如何使用 Spring Boot with MySQL 数据库和 JPA？

Question

我想设置 Spring 使用 MySQL 和 JPA 启动。为此，我创建：人

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

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 class 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

作为示例，我使用：spring-boot-sample-data-jpa/pom.xml

Answer 1

我像你一样创建了一个项目。结构看起来像这样

类只是从您那里复制粘贴的。

我将 application.properties 更改为：

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

但我认为你的问题出在你的 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：我更改了我的用户名。该示例的 link 现在是 https://github.com/Yannic92/WhosebugExamples/tree/master/SpringBoot/MySQL

Answer 2

您可以将 Application.java 移动到 java 下的文件夹。

Answer 3

将类移动到存储库、控制器、域等特定包中时，仅通用 @SpringBootApplication 是不够的。

您必须指定组件扫描的基础包

@ComponentScan("base_package")

对于 JPA

@EnableJpaRepositories(basePackages = "repository")

也是必需的，因此 spring 数据将知道在何处查找存储库接口。

Answer 4

在spring boot reference里面说：

When a class doesn’t include a package declaration it is considered to be in the “default package”. The use of the “default package” is generally discouraged, and should be avoided. It can cause particular problems for Spring Boot applications that use @ComponentScan, @EntityScan or @SpringBootApplication annotations, since every class from every jar, will be read.

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 annotation.just 中添加 scanBasePackages like@SpringBootApplication(scanBasePackages={"domain","contorller"..})

Answer 5

对于基于 Jpa 的应用程序：基础包扫描 @EnableJpaRepositories(basePackages = "repository") 你可以试试一次！！！
项目结构

com
 +- stack
     +- app
     |   +- Application.java
     +- controller
     |   +- EmployeeController.java
     +- service
     |   +- EmployeeService.java
     +- repository
     |   +- EmployeeRepository.java
     +- model
     |   +- Employee.java
-pom.xml
dependencies: 
    mysql, lombok, data-jpa

application.properties

#Data source :
spring.datasource.url=jdbc:mysql://localhost:3306/employee?useSSL=false
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.generate-ddl=true
spring.datasource.driverClassName=com.mysql.jdbc.Driver

#Jpa/Hibernate :
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
spring.jpa.hibernate.ddl-auto = update

Employee.java

@Entity
@Table (name = "employee")
@Getter
@Setter
public class Employee {

    @Id
    @GeneratedValue (strategy = GenerationType.IDENTITY)
    private Long id;

    @Column (name = "first_name")
    private String firstName;
    @Column (name = "last_name")
    private String lastName;
    @Column (name = "email")
    private String email;
    @Column (name = "phone_number")
    private String phoneNumber;
    @Column (name = "emp_desg")
    private String desgination;
}

EmployeeRepository.java

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {
}

EmployeeController.java

@RestController
public class EmployeeController {

    @Autowired
    private EmployeeService empService;

    @GetMapping (value = "/employees")
    public List<Employee> getAllEmployee(){
        return empService.getAllEmployees();
    }

    @PostMapping (value = "/employee")
    public ResponseEntity<Employee> addEmp(@RequestBody Employee emp, HttpServletRequest 
                                         request) throws URISyntaxException {
        HttpHeaders headers = new HttpHeaders();
        headers.setLocation(new URI(request.getRequestURI() + "/" + emp.getId()));
        empService.saveEmployee(emp);
        return new ResponseEntity<Employee>(emp, headers, HttpStatus.CREATED);
    }

EmployeeService.java

public interface EmployeeService {
    public List<Employee> getAllEmployees();
    public Employee saveEmployee(Employee emp);
}

EmployeeServiceImpl.java

@Service
@Transactional
public class EmployeeServiceImpl implements EmployeeService {

    @Autowired
    private EmployeeRepository empRepository;

    @Override
    public List<Employee> getAllEmployees() {
        return empRepository.findAll();
    }

    @Override
    public Employee saveEmployee(Employee emp) {
        return empRepository.save(emp);
    }
}

EmployeeApplication.java

@SpringBootApplication
@EnableJpaRepositories(basePackages = "repository")
public class EmployeeApplication {
    public static void main(String[] args) {
        SpringApplication.run(EmployeeApplication.class, args);
    }
}

Answer 6

您的代码在默认包中，即您在 src/main/java 中拥有所有文件的源代码，没有自定义包。我强烈建议你创建包 n 然后将你的源文件放入其中。

Ex-
 src->
     main->
          java->
                com.myfirst.example
                   Example.java
                com.myfirst.example.controller
                   PersonController.java
                com.myfirst.example.repository
                  PersonRepository.java
                com.myfirst.example.model
                   Person.java

希望能解决您的问题。

Answer 7

请添加mysql-connector-java依赖

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>

并在 application.properties

中添加以下属性

# Data Source properties
spring.datasource.url=jdbc:mysql://localhost:3306/yourDatabaseName?useSSL=false
spring.datasource.username=root
spring.datasource.password=YourPassword
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# JPA properties 
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
spring.jpa.show-sql=true
# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto = update

如何使用 Spring Boot with MySQL 数据库和 JPA？

How to use Spring Boot with MySQL database and JPA?

java

mysql

spring

jpa

spring-boot