如何在MySQL数据库和JPA中使用Spring Boot？

Question

我想用MySQL和JPA设置Spring Boot。为此，我创建了：Person

package domain;

import javax.persistence.*;

@Entity
@Table(name = "person")
public class Person {

@Id
@GeneratedValue
private Long id;

@Column(nullable = false)
private String firstName;

// setters and getters
}

PersonRepository公司

package repository;

import domain.Person;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.repository.CrudRepository;


public interface PersonRepository extends CrudRepository<Person, Long> {

Page<Person> findAll(Pageable pageable);
}

个人控制器

package controller;

import domain.Person;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import repository.PersonRepository;

@Controller
public class PersonController {

@Autowired
private PersonRepository personRepository;

@RequestMapping("/")
@ResponseBody
public String test() {
    Person person = new Person();
    person.setFirstName("First");
    person.setLastName("Test");
    personRepository.save(person);
    return "hello";
}
}

开始上课示例：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Example {

public static void main(String[] args) throws Exception {
    SpringApplication.run(Example.class, args);
}

}

对于数据库配置，我创建application.properties

spring.jpa.hibernate.ddl-auto=create-drop
spring.jpa.properties.hibernate.globally_quoted_identifiers=true

spring.datasource.url=jdbc:mysql://localhost/test_spring_boot
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driverClassName=com.mysql.jdbc.Driver

所以我有项目结构：

但结果我有例外：

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [Example]; nested exception is java.io.FileNotFoundException: class path resource [org/springframework/security/config/annotation/authentication/configurers/GlobalAuthenticationConfigurerAdapter.class] cannot be opened because it does not exist

作为一个例子，我使用：spring boot示例数据jpa/pom。xml

Answer 1

在Spring启动参考中，它说：

当一个类不包含包声明时，它被认为是在“默认包”中。通常不鼓励使用“默认包”，应该避免。它可能会给使用@ComponentScan、@EntityScan或@SpringBootApplication注释的Spring Boot应用程序带来特殊问题，因为每个jar中的每个类都将被读取。

com
 +- example
     +- myproject
         +- Application.java
         |
         +- domain
         |   +- Customer.java
         |   +- CustomerRepository.java
         |
         +- service
         |   +- CustomerService.java
         |
         +- web
             +- CustomerController.java

在你的情况下。您必须在SpringBootApplication注释中添加scanBasePackages。就像SpringBootApplication（scanBasePackages={“domain”，“contorller”。}）

Answer 2

当将类移动到特定的包（如存储库、控制器、域）中时，仅使用通用@SpringBootApplication是不够的。

您必须为组件扫描指定基本包

@ComponentScan("base_package")

对于JPA

@EnableJpaRepositories(basePackages = "repository")

也需要，因此spring数据将知道在哪里查找存储库接口。

Answer 3

我像你一样创建了一个项目。结构看起来像这样

这些类只是从你的复制粘贴。

我把application.properties改成这样：

spring.datasource.url=jdbc:mysql://localhost/testproject
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.jpa.hibernate.ddl-auto=update

但我认为你的问题在于你的pom.xml：

<?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>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.1.RELEASE</version>
</parent>

<artifactId>spring-boot-sample-jpa</artifactId>
<name>Spring Boot JPA Sample</name>
<description>Spring Boot JPA Sample</description>

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <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>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

检查这些文件是否存在差异。希望这有帮助

更新1：我更改了用户名。示例的链接现在是https://github.com/Yannic92/stackOverflowExamples/tree/master/SpringBoot/MySQL