Mybatis SpringBoot integration
Create a SpringBoot project
Here, I choose Spring Initializr in Idea for creation, which can also be created inIO and download it.
Fill in the project name
Check dependencies, Web, JDBC, MyBatis, MySQL
Project created successfully!
Create a user table
Here, for simplicity, I create the user table in a database named Demo:
Insert three pieces of data:
| id | username | age | address |
|---|---|---|---|
| 1 | Zhang SAN | 22 | hangzhou |
| 2 | Li si | 19 | Beijing |
| 3 | Cathy | 33 | Shanghai |
The configuration file
Open the application.properties file and do the following:
# port
server.port=8080
# MySQL configuration
spring.datasource.url=jdbc:mysql:///demo? serverTimezone=Asia/Shanghai
spring.datasource.username=root
spring.datasource.password=123456
# MyBatis configuration
mybatis.mapper-locations=classpath:mapper/*.xml
Copy the codeOr you can configure it with yml, and the effect is the same.
server:
port: 8080
spring:
datasource:
url: jdbc:mysql:///demo? serverTimezone=Asia/Shanghai
username: root
password: 123456
mybatis:
mapper-locations: classpath:mapper/*.xml
type-aliases-package: com.korilweb.demo_mybatis.entity
Copy the codeWrite the User class
Create an Entity folder and create class user.java:
package com.korilweb.demo_mybatis.entity;
public class User {
public Integer id;
public String username;
public Integer age;
public String address;
public Integer getId(a) {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername(a) {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public Integer getAge(a) {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getAddress(a) {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString(a) {
return "User{" +
"id=" + id +
", username='" + username + '\' ' +
", age=" + age +
", address='" + address + '\' ' +
'} '; }}Copy the codeWrite Mapper XML files
Under the Resources folder, create a new folder named mapper that will hold all the XML files
In the mapper folder, create a new file named user-mapper. XML:
<! DOCTYPEmapper
PUBLIC "- / / mybatis.org//DTD Mapper / 3.0 / EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.korilweb.demo_mybatis.dao.UserMapper">
<select id="selectUserById" resultType="com.korilweb.demo_mybatis.entity.User">
select id, username, age, address
from user
where id = #{id}
</select>
</mapper>
Copy the codeHere, the resultType can be shortened to User, but you need to configure one more entry in application.properties:
mybatis.type-aliases-package=com.korilweb.demo_springcloud.entity
Copy the codeWrite the dao layer
Create a new DAO folder and create the interface usermapper.java:
package com.korilweb.demo_mybatis.dao;
import com.korilweb.demo_mybatis.entity.User;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface UserMapper {
User selectUserById(int id);
}
Copy the codeWe annotate the UserMapper with @mapper, but if we add @mapper to each written Mapper, we can instead annotate the startup class with @mapperscan and specify the package path of the Mapper to be scanned in parentheses:
package com.korilweb.demo_mybatis;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan("com.korilweb.demo_mybatis.dao") // With this annotation, we don't need to write @mapper for every Mapper
public class DemoMybatisApplication {
public static void main(String[] args) { SpringApplication.run(DemoMybatisApplication.class, args); }}Copy the codeWrite the service layer
Create a new service folder and create the class userService.java:
package com.korilweb.demo_mybatis.service;
import com.korilweb.demo_mybatis.dao.UserMapper;
import com.korilweb.demo_mybatis.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class UserService {
@Autowired
private UserMapper userMapper;
public User findUserById(int id) {
returnuserMapper.selectUserById(id); }}Copy the codeWrite the test
@Autowired
private UserService userService;
@Test
void findUserByIdTest(a) {
User userById = userService.findUserById(1);
System.out.println(userById);
}
Copy the codeTest results:
User{id=1, username=' zhang3 ', age=22, address=' zhang3 '}Copy the codeSome other simple function implementation (add, delete, change and check)
Find all Users
Add a method to UserMapper first:
List<User> selectAllUsers(a);
Copy the codeThen, write the corresponding SQL statement in user-mapper. XML:
<select id="selectAllUsers" resultType="com.korilweb.demo_mybatis.entity.User">
select id, username, age, address
from user
</select>
Copy the codeFinally, call the UserMapper method inside the UserService:
public List<User> findAllUsers(a) {
return userMapper.selectAllUsers();
}
Copy the codeTesting:
@Test
void findAllUsersTest(a) {
List<User> users = userService.findAllUsers();
for(User user : users) { System.out.println(user); }}Copy the codeTest results:
User{id=1, username=' zhang ', age=22, address=' wang '} User{id=2, username=' li ', age=19, address=' Beijing '} User{id=1, username=' zhang ', age=22, address=' wang '} Username =' wang5 ', age=33, address=' wang5 '}Copy the codeAdd a user
UserMapper. Java:
int insertUser(User user);
Copy the codeuser-mapper.xml
<insert id="insertUser" parameterType="com.korilweb.demo_mybatis.entity.User">
insert into user (username, age, address)
values (#{username}, #{age}, #{address})
</insert>
Copy the codeUserService.java
public int addUser(User user) {
return userMapper.insertUser(user);
}
Copy the codeTesting:
@Test
void addUserTest(a) {
User user = new User();
user.setUsername("Daisy");
user.setAge(18);
user.setAddress("Guangzhou");
int result = userService.addUser(user);
System.out.println(result);
}
Copy the codeTest results:
Returns 1, and you can see that the new user has been added to the database
Update a user’s information
UserMapper. Java:
int updateUserInfo(User user);
Copy the codeUser – mapper. XML:
<update id="updateUserInfo" parameterType="com.korilweb.demo_mybatis.entity.User">
update user
set username = #{username}, age = #{age}, address = #{address}
where id = #{id}
</update>
Copy the codeUserService. Java:
public int changeUserInfo(User user) {
return userMapper.updateUserInfo(user);
}
Copy the codeTesting:
@Test
void changeUserInfoTest(a) {
User user = new User();
user.setId(1);
user.setUsername("Zhang Sanfeng");
user.setAge(88);
user.setAddress("Fujian");
int result = userService.changeUserInfo(user);
System.out.println(result);
}
Copy the codeTest results:
Returns 1, and you can see in the database that the user information with ID =1 has changed
Deleting a User
UserMapper. Java:
int deleteUserById(int id);
Copy the codeUser – mapper. XML:
<delete id="deleteUserById">
delete from user
where id = #{id}
</delete>
Copy the codeUserService. Java:
public int deleteUserById(int id) {
return userMapper.deleteUserById(id);
}
Copy the codeTesting:
@Test
void deleteUserByIdTest(a) {
int result = userService.deleteUserById(1);
System.out.println(result);
}
Copy the codeTest results:
Return 1, and you can see that the data with id=1 is deleted
code
Code has been uploaded to Gitee:
Gitee.com/ding_jing_h…