mybatis介绍和mybatis快速入门

1.mybatis介绍

mybatis是支持普通sql查询，存储过程和该机映射的持久层（把java对象存储到数据库中）框架。几乎消除jdbc代码和手动设置参数以及对结果集的检索封装。mybatis可以使用映射文件xml，接口dao来操作实体类bean。

2.mybatis快速入门

1.建立数据库表users

create database mybatis;

use mybatis;

CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, NAME

VARCHAR(20), age INT);

INSERT INTO users(NAME, age) VALUES('Tom', 12);

INSERT INTO users(NAME, age) VALUES('Jack', 11);

2.建立相应实体类Users

public class Users {

       private int id;

       private String name;

       private int age;

       public Users() {

              super();

       }

       public Users(int id, String name, int age) {

              super();

              this.id = id;

              this.name = name;

              this.age = 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 "Users [id=" + id + ", name=" + name + ", age=" + age + "]";

       }

}

3.建立相应映射文件UsersMapper.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">

<!-- namespace是命名空间，暂时原来区分id，被外面调用用，名字可以随意但后面和dao一起那么namespace要和dao全类名一致 -->

<mapper namespace="Test">

       <!--

              select：sql查询语句的标签，

              id：相当于方法名称，

              parameterType：传入参数类型（输入类型），要写全类名

              resultType：传出参数类型（输出类型），要写全类名

        -->

        <!-- 通过id查询 -->

       <select id="selectById" parameterType="int"

              resultType="com.zhiyou100.kfs.bean.Users">

              select * from users where id=#{id}

       </select>

</mapper>

4.建立mybatis的配置文件，并注册UserMapper.xml映射文件

<?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">

                            <!-- driver驱动 -->

                            <property name="driver" value="com.mysql.jdbc.Driver" />

                            <!--

                                   url：数据库地址

                                   username：数据库用户名

                                   password：数据库密码

                             -->

                            <property name="url"

                                   value="jdbc:mysql://localhost:3306/mybatis" />

                            <property name="username" value="root" />

                            <property name="password" value="123" />

                     </dataSource>

              </environment>

       </environments>

       <!-- 配置映射文件UserMapper.xml -->

       <mappers>

              <mapper resource="com/zhiyou100/kfs/mapper/UsersMapper.xml"/>

       </mappers>

</configuration>

5.在单元测试里测试

class TestMybatis {

       @Test

       void test() throws Exception {

              //1.获取配置文件config.xml加入到io流中

              InputStream inputStream = Resources.getResourceAsStream("config.xml");

              //2.通过SqlSessionFatoryBuilder的builder创建sqlsessionfatory

              SqlSessionFactory sqlSessionFatory = new SqlSessionFactoryBuilder().build(inputStream);

              //3.通过sqlSessionFactory的openSession方法创建SqlSession

              SqlSession sqlSession=sqlSessionFatory.openSession();

              //4.调用sqlSession的selectOne来使用通过id查询一个用户

              //第一个参数是映射文件的namespace.方法名，第二个参数是传入sql语句的参数，这里是id

              Users user=sqlSession.selectOne("Test.selectById",1);

              System.out.println(user);

              //最后一个页是很重要的一个：关闭资源

              sqlSession.close();    }

}