简单的Mybatis项目

1.配置Maven依赖

依赖 
 1 <dependencies>
 2         <!-- mysql数据库驱动依赖  1 -->
 3         <dependency>
 4             <groupId>mysql</groupId>
 5             <artifactId>mysql-connector-java</artifactId>
 6             <version>8.0.19</version>
 7         </dependency>
 8         <!-- mybatis驱动 -->
 9         <dependency>
10             <groupId>org.mybatis</groupId>
11             <artifactId>mybatis</artifactId>
12             <version>3.5.2</version>
13         </dependency>
14         <!--   JUnit是用于测试单元   -->
15         <dependency>
16             <groupId>junit</groupId>
17             <artifactId>junit</artifactId>
18             <version>4.13.1</version>
19             <scope>test</scope>
20         </dependency>
21         
22     </dependencies>

 

2.配置环境文件mybatis-config.xml

 注意：　　　每一个Mapper.XML都需要在核心配置里面注册 

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 <configuration>
 6     <environments default="development">
 7         <environment id="development">
 8             <transactionManager type="JDBC"/>
 9             <dataSource type="POOLED">
10                 <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
11                 <property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=GMT%2B8"/>
12                 <property name="username" value="root"/>
13                 <property name="password" value="123456789"/>
14             </dataSource>
15         </environment>
16     </environments>
17     <mappers>
18         <mapper resource="com/zxy/dao/UserMapper.xml"/>
19     </mappers>
20 </configuration>

mapper不同配置方法（可以留印象）：

1 下面两种方式注意：  1.接口和Mapper配置文件同名 2.接口和Mapper配置文件在同一个包下
2         <package name="com.zxy.dao"/>          
3         <mapper class="com.zxy.dao.UserMapper"/>

 

 

3.编写MybatisUtils工具类

 1 package com.zxy.utils;
 2 
 3 
 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 
 9 import java.io.IOException;
10 import java.io.InputStream;
11 
12 //sqlSessionFactory  ----> sqlSession
13 public class MybatisUtils {
14     private static SqlSessionFactory sqlSessionFactory;
15     static {
16         try {
17             //1.获取sqlSessionFactory对象
18             String resource = "mybatis-config.xml";
19             InputStream inputStream = Resources.getResourceAsStream(resource);
20             sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
21         } catch (IOException e) {
22             e.printStackTrace();
23         }
24     }
25     //SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句
26     public static SqlSession getSqlSession(){
27         return sqlSessionFactory.openSession();
28     }
29 }

 

4.编写实体类User

记得数据库和实体类一一对应

 1 package com.zxy.pojo;
 2 
 3 public class User {
 4     private int id;
 5     private String name;
 6     private String pwd;
 7 
 8     public User() {
 9     }
10 
11     public User(int id, String name, String password) {
12         this.id = id;
13         this.name = name;
14         this.pwd = password;
15     }
16 
17     public int getId() {
18         return id;
19     }
20 
21     public void setId(int id) {
22         this.id = id;
23     }
24 
25     public String getName() {
26         return name;
27     }
28 
29     public void setName(String name) {
30         this.name = name;
31     }
32 
33     public String getPassword() {
34         return pwd;
35     }
36 
37     public void setPassword(String password) {
38         this.pwd = password;
39     }
40 
41     @Override
42     public String toString() {
43         return "User{" +
44                 "id=" + id +
45                 ", name='" + name + '\'' +
46                 ", password='" + pwd + '\'' +
47                 '}';
48     }
49 }
实体类

 

 

5.实体类UseDaor的接口（初学者适应  最好写成UserMapper）

1 package com.zxy.dao;
2 
3 import com.zxy.pojo.User;
4 
5 import java.util.List;
6 
7 public interface UserDao {
8     List<User> getUserList();
9 }

 

6.编写基于 XML的对于sql的映射语句UserMapper.xml

 　　
　1、namespace绑定一个对应的Dao/Mapper接口 
　2，这个XML的文件一般写在Dao目录下在pom.xml中配置文件过滤规则 Xml资源文件无法导出，找不到Mapper.xml文件
　　　　　　　　　　　　　　　　　　　　　　　　点此连接可以得到配置代码
 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper
 3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 
 6 
 7 <mapper namespace="com.zxy.dao.UserDao">
 8     <select id="getUserList" resultType="com.zxy.pojo.User">
 9         select * from mybatis.user;
10     </select>
11 </mapper>

 

7.编写测试类

public class UserDaoTest {
        @Test
        public void test(){
            //1.获取sqlSession对象
            SqlSession sqlSession = MybatisUtils.getSqlSession();
            //2.
            UserDao userDao = sqlSession.getMapper(UserDao.class);
            List<User> userList = userDao.getUserList();

            for ( User user :userList) {
                System.out.println(user);
            }
            //关闭SqlSession
            sqlSession.close();
        }
}

 

posted @ 2022-10-16 17:08  西东怪  阅读(65)  评论(0)  编辑  收藏  举报
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