Springboot学习（一）

整合Mybatis实现CRUD

1. 引入依赖

引入druid-starter（数据源）

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.17</version>
        </dependency>

引入mybatis依赖

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.4</version>
        </dependency>

2.Mybatis配置实例（application.yaml)

spring:
  datasource:
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/db_orange?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
    driver-class-name: com.mysql.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource

mybatis:
  druid:
      stat-view-servlet: #监控页的配置
        enabled: true
        login-password: 123456
        login-username: admin
        reset-enable: false

      web-stat-filter: # 监控web
        enabled: true
        url-pattern: "/*"
        exclusions: "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*"
      aop-patterns: com.orange.admin.*

      filters: stat,wall  #底层开启功能，stat(sql监控),wall(防火墙)
      filter: # 对上面filters里面的stat的详细配置
        stat:
          slow-sql-millis:  1000
          log-slow-sql: true
          enabled: true

        wall:
          enabled: true
          config:
            drop-table-allow: false
  #  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations:  classpath:mybatis/mapper/*.xml
  configuration:
    map-underscore-to-camel-case: true

2.1在application.yaml配置mybatis规则

mybatis:
  config-location: classpath:mybatis/mybatis-config.xml  #全局配置文件位置
  mapper-locations: classpath:mybatis/mapper/*.xml  #sql映射文件位置

2.2mybatis-config.xml实例（驼峰命名开启）

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
<!--<settings>&lt;!&ndash;驼峰命名&ndash;&gt;-->
<!--    <setting name="mapUnderscoreToCamelCase" value="true"/>-->
<!--</settings>-->

</configuration>

也可以不写全局配置文件，在application.yaml中将配置放在都放在configuration配置项中即可。

#  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations:  classpath:mybatis/mapper/*.xml
  configuration:
    map-underscore-to-camel-case: true

2.3 mapper接口实例

<?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.orange.admin.Mapper.UserMapper">
    <!--    id 对应方法名 resultType对应返回类型 注意要写全路径名 -->
    <select id="getUser" resultType="com.orange.admin.bean.User">
        select * from  user where  id=#{id}
    </select>
    
</mapper>

整合MyBatis-Plus

1引入依赖

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>

优点：只需要我们的Mapper继承 BaseMapper 就可以拥有crud能力

@Mapper
public interface UserMapper extends BaseMapper<User> {

}

2用mybatis-plus实现用户的查询与删除

实体类User

@AllArgsConstructor
@NoArgsConstructor
@Data
@TableName("")指定数据库的表名
public class User {
    /**
     * 所有属性都应该在数据库中
     */
    @TableField(exist = false)  //当前属性表中不存在
    private String userName;
    @TableField(exist = false)
    private String password;


    //以下是数据库字段
    private Long id;
    private String name;
    private Integer age;
    private String email;

}

接口 UserService 继承IService

//泛型就是查询哪些数据类型
public interface UserService extends IService<User> {
}

实现类 UserServiceImpl 继承ServiceImpl

@Service
//泛型中 第一个参数 操作哪个mapper 返回类型
public class UserServiceImpl extends ServiceImpl<UserMapper,User> implements UserService {
}

Controller

    @Autowired
    UserService userService;
    @GetMapping("/dynamic_table")
    //分页功能
    public String dynamic_table(@RequestParam(value = "pn",defaultValue = "1")Integer pn, Model model){
        Page<User> page = new Page<>(pn, 2);//2表示每页显示几条数据
        //queryWrapper 查询条件
        IPage<User> userspage = userService.page(page, null);
        //long current = userspage.getCurrent(); 当前页
        //long pages = userspage.getPages(); 总页数

        model.addAttribute("users",userspage);

        return "table/dynamic_table";
    }
//删除功能
@GetMapping("/user/delete/{id}")
    public String deleteUser(@PathVariable("id") int id,
                             RedirectAttributes re,
                             @RequestParam(value = "pn",defaultValue = "1") Integer pn) {

        userService.removeById(id);
        re.addAttribute("pn",pn);
        return "redirect:/dynamic_table";
    }

注意要实现mybatis-plus的分页功能 还需配置分页拦截器

@Configuration
public class MyBatisConfig {


    /**
     * MybatisPlusInterceptor
     * @return
     */
    @Bean
    public MybatisPlusInterceptor paginationInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        // 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求  默认false
        // paginationInterceptor.setOverflow(false);
        // 设置最大单页限制数量，默认 500 条，-1 不受限制
        // paginationInterceptor.setLimit(500);
        // 开启 count 的 join 优化,只针对部分 left join

        //这是分页拦截器
        PaginationInnerInterceptor paginationInnerInterceptor = new PaginationInnerInterceptor();
        paginationInnerInterceptor.setOverflow(true);
        paginationInnerInterceptor.setMaxLimit(500L);
        mybatisPlusInterceptor.addInnerInterceptor(paginationInnerInterceptor);

        return mybatisPlusInterceptor;
    }
}

前端页面

当前第[[${users.current}]]页  总计 [[${users.pages}]]页  共[[${users.total}]]条记录
<!--根据页数来产生按钮--><!--#numbers.sequence(from,to)-->
                            <li th:class="${num == users.current?'active':''}" th:each="num:${#numbers.sequence(1,users.pages)}">
                                <a th:href="@{/dynamic_table(pn=${num})}">[[${num}]]</a>
                            </li>