11Mybatis_mybatis开发Dao的方法

在介绍开发Dao的方法之前先介绍下SqlSession。

1.先介绍一下SqlSessionFactoryBuilder：通过SqlSessionFactoryBuilder创建会话工厂SqlSessionFactory

将SqlSessionFactoryBuilder当成一个工具类使用即可，不需要使用单例管理SqlSessionFactoryBuilder。

在需要创建SqlSessionFactory时候，只需要new一次SqlSessionFactoryBuilder即可。

2.再介绍一下SqlSessionFactory:

通过SqlSessionFactory创建SqlSession，使用单例模式管理sqlSessionFactory（工厂一旦创建，使用一个实例）。将来mybatis和spring整合后，使用单例模式管理sqlSessionFactory。

3.最后重点介绍一下sqlSession：

sqlSession的诞生过程是这样的：我们先用SqlSessionFactoryBuilder创建一个SqlSessionFactory。然后再通过SqlSessionFactory创建一个SqlSession.

SqlSession是一个面向用户（程序员）的接口。

SqlSession中提供了很多操作数据库的方法：如：selectOne(返回单个对象)、selectList（返回单个或多个对象）、。

SqlSession是线程不安全的，在SqlSesion实现类中除了有接口中的方法（操作数据库的方法）还有数据域属性。

SqlSession最佳应用场合在方法体内，定义成局部变量使用。

现在我们来介绍原始Dao开发的方法（程序员需要写dao接口以及dao的实现类）：

思路：、

程序员需要写dao接口和dao实现类。

需要向dao实现类中注入SqlSessionFactory，在方法体内通过SqlSessionFactory创建SqlSession

案例如下：

先给出案例的结构图：

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" alt="" />

第一步：先写po包下面的Uer实体类:

package cn.itcast.mybatis.po;

import java.util.Date;

public class User {
private int id;//主键
private String username;//用户的名称
private Date birthday;//生日
private String sex;//性别
private String address;//地址
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getUsername() {
    return username;
}
public void setUsername(String username) {
    this.username = username;
}
public Date getBirthday() {
    return birthday;
}
public void setBirthday(Date birthday) {
    this.birthday = birthday;
}
public String getSex() {
    return sex;
}
public void setSex(String sex) {
    this.sex = sex;
}
public String getAddress() {
    return address;
}
public void setAddress(String address) {
    this.address = address;
}

}

第二步：编写SqlMapConfig.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>
    <!-- 和spring整合后 environments配置将废除-->
    <environments default="development">
        <environment id="development">
        <!-- 使用jdbc事务管理-->
            <transactionManager type="JDBC" />
        <!-- 数据库连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/mybaits?characterEncoding=utf-8" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>

    <!-- 把映射文件(sqlmap/user.xml)加载进sqlMapConfig.xml-->
        <mappers>
        <mapper resource="sqlmap/user.xml"/>
         </mappers>

</configuration>

第三步：编写user.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">
<!-- nanmespace:命名空间。 作用就是对sql进行分类话管理，理解Sal分离

注意：使用mapper代理方式，namespace有特殊重要的作用
-->

<mapper namespace="test">

    <!-- 根据id获取用户信息 -->
    <!-- 在映射文件中配置很多sql语句 -->
    <!--
    id:标识映射文件中的sql;
    将sql语句封装到mappedStatement对象中，所以将id称为statement的id;parmenterType：指定输入的参数的类型，这里指定的int型
    #{}表示一个占位符号；
    #{id}:其中的id表示接收输入的参数，参数名称就是id,如果输入参数就是简单类型，#{}中的参数名可以任意，可以value或其它名称
    resultType：指定的sql输出结果的所映射的java对象类型，select指定resultType表示将单条记录映射成的java对象；

     -->
    <select id="findUserById" parameterType="int" resultType="cn.itcast.mybatis.po.User">
        select * from user where id = #{id}
    </select>
    <!-- 自定义条件查询用户列表
    resultType指的是单条记录所映射的java类型，不管查询的是多条还是单条
     -->
    <select id="findUserByUsername" parameterType="java.lang.String"
            resultType="cn.itcast.mybatis.po.User">
       select * from user where username like '%${value}%'
    </select>
<!--
添加用户:
 partmentType:指定输入参数类型是pojo（包括用户的信息）
#{}中指定pojo的属性名，接收到pojo对象的属性值

