初识MyBatis

ORM:对象关系映射，它只是一种规则。

像MyBatis，Hibernate对jdbc进行了封装。

第一章 回顾JDBC开发
1.优点:简单易学，上手快，非常灵活构建SQL(自己写的)，效率高。
2.缺点：代码繁琐(各种try..catch..)，难以写出高质量的代码(例如:资源的释放,SQL注入安全性等)，开发者既要写业务逻辑，又要写对象(连接对象等)的创建和销毁，必须关注底层具体数据库的语法(例如:分页)(MySQL的分页和Oracle的分页语句不同)。
3.适合于超大批量数据的操作，速度快。

开发步骤：
1.加载数据库的驱动Class.forName().
2.通过DriverManager获取数据库的连接.
3.通过Connection获取Statement或PreparedStatement.
4.将SQL语句绑定到Statement或PreparedStatement中去，准备向数据库发送SQL语句.
5.执行完SQL语句之后，返回对象的结果.
ResultSet set = ps.executeQuery(查询)/int i = ps.executeUpdate(增/删/改),返回影响记录数.
6.依次关闭连接对象ResultSet/Statement/Connection.
如果上述操作需要非查询操作的话，还需要事务的支持，简单的写下代码.
connection.setAutoCommit(false);
connection.commit();
connection.rollback();

第二章 回顾hibernate单表开发
1）优点：不用写SQL，完全以面向对象的方式设计和访问，不用管底层具体数据库的语法，（例如：分页）便于理解。
2）缺点：处理复杂业务时，灵活度差, 复杂的HQL难写难理解，例如多表查询的HQL语句
3）适合于中小批量数据的操作，速度慢。

开发步骤：
1.创建Configuration,加载src/hibernate.cfg.xml配置文件，该配置文件中又去加载xx.hbm.xml文件.
2.通过Configuration创建SessionFactory.
3.通过SessionFactory创建Session.
4.通过Session创建Transaction
5.如果做增删改的话一定要事务,如果做查询的话，事务可选.
6.操作Session的常用API,例如：save()/update()/delete()/get().
7.提交事务,出错后事务回滚.
8.关闭Session.

第三章 什么是MyBatis，MyBatis有什么特点
1.基于上述二种支持，我们需要在中间找到一个平衡点，结合它们的优点，摒弃它们的缺点，这就是MyBatis，现今MyBatis被广泛的企业所采用。
2.MyBatis本是apache的一个开源项目iBatis, 2010年这个项目由apache software foundation 迁移到了google code，并且改名为MyBatis 。2013年11月迁移到Github。
3.iBatis一词来源于"internet"和"abatis"的组合，是一个基于Java的持久层框架。iBatis提供的持久层框架包括SQL Maps和Data Access Objects（DAO）
4.JDBC/DBUtils/Spring DAO，Hibernate/Spring ORM，MyBatis同属于ORM解决方案之一。
第四章 MyBatis快速入门
准备开发环境

1.创建项目MyBatis_Study，普通的java项目或者是JavaWeb项目均可，如下图所示：

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" 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2.添加项目所需的两个主要jar包:mybatis-3.2.8.jar和mysql-connector-java-5.0.8-bin.jar,以及有关的日志包.

aaarticlea/png;base64,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" alt="" />

3.创建MySQL数据库和表.

SQL脚本如下：

创建表的语句不规范！！请自觉忽略。待我补规范语法，这个请自觉忽略

CREATE DATABASE mybatis;
USE mybatis;
CREATE TABLE student(
   id  INT(5) PRIMARY KEY,
   NAME VARCHAR(10),
   sal DOUBLE(8,2)
)

执行此脚本，完成数据库和表的创建工作。

4.创建与数据库表对应的实体。

package com.winner.entity;

/**
 * Created by winner_0715 on 2016/3/23.
 * student表对应的实体类
 */
public class Student {

    private Integer id;//最好使用包装类型
    private String name;
    private Double sal;//最好使用包装类型

