mybatis入门（二）--简单入门例子

下面介绍一个最基本的Mybatis入门程序(java project ---oracle数据库)。

      1.首先在数据库中创建表create table t_user(id number(11),username varchar2(20));

 

      2.Eclipse---New--JavaProject,导入相关jar包。（自己测试，随便建了个javaproject工程）

      在src下面分别添加vo、maps、dao以及util包。

 

      3.在根目录下建立文件mybatis.cfg.xml,当然名称可以随便自定义，具体内容如下：

  

<?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>
	<!-- 引入外部文件 -->
	<properties resource="config.properties"></properties>
	<!-- end properties -->
	<typeAliases>
		<typeAlias alias="User" type="com.mybatis.test.vo.User" />
	</typeAliases>
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<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="com/mybatis/test/maps/User.xml" />
	</mappers>
</configuration>

 

 

 

 上面代码段中出现

<!-- 引入外部文件 -->
	<properties resource="config.properties"></properties>
	<!-- end properties --

 

在根目录下新建文件config.properties,具体内容如下：

driver=oracle.jdbc.driver.OracleDriver
url=jdbc:oracle:thin:@10.45.218.152:1431:SZSTAGE
username=root
password=root

      4.在vo包下面新建使实体类User.java,具体内容如下：

package com.mybatis.test.vo;
public class User {
	private int id;
	private String userName;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	@Override
	public String toString()
	{return "id is:"+id+" name is: "+ userName;}
}

 5.在maps包下新建xml文件User.xml,具体代码如下：

<?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="User">
    
	<select id="selectUser" parameterType="int" resultType="User">
		select * from t_user where id = #{id}
    </select>
    <select id="selectAllUser" resultType="User">
        select id, username from t_user
    </select>
    <insert id="insertUser" parameterType="User">
        insert into t_user(id,username) values (#{id}, #{userName})
    </insert>
</mapper>

 6.在util包中新建辅助类DBUtil,具体内容如下：

package com.mybatis.test.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 DBUtil {
	private static String resource = "mybatis.cfg.xml";
	private static Reader reader;
	private static SqlSessionFactory sqlSessionFactory;
	public static SqlSessionFactory getSqlSessionFactory()
	{
		try {
			reader = Resources.getResourceAsReader(resource);
		} catch (IOException e) {
			System.out.println("IO异常");}
		sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
		return sqlSessionFactory;
	}
}

 7.在dao包中新建类UserDAO，具体代码如下：

package com.mybatis.test.dao;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import com.mybatis.test.util.DBUtil;
import com.mybatis.test.vo.User;
public class UserDAO {
	private static SqlSessionFactory sqlSessionFactory = DBUtil
			.getSqlSessionFactory();
	/**
	 * 通过id获得User
	 * 
	 * @param id
	 * @return
	 */
	public User getUserById(int id) {
		SqlSession session = sqlSessionFactory.openSession();
		try {
			User user = (User) session.selectOne("User.selectUser", id);
			return user;
		} finally {
			session.close();
		}
	}
	public List<User> getAllUser() {
		SqlSession session = sqlSessionFactory.openSession();
		try {
			List<User> users = (List<User>) session.selectList("User.selectAllUser");
			return users;
		} finally {
			session.close();
		}
	}
	public int addUser(User user) {
		SqlSession session = sqlSessionFactory.openSession();
		try {
			int i = session.insert("User.insertUser", user);
			if(i >= 1) session.commit();
			return i;
		} finally {
			session.close();
		}
	}

 8.在util包中新建Test类，进行测试，具体内容如下：

package com.mybatis.test.util;
import java.util.List;
import com.mybatis.test.dao.UserDAO;
import com.mybatis.test.vo.User;
public class Test {
	public static void main(String[] args) {
		UserDAO userDao = new UserDAO();
		User user = new User();
		user.setId(4);
		user.setUserName("Zhuzi");
		//添加
		System.out.println(userDao.addUser(user));
		//查询
		System.out.println(userDao.getUserById(4));
		List<User> users = userDao.getAllUser();
		for (User u : users) {
			System.out.println(u);
		}
	}
}