 -->
    <insert id="insertuser" parameterType="cn.itcast.mybatis.po.User">

        <!--
               将插入的数据主键返回，返回到user对象中去。
         SELECT LAST_INSERT_ID():得到刚insert进去的记录的主键值，
         这个方法只适用于自增长的主键。
         KeyProperty:将查询得到的主键值设置到paramaterType指定的对象的哪个属性。
         order:SELECT LAST_INSERT_ID()执行的顺序。相对于insert语句来说它的执行顺序。
         resultType:指定SELECT LAST_INSERT_ID()的结果类型
        -->
       <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">

           SELECT LAST_INSERT_ID()
       </selectKey>  

       <!-- 以上的代码是为了实现返回主键的功能 -->
       insert into user(username,birthday,sex,address) value(#{username},#{birthday},#{sex},#{address})
    </insert>

    <!-- 删除用户 -->
      <delete id="deleteUser" parameterType="java.lang.Integer">
          delete from user where id=#{id}

      </delete>
      <!-- 更新用户 -->
      <update id="updetaUser" parameterType="cn.itcast.mybatis.po.User">
        update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address}
        where id=#{id}

      </update>

</mapper>

第四步：编写UserDao.java

package cn.itcast.mybatis.Dao;

import cn.itcast.mybatis.po.User;

public interface UserDao {
    //查找用户
public User findUserById(int id);
//增加用户
public void insertUser(User user);

}

第五步：编写UserDao的实现类UserDaoimpl.java

package cn.itcast.mybatis.Dao;

import java.util.Date;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import cn.itcast.mybatis.po.User;

public class UserDaoimpl implements UserDao {
private SqlSessionFactory sqlSessionFactory;
    public UserDaoimpl(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory=sqlSessionFactory;
    }
    @Override
    public User findUserById(int id) {
        SqlSession sqlSession=sqlSessionFactory.openSession();
        User user=sqlSession.selectOne("test.findUserById", id);
        return user;
    }

    @Override
    public void insertUser(User user) {
        SqlSession sqlSession=sqlSessionFactory.openSession();

        sqlSession.insert("test.insertuser", user);
        sqlSession.commit();
        sqlSession.close();
    }

}

第六步：编写Mybatis_daotest.java

package cn.itcast.mybatis.first;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;

import cn.itcast.mybatis.Dao.UserDao;
import cn.itcast.mybatis.Dao.UserDaoimpl;
import cn.itcast.mybatis.po.User;

public class Mybatis_daotest {
    //会话工厂
    private SqlSessionFactory sqlSessionFactory;
@Before
public void setup() throws IOException
{

String resource="SqlMapConfig.xml";
InputStream inputStream=Resources.getResourceAsStream(resource);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);

}
@Test
public void testDao()
{

    UserDao userDao=new UserDaoimpl(sqlSessionFactory);
    User user=userDao.findUserById(29);
    System.out.println(user.getUsername());

}
}

结果：输出王王；运行结果正确。

上面是Dao的开发，但是存在一些问题，我们来总结一下原始dao开发问题。

1、dao接口实现类方法中存在大量模板方法，设想能否将这些代码提取出来，大大减轻程序员的工作量。

比如这些代码都要重复去写：

sqlSession.commit();
        sqlSession.close();

2、调用sqlsession方法时将statement的id硬编码了

User user=sqlSession.selectOne("test.findUserById", id);

3、调用sqlsession方法时传入的变量，由于sqlsession方法使用泛型，即使变量类型传入错误，在编译阶段也不报错，不利于程序员开发。

比如User user=sqlSession.selectOne("test.findUserById", id);我这么写也是可以的User user=sqlSession.selectOne("test.findUserById", new Object());

因为这些问题，我们接下来要学习mapper代理的方法