MyBatis-----初识MyBatis--封装---别名---properties

Posted 2020-10-05 Angelye

一、核心配置文件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 3 "http://mybatis.org/dtd/mybatis-3-config.dtd">
 4 <configuration>
 5      <!-- 最开始加载引用db.properties文件 -->
 6     <properties resource="db.properties"/>
 7     <!-- 取别名    以下情况别名为类名 -->
 8      <typeAliases>
 9          <package name="com.myBatis.entity"/>
10      </typeAliases>
11     <!-- 
12         development : 开发模式
13         work : 工作模式
14      -->
15     <environments default="development">
16         <environment id="development">
17             <transactionManager type="JDBC" />
18             <!-- 配置数据库连接信息 -->
19             <dataSource type="POOLED">
20                 <property name="driver" value="${driver}" />
21                 <property name="url" value="${url}" />
22                 <property name="username" value="${username}" />
23                 <property name="password" value="${password}" />
24             </dataSource>
25         </environment>
26     </environments>
27     <!-- 引用映射文件 -->
28     <mappers >
29         <mapper resource="com/myBatis/mapper/userMapper.xml"/>
30     </mappers>
31 </configuration>

View Code

二、实体类

 1 package com.myBatis.entity;
 2 
 3 public class EUser {
 4     private Integer id;
 5     private String name;
 6     private Integer age;
 7     public int getId() {
 8         return id;
 9     }
10     public String getName() {
11         return name;
12     }
13     public void setName(String name) {
14         this.name = name;
15     }
16     public Integer getAge() {
17         return age;
18     }
19     public void setAge(Integer age) {
20         this.age = age;
21     }
22     public void setId(Integer id) {
23         this.id = id;
24     }
25     @Override
26     public String toString() {
27         return "EUser [id=" + id + ", name=" + name + ", age=" + age + "]";
28     }
29     
30     
31     
32 }

EUser.java

三、实体类的映射文件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 
 3 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 4     <!-- 
 5     为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，
 6     这样就能够保证namespace的值是唯一的 
 7     -->
 8     <mapper namespace="com.myBatis.mapper.userMapper.xml">
 9         <!-- 根据id查询得到一个user对象 -->
10         <select id="getUser" parameterType="int" resultType="EUser">
11             select * from users where id=#{id}
12         </select>
13         <!--  根据id查询删除一个user对象 -->
14         <delete id="deleteUser" parameterType="EUser">
15             delete from users where id=#{id}
16         </delete>
17           <!-- 创建用户(Create) -->
18         <insert id="addUser" parameterType="EUser">
19             insert into users values(null,#{name},#{age})
20         </insert>
21          <!-- 修改用户(Update) -->
22         <update id="updateUser" parameterType="EUser">
23             update users set name=#{name},age=#{age} where id=#{id}
24         </update>
25     </mapper>
26     

View Code

四、封装类

 1 package com.myBatis.util;
 2 
 3 
 4 import java.io.IOException;
 5 import java.io.Reader;
 6 
 7 import org.apache.ibatis.io.Resources;
 8 import org.apache.ibatis.session.SqlSession;
 9 import org.apache.ibatis.session.SqlSessionFactory;
10 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
11 
12 public class myBtaisUtil {
13     static Reader reader=null;
14     static SqlSessionFactory sqlSessionFactory= null;
15     static SqlSession sqlSession = null;
16     /**
17      * 加载核心配置文件
18      * 获取SqlSessionFactory
19      * @return SqlSessionFactory
20      */
21     public static SqlSessionFactory getsqlSessionFactory() {
22         try {
23             reader = Resources.getResourceAsReader("SqlMapConfig.xml");
24             sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
25         } catch (IOException e) {
26             e.printStackTrace();
27         }
28         return sqlSessionFactory;
29     }
30     /**
31      * 获取SqlSession
32      * @return SqlSession
33      */
34     public static SqlSession getsqlSession() {
35         return sqlSession= getsqlSessionFactory().openSession(true);
36     }
37 }

myBtaisUtil.java

五、properties文件

1 driver=com.mysql.jdbc.Driver
2 url=jdbc:mysql:///mybatis
3 username=root
4 password=root

db.properties

六、测试类

 1 package myBatisTest;
 2 import java.io.IOException;
 3 import java.io.Reader;
 4 import org.apache.ibatis.io.Resources;
 5 import org.apache.ibatis.session.SqlSession;
 6 import org.apache.ibatis.session.SqlSessionFactory;
 7 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 8 import org.junit.Test;
 9 
10 import com.myBatis.entity.EUser;
11 import com.myBatis.util.myBtaisUtil;
12 
13 public class TestUser {
14     //修改
15     @Test
16     public void testUpdateUser() {
17         SqlSession sqlSession=myBtaisUtil.getsqlSession();
18         //先查找
19          String select = "com.myBatis.mapper.userMapper.xml.getUser";
20          EUser  user = sqlSession.selectOne(select, 7);
21          System.out.println(user);
22          //再修改
23         user.setName("改啦7777");
24         user.setAge(50);
25         String update = "com.myBatis.mapper.userMapper.xml.updateUser";
26         int i = sqlSession.update(update, user);
27          System.out.println(i);
28          EUser  user1= sqlSession.selectOne(select, 7);
29          System.out.println(user1);
30     }
31     //添加
32     @Test
33     public void testAddUser() {
34         SqlSession sqlSession=myBtaisUtil.getsqlSession();
35          String add = "com.myBatis.mapper.userMapper.xml.addUser";
36          EUser user = new EUser();
37         user.setName("用户孤傲苍狼");
38         user.setAge(20);
39         int i = sqlSession.insert(add, user);
40          System.out.println(i);
41     }
42     //删除
43     @Test
44     public void testDeleteUser() {
45         SqlSession sqlSession=myBtaisUtil.getsqlSession();
46         String delete = "com.myBatis.mapper.userMapper.xml.deleteUser";
47         int i= sqlSession.delete(delete, 6);
48         System.out.println(i);
49     }
50     //查询
51     @Test
52     public void testGetUser() {
53         SqlSession sqlSession=myBtaisUtil.getsqlSession();
54         String select = "com.myBatis.mapper.userMapper.xml.getUser";
55         EUser  user = sqlSession.selectOne(select, 1);
56         System.out.println(user);
57     }
58 }

TestUser.java

 

 

注：

类的映射文件中的<mapper namespace="com.myBatis.mapper.userMapper.xml">  映射文件后缀名可不写

测试类中的 String select = "com.myBatis.mapper.userMapper.xml.getUser";   映射文件后缀名可不写

 

参考：MyBatis学习总结(二)——使用MyBatis对表执行CRUD操作

MyBatis学习总结(三)——优化MyBatis配置文件中的配置

学习 MyBatis学习总结(四)——解决字段名与实体类属性名不相同的冲突