mybatis 入门HelloWorld

最新推荐文章于 2020-11-23 08:16:41 发布

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本文介绍了一个使用MyBatis实现的实战案例，包括项目的搭建过程、关键配置文件的编写方法、测试代码的实现方式等。

新项目使用MyBatis，所以学习一下：

mybatis 下载地址：

http://code.google.com/p/mybatis/

MyBatis测试版项目架构

1。引入三个包：见项目Referenced Libraries下

2。各个类源代码：

User.java

package cn.bean;

public class User {
	private int id;
	private String name;

	public User() {
	}

	public User(String name) {
		this(0, name);
	}

	public User(int id, String name) {
		this.id = id;
		this.name = name;
	}

	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;
	}

	@Override
	public String toString() {
		return "id: " + id + ", name: " + name;
	}
}

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" parameterType="int" resultType="User">
		<![CDATA[  
        select * from user where id = #{id}  
    ]]>
	</select>
</mapper>

mybatis.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>
	<typeAliases>  
        <typeAlias alias="User" type="cn.bean.User" />  
    </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/test" />
				<property name="username" value="root" />
				<property name="password" value="123456" />
			</dataSource>
		</environment>
	</environments>
	<mappers>  
        <mapper resource="cn/bean/User.xml" />  
    </mappers>  
</configuration>

3。测试代码：

UserInfoTest.java

package cn.test;

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;

import cn.bean.User;

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

4。在运行程序前，需要新建mysql数据库test，及数据库表user，并插入一条记录。

sql语句：

CREATE TABLE `user` (
   `id` int(11) NOT NULL auto_increment,
   `name` varchar(128) default NULL,
   PRIMARY KEY  (`id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8

INSERT INTO `test`.`user_info`(`id`,`name`) VALUES ( '1','zhangsan');

5。右击运行，输出结果

log4j:WARN No appenders could be found for logger (org.apache.ibatis.logging.LogFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
id: 1, name: zhangsan