我正在做一个在线教程，在我需要处理数据库和添加jpa的步骤中，我无法在我的项目中访问它。
我已经成功地将依赖项放入了pom.xml文件中，并且没有收到任何错误。我还可以通过我的www.example.com文件访问spring jpaapplication.properties。问题是当我想扩展CrudRepository时，它没有被识别...然后我意识到当我手动导入时，它不会导入org.springframework.data。
我已将Maven设置为始终更新快照。
这是我的pom.xml文件。我为格式问题道歉，但我无法让它以intellij中的正确格式显示在stackoverflow上：

<?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.example</groupId>
<artifactId>demo3</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>demo3</name>
<description>Demo project for Spring Boot</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.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-web</artifactId>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>

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

和我的“application.properties”文件：

spring.datasource.url=***    
spring.datasource.username=***
spring.datasource.password=***

spring.jpa.database=MYSQL

spring.jpa.hibernate.ddl-auto = update

spring.jpa.show-sql=false

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

奶酪类：

package com.example.demo.models;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

@Entity
public class Cheese {

    @Id
    @GeneratedValue
    private int id;

    @NotNull
    @Size(min=3, max=20)
    private String name;

    @NotNull
    @Size(min=1, message = "Description must not be empty")
    private String description;

    public Cheese(String name, String description) {
        this.name = name;
        this.description = description;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }
}

CheeseDao（使用Spring Data /CrudRepository的接口）

package com.example.demo.models;
import com.example.demo.models.Cheese;

public class CheeseDao extends CrudRepository<Cheese, Integer> {
}