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

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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)
    );

 

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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}  
    
    
    
     select * from t_user where id=#{id}
    
    
    
     select * from t_user
      
    

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：

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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