优化配置之 -----配置别名
1) 给某个bean指定一个别名，修改mybatis-config.xml文件
2) 给一个包下面的所有的bean指定，别名默认是类名首字母小写
3) 可以通过@Alias修改包下面的默认别名，在类上面添加@Alias(value=”别名”)
例子：
1.创建项目
2.建包建配置文件
com.qf.entity
com.qf.dao
com.qf.mapper
com.qf.utils
mybatis-config.xml
3.con.qf.entity包中创建实体类
package com.qf.entity;
import org.apache.ibatis.type.Alias;
@Alias(value="user1")
public class User {
private Integer id;
private String name;
private String password;
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", password=" + password + "]";
}
}
4.con.qf.dao包中创建接口
package com.qf.dao;
import java.util.List;
import com.qf.entity.User;
public interface IUserDao {
public User getUserById(Integer id);
public void add(User user);
public void delete(Integer id);
public void update(User user);
public List<User> getUserList();
}
5.配置jdbc.properties配置文件
jdbc.url =jdbc:mysql://localhost:3306/1707_hibernate jdbc.name=root jdbc.password=root jdbc.driver=com.mysql.jdbc.Driver
配置mybatis-config.xml配置文件
1.给一个实体类起别名：
在mybatis-config.xml里面配置，
<typeAlias type="com.qf.entity.User" alias="user"/>
2.给一个包下面的所有类起别名，默认的别名是类名首字母小写
3）通过@Alias注解修改默认的别名 在类名上加注解@Alias(value="注解")
<?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> <!-- 加载属性文件 resource:本地资源文件 --> <properties resource="jdbc.properties"></properties> <typeAliases> <!-- 给一个对象起别名 --> <!-- <typeAlias type="com.qf.entity.User" alias="user"/> --> <!-- 给一个包下面的所有类起别名，默认的别名是类名首字母小写,可以通过@Alias注解修改默认的别名 --> <package name="com.qf.entity"/> </typeAliases> <environments default="development"> <environment id="development"> <transactionManager type="JDBC" /> <dataSource type="POOLED"> <property name="driver" value="${jdbc.driver}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.name}" /> <property name="password" value="${jdbc.password}" /> </dataSource> </environment> </environments> </configuration>
6.com.qf.mapper包创建接口的映射文件
<?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">
<!-- namespace指的就是接口的全类名 -->
<mapper namespace="com.qf.dao.IUserDao">
<!--
id:方法名称
resultType:返回类型
-->
<select id="getUserById" resultType="user1">
select * from t_user where id = #{id}
</select>
<!-- parameterType:方法的参数类型 -->
<insert id="add" parameterType="user1">
insert into t_user (name,password) values(#{name},#{password})
</insert>
<update id="update">
update t_user set name = #{name},password = #{password} where id = #{id}
</update>
<delete id="delete" parameterType="java.lang.Integer">
delete from t_user where id = #{id}
</delete>
<!--
方法返回集合的时候resultType要配置集合中的类型
-->
<select id="getUserList" resultType="user1">
select * from t_user
</select>
</mapper>
7.在mybatis-config.xml里面读取Mapper文件
<!-- Mapper文件 --> <mappers> <mapper resource="com/qf/mapper/IUserDao.xml" /> </mappers>
8.com.qf.util工具类
package com.qf.utils;
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;
import org.xml.sax.InputSource;
public class MyBatisUtil {
private static SqlSessionFactory sqlSessionFactory;
public static SqlSessionFactory getSqlSessionFactory() {
if (sqlSessionFactory == null) {
initSqlSessionFactory(); // 为空再去参加
}
return sqlSessionFactory;
}
private static void initSqlSessionFactory() {
InputStream ips = null;
try {
// 1.指定配置文件
ips = Resources.getResourceAsStream("mybatis-config.xml");
// 2.赋值操作
synchronized (MyBatisUtil.class) {
if (sqlSessionFactory == null) {
sqlSessionFactory = new SqlSessionFactoryBuilder().build(ips);
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (ips != null) {
try {
ips.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
9.测试类
package com.qf.dao;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.log4j.Logger;
import org.junit.Test;
import com.qf.entity.User;
import com.qf.utils.MyBatisUtil;
public class UserDaoTest {
private Logger logger = Logger.getLogger(UserDaoTest.class);
@Test
public void testGetUserById() {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
IUserDao userDao = sqlSession.getMapper(IUserDao.class);
User user = userDao.getUserById(9);
sqlSession.close();
}
}
