使用 MySQL 的 Spring-boot 示例

Created: November-22, 2018

我们将遵循 spring-boot 和 spring-data-jpa 的官方指南。我们将使用 gradle 构建应用程序。

创建 gradle 构建文件

build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:1.4.3.RELEASE")
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'idea'
apply plugin: 'org.springframework.boot'

jar {
    baseName = 'gs-accessing-data-jpa'
    version =  '0.1.0'
}

repositories {
    mavenCentral()
    maven { url "https://repository.jboss.org/nexus/content/repositories/releases" }
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

dependencies {
    compile("org.springframework.boot:spring-boot-starter-data-jpa")
    runtime('mysql:mysql-connector-java')
    testCompile("junit:junit")
}

创建客户实体

src / main / JAVA /你好/ Customer.java

@Entity
public class Customer {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;
    private String firstName;
    private String lastName;

    protected Customer() {}

    public Customer(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    @Override
    public String toString() {
        return String.format(
                "Customer[id=%d, firstName='%s', lastName='%s']",
                id, firstName, lastName);
    }
}

创建存储库

src / main / JAVA /你好/ CustomerRepository.java

import java.util.List;
import org.springframework.data.repository.CrudRepository;

public interface CustomerRepository extends CrudRepository<Customer, Long> {
    List<Customer> findByLastName(String lastName);
}

创建 application.properties 文件

################### DataSource Configuration ##########################
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/your_database_name
jdbc.username=username
jdbc.password=password

init-db=false

################### Hibernate Configuration ##########################

hibernate.dialect=org.hibernate.dialect.MySQLDialect
hibernate.show_sql=true
hibernate.hbm2ddl.auto=update

创建 PersistenceConfig.java 文件

在第 5 步中，我们将定义如何加载数据源以及我们的应用程序如何连接到 MySQL。上面的代码片段是我们连接 MySQL 所需的最低配置。这里我们提供两个 bean：

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages="hello")
public class PersistenceConfig 
{
    @Autowired
    private Environment env;
 
    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory()
    {
        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
 
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setGenerateDdl(Boolean.TRUE);
        vendorAdapter.setShowSql(Boolean.TRUE);
 
        factory.setDataSource(dataSource());
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setPackagesToScan("hello");
 
        Properties jpaProperties = new Properties();
        jpaProperties.put("hibernate.hbm2ddl.auto", env.getProperty("hibernate.hbm2ddl.auto"));
        factory.setJpaProperties(jpaProperties);
 
        factory.afterPropertiesSet();
        factory.setLoadTimeWeaver(new InstrumentationLoadTimeWeaver());
        return factory;
    }
     
    @Bean
    public DataSource dataSource()
    {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
        dataSource.setUrl(env.getProperty("jdbc.url"));
        dataSource.setUsername(env.getProperty("jdbc.username"));
        dataSource.setPassword(env.getProperty("jdbc.password"));
        return dataSource;
    }
      
}

LocalContainerEntityManagerFactoryBean 这为我们提供了 EntityManagerFactory 配置的句柄，并允许我们进行自定义。它还允许我们在组件中注入 PersistenceContext，如下所示：

@PersistenceContext
private EntityManager em;

DataSource 这里我们返回 DriverManagerDataSource 的一个实例。它是标准 JDBC DataSource 接口的简单实现，通过 bean 属性配置普通的旧 JDBC 驱动程序，并为每个 getConnection 调用返回一个新的 Connection。请注意，我建议严格使用它进行测试，因为有更好的替代品，如 BasicDataSource 可用。请参阅此处了解更多详情

创建一个 Application 类

src / main / JAVA /你好/ Application.java

 @SpringBootApplication
 public class Application {

     private static final Logger log = LoggerFactory.getLogger(Application.class);

     @Autowired
     private CustomerRepository repository;

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

     @Bean
     public CommandLineRunner demo() {
         return (args) -> {
             // save a couple of customers
             repository.save(new Customer("Jack", "Bauer"));
             repository.save(new Customer("Chloe", "O'Brian"));
             repository.save(new Customer("Kim", "Bauer"));
             repository.save(new Customer("David", "Palmer"));
             repository.save(new Customer("Michelle", "Dessler"));

             // fetch all customers
             log.info("Customers found with findAll():");
             log.info("-------------------------------");
             for (Customer customer : repository.findAll()) {
                 log.info(customer.toString());
             }
             log.info("");

             // fetch an individual customer by ID
             Customer customer = repository.findOne(1L);
             log.info("Customer found with findOne(1L):");
             log.info("--------------------------------");
             log.info(customer.toString());
             log.info("");

             // fetch customers by last name
             log.info("Customer found with findByLastName('Bauer'):");
             log.info("--------------------------------------------");
             for (Customer bauer : repository.findByLastName("Bauer")) {
                 log.info(bauer.toString());
         }
         log.info("");
     };
 }

}

运行应用程序

如果你使用的是像 STS 这样的 IDE ，只需右键单击你的项目 - >运行方式 - > Gradle(STS) 构建…在任务列表中，键入 bootRun 和 Run。

如果在命令行上使用 gradle ，则可以按如下方式运行应用程序：

./gradlew bootRun

你应该看到这样的东西：

== Customers found with findAll():
Customer[id=1, firstName='Jack', lastName='Bauer']
Customer[id=2, firstName='Chloe', lastName='O'Brian']
Customer[id=3, firstName='Kim', lastName='Bauer']
Customer[id=4, firstName='David', lastName='Palmer']
Customer[id=5, firstName='Michelle', lastName='Dessler']

== Customer found with findOne(1L):
Customer[id=1, firstName='Jack', lastName='Bauer']

== Customer found with findByLastName('Bauer'):
Customer[id=1, firstName='Jack', lastName='Bauer']
Customer[id=3, firstName='Kim', lastName='Bauer']