MyBatis学习笔记（二）：快速入门实例
MyBatis学习笔记（二）：快速入门实例
目录
MyBatis学习笔记（二）：快速入门实例
1. 开发环境准备
2. 相关类及配置文件准备
3. 测试代码准备
在上一篇文章中，笔者已经介绍了MyBatis的架构和运作流程，本篇文章将结合一个完整的实例介绍MyBatis的用法。
1. 开发环境准备
1. 创建一个测试用的maven工程，当然，Java工程或者JavaWeb工程也是可以的。如下所示：
2. 在maven工程的pom文件中添加响应的依赖：
org.mybatis
mybatis
3.4.6
mysql
mysql-connector-java
6.0.6
3. 启动MySql数据库，并创建一个表：t_user
create table t_user(
id int primary key auto_increment,
username varchar(20),
password varchar(20),
account decimal(10,2)
);
2. 相关类及配置文件准备
1. 创建一个与数据表 t_user 对应的Java Bean：UserBean
package com.yingshulan.mybatis.mybatis_learning;
import java.io.Serializable;
public class UserBean implements Serializable
{
private static final long serialVersionUID = 1L;
private Integer id;
private String username;
private String password;
private Double account;
public UserBean()
{
super();
}
public UserBean(String username, String password, Double account)
{
super();
this.username = username;
this.password = password;
this.account = account;
}
public UserBean(Integer id, String username, String password, Double account)
{
super();
this.id = id;
this.username = username;
this.password = password;
this.account = account;
}
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 getPassword()
{
return password;
}
public void setPassword(String password)
{
this.password = password;
}
public Double getAccount()
{
return account;
}
public void setAccount(Double account)
{
this.account = account;
}
@Override
public String toString()
{
return "UserBean [id=" + id + ", username=" + username + ", password=" + password
+ ", account=" + account + "]";
}
}2. 为UserBean创建对应的增、删、改、查接口类：UserMapper.java，代码如下：
package com.yingshulan.mybatis.mybatis_learning;
import java.util.List;
public interface UserMapper
{
/**
* 新增用戶
* @param user
* @return
* @throws Exception
*/
public int insertUser(UserBean user) throws Exception;
/**
* 修改用戶
* @param user
* @param id
* @return
* @throws Exception
*/
public int updateUser(UserBean user, int id) throws Exception;
/**
* 刪除用戶
* @param id
* @return
* @throws Exception
*/
public int deleteUser(int id) throws Exception;
/**
* 根据id查询用户信息
* @param id
* @return
* @throws Exception
*/
public UserBean selectUserById(int id) throws Exception;
/**
* 查询所有的用户信息
* @return
* @throws Exception
*/
public List selectAllUser() throws Exception;
}
3. 接口类中的方法要与实际的SQL语句对应起来，需要一个映射配置文件：UserMapper.xml，如下所示：
insert into t_user (username,password,account) values (#{username},#{password},#{account})
update t_user set username=#{username},password=#{password},account=#{account} where id=#{id}
delete from t_user where id=#{id}
4. MyBatis配置文件，每个MyBatis应用程序主要都是使用SqlSessionFactory实例的，一个SqlSessionFactory实例可以通过SqlSessionFactoryBuilder获得。SqlSessionFactoryBuilder可以从一个xml配置文件或者一个预定义的配置类的实例获得。本例中采用的是xml配置文件，命名为：mybatis.cfg.xml，如下所示：
3. 测试代码准备
为了验证完整的流程，需创建一个测试类：UserService.java
package com.yingshulan.mybatis.mybatis_learning;
import java.io.Reader;
import java.util.List;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class UserService
{
public static SqlSession session;
public static void main(String[] args)
{
try
{
//使用MyBatis提供的Resources类加载mybatis的配置文件
Reader reader = Resources.getResourceAsReader("mybatis.cfg.xml");
//构建sqlSession的工厂 ,并开启 SqlSession
session = new SqlSessionFactoryBuilder().build(reader).openSession();
}
catch (Exception e)
{
e.printStackTrace();
}
insertUser();
// deleteUser();
selectUserById();
selectAllUser();
}
/**
* 新增用户
*/
private static void insertUser()
{
System.out.println("****************Insert User********************");
UserMapper mapper = session.getMapper(UserMapper.class);
UserBean user = new UserBean("zhuliu", "123adfg9", 34567.0);
try
{
mapper.insertUser(user);
System.out.println(user.toString());
session.commit();
}
catch (Exception e)
{
e.printStackTrace();
session.rollback();
}
}
/**
* 删除用户
*/
private static void deleteUser()
{
System.out.println("****************Delete User********************");
UserMapper mapper = session.getMapper(UserMapper.class);
try
{
mapper.deleteUser(1);
session.commit();
}
catch (Exception e)
{
e.printStackTrace();
session.rollback();
}
}
/**
* 根据id查询用户
*/
private static void selectUserById()
{
System.out.println("****************Select User By ID********************");
UserMapper mapper = session.getMapper(UserMapper.class);
try
{
UserBean user = mapper.selectUserById(1);
System.out.println(user.toString());
session.commit();
}
catch (Exception e)
{
e.printStackTrace();
session.rollback();
}
}
/**
* 查询所有的用户
*/
private static void selectAllUser()
{
System.out.println("****************Select All User********************");
UserMapper mapper = session.getMapper(UserMapper.class);
try
{
List userList = mapper.selectAllUser();
for (UserBean user : userList)
{
System.out.println(user.toString());
}
session.commit();
}
catch (Exception e)
{
e.printStackTrace();
session.rollback();
}
}
}
插入四条记录后的运行结果：
UserBean [id=4, username=zhuliu, password=123adfg9, account=34567.0]
****************Select User By ID********************
UserBean [id=1, username=zhangsan, password=abcd1234, account=1234.0]
****************Select All User********************
UserBean [id=1, username=zhangsan, password=abcd1234, account=1234.0]
UserBean [id=2, username=lisi, password=123456789, account=13456.0]
UserBean [id=3, username=wangwu, password=123adfg9, account=34567.0]
UserBean [id=4, username=zhuliu, password=123adfg9, account=34567.0]查询数据库 t_user：
参考文献：
1. 博客：MyBatis学习笔记(一）入门 https://www.cnblogs.com/hellokitty1/p/5216025.html