java - 如何使用 mysql 解决 Spring Boot 应用程序上的 "Communications link failure"问题？

Question

我开发了一个基于 Heroku 的 "Getting Started on Heroku with Java" 的 Spring Boot 应用程序。之后我开始配置mysql作为数据库。 This 是我在整个方法中遵循的教程。当我使用 heroku local web 在本地运行应用程序时，一切都运行良好。我可以发出 GET 请求并获取存储在数据库中的数据。我可以发出 POST 请求并向数据库添加新数据。但如果我将其部署到生产中，我会在日志中看到抛出的异常。以下是当我启动在 Heroku 提供的 url 上运行的应用程序时看到的日志的相关部分，在本例中:https://danef-dictionary-api.herokuapp.com/

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
Jan 04 02:24:27 danef-dictionary-api app/web.1 
Jan 04 02:24:27 danef-dictionary-api app/web.1 The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.18.jar:8.0.18]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.18.jar:8.0.18]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.18.jar:8.0.18]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.18.jar:8.0.18]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.18.jar:8.0.18]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199) ~[mysql-connector-java-8.0.18.jar:8.0.18]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-3.4.1.jar:na]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:353) ~[HikariCP-3.4.1.jar:na]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:201) ~[HikariCP-3.4.1.jar:na]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:473) [HikariCP-3.4.1.jar:na]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:562) [HikariCP-3.4.1.jar:na]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) [HikariCP-3.4.1.jar:na]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-3.4.1.jar:na]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess.obtainConnection(JdbcEnvironmentInitiator.java:180) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:68) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:152) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:175) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:118) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1202) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1233) [hibernate-core-5.4.9.Final.jar:5.4.9.Final]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) [spring-orm-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) [spring-orm-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:391) [spring-orm-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:378) [spring-orm-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) [spring-orm-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1855) [spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1792) [spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) [spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) [spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) [spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) [spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) [spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1108) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
Jan 04 02:24:27 danef-dictionary-api app/web.1  at net.danef.DanefDictionaryApiApplication.main(DanefDictionaryApiApplication.java:12) ~[classes/:na]

从异常(exception)情况中，我选择了第一个“常见链接失败”并将其用于该问题的标题中。我可能已经尝试了所有我能找到的解决方案，因此如果您知道您认为有帮助的博客文章或答案，请随时重定向我。

我的application.properties文件:

spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect
spring.jpa.generate-ddl=true
spring.datasource.url=jdbc:mysql://localhost:3306/db_words?useSSL=false
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=myusername
spring.datasource.password=mypassword

“myusername”和“mypassword”只是占位符。我在代码中使用我的凭据。

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 https://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>2.2.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>net.danef</groupId>
    <artifactId>danef-dictionary-api</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>danef-dictionary-api</name>
    <description>Danef Dictionary API</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

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

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>3.0.1</version>
                <executions>
                    <execution>
                        <id>copy-dependencies</id>
                        <phase>package</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

如果您想查看完整版本的日志，请参阅此链接:https://paste.ubuntu.com/p/wqZPXqyYFM/

Answer 1

我通过在 Heroku 中设置 ClearDB 插件解决了我的问题。添加插件后，我就有了一个远程数据库 URL。将远程 URL 设置为 datasource.url 解决了问题。我的 application.properties 文件现在看起来像这样。

spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect
spring.jpa.generate-ddl=true
spring.datasource.url=jdbc:mysql://`remote_database_url`
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=samet
spring.datasource.password=password

设置不带反引号的远程数据库 URL。