SpringBoot整合mybatis

这两天学习了一下SpringBoot的相关内容,记录一下

1.创建一个SpringBoot项目后,引入依赖(其中lombok插件需要自己安装)

<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>
   <groupId>com.jt.1902</groupId>
   <artifactId>springboot-mybatis</artifactId>
   <version>0.0.1-SNAPSHOT</version>

   <properties>
      <java.version>1.8</java.version>
   </properties>

   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>2.1.3.RELEASE</version>
      <relativePath />
   </parent>

   <dependencies>
<dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
      </dependency>

      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
      </dependency>

<!--添加属性注入依赖 -->
<dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-configuration-processor</artifactId>
         <optional>true</optional>
      </dependency>

<!--引入插件lombok 自动的set/get/构造方法插件 -->
<dependency>
         <groupId>org.projectlombok</groupId>
         <artifactId>lombok</artifactId>
      </dependency>

<!--支持热部署 -->
<dependency>
         <groupId>org.springframework</groupId>
         <artifactId>springloaded</artifactId>
         <version>1.2.8.RELEASE</version>
      </dependency>

<dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-devtools</artifactId>
      </dependency>

<!--引入数据库驱动 -->
<dependency>
         <groupId>mysql</groupId>
         <artifactId>mysql-connector-java</artifactId>
         <scope>runtime</scope>
      </dependency>

<!--引入druid数据源 -->
<dependency>
         <groupId>com.alibaba</groupId>
         <artifactId>druid</artifactId>
         <version>1.1.12</version>
      </dependency>


      <!--spring整合mybatis-plus -->
<dependency>
         <groupId>com.baomidou</groupId>
         <artifactId>mybatis-plus-boot-starter</artifactId>
         <version>3.0.6</version>
      </dependency>
   </dependencies>

   <build>
      <plugins>
         <plugin>
            <groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
      </plugins>
   </build>
</project>

2.创建如下结构文件

(1)表的结构:

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` char(40) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `age` int(11) NULL DEFAULT NULL,
  `sex` char(40) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE,
  INDEX `cc`(`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 56 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

SET FOREIGN_KEY_CHECKS = 1;

 (2)编写实体类com.jt.pojo.User

@Accessors 注解用来配置lombok如何产生和显示getters和setters的方法。

chain表示生成的方法名是setxx() getxx()的样子

@Data //set/get/toString
@Accessors(chain = true) //链式加载
@NoArgsConstructor //无参构造
@AllArgsConstructor //有参构造
@TableName("user") //对象与数据表完成映射
public class User implements Serializable{
@TableId(type=IdType.AUTO) //主键自动
private Integer id;
//@TableField("name")
private String name;
//@TableId("age")
private Integer age;
private String sex;
}

(3)编写接口com.jt.mapper.UserMapper

该接口继承自mybatisplus的BaseMapper接口

public interface UserMapper 
extends BaseMapper<User>{
   
//查询全部的user表中的数据
List<User> findAll();

/**
    * 规定: Mybatis中要求数据传参必须是单值
* 方案:
    *     0.本身就是单值               id
    *     1.利用对象将数据封装    id age name
    *     2.将数据封装为map集合.  @Param("key")int id
    *     3.将数据封装为array/list
    * @param user
* @return
*/
@Insert("insert into user values(null,#{name},#{age},#{sex})")
int insertUser(User user);
   
//实现用户修改 age=18的 名称改为xxx
@Update("update user set name=#{name} where age=#{age}")
int updateUser(User user);

}

(4)编写在resources文件中创建mybatis/mapper/UserMapper.xml文件

namespace与接口对应,id与方法名对应

<?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.jt.mapper.UserMapper">

<select id="findAll" resultType="com.jt.pojo.User">
select * from user
</select>
   
<!-- <insert id="insertUser">
      insert into user values(null,#{name},#{age},#{sex})
   </insert> -->
   
   <!-- <update id="updateUser">
      update user set name=#{name} where age=#{age}
   </update> --> 
</mapper>

(5)编写接口com,jt.service.UserService

public interface UserService {

List<User> findAll();

int insertUser(User user);
   
int updateUser(User user);
}

(6)编写实现类com.jt.service.UserServiceImpl

在实现类里利用@AutoWired注解进行自动装配,而不是在接口上

@Service
public class UserServiceImpl implements UserService{

@Autowired
private UserMapper userMapper;

