idea+mybatis

 

1. 打开idea
2. 新建项目（这个父项目就像一个大容器，用来管理模块的，没有具体的逻辑。可以把其他模块都用到的依赖jar包都放在这里，这样的话，子模块就不需要都增加一次依赖了。）或者模块Module
3. 建立maven
4. 填写groupid和artifactid，groupid是项目id，写你的项目名，artifactid是模块id（这里是父模块id）。继续next ，写项目名，完成。这些都是随意，看个人喜好。
5. 一路next即可
6. 目录结构
7. User1.java

   package com.etc.pojo;
   
   public class User1 {
       private Long id;
       private String userName;
       private String pwd;
   
     setter getter....
   }
   

    

8. UserMapper.java

   package com.etc.dao;
   
   import com.etc.pojo.User1;
   
   
   public interface UserMapper {
   
       public User1 selectAll(Long id);
   }
   

    

9. SqlSessionFactoryUtils.java(注意引入的类，有些类名一样。“org.apache.ibatis”)

   package com.etc.utils;
   
   import org.apache.ibatis.session.SqlSession;
   import org.apache.ibatis.session.SqlSessionFactory;
   
   import org.apache.ibatis.io.Resources;
   import org.apache.ibatis.session.SqlSessionFactoryBuilder;
   
   import java.io.IOException;
   import java.io.InputStream;
   
   public class SqlSessionFactoryUtils {
       //锁
       private final static Class<SqlSessionFactoryUtils> LOCK = SqlSessionFactoryUtils.class;
   
       private static SqlSessionFactory sqlSessionFactory;
   
       //构造方法使用private，使得不能用new来生成它，只能用反射
       private SqlSessionFactoryUtils(){}
   
       private static SqlSessionFactory getSqlSessionFactory(){
           //防止多线程中多次实例化SqlSessionFactory对象，保证SqlSessionFactory的唯一性
           synchronized (LOCK){
               if(sqlSessionFactory != null){
                   return sqlSessionFactory;
               }
               String resource = "mybatis-config.xml";
               InputStream inputStream;
   
               try {
                   inputStream = Resources.getResourceAsStream(resource);
                   sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
               }catch (IOException e){
                   e.printStackTrace();
                   return null;
               }
               return sqlSessionFactory;
           }
   
   
       }
   
       public static SqlSession openSqlSession(){
           if(sqlSessionFactory == null){
               getSqlSessionFactory();
           }
           return getSqlSessionFactory().openSession();
   
       }
   }
   

10. log4j.properties

    log4j.rootLogger=DEBUG , stdout
    log4j.logger.org.mybatis=DEBUG
    log4j.appender.stdout=org.apache.log4j.ConsoleAppender
    log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
    log4j.appender.stdout.layout.ConversionPattern=%5p %d %c: %m%n

     

11. mybatis-config.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>
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql://localhost:3306/demo"/>
                    <property name="username" value="admin"/>
                    <property name="password" value="123456"/>
                </dataSource>
            </environment>
        </environments>
        <mappers>
            <mapper resource="mapper/UserMapper.xml"/>
        </mappers>
    </configuration>

     

12. UserMapper.xml

    <?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">
    
    <mapper namespace="com.etc.dao.UserMapper">
        <select id="selectAll" resultType="com.etc.pojo.User1" parameterType="long">
                select userName , pwd from User1 where id = #{id}
            </select>
    </mapper>
    

     

13. Main.java

    package com.etc;
    
    import com.etc.dao.UserMapper;
    import com.etc.pojo.User1;
    import com.etc.utils.SqlSessionFactoryUtils;
    import org.apache.ibatis.session.SqlSession;
    
    import org.apache.log4j.Logger;
    /**
     * Created by shkstart on 2019/1/23
     */
    public class Main {
        public static void main(String[] args) {
    
            Logger logger = Logger.getLogger(Main.class);
    
            SqlSession sqlSession = null;
    
            try {
                sqlSession = SqlSessionFactoryUtils.openSqlSession();
                UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
                User1 user1 = userMapper.selectAll(1L);
                logger.info(user1.getUserName());
            }finally {
                if(sqlSession != null){
                    sqlSession.close();
                }
            }
    
    
    
        }
    }