• mybatis学习笔记(二)-- 使用mybatisUtil工具类体验基于xml和注解实现


    • 项目结构

       基础入门可参考:mybatis学习笔记(一)-- 简单入门(附测试Demo详细过程)

    • 开始体验

      1、新建项目,新建类MybatisUtil.java,路径:src/util/MybatisUtil.java

    package util;
    
    import java.io.InputStream;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    public class MybatisUtil {
    
        /**
         * 获取SqlSessionFactory
         * @return SqlSessionFactory
         */
        public static SqlSessionFactory getSqlSessionFactory() {
            String resource = "conf.xml";
            InputStream is = MybatisUtil.class.getClassLoader().getResourceAsStream(resource);
            SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
            return factory;
        }
        
        /**
         * 获取SqlSession
         * @return SqlSession
         */
        public static SqlSession getSqlSession() {
            return getSqlSessionFactory().openSession();
        }
        
        /**
         * 获取SqlSession
         * @param isAutoCommit 
         *         true 表示创建的SqlSession对象在执行完SQL之后会自动提交事务
         *         false 表示创建的SqlSession对象在执行完SQL之后不会自动提交事务,这时就需要我们手动调用sqlSession.commit()提交事务
         * @return SqlSession
         */
        public static SqlSession getSqlSession(boolean isAutoCommit) {
            return getSqlSessionFactory().openSession(isAutoCommit);
        }
    }

      2、编写用户实体类User.java,路径:src/main/User.java

    package main;
    
    public class User {
       
        private int id;
        private String name;
        private int age;
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    }

      3、编写mapper,以“新增用户”为示范案例

      

      (1)基于xml实现,定义操作用户表的sql映射文件UserMapper.xml,路径:src/mapper/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="mapper.UserMapper">
    
         <!-- 新增用户 -->
        <insert id="addUser" parameterType="main.User">
            insert into tb_user(name,age) values(#{name},#{age})
        </insert>
    
    </mapper>

      (2)基于注解实现,定义sql映射的接口,使用注解指明方法要执行的SQL,新建UserMapperI.java,路径:src/mapper/UserMapperI.java

    package mapper;
    
    import java.util.List;
    import main.User;
    import org.apache.ibatis.annotations.Delete;
    import org.apache.ibatis.annotations.Insert;
    import org.apache.ibatis.annotations.Select;
    import org.apache.ibatis.annotations.Update;
    
    public interface UserMapperI {
    
        //使用@Insert注解指明add方法要执行的SQL
        @Insert("insert into tb_user(name, age) values(#{name}, #{age})")
        public int add(User user);
        
    }

      4、添加配置文件,新建conf.xml文件,路径:src/conf.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" />
                <!-- 配置数据库连接信息 -->
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver" />
                    <property name="url" value="jdbc:mysql://localhost:3306/test" />
                    <property name="username" value="root" />
                    <property name="password" value="123456" />                              
                </dataSource>
            </environment>
        </environments>   
        
          <mappers>
            <!-- 注册userMapper.xml文件(基于xml实现)--> 
            <mapper resource="mapper/userMapper.xml"/>
            <!-- 注册UserMapper映射接口(基于注解实现)-->
            <mapper class="mapper.UserMapperI"/>
        </mappers>
    
    </configuration>

    5、编写测试函数

    (1)测试基于xml实现

    public static void testAddByXmlMapper(){
        //SqlSession sqlSession = MyBatisUtil.getSqlSession(false);
        SqlSession sqlSession = MybatisUtil.getSqlSession(true);   
        String statement = "mapper.UserMapper.addUser";//映射sql的标识字符串
        User user = new User();
        user.setName("lucy");
        user.setAge(22);
        //执行插入操作
        int retResult = sqlSession.insert(statement,user);
        //手动提交事务
        //sqlSession.commit();
        //使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(retResult);
    }
     * 注解:

      SqlSession sqlSession = MybatisUtil.getSqlSession(true);

      true 表示创建的SqlSession对象在执行完SQL之后会自动提交事务

      false 表示创建的SqlSession对象在执行完SQL之后不会自动提交事务,这时就需要我们手动调用sqlSession.commit()提交事务

    (2)测试基于注解实现

    public void testAddByAnnotationMapper() {
        SqlSession sqlSession = MybatisUtil.getSqlSession(true);
        // 得到UserMapperI接口的实现类对象,UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        User user = new User();
        user.setName("tom");
        user.setAge(20);
        int add = mapper.add(user);
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(add);
    }

      

      到此结束~ (@_@)以上...

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  • 原文地址:https://www.cnblogs.com/lmei/p/7100256.html
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