映射方法的id同。
*
*/
public interface UserMapper {
public List<User> selectUsers();
public void insertUser(User user);
public void updateUser(User user);
public void deleteUser(User user);
}


MyBatis文件，其中定义了产生SqlSessionFactory的工厂单例类。

package com.chl.mybatis;
import java.io.IOException;
import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
/**
* @author chl
* 工厂单例模式，生成SqlSessionFactory实例。
*
*/
public class MyBatis {
private MyBatis(){};
private static SqlSessionFactory ssf = null;
public static SqlSessionFactory getSessionFactory() throws IOException{
if(null == ssf){
String resource = "com/chl/mybatis/data/mybatisConfig.xml";
Reader reader = Resources.getResourceAsReader(resource);
ssf = new SqlSessionFactoryBuilder().build(reader);
}//if
return ssf;
}
}


User文件，定义了User javabean实体类。

package com.chl.mybatis.domain;
public class User {
private String userName = "";
private String sex = "";
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
}


userAction类，方法体中获取SqlSessionFactory实例，获得SqlSession，获取SqlMapper，然后调用映射的方法。

package com.chl.mybatis.action;
import java.io.IOException;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import com.chl.mybatis.MyBatis;
import com.chl.mybatis.data.UserMapper;
import com.chl.mybatis.domain.User;
/**
* @author chl
* 对user的操作。
* 其中将SqlSession放于方法级范围。
*/
public class UserAction {
public void insert(User user){
SqlSessionFactory ssf = null;
SqlSession session = null;
try {
ssf = MyBatis.getSessionFactory();
session = ssf.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
userMapper.insertUser(user);
selectAll();
System.out.println("==================================");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
if(null != session){
session.close();
session = null;
}
}
}
public void update(User user){
SqlSessionFactory ssf = null;
SqlSession session = null;
try {
ssf = MyBatis.getSessionFactory();
session = ssf.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
userMapper.updateUser(user);
selectAll();
System.out.println("==================================");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
if(null != session){
session.close();
session = null;
}
}
}
public void selectAll(){
SqlSessionFactory ssf = null;
SqlSession session = null;
try {
ssf = MyBatis.getSessionFactory();
session = ssf.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
List<User> users = userMapper.selectUsers();
for(User u : users){
System.out.println(u.getUserName()+"    "+u.getSex());
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
if(null != session){
session.close();
session = null;
}
}
}
public void delete(User user){
SqlSessionFactory ssf = null;
SqlSession session = null;
try {
ssf = MyBatis.getSessionFactory();
session = ssf.openSession();
UserMapper um = session.getMapper(UserMapper.class);
um.deleteUser(user);
selectAll();
System.out.println("==================================");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
if(null != session){
session.close();
session = null;
}
}
}
}