前面已经介绍到了参数的传递，但是在真个过程中都使用的是全类名。本篇介绍使用别名：
1.创建实体类
package org.mybatis.typeAliases;
import org.apache.ibatis.type.Alias;
public class Employee {
private Integer id;
private String lastName;
private String email;
private String gender;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public String toString() {
return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email
+ ", gender=" + gender + "]";
}
}
2.创建mapper接口
package org.mybatis.typeAliases;
public interface EmployeeMapper {
public Employee getEmpById(Integer id);
}
3.创建主配置文件
<?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>
<!--
引入外部资源文件
resource:引入类路径下的资源文件
url:引入磁盘或者网络路径下的资源文件
-->
<properties resource="db.properties"></properties>
<!--
配置驼峰命名规则
-->
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
<!--
typeAliases:别名处理器，为java类起别名
-->
<typeAliases>
<!-- type为全类名，alias为别名，这里是指定一个类 -->
<typeAlias type="org.mybatis.typeAliases.Employee" alias="emp"/>
</typeAliases>
<!-- 默认development是开发环境，如果改成test则表示使用测试环境 -->
<environments default="dev_mysql">
<environment id="dev_mysql">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${mysql.driver}" />
<property name="url" value="${mysql.url}" />
<property name="username" value="${mysql.username}" />
<property name="password" value="${mysql.password}" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mapper/typeAliasesmapper.xml"/>
</mappers>
</configuration>
4.创建mapper配置文件
<?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:名稱空間，使用接口后，該項的值為接口的全類名
id:標籤的唯一標識，使用接口后，跟接口中的方法名進行綁定
resultType:返回值類型，想要封裝成什麼對象
{id}:從傳遞的參數取得的值
public Employee getEmpById(Integer id);
-->
<mapper namespace="org.mybatis.typeAliases.EmployeeMapper">
<!-- resultType使用别名 -->
<select id="getEmpById" resultType="emp">
select id,last_name,email,gender from mybatis_employee where id ={id}
</select>
</mapper>
5.创建测试类
package org.mybatis.typeAliases;
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.junit.Test;
import org.mybatis.typeAliases.Employee;
/**
* 使用接口式編程
*/
public class MybatisTest {
@Test
public void testMybatis() {
String resource = "mybatis-config-typeAliases.xml";//全局配置文件
InputStream inputStream = null;
SqlSessionFactory sqlSessionFactory = null;
SqlSession sqlSession = null;
try {
inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
sqlSession = sqlSessionFactory.openSession();
EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
Employee emp = mapper.getEmpById(2);
System.out.println(emp);
} catch (IOException e) {
e.printStackTrace();
} finally {
sqlSession.close();
}
}
}
6.测试结果
DEBUG - Logging initialized using ‘class org.apache.ibatis.logging.slf4j.Slf4jImpl’ adapter.
DEBUG - PooledDataSource forcefully closed/removed all connections.
DEBUG - PooledDataSource forcefully closed/removed all connections.
DEBUG - PooledDataSource forcefully closed/removed all connections.
DEBUG - PooledDataSource forcefully closed/removed all connections.
DEBUG - Openning JDBC Connection
DEBUG - Created connection 665188480.
DEBUG - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@27a5f880]
DEBUG - ==> Preparing: select id,last_name,email,gender from mybatis_employee where id = ?
DEBUG - ==> Parameters: 2(Integer)
Employee [id=2, lastName=lisi, email=tang_greatman@qq.com, gender=2]
DEBUG - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@27a5f880]
DEBUG - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@27a5f880]
DEBUG - Returned connection 665188480 to pool.
7.使用注解方案
Employee实体添加注解empp
@Alias("empp")
public class Employee {
private Integer id;
private String lastName;
private String email;
private String gender;
主配置文件使用包扫描
<typeAliases>
<!-- type为全类名，alias为别名，这里是指定一个类 -->
<!-- <typeAlias type="org.mybatis.typeAliases.Employee" alias="emp"/>-->
<!-- 为包下的所有类起别名，默认为类名大小写（不区分大小写） -->
<package name="org.mybatis.typeAliases"/>
</typeAliases>
映射配置文件使用别名empp
<!-- <select id="getEmpById" resultType="Employee"> -->
<!-- 如果上面没有添加注解empp，那么这里的resultType的值填写类名小写employee也可以进行数据封装，但是如果一个工程中出现多个类名相同的类就容易出现错误，所以不建议使用 -->
<select id="getEmpById" resultType="empp">
select id,last_name,email,gender from mybatis_employee where id ={id}
</select>
运行结果：
DEBUG - Checking to see if class org.mybatis.typeAliases.MybatisTest matches criteria [is assignable to Object]
DEBUG - PooledDataSource forcefully closed/removed all connections.
DEBUG - PooledDataSource forcefully closed/removed all connections.
DEBUG - PooledDataSource forcefully closed/removed all connections.
DEBUG - PooledDataSource forcefully closed/removed all connections.
DEBUG - Openning JDBC Connection
DEBUG - Created connection 1399499405.
DEBUG - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@536aaa8d]
DEBUG - ==> Preparing: select id,last_name,email,gender from mybatis_employee where id = ?
DEBUG - ==> Parameters: 2(Integer)
Employee [id=2, lastName=lisi, email=tang_greatman@qq.com, gender=2]
DEBUG - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@536aaa8d]
DEBUG - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@536aaa8d]
DEBUG - Returned connection 1399499405 to pool.