Mybaties学习

基于现在Mybatis 我没有学习太多，就基于简单的增删改查进行基础学习。

学习资源来自    http://www.cnblogs.com/xdp-gacl/p/4261895.html

1  引入jar包

【mybatis】

　　mybatis-3.1.1.jar

【MYSQL驱动包】
　　　　mysql-connector-java-5.1.7-bin.jar

2 2 建立对应数据库表

3 在src目录创建配置文件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://127.0.0.1:3306/mybatis" />
 <property name="username" value="root" />
 <property name="password" value="s1127736971" />
 </dataSource>
 </environment>
 </environments>

 <mappers><!-- 这里下面是mapper的注册-->
 <mapper resource="my/Mapper/userMapper.xml"/>
 <!-- <mapper resource="my.Mapper.userMapper2"/>  记得用class 这是错误的-->
 <mapper class="my.Mapper.userMapper2"/>
 </mappers>

 </configuration>

4 编写对应的User类

package my.domain;

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;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
    }
}

5 编写对应的映射文档Mapper（xml） 之后在对应的conf中添加Mapper（上面已经写好）

<?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+sql映射文件名，这样就能够保证namespace的值是唯一的
例如namespace="me.gacl.mapping.userMapper"就是me.gacl.mapping(包名)+userMapper(userMapper.xml文件去除后缀)
 -->
<mapper namespace="my.Mapper.userMapper">
    <!-- 在select标签中编写查询的SQL语句， 设置select标签的id属性为getUser，id属性值必须是唯一的，不能够重复
    使用parameterType属性指明查询时使用的参数类型，resultType属性指明查询返回的结果集类型
    resultType="me.gacl.domain.User"就表示将查询结果封装成一个User类的对象返回
    User类就是users表所对应的实体类
    -->
    <!--
        根据id查询得到一个user对象
     -->
    <select id="getUser" parameterType="int"
        resultType="my.domain.User">
        select * from users where id=#{id}
    </select>

    <insert id="insertUser" parameterType="my.domain.User">
    insert into users(name,age) values(#{name},#{age})
    </insert>

    <delete id="deleteUser" parameterType="int">
    delete from users where id=#{id}
    </delete>

     <update id="updateUser" parameterType="my.domain.User">
     update users set name=#{name},age=#{age} where id=#{id}
     </update>

     <select id="getUsers" resultType="my.domain.User">
     select * from users
     </select>

</mapper>

编写测试类

package Test;

import static org.junit.Assert.*;

import java.io.IOException;
import java.io.Reader;
import java.util.Collection;

import my.Mapper.userMapper2;
import my.domain.User;

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

public class test2 {

//    Reader reader = Resources.getResourceAsReader(config); 这个方法是错误的，大概是里面不能用静态？
    //SqlSessionFactory sqlFactory = new SqlSessionFactoryBuilder().build(reader);
    //SqlSession sqlSession = sqlFactory.openSession();

    public SqlSession getSqlSession() throws IOException{
        String config = "conf.xml";
        Reader reader = Resources.getResourceAsReader(config);
        SqlSessionFactory sqlFactory = new SqlSessionFactoryBuilder().build(reader);
        return sqlFactory.openSession();
    }

    @Test
    public void add() throws IOException {
       SqlSession sqlSession = getSqlSession();
        String statement = "my.Mapper.userMapper.insertUser";
        User user = new User();

        user.setAge(10);
        user.setName("猛虎捕食");
        sqlSession.insert(statement, user);
        sqlSession.commit();//需要commit 不然没有效果，教程却不用？
        sqlSession.close();
    }

    @Test
    public void update() throws IOException{
        SqlSession sqlSession = getSqlSession();
        String statement = "my.Mapper.userMapper.updateUser";

        User user = new User();
        user.setId(1);
        user.setAge(10);
        user.setName("这是改后");
        sqlSession.update(statement, user);
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void delete() throws IOException{
        SqlSession sqlSession = getSqlSession();
        String statement = "my.Mapper.userMapper.deleteUser";

        sqlSession.delete(statement, 10);
        sqlSession.commit();
        sqlSession.close();

    }

    @Test
    public void queryAll() throws IOException{//这是第二种方式写的用法
        SqlSession sqlSession = getSqlSession();
        String statement = "my.Mapper.userMapper.getUsers";

        Collection<User> users = sqlSession.selectList(statement);
        System.out.println(users);
        sqlSession.close();
    }

    @Test
    public void insert () throws IOException{
        SqlSession sqlSession = getSqlSession();
        userMapper2 mapper = sqlSession.getMapper(userMapper2.class);
        User user = new User();
        user.setAge(15);
        user.setName("猛虎爬树");
        int result = mapper.add(user);
        sqlSession.commit();
        sqlSession.close();
        System.out.println(result);

    }

}

工程大概目录

mybatis的语句还有另一种写法

基于注解的实现，首先要先写出映射接口

package my.Mapper;

import java.util.List;

import my.domain.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 userMapper2 {

    @Insert("insert into users(name,age) values(#{name},#{age})")
    public int add(User user);

    @Delete(" delete from users where id=#{id}")
    public int delete();

    @Update("update users set name=#{name},age=#{age} where id= #{id}")
    public int update();

    @Select("select * from users")
    public List<User>getAll();
}

之后直接在上面的conf.xml文件添加类后缀的配置

代码简单测试在上面测试类的之后一个方法，到这完成基本增删改查配置。

注意点：

sqlSessionFactory需要commit 和close才能成功

基本流程是，用mybatis的Resouces读取配置文件来开启SqlSession，选择需要执行的语句，SqlSession提交执行语句。

注解形式则不是选择执行语句，而是选择对应接口类。

mybatis的自动生成。。。懒人福利

下载对应jar包 ，在配置好generatorConfig，运行，自动生成Dao（mapper） 、实体类、xml配置。

generatorConfig 模板如下

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
  PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
  "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
<!-- 数据库驱动-->
    <classPathEntry  location="mysql-connector-java-5.0.8-bin.jar"/>
    <context id="DB2Tables"  targetRuntime="MyBatis3">
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>
        <!--数据库链接URL，用户名、密码 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://127.0.0.1:3306/mybatis" userId="root" password="s1127736971">
        </jdbcConnection>
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>
        <!-- 生成模型的包名和位置-->
        <javaModelGenerator targetPackage="com.book.pojo" targetProject="src">
            <property name="enableSubPackages" value="true"/>
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <!-- 生成映射文件的包名和位置-->
        <sqlMapGenerator targetPackage="com.book.mapping" targetProject="src">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>
        <!-- 生成DAO的包名和位置-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.book.dao" targetProject="src">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>
        <!-- 要生成的表 tableName是数据库中的表名或视图名 domainObjectName是实体类名-->
        <table tableName="users" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
    </context>
</generatorConfiguration>