MyBatis实战

Posted 2020-08-11

MyBatis实战

MyBatis简介

MyBatis 是支持定制化 SQL、存储过程以及高级映射的优秀的持久层框架。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以对配置和原生Map使用简单的 XML 或注解，将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java对象)映射成数据库中的记录。

MyBatis快速上手

开发环境准备

说明，本系列教程所有的代码均是在Intellij Idea 16.02版本的IDE上编写的。

1.项目结构

项目结构

2.添加依赖

• mybatis-3.4.1.jar

• mysql-connector-java-6.0.3.jar

• hamcrest-core-1.3.jar

• junit-4.12.jar

查询数据库中的记录

1.创建数据库和数据表

• 创建数据表

SET NAMES utf8;

SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------

--  Table structure for `users`

-- ----------------------------

DROP TABLE IF EXISTS `users`;

CREATE TABLE `users` (

`id` int(11) NOT NULL AUTO_INCREMENT,

`name` varchar(45) NOT NULL,

`pwd` varchar(45) NOT NULL,

`age` int(11) NOT NULL ,

`email` varchar(45) NOT NULL ,

`tel` varchar(45) NOT NULL,

`addr` varchar(45) NOT NULL,

PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=580317 DEFAULT CHARSET=utf8;

 

• 向表中添加数据

INSERT INTO `users`

VALUES

(‘580314‘, ‘Richard‘, ‘123456‘, ‘21‘, ‘[email protected]‘, ‘13627341394‘, ‘ISS‘),

(‘580315‘, ‘QinJiangbo‘, ‘123456‘, ‘22‘, ‘[email protected]‘, ‘13627341394‘, ‘Hongshan Square‘),

(‘580316‘, ‘Oliver‘, ‘whuiss‘, ‘22‘, ‘[email protected]‘, ‘13627341394‘, ‘ISS‘);

 

2.创建用户POJO类User.java

 

 

package com.qinjiangbo.pojo;

/**

* Date: 9/13/16

* Author: [email protected]

*/

public class User {

// 实体类的属性名称和数据库中的字段名称要一一对应起来

private long id;

private String name;

private String pwd;

private int age;

private String email;

private String tel;

private String addr;

public long getId() {

return id;

}

public void setId(long id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getPwd() {

return pwd;

}

public void setPwd(String pwd) {

this.pwd = pwd;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

public String getEmail() {

return email;

}

public void setEmail(String email) {

this.email = email;

}

public String getTel() {

return tel;

}

public void setTel(String tel) {

this.tel = tel;

}

public String getAddr() {

return addr;

}

public void setAddr(String addr) {

this.addr = addr;

}

@Override

public String toString() {

return "User{" +

"id=" + id +

", name=‘" + name + ‘\‘‘ +

", pwd=‘" + pwd + ‘\‘‘ +

", age=" + age +

", email=‘" + email + ‘\‘‘ +

", tel=‘" + tel + ‘\‘‘ +

", addr=‘" + addr + ‘\‘‘ +

‘}‘;

}

}

 

3.添加MyBatis的配置文件configure.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>

<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/mybatis"/>

<property name="username" value="Richard"/>

<property name="password" value="123456"/>

</dataSource>

</environment>

</environments>

<mappers>

    <!-- 注册Mapper映射XML文件 -->

<mapper resource="com/qinjiangbo/dao/UserMapper.xml"></mapper>

</mappers>

</configuration>

NOTE 上面是数据库相关的配置，各位读者可以根据自己的实际情况进行相应的配置。

4.编写Mapper映射XML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.qinjiangbo.dao.UserMapper">

<select id="findUserById" parameterType="int"

resultType="com.qinjiangbo.pojo.User">

SELECT * FROM users WHERE  id = #{id}

</select>

</mapper>

 

5.编写测试实例

 

package com.qinjiangbo.test;

import com.qinjiangbo.pojo.User;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import org.junit.Test;

import java.io.InputStream;

/**

* Date: 9/13/16

* Author: [email protected]

*/

public class MyBatisTest1 {

@Test

public void testFindUserById() {

// 注意这个地方,不少人会直接写configure.xml, 这样会一直取不到值,从而报空指针,

// 需要写全这个资源的全路径

String config = "com/qinjiangbo/conf/configure.xml";

InputStream inputStream = MyBatisTest1.class.getClassLoader().getResourceAsStream(config);

SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);

SqlSession sqlSession = factory.openSession();

String statement = "com.qinjiangbo.dao.UserMapper.findUserById";

User user = sqlSession.selectOne(statement, 580314);

System.out.println(user);

}

}

6.测试结果

查询用户信息测试结果

稿源：勤快学QKXue.NET

扩展阅读：

MyBatis实战（一）
http://qkxue.net/info/24308/MyBatis
MyBatis实战（三）
http://qkxue.net/info/29369/MyBatis
MyBatis实战（四）
http://qkxue.net/info/30378/MyBatis
MyBatis实战（五）
http://qkxue.net/info/31568/MyBatis
MyBatis实战（六）
http://qkxue.net/info/33106/MyBatis