把IUserDao.xml移除,在dao接口的方法上使用@Select注解,并且指定SQL语句 同时需要在SqlMapConfig.xml中的mapper配置时,使用class属性指定dao接口的全限定类名。
数据库user表的字段:
package com.itheima.domain;
import java.io.Serializable;
import java.util.Date;
public class User implements Serializable {
private Integer id;
private String username;
private String address;
private String sex;
private Date birthday;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", address='" + address + '\'' +
", sex='" + sex + '\'' +
", birthday=" + birthday +
'}';
}
}
package com.itheima.dao;
import com.itheima.domain.User;
import org.apache.ibatis.annotations.Select;
import java.util.List;
/*
* 在mybatis针对CRUD一共有四个注解
* @Select @Insert @Update @Delete
* */
public interface IUserDao {
//查询所有用户
@Select("select * from user")
List<User> findAll();
}
SqlMapConfig.xml
<?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>
<!--引入外部配置文件-->
<properties resource="jdbcConfig.properties"></properties>
<!--配置别名-->
<typeAliases>
<package name="com.itheima.domain"/>
</typeAliases>
<!--配置环境-->
<environments default="mysql">
<environment id="mysql">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<!--指定带有注解的dao接口所在位置-->
<mappers>
<package name="com.itheima.dao"/>
</mappers>
</configuration>
本来下一步要创建映射配置文件,但我们这里使用注解开发,不用这一步
package com.itheima.test;
import com.itheima.dao.IUserDao;
import com.itheima.domain.User;
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 java.io.InputStream;
import java.util.List;
public class MybatisannoTest {
/*测试基于注解的mybatis使用*/
public static void main(String[] args) throws Exception{
//1.获取字节输入流
InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
//2.根据字节输入流构建SqlSessionFactory
SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(in);
//3.根据SqlSessionFactory生产一个SqlSession
SqlSession session=factory.openSession();
//4.使用SqlSession获取Dao的代理对象
IUserDao userDao=session.getMapper(IUserDao.class);
//5.执行Dao的方法
List<User> users=userDao.findAll();
for(User user:users){
System.out.println(user);
}
//6.释放资源
session.close();
in.close();
}
}
可以看到数据库中的记录被查询出来