spring boot学习系列之整合Mybatis持久层2

java springboot

MyBatis是一个基于Java的持久层框架，它支持定制化 SQL、存储过程以及高级映射。现将spring boot整合Mybatis。

添加依赖

添加mybatis的依赖

<!– https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter –>
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.3.0</version>
</dependency>

项目会自动加载application.properties,在里面定义mybatis配置路径和数据源

#加载mybatis配置文件
mybatis.mapper-locations =classpath:mapper/*Mapper.xml
mybatis.config-location =classpath:mapper/config/sqlConfig.xml
#定义别名
mybatis.type-aliases-package =com.wenqy.domain
#数据源
spring.datasource.url =jdbc:mysql://localhost:3306/wordpress
spring.datasource.driver-class-name =com.mysql.jdbc.Driver
spring.datasource.username =root
spring.datasource.password =123456
spring.datasource.max-active=10
spring.datasource.max-idle=5
spring.datasource.min-idle=0

添加mysql的jdbc依赖

<!– https://mvnrepository.com/artifact/mysql/mysql-connector-java –>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.42</version>
</dependency>

接下来就是mybatis的规范编程

定义domain bean

public class User implements Serializable{
    private int id;
    private String name;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

定义mybatis Mapper 接口

@Mapper
public interface UserMapper {
    /**
     * 
    * @Title: findAll 
    * @Description:
    * @param     
    * @return List<User>     
    * @throws
     */
    public List<User> findAll();
    /**
     * 
    * @Title: getUserById 
    * @Description:
    * @param @param id
    * @param 
    * @return User
    * @throws
     */
    public User getUserById(int id);
}

使用Mapper注解进行注入

定义UserMapper.xml映射文件

<!– namespace必须指向Dao接口 –>
<mapper namespace=“com.wenqy.mapper.UserMapper”>
    <!– 所有列 –>
    <sql id=“Column_list”>
        id,
        name
    </sql>
    <resultMap id=“ListUser” type=“com.wenqy.domain.User” >
        <id  column=“id” property=“id” />
        <result column=“name” property=“name” />
    </resultMap>
    <!– 根据ID查询数据 –>
    <select id=“getUserById” parameterType=“int” resultMap=“ListUser”>
        SELECT
        <include refid=“Column_list” />
        FROM user
        WHERE id = #{id}
    </select>
    <!– 查询所有用户 –>
    <select id=“findAll” resultType=“com.wenqy.domain.User”>
        SELECT * FROM user
    </select>
</mapper>

定义service接口

public interface UserService {
    /**
     * 
    * @Title: findAll 
    * @Description:
    * @param     
    * @return List<User>     
    * @throws
     */
    public List<User> findAll();
    /**
     * 
    * @Title: getUserById 
    * @Description:
    * @param @param id
    * @param 
    * @return User
    * @throws
     */
    public User getUserById(int id);
}

定义service实现类

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;
    public List<User> findAll() {
        List<User> userList = userMapper.findAll();
        return userList;
    }
    public User getUserById(int id) {
        User userById = userMapper.getUserById(id);
        return userById;
    }
}

定义表现层

@RestController
@RequestMapping(“/user”)
public class UserController {
    @Autowired
    private UserService userService;
    @RequestMapping(“/{id}”)
    public User getUserById(@PathVariable(“id”) int id) {
        User userById = userService.getUserById(id);
        return userById;
    }
    @RequestMapping(“/findAll”)
    public List<User> findAll() {
        List<User> findAll = userService.findAll();
        return findAll;
    }
//  public static void main(String[] args) {
//      SpringApplication.run(UserController.class, args);
//  }
}

访问路由，效果图

为mybatis添加分页插件

添加分页依赖

<!–pagehelper–>
    <dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.1.2</version>
</dependency>

在application.properties 添加分页配置

#pagehelper
pagehelper.helperDialect=mysql
pagehelper.reasonable=true
pagehelper.supportMethodsArguments=true
pagehelper.params=count=countSql

控制层,在控制层加入PageHelper分页工具类方法。

/**
     * 
    * @Title: findByPage 
    * @Description: 分页查询
    * @param @param pageNo
    * @param 页数 
    * @return List<User>   页数据 
    * @throws
     */
    @RequestMapping(“/find/{pageNo}”)
    public List<User> findByPage(@PathVariable(“pageNo”) int pageNo) {
        PageHelper.startPage(pageNo, 5);
        List<User> findAll = userService.findAll();
        System.out.println(“Total: “ + ((Page<User>) findAll).getTotal());
        return findAll;
    }

查询结果

Springboot快速开发，的确是如此的优雅，如此的简洁。我启动项目的时候却报错了，说无法连接数据库，发现是application.properties配置有前缀空格，而项目不是用utf8编码的，弄了我好久，这让我无比郁闷。。。

参考：

http://www.mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/index.html

https://github.com/pagehelper/pagehelper-spring-boot

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最后编辑时间为: Nov 8,2020