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mybatis笔记-基础示例

mybatis笔记-基础示例

作者: 欢喜流年 | 来源:发表于2019-06-25 23:37 被阅读2次

    准备环境:安装jdk 、maven、mysql、Intellij IDEA

    官方文档:http://www.mybatis.org/mybatis-3/zh/index.html

    示例步骤

    1.新建maven项目

    1.png

    2.在pom.xml中配置mybatis、mysql依赖

    
    <dependencies>
    
    <dependency>
    
    <groupId>org.mybatis</groupId>
    
    <artifactId>mybatis</artifactId>
    
    <version>3.5.1</version>
    
    </dependency>
    
    <dependency>
    
    <groupId>mysql</groupId>
    
    <artifactId>mysql-connector-java</artifactId>
    
    <version>5.1.38</version>
    
    </dependency>
    
    </dependencies>
    
    

    3.启动本地mysql服务,创建mysql数据库student,数据库中创建student表

    2.png

    4.创建Student类,类中属性与student表中字段一 一对应

    public class Student{
    
    int id;
    
    String name;
    
    String sex;
    
    public Student(){
    
    }
    
    public Student(int id,String name,String sex){
    
    this.id=id;
    
    this.name=name;
    
    this.sex=sex;
    
    }
    
    public int getId(){
    
    returnid;
    
    }
    
    public void setId(intid){
    
    this.id=id;
    
    }
    
    public String getName(){
    
    returnname;
    
    }
    
    public void setName(String name){
    
    this.name=name;
    
    }
    
    public String getSex(){
    
    returnsex;
    
    }
    
    public void setSex(String sex){
    
    this.sex=sex;
    
    }
    
    @Override
    
    public String toString(){
    
    return"Student{"+
    
    "id="+id+
    
    ",name='"+name+'\''+
    
    ",sex='"+sex+'\''+
    
    '}';
    
    }
    
    }
    

    5.创建studentMapper.xml,在此文件中管理sql语句

    <?xmlversion="1.0"encoding="UTF-8"?>
    
    <!DOCTYPEmapper
    
    PUBLIC"-//mybatis.org//DTDMapper3.0//EN"
    
    "[http://mybatis.org/dtd/mybatis-3-mapper.dtd](http://mybatis.org/dtd/mybatis-3-mapper.dtd)">
    
    <mapper namespace="orm.mapper.studentMapper">
    
    <!--resultType:返回值类型 parameterType:参数类型-->
    
    <selectid="selectById"
    
    resultType="orm.entity.Student" parameterType="int">
    
    select*from student where id=#{id}
    
    </select>
    
    </mapper>
    

    6.创建config.xml配置文件,配置数据库连接信息、mapper信息

    <?xmlversion="1.0"encoding="UTF-8"?>
    
    <!DOCTYPEconfiguration
    
    PUBLIC"-//mybatis.org//DTDConfig3.0//EN"
    
    "[http://mybatis.org/dtd/mybatis-3-config.dtd](http://mybatis.org/dtd/mybatis-3-config.dtd)">
    
    <configuration>
    
    <environments default="development">
    
    <environment id="development">
    
    <transactionManager type="JDBC"/>
    
    <!--此处配置数据库连接信息
    
    type="POOLED":为用链接池方式访问数据库-->
    
    <dataSource type="POOLED">
    
    <property name="driver" value="com.mysql.jdbc.Driver"/>
    
    <property name="url" value="jdbc:mysql://localhost:3306/student"/>
    
    <property name="username" value="root"/>
    
    <property name="password" value="xiaofu"/>
    
    </dataSource>
    
    </environment>
    
    </environments>
    
    <mappers>
    
    <mapper resource="orm/mapper/studentMapper.xml"/>
    
    </mappers>
    
    </configuration>
    

    7.测试一下

    public class FirstBasicDemoTest{
    
    public static void main(String[] args){
    
    //获取sqlsession对象
    
    String resource="firstBasicDemoConfigure.xml";
    
    Reader reader=null;
    
    try{
    
    reader=Resources.getResourceAsReader(resource);
    
    }catch(IOExceptione){
    
    e.printStackTrace();
    
    }
    
    SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(reader);
    
    SqlSessionsession=sqlSessionFactory.openSession();
    
    //进行查询操作
    
    Stringstatment="orm.mapper.studentMapper.selectById";
    
    Studentstudent=session.selectOne(statment,1);
    
    System.out.println(student);
    
    }
    
    }
    

    运行结果:

    image

    运行程序时可能会报错:

    mybatis读取配置文件报错:Could not find resource firstBasicDemoConfigure.xml
    原因:在classes目录下没有找到配置文件,所以配置文件没有在编译范围
    解决:在pom.xml中添加下方配置

    <build>
    
    <resources>
    
    <resource>
    
    <directory>src/main/java</directory>
    
    <includes>
    
    <include>**/*.xml</include>
    
    </includes>
    
    <filtering>true</filtering>
    
    </resource>
    
    </resources>
    
    </build>
    

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