建立第一個MyBatis例項

(1)，建立資料庫中的表;
(2)，建立專案並新增MyBatis框架所需的jar包;
(3)，編寫實體類;
(4)，編寫與實體類對應的對映介面(xxxMapper.java),以及對映配置檔案(xxxMapper.xml);
(5)，配置MyBatis框架的配置檔案(mybatis-config.xml);
(6)，編寫MyBatis框架工具類;
(7)，編寫測試應用類並執行;

1,建立表: tb_student

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

2,建立專案

新增所需的jar包到/WEB-INF/lib

3,編寫實體類

編寫與tb_student表對應的實體類Student，程式碼如下

package com.mybatis.pojos;

public class Student {
    private int id;
    private String name;
    private int score;

    //必須要有無參的構造方法，不然根據StudentMapper.xml中的配置，在查詢資料庫時，將不能反射構造出Student實列
 

    public Student(){       
    }

    //帶引數的構造方法
    public Student(int id,String name,int score){
        this.id=id;
        this.name=name;
        this.score=score;
    }

    @Override
    public String toString(){
        return "學號: "+id+"\n姓名: "+name+"\n成績: "+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,關係對映

編寫與Student實體類所對應的對映介面StudentMapper，該介面是用於資料訪問操作的介面，程式碼如下

package com.mybatis.mapper;

import com.mybatis.pojos.Student;

public interface StudentMapper {
    public void insertStudent(Student student);//新增學生物件

    public Student getStudent(String name); //查詢學生物件
}

編寫對應的對映配置檔案StudentMapper.xml，程式碼如下

<?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>

    <!-- 這裡的id必須和StudentMapper介面中的介面方法名相同,不然執行時會報錯 -->
    <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

程式碼如下

<?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，編寫MyBatisUtil工具類

用於獲取SqlSessionFactory物件，程式碼如下

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{
            //載入"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，編寫測試應用類

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) {        

//      //新增4個學生物件
//      addStudent(new Student(1,"it",89));
//      addStudent(new Student(2,"is",98));
//      addStudent(new Student(3,"so",99));
//      addStudent(new Student(4,"easy",99));

        //根據姓名查詢
        Student student=getStudent("niu");
        System.out.println(student.toString());
    }

    //新增學生資訊
    public static void addStudent(Student student){
        //開啟SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        try{
            //獲取Mapper物件
            StudentMapper studentMapper=sqlSession.getMapper(StudentMapper.class);
            //插入操作
            studentMapper.insertStudent(student);
            //提交SqlSession
            sqlSession.commit();
            System.out.println("新增成功");
        }finally{
            //關閉sqlSession
            sqlSession.close();
        }
    }

    //根據姓名查詢學生資訊
    public static Student getStudent(String name){
        Student student=null;
        //開啟SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        try{
            //獲取Mapper物件
            StudentMapper studentMapper=sqlSession.getMapper(StudentMapper.class);
            //查詢操作
            student=studentMapper.getStudent(name);     
        }finally{
            //關閉sqlSession
            sqlSession.close();
        }
        return student;
    }
}

專案檔案目錄如下: