Spring Boot（二）之与Mybatis结合使用

雨点打透心脏的1/2处 2022-05-16 09:06 196阅读 0赞

### Spring Boot（二）之与Mybatis结合使用 ###

这是使用的是mybatis的xml方式，还有注解的方式

#### 1.创建项目 ####

1.1 创建一个Project

![image][]

1.2 编辑Project Metadata

![image][image 1]

1.3 添加Web程序和SQL程序

**添加Web程序**

![image][image 2]

勾选Web程序

**添加SQL程序**

![image][image 3]

勾选MySQL，JDBC，MyBatis三项

点击Next

1.4 选择项目路径

![image][image 4]

点击Finish，项目创建完成

1.5 创建项目完成

项目目录结构

![image][image 5]

#### 2.pom.xml依赖 ####

在项目创建完成，会在pom.xml文件中生成对应的依赖和build插件。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>
    
        <groupId>com.zhang</groupId>
        <artifactId>springboot-mybatis-demo</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        
        <packaging>jar</packaging>
    
        <name>springboot-mybatis-demo</name>
        <description>Demo project for Spring Boot</description>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.0.4.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <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-jdbc</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>1.3.2</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>

除此之外，我们还需要添加其他的依赖（也可以不使用的），如：

<dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid-spring-boot-starter</artifactId>
        <version>1.1.9</version>
    </dependency>

关于[alibaba的druid数据库连接池][alibaba_druid]，大家可以自行百度

#### 3.application.yml配置编写 ####

将application.properties文件重命名为application.yml（个人喜好）

编译application.yml，添加配置

server:
      port: 8080
    
    spring:
        datasource:
            name: mysql_test
            type: com.alibaba.druid.pool.DruidDataSource
            #druid相关配置
            druid:
              #监控统计拦截的filters
              filters: stat
              driver-class-name: com.mysql.jdbc.Driver
              #基本属性
              url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true
              username: root
              password: root
              #配置初始化大小/最小/最大
              initial-size: 1
              min-idle: 1
              max-active: 20
              #获取连接等待超时时间
              max-wait: 60000
              #间隔多久进行一次检测，检测需要关闭的空闲连接
              time-between-eviction-runs-millis: 60000
              #一个连接在池中最小生存的时间
              min-evictable-idle-time-millis: 300000
              validation-query: SELECT 'x'
              test-while-idle: true
              test-on-borrow: false
              test-on-return: false
              #打开PSCache，并指定每个连接上PSCache的大小。oracle设为true，mysql设为false。分库分表较多推荐设置为false
              pool-prepared-statements: false
              max-pool-prepared-statement-per-connection-size: 20
    
    
    # mybatis
    mybatis:
      mapper-locations: classpath:mapper/*.xml type-aliases-package: com.zhang.springbootmybatisdemo.domain

mapper-locations:配置mapper文件的路径

type-aliases-package:配置domain对象路径

#### 4.创建Controller，Service，Dao，Domain实例 ####

4.1 创建Controller

@RestController
    @RequestMapping("/user")
    public class UserController { 
    
        @Autowired
        private UserService userService;
    
        @PostMapping("/add")
        public int add(@RequestBody User user) {
            return userService.addUser(user);
        }
    
        @ResponseBody
        @PostMapping("/search")
        public User searchById(@RequestBody User user) {
            return userService.searchById(user.getUserId());
        }
    
        @ResponseBody
        @PostMapping("/searchall")
        public List<User> searchAll() {
            return userService.searchAll();
        }
    
    }

4.2 创建Service

@Component
    public interface UserService {
        int addUser(User user);
    
        User searchById(String userId);
    
        List<User> searchAll();
    }

@Component: 在UserService上添加Component注解，防止UserController中的userService属性自动注入是出现编译错误。

ServiceImpl的实现类

@Service(value = "userService")
    public class UserServiceImpl implements UserService { 
    
        @Autowired
        private UserDao userDao;
    
        @Override
        public int addUser(User user) {
            return userDao.add(user);
        }
    
