创建第一个MyBatis实例(详细)

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创建第一个MyBatis实例

(1)，创建数据库中的表;
(2)，创建项目并添加MyBatis框架所需的jar包;
(3)，编写实体类;
(4)，编写与实体类对应的映射接口(xxxMapper.java),以及映射配置文件(xxxMapper.xml);
(5)，配置MyBatis框架的配置文件(mybatis-config.xml);
(6)，编写MyBatis框架工具类;
(7)，编写测试应用类并运行;

1,创建表: tb_student

create table TB_STUDENT(    id int not null,   `name`VARCHAR(50) not null,    score int not null,    PRIMARY KEY(id));

2,创建项目

添加所需的jar包到/WEB-INF/lib

3,编写实体类

编写与tb_student表对应的实体类Student，代码如下

package com.mybatis.pojos;public class Student {    private int id;    private String name;    private int score;    //必须要有无参的构造方法，不然根据StudentMapper.xml中的配置，在查询数据库时，将不能反射构造出Student实列    public Student(){           }    //带参数的构造方法    public Student(int id,String name,int score){        this.id=id;        this.name=name;        this.score=score;    }    @Override    public String toString(){        return "学号: "+id+"\n姓名: "+name+"\n成绩: "+score;    }    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 getScore() {        return score;    }    public void setScore(int score) {        this.score = score;    }           }

4,关系映射

编写与Student实体类所对应的映射接口StudentMapper，该接口是用于数据访问操作的接口，代码如下

package com.mybatis.mapper;import com.mybatis.pojos.Student;public interface StudentMapper {    public void insertStudent(Student student);//添加学生对象    public Student getStudent(String name); //查找学生对象}

编写对应的映射配置文件StudentMapper.xml，代码如下

<?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.mapper.StudentMapper">    <insert id="insertStudent" parameterType="Student">        insert into tb_student(id,name,score)values(#{id},#{name},#{score})         </insert>    <!-- 这里的id必须和StudentMapper接口中的接口方法名相同,不然运行时会报错 -->    <select id="getStudent" resultType="Student"        parameterType="java.lang.String" >        select id,name,score from tb_student where name=#{name}    </select></mapper>

5,配置mybatis-config.xml

代码如下

<?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>    <settings>        <setting name="cacheEnabled" value="false" />        <setting name="useGeneratedKeys" value="true" />        <setting name="defaultExecutorType" value="REUSE" />        </settings>    <typeAliases>        <typeAlias alias="Student" type="com.mybatis.pojos.Student" />    </typeAliases>      <environments default="development">        <environment id="development">            <transactionManager type="jdbc" />            <dataSource type="POOLED">                <property name="driver"                    value="com.mysql.jdbc.Driver"/>                <property name="url"                    value="jdbc:mysql://localhost:3306/hibernateuser" />                <property name="username"   value="root" />                <property name="password"   value="root" />                     </dataSource>        </environment>    </environments>    <mappers>        <mapper resource = "com/mybatis/mapper/StudentMapper.xml"></mapper>    </mappers></configuration>

6，编写MyBatisUtil工具类

用于获取SqlSessionFactory对象，代码如下

package com.mybatis.util;import java.io.IOException;import java.io.Reader;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class MyBatisUtil {    private final static SqlSessionFactory sqlSessionFactory;    static{        String resource="mybatis-config.xml";        Reader reader=null;        try{            //加载"mybatis-config.xml            reader = Resources.getResourceAsReader(resource);        }catch(IOException e){            System.out.println(e.getMessage());        }        sqlSessionFactory =new SqlSessionFactoryBuilder().build(reader);    }    public static SqlSessionFactory getSqlSessionFactory(){        return sqlSessionFactory;    }}

7，编写测试应用类

package com.mybatis;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import com.mybatis.mapper.StudentMapper;import com.mybatis.pojos.Student;import com.mybatis.util.MyBatisUtil;public class MyBatisDemo {    static SqlSessionFactory sqlSessionFactory=MyBatisUtil.getSqlSessionFactory();    public static void main(String[] args) {        //      //添加4个学生对象//      addStudent(new Student(1,"it",89));//      addStudent(new Student(2,"is",98));//      addStudent(new Student(3,"so",99));//      addStudent(new Student(4,"easy",99));        //根据姓名查找        Student student=getStudent("niu");        System.out.println(student.toString());    }    //添加学生信息    public static void addStudent(Student student){        //打开SqlSession        SqlSession sqlSession = sqlSessionFactory.openSession();        try{            //获取Mapper对象            StudentMapper studentMapper=sqlSession.getMapper(StudentMapper.class);            //插入操作            studentMapper.insertStudent(student);            //提交SqlSession            sqlSession.commit();            System.out.println("添加成功");        }finally{            //关闭sqlSession            sqlSession.close();        }    }    //根据姓名查找学生信息    public static Student getStudent(String name){        Student student=null;        //打开SqlSession        SqlSession sqlSession = sqlSessionFactory.openSession();        try{            //获取Mapper对象            StudentMapper studentMapper=sqlSession.getMapper(StudentMapper.class);            //查找操作            student=studentMapper.getStudent(name);             }finally{            //关闭sqlSession            sqlSession.close();        }        return student;    }}

项目文件目录如下: