mybatis學習之入門篇

初次使用mybatis，做好筆記，自己寫個例子。

MyBatis 本是apache的一個開源項目iBatis, 2010年這個項目由apache software foundation 遷移到了google code，並且改名爲MyBatis.本文只針對Mybatis如何使用做了一個小實例，無依賴框架spring,單獨使用。本文使用Mybatis—3.1.1版本 下載Mybatis—3.1.1 .jar包 將主jar包以及lib下所有jar包複製到工程web-inf下lib中

做爲持久層框架就一定要和數據庫打交道

首先我們建立我們要使用到的庫表

role表 創建sql語句

CREATE TABLE `role` (
  `roleId` bigint(20) NOT NULL AUTO_INCREMENT,
  `roleName` varchar(50) NOT NULL,
  PRIMARY KEY (`roleId`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8

User表 創建sql語句

CREATE TABLE `user` (
  `userId` bigint(20) NOT NULL AUTO_INCREMENT,
  `userName` varchar(30) NOT NULL,
  `password` varchar(80) NOT NULL,
  `role_id` bigint(20) NOT NULL,
  PRIMARY KEY (`userId`),
  KEY `fk_role` (`role_id`),
  CONSTRAINT `fk_role` FOREIGN KEY (`role_id`) REFERENCES `role` (`roleId`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8

然後創建實體類

package com.mybatis.domain;

public class Role {
	public int roleId;
	public String roleName;
	public int getRoleId() {
		return roleId;
	}
	public void setRoleId(int roleId) {
		this.roleId = roleId;
	}
	public String getRoleName() {
		return roleName;
	}
	public void setRoleName(String roleName) {
		this.roleName = roleName;
	}

}

package com.mybatis.domain;

public class User {
	private int userId;
	private String userName;
	private String password;
	private int role_id;
	private Role role;
	
	public Role getRole() {
		return role;
	}
	public void setRole(Role role) {
		this.role = role;
	}
	public int getUserId() {
		return userId;
	}
	public void setUserId(int userId) {
		this.userId = userId;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public int getRole_id() {
		return role_id;
	}
	public void setRole_id(int role_id) {
		this.role_id = role_id;
	}

}

接下來我們定義接口

package com.mybatis.Dao;

import java.util.List;
import com.mybatis.domain.User;

public interface UserDao {
public int insert(User user);

public int update(User user);

public int delete(String userName);

public List<User> selectAll();

public int countAll();

public User findByName(String username);
}

創建加入此接口的映射配置文件——UserDaoMapper.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="com.mybatis.Dao.UserDao">
    <select id="countAll" resultType="int">
        select count(*) c from user;
    </select>
    <select id="selectAll" resultType="com.mybatis.domain.User">
        select * from user order by userName asc
    </select>
    <insert id="insert"  parameterType="com.mybatis.domain.User">
        insert into user(userName,password) values(#{userName},#{password})
    </insert>
    <update id="update" parameterType="com.mybatis.domain.User">
        update user set userName=#{userName},password=#{password} where userName=#{userName}
    </update>
    <delete id="delete" parameterType="int">
        delete from user where userName=#{userName}
    </delete>
    <select id="findByName" parameterType="String" resultType="com.mybatis.domain.User">
        select * from user where userName=#{userName}
        <!-- <if test="userName!=null">
        	and userName=#{userName}
        </if> -->
    </select>
    <select id="findByCon" parameterType="int" resultMap="byCon_result">
    	select
 			u.userId,
			u.userName,
			u.`password`,
			u.role_id,
			r.roleId,
			r.roleName
		from
    		user u left join role r
    		on
    		u.role_id=r.roleId
		where
    		u.userId=#{id}
    </select>
    <resultMap type="com.mybatis.domain.User" id="byCon_result">
    	<id column="id" property="userId"/>
    	<result column="userName" property="userName"/>
    	<result column="password" property="password"/>
    	<result column="role_id" property="role_id"/>
    	<association property="role" javaType="com.mybatis.domain.Role">
    		<id column="roleId" property="roleId"/>
    		<result column="roleName" property="roleName"/>
    	</association>
    </resultMap>
</mapper> 

接着需要創建mybatis主配置文件——MyBatis-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/mybatistest?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull" />
                <property name="username" value="root" />
                <property name="password" value="admin" />
            </dataSource>
        </environment>
    </environments>	
    <mappers>
        <mapper resource="com/mybatis/domain/UserDaoMapper.xml"/>
    </mappers>
</configuration>

最後我們編寫測試程序

package com.mybatis.test;

import java.io.IOException;
import java.io.Reader;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Iterator;
import java.util.List;

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 org.apache.ibatis.session.SqlSessionManager;

import com.mybatis.Dao.UserDao;
import com.mybatis.domain.Role;
import com.mybatis.domain.User;

public class UserDaoTest {
	
	private static SqlSessionFactory getSessionFactory(){
		SqlSessionFactory sessionFactory = null;
		String resource = "MyBatis-Configuration.xml";
		try {
			sessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource));
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return sessionFactory;
	}
	public static void main(String[] args) {
		
		SqlSession sqlSession = getSessionFactory().openSession();
		UserDao userDao = sqlSession.getMapper(UserDao.class);
		//根據username查詢用戶
		User user1 = sqlSession.selectOne("findByName","zhangsan");
		System.out.println(user1.getUserName());
		//根據id查詢
		User user = sqlSession.selectOne("findByCon",1);
		System.out.println(user.getUserName());
		//查詢全部
		List<User> users = userDao.selectAll();
		for (int i = 0; i < users.size(); i++) {
			User us = users.get(i);
			System.out.println("用戶名："+us.getUserName());
			System.out.println("密碼："+us.getPassword());
		}
	
		User user2 = new User();
		user2.setUserName("wangwu");
		user2.setPassword("123");
		user2.setRole_id(1);
		try {
			//增加用戶
			int nu = userDao.insert(user2);
			sqlSession.commit();
			System.out.println("增加"+nu+"個用戶");
		} catch (Exception e) {
			// TODO Auto-generated catch block
			sqlSession.rollback();
			e.printStackTrace();
		}finally{
			sqlSession.close();
		}		
	}
}