目录

使用的数据库配置参考笔记-example数据库内容

项目根目录添加porm文件

      
     
      4.0.0
       
     
      com.hao.example
       
     
      MavenMybatis
       
     
      0.0.1-SNAPSHOT
       
         
          
            
       
        mysql
             
       
        mysql-connector-java
             
       
        5.1.32
           
          
          
            
       
        org.mybatis
             
       
        mybatis
             
       
        3.3.0
           
        
       
         
            
             
               
        
         org.apache.maven.plugins
                
        
         maven-compiler-plugin
                
                  
         1.7          
         
          1.7
                 
              
           
          
            
               
                
        
         src/main/java
                
                  
         
          **/*.properties
                   
         
          **/*.xml
                 
                
        
         false
              
             
             
               
        
         src/main/resources
                
                  
         
          **/*.properties
                   
         
          **/*.xml
                 
                
        
         false
              
           
        
     
    

在src/main/resources下创建数据库对应的实体类：Admin，其符合JavaBean的标准

package com.hao.example.po;public class Admin {    private Integer id;    private String username;    private String password;        public Admin() {    }        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;    }    @Override    public String toString() {        return "Admin [id=" + id + ", username=" + username + ", password="                + password + "]";    }}

在src/main/java下创建AdminMapper接口，用于操作Admin类

AdminMapper和Hibernate中的AdminDao是一个东西，只不过在Mybatis更习惯称为Mapper

package com.hao.example.mapper;import com.hao.example.po.Admin;public interface AdminMapper {    public Admin getAdmin(Integer id);    public int deleteAdmin(Integer id);    public int insertAdmin(Admin admin);}

在src/main/resources下添加数据库配置文件：db.properties

jdbc.driver=com.mysql.jdbc.Driverjdbc.url=jdbc:mysql://localhost:3306/example?characterEncoding=utf-8jdbc.username=rootjdbc.password=h66666

在src/main/resources下添加mybatis配置文件：mybatis-config.xml

在AdminMapper接口的同一目录下创建AdminMapper.xml文件

AdminMapper.xml相当于AdminMapper接口的实现类，Mybatis框架会利用动态代理技术，将AdminMapper.xml文件转化为AdminMapper接口的实现类，因此要注意，AdminMapper接口中的函数，在AdminMapper.xml文件中都要有对应的标签，以执行相应的SQL语句

    
      
         select * from admin where id = #{id}    
     
          insert into admin(username, password) values(#{username}, #{password})  
       
     
          delete from admin where id = #{id}  
     
    

创建工具类：SqlSessionFactoryUtil类，用于启动Mybatis，获得Mybatis的相关入口

package com.hao.example.utils;import java.io.InputStream;import java.util.logging.Level;import java.util.logging.Logger;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;/** * 创建SqlSessionFactory的工具类，实现为单例模式 * */public class SqlSessionFactoryUtil {        // SqlSessionFactory对象    private static SqlSessionFactory sqlSessionFactory = null;    // 类线程锁    private static final Class
    
      CLASS_LOCK = SqlSessionFactoryUtil.class;        /**     * 私有化默认构造函数     */    private SqlSessionFactoryUtil() {    }        /**     * 构建SqlSessionFactory     * @return     */    public static SqlSessionFactory initSqlSessionFactory(){        String resource = "mybatis-config.xml";        InputStream inputStream = null;        try {            inputStream = Resources.getResourceAsStream(resource);        } catch (Exception e) {            Logger.getLogger(SqlSessionFactoryUtil.class.getName()).log(Level.SEVERE, null, e);        }                // 为了避免并发状态下的SqlSessionFactory不唯一，需要添加锁        synchronized(CLASS_LOCK){            if(sqlSessionFactory == null){                sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);            }        }        return sqlSessionFactory;    }        /**     * 获得一个新的Session     * @return     */    public static SqlSession openSession(){        if(sqlSessionFactory == null){            initSqlSessionFactory();        }        return sqlSessionFactory.openSession();    }    }
    

执行main函数，测试代码，若能成功运行则构建正确

package com.hao.example.main;import org.apache.ibatis.session.SqlSession;import com.hao.example.mapper.AdminMapper;import com.hao.example.po.Admin;import com.hao.example.utils.SqlSessionFactoryUtil;public class Main {        public static void main(String[] args) throws Exception {                SqlSession sqlSession = null;                try {            sqlSession = SqlSessionFactoryUtil.openSession();            AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);                        Admin admin = adminMapper.getAdmin(2);            System.out.println(admin);                        sqlSession.commit();                    } catch (Exception e) {            System.out.println(e);            sqlSession.rollback();        }finally{            if(sqlSession != null){                sqlSession.close();            }        }    }    }