        @Override
        public User searchById(String userId) {
            return userDao.searchById(userId);
        }
    
        @Override
        public List<User> searchAll() {
            return userDao.searchAll();
        }
    }

@Service(value = “userService”)：指定UserController中userService参数的实现对象。

4.3 编写User

public class User {
        private String userId;
        private String username;
        private String password;
        ...
        // 省略 get set
    }

4.4 编写UserDao

@Component
    public interface UserDao {
        int add(User user);
        User searchById(String userId);
        List<User> searchAll();
    }

这里需要注意一个问题，需要在启动类SpringbootMybatisDemoApplication上面加上一个MappingScan的注解，在程序是，扫描dao中的类。

@SpringBootApplication
    @MapperScan("com.zhang.springbootmybatisdemo.dao")
    public class SpringbootMybatisDemoApplication { 
    
        public static void main(String[] args) {
            SpringApplication.run(SpringbootMybatisDemoApplication.class, args);
        }
    }

**额外注意：@MapperScan(“com.zhang.springbootmybatisdemo.dao”)**

#### 5.编写Mapping的xml ####

<?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.zhang.springbootmybatisdemo.dao.UserDao">
        <sql id="BASE_TABLE">
            tb_user
        </sql>
    
        <sql id="BASE_COLUMN">
            user_id,username,password
        </sql>
    
        
        <resultMap id="BaseResultMap" type="com.zhang.springbootmybatisdemo.domain.User">
            <result column="user_id" property="userId" jdbcType="VARCHAR"/>
            <result column="username" property="username" jdbcType="VARCHAR"/>
            <result column="password" property="password" jdbcType="VARCHAR"/>
        </resultMap>
    
        <insert id="add" parameterType="com.zhang.springbootmybatisdemo.domain.User">
          insert into
          tb_user(user_id,username,password)
          values(#{userId,jdbcType=VARCHAR},#{username,jdbcType=VARCHAR},#{password,jdbcType=VARCHAR})
        </insert>
    
        
        <select id="searchById" parameterType="java.lang.String" resultMap="BaseResultMap">
            SELECT
            <include refid="BASE_COLUMN"/>
            FROM
            <include refid="BASE_TABLE"/>
            WHERE user_id = #{userId,jdbcType=VARCHAR}
        </select>
    
        <select id="searchAll" resultMap="BaseResultMap">
            SELECT
            <include refid="BASE_COLUMN"/>
            FROM
            <include refid="BASE_TABLE"/>
        </select>
    </mapper>

这里需要当心，指定参数的全路径名称是否正确。

#### 6.测试运行 ####

6.1 插入数据，如下

插入数据1:

![image][image 6]

插入数据2:

![image][image 7]

查询mysql

![image][image 8]

6.2 查询数据，如下

指定userId查询

![image][image 9]

查询所有数据

![image][image 10]

这里基本上将Spring Boot与Mybatis的结合实现了。

[image]: /images/20220516/cd999f09ecc8435d9890661b9a5fe9b1.png
[image 1]: /images/20220516/f9cf33c9923d4e1e846d96f529449800.png
[image 2]: /images/20220516/7ce9ee6e00fe449b909dd201c92bbd49.png
[image 3]: /images/20220516/638d782002794d90a340808cef51c94e.png
[image 4]: /images/20220516/5fe7befd29394622bd7d49f78f2b05a1.png
[image 5]: /images/20220516/94d5366a43e740d0b5324f38ac83ca10.png
[alibaba_druid]: https://blog.csdn.net/ikownyou/article/details/79022560
[image 6]: /images/20220516/1605c845e59d4ee0bd033d80e7d9a4de.png
[image 7]: /images/20220516/a69f89957d4d44899a215bed4f49edb5.png
[image 8]: /images/20220516/b0a955ae16f94c11b4df2235107ad37d.png
[image 9]: /images/20220516/55695eb6b4a7447aac02623eb08fcf0f.png
[image 10]: /images/20220516/0e648da85b0743749ce0f6be540841aa.png