Mybatis——Mybatis入门项目从创建到完成的完整过程【单表的增删改查】

1. 前期准备

1.1 新建库建表

SQL文件

#创建数据库ssm
CREATE DATABASE ssm DEFAULT CHARSET utf8;

#使用(打开)ssm数据库
use ssm;

#创建表student
CREATE TABLE `student` (
`id` int(11)  AUTO_INCREMENT primary key ,
`name` varchar(255) DEFAULT NULL,
`email` varchar(255) DEFAULT NULL,
`age` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

insert into student(name,email,age) values('张三','zhangsan@126.com',22);
insert into student(name,email,age) values('李四','lisi@126.com',21);
insert into student(name,email,age) values('王五','wangwu@163.com',22);
insert into student(name,email,age) values('赵六','zhaoliun@qq.com',24);
select * from student;
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1. 2 新建maven项目

关于Maven的配置请参考以下文章：

maven的下载以及安装
idea中Maven的配置，项目的创建

新建maven模块

第二步：进入模块创建窗口

第四步：new Moudle

第五步：选择Maven

第六步：输入项目名，修改仓库地址等信息

1.3 修改目录

将项目目录补充完整

1.4 在idea中添加数据库的可视化

选择Mysql后执行以下操作

2. 后期实现

2.1 修改pom.xml文件,添加依赖 和资源文件指定

添加mybatis和mysql的依赖

 
    <dependency>
      <groupId>org.mybatisgroupId>
      <artifactId>mybatisartifactId>
      <version>3.5.6version>
    dependency>
    
    <dependency>
      <groupId>mysqlgroupId>
      <artifactId>mysql-connector-javaartifactId>
      <version>8.0.29version>
    dependency>
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在build标签中添加资源文件的指定

  
    <resources>
      <resource>
        <directory>src/main/javadirectory>
        <includes>
          <include>**/*.xmlinclude>
          <include>**/*.propertiesinclude>
        includes>
      resource>

      <resource>
        <directory>src/test/javadirectory>
        <includes>
          <include>**/*.xmlinclude>
          <include>**/*.propertiesinclude>
        includes>
      resource>
    resources>
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2.2 添加jdbc.properties属性文件(数据库的配置)

复制时修改名称和密码

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/ssm?useUnicode=true&characterEncoding=utf8
username=root
password=111111
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2.3 添加SqlMapConfig.xml文件,MyBatis的核心配置文件

DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    
    <properties resource="jdbc.properties">properties>

    
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    settings>

    <typeAliases>
        

        
        <package name="com.lcl.pojo">package>
    typeAliases>

    
    <environments default="development">
        <environment id="development">
            
            <transactionManager type="JDBC">transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            dataSource>
        environment>
    environments>

    
    <mappers>
        
        <mapper resource="StudentMapper.xml">mapper>
    mappers>
configuration>
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2.4 创建实体类Student,用来封装数据

不用说，此项最简单直接生成即可，需要有属性的get和set方法，以及三个构造器：无参构造器，所有属性构造器，缺少主键的构造器，以及toString 方法【方便输出】

public class Student {
    private Integer id;
    private String name;
    private String email;
    private Integer age;

    public Student() {
    }

    public Student(Integer id, String name, String email, Integer age) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.age = age;
    }

    public Student(String name, String email, Integer age) {
        this.name = name;
        this.email = email;
        this.age = age;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", age=" + age +
                '}';
    }
}
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2.5 添加完成学生表的增删改查的功能的StudentMapper.xml文件

实际上就是sql语句的编写，

DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">



<mapper namespace="lcl">
    
    <select id="getAll" resultType="student" >
        select id,name,email,age from student
    select>

    
    
    <select id="getById" parameterType="int" resultType="student">
        select id,name,email,age from student where id = #{id}
    select>

    
    <select id="getByName" parameterType="string" resultType="student">
        select id,name,email,age from student where name like '%${name}%'
    select>

    
    <insert id="insert" parameterType="student">
        insert into student(name,email,age) values (#{name},#{email},#{age})
    insert>

    
    <delete id="delete" parameterType="int">
        delete from student where id = #{id}
    delete>

    
    <update id="update" parameterType="student">
        update student set name=#{name},email=#{email},age=#{age}
        where id=#{id}
    update>
mapper>
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3. 实现测试

3.1 创建测试类,进行功能测试

测试项目的增删改查功能
   采用注解的形式，完成刚开始的获取SqlSession对象，以及使用After完成最后关闭SqlSession对象的操作。

public class MyTest {T

    SqlSession sqlSession;

    @Before
    public void openSqlSession() throws IOException {
        //使用文件流读取核心配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");

        //创建SqlSessionFactory工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);

        //取出SqlSession对象
        sqlSession = factory.openSession();
    }

    @After
    public void closeSqlSession(){
        //关闭SqlSession
        sqlSession.close();
    }


    @Test
    public void testGetAll() throws IOException {
        //完成查询操作
        List<Student> studentList = sqlSession.selectList("lcl.getAll");
        studentList.forEach(student -> System.out.println(student));
    }

    @Test
    public void testGetById() throws IOException {
        //执行查询语句
        Student stu = sqlSession.selectOne("lcl.getById", 1);
        System.out.println(stu);
    }

    /*一下均可修改*/

    @Test
    public void testGetByName() throws IOException {
        //读取配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建SqlSessionFactory
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //读取SqlSession对象
        SqlSession sqlSession = factory.openSession();
        //执行查询
        List<Student> studentList = sqlSession.selectList("lcl.getByName","an");
        studentList.forEach(student -> System.out.println(student));
        //关闭资源
        sqlSession.close();
    }

    @Test
    public void testInsert() throws IOException {
        int num = sqlSession.insert("lcl.insert",new Student("zhaoliu","zhaoliu@126.com",21));
        //在执行增删改操作时，需要手动提交事务
        sqlSession.commit();
        System.out.println(num);
    }

    @Test
    public void testDelete() throws IOException {
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建SqlSessionFactory
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //创建SqlSession对象
        SqlSession sqlSession = factory.openSession();
        //执行删除语句
        int num = sqlSession.delete("lcl.delete",6);
        System.out.println(num);
        //提交事务并关闭资源
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void testUpdate() throws IOException {
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建SqlSessionFactory
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //创建SqlSession对象
        SqlSession sqlSession = factory.openSession();
        //执行删除语句
        int num = sqlSession.update("lcl.update",new Student(3,"王五","王五@126.com",22));
        System.out.println(num);
        //提交事务并关闭资源
        sqlSession.commit();
        sqlSession.close();
    }
}
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