SpringBoot2.1.3整合MyBatis3.5.0完整小案例(基于IDEA)
这几天我准备学习一下Spring Cloud,但是发现在开始整合Mybatis的时候我把之前学过的基本都遗忘了,不经感慨,计算机的知识真的是学得快,忘得也快啊,所以我打算把接下来学过的知识放在博客上。我从网上借鉴了一个小的案例,然后修改了一下,在此给大家分享一个小的整合案例,也以防自己以后遗忘可以拿来借鉴。
好了,废话不多数了,接下来是项目结构图,如下所示:
我们都知道Spring Boot是约定大于配置的,所以我们先把配置文件写好,首先是pom.xml文件,我们添加mybatis以及mysql的依赖包,代码如下:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.chen</groupId>
<artifactId>spring-boot-mybatis-demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>spring-boot-mybatis-demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- mybatis与springboot的依赖 -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.0.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
然后是application.yml,这里我们建了两个文件,一个是application.yml,另一个是application-dev.yml,其中application.yml是把application-dev.yml整合进去了,如果一个项目有多个环境,那么application-dev.yml则代表了生产环境,如果系统有多个环境,那么可以分开写,然后整合到application.yml中即可。其中application-dev.yml代码如下:
#端口
server:
port: 8080
#spring连接数据库配置
spring:
datasource:
username: root
password: 123456
url: jdbc:mysql://localhost:3306/springdatajpa?serverTimezone=GMT%2B8&characterEncoding=utf8
driver-class-name: com.mysql.cj.jdbc.Driver
#mybatis配置环境
mybatis:
mapper-locations: classpath:mapping/*Mapper.xml
type-aliases-package: com.chen.entity
#显示sql
logging:
level:
com:
chen:
mapper : debug
application.yml代码如下:
spring:
profiles:
active: dev
接下来我们新建一个实体类User,代码如下:
package com.chen.entity;
/**
* @Author:autumn_leaf
* @Date:2019/03/17
* 用户实体类
*/
public class User {
private Integer id;
private String loginName;
private String username;
private char sex;
private int age;
public User() {
super();
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLoginName() {
return loginName;
}
public void setLoginName(String loginName) {
this.loginName = loginName;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public char getSex() {
return sex;
}
public void setSex(char sex) {
this.sex = sex;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", loginName='" + loginName + '\'' +
", username='" + username + '\'' +
", sex=" + sex +
", age=" + age +
'}';
}
}
接着我们建一个接口类UserMapper,代码如下:
package com.chen.mapper;
import com.chen.entity.User;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
/**
* @Author:autumn_leaf
* @Date:2019/03/17
*/
@Mapper
//此处用@Repository也行
public interface UserMapper {
User findById(int id);
List<User> findAll();
}
接口类好了,我们在resources目录下面新建一个包mapping,然后新建UserMapper.xml文件,这里面查找所有用户信息虽然返回list类型,但是写成List会报错,所以我们仍然写成User类型,源码如下:
<?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="com.chen.mapper.UserMapper">
<select id="findById" resultType="com.chen.entity.User">
select * from tb_user where id = #{id}
</select>
<!-- 返回值为list,resultType仍为User,而不是List -->
<select id="findAll" parameterType="java.lang.String" resultType="com.chen.entity.User">
select * from tb_user
</select>
</mapper>
接下来我们来创建服务层,其中服务接口类为UserService,源码如下:
package com.chen.service;
import com.chen.entity.User;
import java.util.List;
/**
* @Author:autumn_leaf
* @Date:2019/03/17
* 服务接口类
*/
public interface UserService {
List<User> findAll();
User findById(int id);
}
上述服务接口代码其实和UserMapper接口代码一样,一般情况下都这样,大家可以直接复制过来,然后我们新建一个服务接口继承类UserServiceImpl,源码如下:
package com.chen.service.impl;
import com.chen.entity.User;
import com.chen.mapper.UserMapper;
import com.chen.service.UserService;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.List;
/**
* @Author:autumn_leaf
* @Date:2019/03/17
* 接口实现类
*/
@Service
public class UserServiceImpl implements UserService {
//@Autowired根据类型注入,@Resource根据名称注入,此处@Autowired也行
@Resource
private UserMapper userMapper;
@Override
public List<User> findAll() {
return userMapper.findAll();
}
@Override
public User findById(int id) {
return userMapper.findById(id);
}
}
在上面两处注解bean我们都用的@Resource,其实我们我们在这里用@Autowired也行,一般情况下两者区别相差不大。
到了控制层了,我们新建一个控制类UserController,代码如下:
package com.chen.controller;
import com.chen.entity.User;
import com.chen.service.UserService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
import java.util.List;
@RestController
public class UserController {
@Resource
private UserService userService;
//根据id查询用户信息
@GetMapping("/user/{id}")
public User findById(@PathVariable("id") int id){
return userService.findById(id);
}
//查询所有用户信息
@GetMapping("/user/list")
public List<User> findAll(){
return userService.findAll();
}
}
好了,到了最关键的一步了,我们不要忘记在Application中添加对mapper包的扫描的注解,源码如下:
package com.chen;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan("com.chen.mapper")//扫描mapper
public class SpringBootMybatisDemoApplication {
public static void main(String[] args) {
SpringApplication.run(SpringBootMybatisDemoApplication.class, args);
}
}
好了,写到这儿终于到了调试运行阶段了,我们来运行一下,运行截图如下:
大家如果有什么疑惑可以在评论区留言哦,接下来我会正式进入到Spring Cloud的学习中,也会不断更新博客,及时分享知识给大家!