今天我们继续来讲Java方面的知识。

MyBatis 简介

MyBatis的前身叫iBatis,本是apache的一个开源项目, 2010年这个项目由apache software foundation 迁移到了google code,并且改名为MyBatis。

MyBatis是支持普通SQL查询,存储过程和高级映射的优秀持久层框架。MyBatis消除了几乎所有的JDBC代码和参数的手工设置以及结果集的检索。MyBatis使用简单的XML或注解用于配置和原始映射,将接口和Java的POJOs(Plan Old Java Objects,普通的Java对象)映射成数据库中的记录。

下面分步骤给搭建介绍mybatis 环境搭建

1)在工程下引入mybatis-3.4.1.jar包,再引入数据库(mysql,mssql..)包.

2)在src下新建一个配置文件conf.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>
<!-- 引入外部配置文件 -->
 <properties resource="jdbc.properties" />
 <!-- 配置mybatis运行环境 -->
 <environments default="development">
 <environment id="development">
  <!-- type="JDBC" 代表使用JDBC的提交和回滚来管理事务 -->
  <transactionManager type="JDBC" />  
  <!-- mybatis提供了3种数据源类型,分别是:POOLED,UNPOOLED,JNDI -->
  <!-- POOLED 表示支持JDBC数据源连接池 -->
  <!-- UNPOOLED 表示不支持数据源连接池 -->
  <!-- JNDI 表示支持外部数据源连接池 -->
  <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="userMapper.xml"/>
 </mappers> 
</configuration>

这里是通过外部配置文件来存储数据库存信息的,所以加入一个jdbc.properties的数据库存信息

driver=com.microsoft.sqlserver.jdbc.SQLServerDriver
url=jdbc:sqlserver://127.0.0.1;databaseName=test
username=sa
password=123456

3)建立一个映射文件 userMapper.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="hw.com.ser.IUser">
 <!-- 查询全部用户 -->
 <select id="queryUsers" resultType="hw.com.pojo.User">
  select * from MS_User
 </select>
 <selectid="queryUserById" resultType="hw.com.pojo.User" parameterType="int">
  Select * From Ms_User Where id=#{id}
 </select> 
</mapper>

(这里要注意的是,namespace属性,因为,此实例是通过接口映射的方式,所以,namespace属性一点要写成接口的路径)附图:

MyBaits 入门之MyBatis环境搭建(第一篇) – java笔记 – CFEI.NET-飞网

4)建一个映射接口类

package hw.com.ser;
import java.util.List;
import hw.com.pojo.User;
public interface IUser {
 public List<User> queryUsers();
 public User queryUserById(int id);
}

5)建立一个SqlSessionFactory

package hw.com.util;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.Properties;
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 SqlSessionFactoryUtil {
 private static SqlSessionFactory sqlSessionFactory = null;
 private static final Class CLASS_LOCK = SqlSessionFactoryUtil.class;
 private SqlSessionFactoryUtil() {
 }
 public static SqlSessionFactory initSqlSessionFactory() {
 String resource = "conf.xml";
 InputStream inputStream = null;
 try {
  inputStream = Resources.getResourceAsStream(resource);  
 } catch (IOException e) {
  e.printStackTrace();
 }
 synchronized (CLASS_LOCK) {
  if (sqlSessionFactory == null) {
  sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
  }
 }
 return sqlSessionFactory;
 }
 public static SqlSession openSqlSession(){
 if(sqlSessionFactory==null){
  initSqlSessionFactory();
 }
 return sqlSessionFactory.openSession();
 }
}

6)建一个pojo

package hw.com.pojo;
import java.util.Date;
public class User {
 private String Id;
 private String UserName;
 private String UserPwd;
 private int DeptmentId;
 private String UserTrueName;
 private String Email;
 private int LearnCenterId;
 private Date CreateDate;
 private Date LastModifyDate;
 private int UserStatus;
 public User() {
 super();
 // TODO Auto-generated constructor stub
 }
 public String getId() {
 return Id;
 }
 public void setId(String id) {
 Id = id;
 }
 public String getUserName() {
 return UserName;
 }
 public void setUserName(String userName) {
 UserName = userName;
 }
 public String getUserPwd() {
 return UserPwd;
 }
 public void setUserPwd(String userPwd) {
 UserPwd = userPwd;
 }
 public int getDeptmentId() {
 return DeptmentId;
 }
 public void setDeptmentId(int deptmentId) {
 DeptmentId = deptmentId;
 }
 public String getUserTrueName() {
 return UserTrueName;
 }
 public void setUserTrueName(String userTrueName) {
 UserTrueName = userTrueName;
 }
 public String getEmail() {
 return Email;
 }
 public void setEmail(String email) {
 Email = email;
 }
 public int getLearnCenterId() {
 return LearnCenterId;
 }
 public void setLearnCenterId(int learnCenterId) {
 LearnCenterId = learnCenterId;
 }
 public Date getCreateDate() {
 return CreateDate;
 }
 public void setCreateDate(Date createDate) {
 CreateDate = createDate;
 }
 public Date getLastModifyDate() {
 return LastModifyDate;
 }
 public void setLastModifyDate(Date lastModifyDate) {
 LastModifyDate = lastModifyDate;
 }
 public int getUserStatus() {
 return UserStatus;
 }
 public void setUserStatus(int userStatus) {
 UserStatus = userStatus;
 }
 @Override
 public String toString() {
 return "User [Id=" + Id + ", UserName=" + UserName + ", UserPwd=" + UserPwd + ", DeptmentId=" + DeptmentId
  + ", UserTrueName=" + UserTrueName + ", Email=" + Email + ", LearnCenterId=" + LearnCenterId
  + ", CreateDate=" + CreateDate + ", LastModifyDate=" + LastModifyDate + ", UserStatus=" + UserStatus
  + "]";
 }
}

7) 在main方法下做测试

package hw.com.Day1.main;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import hw.com.pojo.User;
import hw.com.ser.IUser;
import hw.com.util.SqlSessionFactoryUtil;
public class UserTest {
 public static void main(String[] args) { 
 SqlSession sqlSession=null;
 try {
  sqlSession=SqlSessionFactoryUtil.openSqlSession();
  IUser iUser=sqlSession.getMapper(IUser.class);
  List<User> users=iUser.queryUsers();
  if(users.size()>0){
  for (User user : users) {
   System.out.println(user.toString());
  }
  }
 } catch (Exception e) {
  e.printStackTrace();
 }
 }
}

因为水平有限,难免有疏忽或者不准确的地方,希望大家能够直接指出来,我会及时改正。一切为了知识的分享。

后续会有更多的精彩的内容分享给大家。