@Override
public List<User> findAll() {
      
return userMapper.findAll();
   }

@Override
public int insertUser(User user) {
      
return userMapper.insertUser(user);
   }

@Override
public int updateUser(User user) {
      
return userMapper.updateUser(user);
   }
}

(7)编写API接口com.jt.Controller.UserController

@RestController注解相当于@ResponseBody ＋ @Controller合在一起的作用

@RestController
public class UserController {
   
@Autowired
private UserService userService;
//用户通过localhost:8090/findAll获取用户数据
@RequestMapping("/findAll")
public List<User> findAll(){
      
return userService.findAll();
   }
//用户新增
public int insertUser(User user) {
      
return userService.insertUser(user);
   }
   
   
public int updateUser(User user) {
      
return userService.updateUser(user);
   }

（8）在启动类中加入对接口的扫描

@SpringBootApplication
//为mapper接口创建代理对象
@MapperScan("com.jt.mapper")
public class SpringBootRun {
   
public static void main(String[] args) {
      
SpringApplication.run(SpringBootRun.class, args);
   }
}

3.配置文件

在resources中创建application.yml文件，并编写配置

server:
port: 8090
servlet:
context-path: /

#引入数据源配置
spring:
datasource:
#引入druid数据源
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/jtdb?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true
    username: root
    password: root

#mybatis-plush配置
mybatis-plus:
#配置别名包
type-aliases-package: com.jt.pojo
  #配置mapper映射
mapper-locations: classpath:/mybatis/mappers/*.xml
  #开启驼峰映射
configuration:
map-underscore-to-camel-case: true
    
#添加日志输出
logging:
level:
com.jt.mapper: debug 

4.启动并测试

（1）测试UserMapper接口

@SpringBootTest
@RunWith(SpringRunner.class)
public class TestCRUD {
   
@Autowired    //从容器中取值
private UserController userController;
   
@Test
public void insertUser() {
User user = new User();
user.setName("小橘子").setSex("女").setAge(18);
userController.insertUser(user);
System.out.println("入库成功!!!!!");
   }
   
//测试修改
@Test
public void testUpdate() {
User user = new User();
user.setAge(18).setName("哈利波特!!!");
userController.updateUser(user);
   }
}

 （2测试MybatisPlus

@SpringBootTest
@RunWith(SpringRunner.class)
public class TestMybatisPlus {
@Resource
private UserMapper userMapper;
   
@Test
public void insert() {
User user = new User();
user.setName("mybatisplus");
user.setAge(19);
user.setSex("男");
int rows = userMapper.insert(user);
System.out.println("影响行数:"+rows);
   }
   
/**查询用户列表信息
      将对象中不为null的属性当做where条件
      条件:age=18 
关键字说明:
      = eq,> gt,< lt,ge >=,le <=  
   */
@Test
public void testFind() {
//1.方式1.使用对象封装
//User user = new User();
      //user.setAge(18);
      
      //2.直接使用字段赋值
QueryWrapper<User> queryWrapper 
= new QueryWrapper<User>();
//测试等于
//queryWrapper.eq("age",18);
      //测试大于
queryWrapper.ge("age",18);
List<User> userList = 
userMapper.selectList(queryWrapper);
System.out.println(userList);
   }
   
/**
    * 3.数据更新 将年龄为18岁的用户改19岁
* entity:需要修改数据的值
* updateWrapper 条件构造器 充当where条件
*/
@Test
public void testUpdate() {
User user = new User();
user.setAge(19);
UpdateWrapper<User> updateWrapper = 
new UpdateWrapper<>();
updateWrapper.eq("age", 18);
userMapper.update(user, updateWrapper);
   }
   
//删除name字段为null的数据
@Test
public void deleteUser() {
QueryWrapper<User> queryWrapper = new QueryWrapper<User>();
queryWrapper.isNull("name");
userMapper.delete(queryWrapper);
   }
}

@Data //set/get/toString
@Accessors(chain = true) //链式加载
@NoArgsConstructor    //无参构造
@AllArgsConstructor //有参构造
@TableName("user")    //对象与数据表完成映射
public class User implements Serializable{
    @TableId(type=IdType.AUTO)    //主键自动
    private Integer id;
    //@TableField("name")
    private String name;
    //@TableId("age")
    private Integer age;
    private String sex;
}