MyBatis(一)HelloWorld

废话不多说，准备jar包：

• mybatis.jar
• mysql-connection.jar

---

前期准备

• mysql数据库
• navicat或SQLyog
• eclipse

1.新建数据库资源

数据库名：test
表名：users
字段：ID、NAME、AGE、ADDRESS
插入两条数据：

2.新建Java project

项目建成后的目录结构

mybatis，右键new，Folder。Folder name取lib，存放jar包

mybatis，右键new，SourceFolder。Folder name取config，存放全局配置文件

在src目录下，新建包名：com.entity。在该包下新建User实体类

User.java：

package com.entity;public class User {    private int id;    private String name;    private int age;    private String address;    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;    }    public String getAddress() {        return address;    }    public void setAddress(String address) {        this.address = address;    }    @Override    public String toString() {        return "User [id=" + id + ", name=" + name + ", age=" + age + ", address=" + address + "]";    }   }

在config目录下新建全局mybatis配置文件：mybatis-config.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>    <typeAliases>    <!--类型定义，取别名-->        <typeAlias type="com.entity.User" alias="User"/>    </typeAliases>    <environments default="development">        <environment id="development">            <transactionManager type="JDBC"></transactionManager>            <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=""/>            </dataSource>        </environment>    </environments>    <mappers>        <mapper resource="userMapper.xml"/>    </mappers></configuration>

在config目录下新建userMapper.xml的SQL映射文件

<?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="com.mybatis.userMapper">    <select id="selectUserById" parameterType="int" resultType="com.entity.User">        select * from users where id=#{id}    </select></mapper>

在src目录下新建包名com.test 在该包下新建TestMybatis类

package com.test;import java.io.IOException;import java.io.Reader;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 com.entity.User;public class TestMybatis {    private static SqlSessionFactory sqlSessionFactory;    private static SqlSession sqlSession;    public static void main(String[] args) throws IOException {        String resource="mybatis-config.xml";        Reader reader=Resources.getResourceAsReader(resource);        sqlSessionFactory= new SqlSessionFactoryBuilder().build(reader);        sqlSession = sqlSessionFactory.openSession();        String state="com.mybatis.userMapper.selectUserById";        User user=sqlSession.selectOne(state, 1002);        System.out.println(user);        sqlSession.close();    }}

最终目录结构

最终结果