（5）MyBatis小总结：一个简单的例子

最新推荐文章于 2024-01-20 10:54:31 发布

原创最新推荐文章于 2024-01-20 10:54:31 发布 · 326 阅读

0 ·

CC 4.0 BY-SA版权

Spring+SpringMVC+Mybatis，项目实战同时被 3 个专栏收录

125 篇文章

订阅专栏

Spring/MVC/Mybatis

82 篇文章

订阅专栏

mysql/数据库

30 篇文章

订阅专栏

本文介绍了使用MyBatis框架实现简单数据库操作的过程。通过一个具体的案例，详细展示了配置文件、映射文件及Java代码的具体编写方式。

日期：2017/12/6

求职中，加紧学习。（引用自某位前辈）

mybatis即是对JDBC的封装（重复代码的优秀封装），因为是半自动化ORM，所以sql其实需要我们自己写和封装的（xml标签装饰），下面介绍一个最简单的使用例子，实现“select * from employee where id=1”。

准备：

1. Mysql ，eclipse ；

2. jar包： mybatis-3.4.1.jar 、mysql-connector-java-5.1.37-bin.jar、log4j.jar（java常用开发包--log4j.jar ）

3. 目录结构:

|configuration.xml

|testcase.java

|User.java

|User.xml

4.代码

4.1User.java：

package mybatis;

public class User {
	
	private Integer id;
	private String lastName;
	private String email;
	private String gender;
	
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
	public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	@Override
	public String toString() {
		return "Employee [id=" + id + ", lastName=" + lastName + ", email="
				+ email + ", gender=" + gender + "]";
	}
	
	

}

4.2 configuration.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" />
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/test" />
                <property name="username" value="root" />
                <property name="password" value="" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mybatis/User.xml" />
    </mappers>
</configuration>

4.3 User.xml：

<?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="User">
    <select id="selectUser" resultType="mybatis.User">
		select * from employee where id=#{id}
    </select>
</mapper>

4.4 testcase.java：

package mybatis;

import java.io.IOException;
import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;


public class testcase {
	public static void main(String[] args) throws IOException {
        String resource = "mybatis/configuration.xml";  
        Reader reader = Resources.getResourceAsReader(resource);  
        SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(reader);  
        SqlSession session = ssf.openSession();  
        try {  
            User user = (User) session.selectOne("User.selectUser", "1");  
            System.out.println(user);  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            session.close();  
        } 
				
	}

}

测试结果：

log4j:WARN No appenders could be found for logger (org.apache.ibatis.logging.LogFactory).
log4j:WARN Please initialize the log4j system properly.

Employee [id=1, lastName=mmb, email=144@qq.com, gender=0]

测试可用。WHAT IS MORE :(6）MyBatis小总结：一个简单的例子--接口编程改进