com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure Spring boot - spring

Question

i have go through many articles but i cannot solve my problem yet.i am tring this from the morning.
i have done everything correct way why this error coming.please give me the solution to solve this error soon please.
this is the full Error of the code
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure Spring boot
what i tried so far i attached below.
DemoopApplication
package com.springpro.demops;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class DemopsApplication {
public static void main(String[] args) {
SpringApplication.run(DemopsApplication.class, args);
}
}
application.properties
spring.application.name=Demops
server.port=8085
spring.jpa.hibernate.ddl-auto=update
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost::3306/sppos?createDatabaseIfNotExist=true
spring.datasource.username=root
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.MySQL57Dialect
spring.jpa.generate-ddl=true
spring.jpa.show-sql=true
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>2.6.9</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.springpro</groupId>
<artifactId>demops</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demops</name>
<description>Demo project for Spring Boot</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>
<version>8.0.22</version>
</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>
</project>
Full Tracecom.mysql.cj.jdbc.exceptions.CommunicationsException:
Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:364) ~[HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206) ~[HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:476) [HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:561) [HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) [HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-4.0.3.jar:na]
at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess.obtainConnection(JdbcEnvironmentInitiator.java:181) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:68) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:175) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:173) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:127) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1460) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1494) [hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) [spring-orm-5.3.21.jar:5.3.21]
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) [spring-orm-5.3.21.jar:5.3.21]
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:409) [spring-orm-5.3.21.jar:5.3.21]
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:396) [spring-orm-5.3.21.jar:5.3.21]
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) [spring-orm-5.3.21.jar:5.3.21]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863) [spring-beans-5.3.21.jar:5.3.21]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) [spring-beans-5.3.21.jar:5.3.21]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:620) [spring-beans-5.3.21.jar:5.3.21]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) [spring-beans-5.3.21.jar:5.3.21]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) [spring-beans-5.3.21.jar:5.3.21]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.21.jar:5.3.21]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) [spring-beans-5.3.21.jar:5.3.21]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) [spring-beans-5.3.21.jar:5.3.21]
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1154) ~[spring-context-5.3.21.jar:5.3.21]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:908) ~[spring-context-5.3.21.jar:5.3.21]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.21.jar:5.3.21]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.9.jar:2.6.9]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:745) ~[spring-boot-2.6.9.jar:2.6.9]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:420) ~[spring-boot-2.6.9.jar:2.6.9]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) ~[spring-boot-2.6.9.jar:2.6.9]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1317) ~[spring-boot-2.6.9.jar:2.6.9]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) ~[spring-boot-2.6.9.jar:2.6.9]
at com.springpro.demops.DemopsApplication.main(DemopsApplication.java:10) ~[classes/:na]
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_291]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_291]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_291]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_291]
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.NativeSession.connect(NativeSession.java:144) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:956) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826) ~[mysql-connector-java-8.0.22.jar:8.0.22]
... 49 common frames omitted
Caused by: java.net.UnknownHostException: localhost:
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method) ~[na:1.8.0_291]
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:929) ~[na:1.8.0_291]
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1324) ~[na:1.8.0_291]
at java.net.InetAddress.getAllByName0(InetAddress.java:1277) ~[na:1.8.0_291]
at java.net.InetAddress.getAllByName(InetAddress.java:1193) ~[na:1.8.0_291]
at java.net.InetAddress.getAllByName(InetAddress.java:1127) ~[na:1.8.0_291]
at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:132) ~[mysql-connector-java-8.0.22.jar:8.0.22]
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63) ~[mysql-connector-java-8.0.22.jar:8.0.22]
... 52 common frames omitted

Answer 1

Based on configuration & stacktrace, it says:
Caused by: java.net.UnknownHostException: localhost:
This means in your datasource string, you have defined extra :.
I can see that is case as per your application.properties:
spring.datasource.url=jdbc:mysql://localhost::3306/sppos?createDatabaseIfNotExist=true
Can you please remove extra : & use this datasource string again. Also make sure there is no other process currently running on this port (i.e. 3306) & only db is running.
Your correct string should be:
spring.datasource.url=jdbc:mysql://localhost:3306/sppos?createDatabaseIfNotExist=true