　　//无参构造方法必须有
    public Student() {
    }

    public Student(Integer id, String name, Double sal) {
        this.id = id;
        this.name = name;
        this.sal = sal;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Double getSal() {
        return sal;
    }

    public void setSal(Double sal) {
        this.sal = sal;
    }
}

5.在entity目录下创建StudentMapper.xml配置文件,表示表和实体的映射关系，

(位置不一定非得放在实体目录中，命名建议是"实体类名+Mapper.xml")，

相当于Hibernate中的xxx.hbm.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">

<!--
    为这个mapper指定一个唯一的namespace，
    namespace的值习惯上设置成包名+映射文件名，这样就能够保证namespace的值是唯一的.
    这里取映射文件的全限定名，不要.xml后缀名。
    mapper标签，所以这个唯一的标识也起名为xxxxMapper,纯属为了记忆！
 -->
<mapper namespace="com.winner.entity.StudentMapper">
    <!--
        resultMap标签:映射实体与表
        type属性：表示实体全路径名
        id属性：为实体与表的映射取一个任意的唯一的名字
        Map标签，所以这个唯一的标识也起名为xxxMap，同样是为了记忆！
    -->
    <resultMap id="studentMap" type="com.winner.entity.Student">
        <!--
             id标签:映射主键属性
             result标签：映射非主键属性
             property属性:实体的属性名
             column属性：表的字段名
        -->
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="sal" column="sal"/>
    </resultMap>
    <!--
        insert标签：要书写一个insert的ql语句
        id属性：为insert这个sql操作取唯一的名字，可以取Dao中的对应方法名.
        parameterType:要执行的dao中的方法的参数，如果是类的话，必须使用全路径类
    -->
      <insert id="add1">
      <![CDATA[
        INSERT INTO student(id,name,sal) VALUES (1,"zhangsan",2000);
      ]]>
    </insert>

    <insert id="add2" parameterType="com.winner.entity.Student">
        <![CDATA[
        INSERT INTO student(id,name,sal) VALUES (#{id},#{name},#{sal});
      ]]>
    </insert>
　　<!--
　　　　　这里还可以有其他的sql语句
　　-->
</mapper>

6.在src目录下添加Mybatis的配置文件mybatis-config.xml,

相当于Hibernate中的hibernate.cfg.xml，里面有数据库的链接信息。

<?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>

    <!-- 加载类路径下的属性文件 -->
    <properties resource="db.properties"/>

    <!-- 设置一个默认的连接环境信息 -->
    <environments default="mysql_developer">
        <environment id="mysql_developer">
            <!-- mybatis使用jdbc事务管理方式 -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- mybatis使用连接池方式来获取连接 -->
            <dataSource type="POOLED">
                <!-- 配置与数据库交互的4个必要属性 -->
                <property name="driver" value="${mysql.driver}"/>
                <property name="url" value="${mysql.url}"/>
                <property name="username" value="${mysql.username}"/>
                <property name="password" value="${mysql.password}"/>
            </dataSource>
        </environment>
        <!-- 连接环境信息，取一个任意唯一的名字 -->
        <environment id="oracle_developer">
            <!-- mybatis使用jdbc事务管理方式 -->
            <transactionManager type="jdbc"/>
            <!-- mybatis使用连接池方式来获取连接 -->
            <dataSource type="pooled">
                <!-- 配置与数据库交互的4个必要属性 -->
                <property name="driver" value="${oracle.driver}"/>
                <property name="url" value="${oracle.url}"/>
                <property name="username" value="${oracle.username}"/>
                <property name="password" value="${oracle.password}"/>
            </dataSource>
        </environment>
    </environments>

    <!-- 加载映射文件-->
    <mappers>
        <mapper resource="com/winner/entity/StudentMapper.xml"/>
    </mappers>

</configuration>

db.properties

mysql.driver=com.mysql.jdbc.Driver
mysql.url=jdbc:mysql://127.0.0.1:3306/mybatis
mysql.username=root
mysql.password=root

oracle.driver=oracle.jdbc.driver.OracleDriver
oracle.url=jdbc:oracle:thin:@127.0.0.1:1521:orcl
oracle.username=scott
oracle.password=tiger

