MyBatis-----初识MyBatis--

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" "http://mybatis.org/dtd/mybatis-3-config.dtd">
 3 <configuration>
 4     <environments default="development">
 5         <environment id="development">
 6             <transactionManager type="JDBC" />
 7             <!-- 配置数据库连接信息 -->
 8             <dataSource type="POOLED">
 9                 <property name="driver" value="com.mysql.jdbc.Driver" />
10                 <property name="url" value="jdbc:mysql:///mybatis" />
11                 <property name="username" value="root" />
12                 <property name="password" value="root" />
13             </dataSource>
14         </environment>
15     </environments>
16     <!-- 引用映射文件 -->
17     <mappers >
18         <mapper resource="com/myBatis/mapper/userMapper.xml"/>
19     </mappers>
20 </configuration>

SqlMapConfig.xml

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" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 3     <!-- 
 4     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，这样就能够保证namespace的值是唯一的 
 5     -->
 6     <mapper namespace="com.myBatis.mapper.userMapper.xml">
 7     
 8     <!-- 根据id查询得到一个user对象 -->
 9     <select id="getUser" parameterType="int" resultType="com.myBatis.entity.EUser">
10         select * from users where id=#{id}
11     </select>
12     <!--  根据id查询删除一个user对象 -->
13     <delete id="deleteUser" parameterType="com.myBatis.entity.EUser">
14         delete from users where id=#{id}
15     </delete>
16       <!-- 创建用户(Create) -->
17     <insert id="addUser" parameterType="com.myBatis.entity.EUser">
18         insert into users values(null,#{name},#{age})
19     </insert>
20      <!-- 修改用户(Update) -->
21     <update id="updateUser" parameterType="com.myBatis.entity.EUser">
22         update users set name=#{name},age=#{age} where id=#{id}
23     </update>
24     
25     </mapper>

userMapper.xml

四、测试方法

 1 package myBatisTest;
 2 
 3 import java.io.IOException;
 4 import java.io.Reader;
 5 
 6 import org.apache.ibatis.io.Resources;
 7 import org.apache.ibatis.session.SqlSession;
 8 import org.apache.ibatis.session.SqlSessionFactory;
 9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
10 import org.junit.Test;
11 
12 import com.myBatis.entity.EUser;
13 
14 
15 public class TestUser {
16     
17     
18     
19     //修改
20     @Test
21     public void testUpdateUser() {
22         try {
23             Reader reader= Resources.getResourceAsReader("SqlMapConfig.xml");
24             SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
25             SqlSession sqlSession= sqlSessionFactory.openSession(true);
26             //先查找
27              String select = "com.myBatis.mapper.userMapper.xml.getUser";
28              EUser  user = sqlSession.selectOne(select, 5);
29              System.out.println(user);
30              //再修改
31             user.setName("改啦2122");
32             user.setAge(50);
33             String update = "com.myBatis.mapper.userMapper.xml.updateUser";
34             int i = sqlSession.update(update, user);
35              System.out.println(i);
36              EUser  user1= sqlSession.selectOne(select, 5);
37              System.out.println(user1);
38         } catch (IOException e) {
39             e.printStackTrace();
40         } 
41     }
42     
43     
44     //添加
45     @Test
46     public void testAddUser() {
47         try {
48             Reader reader= Resources.getResourceAsReader("SqlMapConfig.xml");
49             SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
50             SqlSession sqlSession= sqlSessionFactory.openSession(true);
51              String add = "com.myBatis.mapper.userMapper.xml.addUser";
52              EUser user = new EUser();
53             user.setName("用户孤傲苍狼");
54             user.setAge(20);
55             int i = sqlSession.insert(add, user);
56              System.out.println(i);
57         } catch (IOException e) {
58             e.printStackTrace();
59         } 
60     }
61     
62     
63     //删除
64     @Test
65     public void testDeleteUser() {
66         try {
67             Reader reader= Resources.getResourceAsReader("SqlMapConfig.xml");
68             SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
69             /**
70              * openSession(true)  手动提交
71              * 数据库中的autocommit针对的是数据库自己以及命令窗口，必须在程序手动提交
72              */
73             SqlSession sqlSession= sqlSessionFactory.openSession(true);
74              String delete = "com.myBatis.mapper.userMapper.xml.deleteUser";
75              int i= sqlSession.delete(delete, 4);
76              System.out.println(i);
77         } catch (IOException e) {
78             e.printStackTrace();
79         } 
80     }
81     
82     
83     //查询
84     @Test
85     public void testGetUser() {
86         
87         try {
88             Reader reader= Resources.getResourceAsReader("SqlMapConfig.xml");
89             SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
90             SqlSession sqlSession= sqlSessionFactory.openSession(true);
91              String select = "com.myBatis.mapper.userMapper.xml.getUser";
92              EUser  user = sqlSession.selectOne(select, 1);
93              System.out.println(user);
94         } catch (IOException e) {
95             e.printStackTrace();
96         } 
97     }
98 }

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(一)——MyBatis快速入门