7.在util目录下创建MyBatisUtil.java工具类

/**
 * Created by winner_0715 on 2016/3/23.
 * 工具类
 */
public class MybatisUtil {
    private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
    private static SqlSessionFactory sqlSessionFactory;
    /**
     * 这个工具类加载时加载mybatis.xml配置文件，注意路径。希望类加载的时候就加载配置文件
     */
    static{
        try {
            Reader reader = Resources.getResourceAsReader("mybatis.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }
    /**
     * 禁止外界通过new方法创建
     */
    private MybatisUtil(){}
    /**
     * 获取SqlSession
     */
    public static SqlSession getSqlSession(){
        //从当前线程中获取SqlSession对象
        SqlSession sqlSession = threadLocal.get();
        //如果SqlSession对象为空
        if(sqlSession == null){
            //在SqlSessionFactory非空的情况下，获取SqlSession对象
            sqlSession = sqlSessionFactory.openSession();
            //将SqlSession对象与当前线程绑定在一起
            threadLocal.set(sqlSession);
        }
        //返回SqlSession对象
        return sqlSession;
    }
    /**
     * 关闭SqlSession与当前线程分开
     */
    public static void closeSqlSession(){
        //从当前线程中获取SqlSession对象
        SqlSession sqlSession = threadLocal.get();
        //如果SqlSession对象非空
        if(sqlSession != null){
            //关闭SqlSession对象
            sqlSession.close();
            //分开当前线程与SqlSession对象的关系，目的是让GC尽早回收
            threadLocal.remove();
        }
    }

    /**
     * 测试
     */
    public static void main(String[] args) {
        Connection conn = MybatisUtil.getSqlSession().getConnection();
        System.out.println(conn!=null?"连接成功":"连接失败");
    }

}

8.在DAO目录下创建StudentDao.java类，这里就不使用接口了，实际项目中必须使用接口.

就像在Hibernate中使用的那样，DAO调用mybatis提供的有关方法完成对数据库的操作。

public class StudentDao {

    public void add1() throws Exception{
        SqlSession sqlSession = null;
        try{
            sqlSession = MybatisUtil.getSqlSession();
            //事务开始（默认）
            //读取StudentMapper.xml映射文件中的SQL语句
            int i = sqlSession.insert("com.winner.entity.StudentMapper.add1");
            System.out.println("本次操作影响了"+i+"行");
            //事务提交
            sqlSession.commit();
        }catch(Exception e){
            e.printStackTrace();
            //事务回滚
            sqlSession.rollback();
            throw e;
        }finally{
            MybatisUtil.closeSqlSession();
        }
    }

    public void add2(Student student) throws Exception{
        SqlSession sqlSession = null;
        try{
            sqlSession = MybatisUtil.getSqlSession();
            //事务开始（默认）
            //读取StudentMapper.xml映射文件中的SQL语句
            sqlSession.insert("com.winner.entity.StudentMapper.add2",student);
            //事务提交
            sqlSession.commit();
        }catch(Exception e){
            e.printStackTrace();
            //事务回滚
            sqlSession.rollback();
            throw e;
        }finally{
            MybatisUtil.closeSqlSession();
        }
    }

    public static void main(String[] args) throws Exception{
        StudentDao dao = new StudentDao();
        //dao.add1();
        dao.add2(new Student(2,"lisi",3000d));
    }
}

想看log4j日志信息的话需要log4j的jar包，然后把log4j.properties放在src下

log4j.rootLogger=debug,stdout,logfile
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %F %p %m%n
log4j.logger.com.ibatis=DEBUG
log4j.logger.com.ibatis.common.jdbc.SimpleDataSource=DEBUG
log4j.logger.com.ibatis.common.jdbc.ScriptRunner=DEBUG
log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientDelegate=DEBUG
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

mybatis工作流程
1.通过Reader对象读取src目录下的mybatis.xml配置文件(该文本的位置和名字可任意)
2.通过SqlSessionFactoryBuilder对象创建SqlSessionFactory对象
3.从当前线程中获取SqlSession对象
4.事务开始，在mybatis中默认
5.通过SqlSession对象读取StudentMapper.xml映射文件中的操作编号，从而读取sql语句
6.事务提交，必写
7.关闭SqlSession对象，并且分开当前线程与SqlSession对象，让GC尽早回收