12

I want to be able to connect a program of mine to a database. But since I have never worked with databases before I am following a tutorial found here: https://www.javacodegeeks.com/2016/03/springboot-working-jdbctemplate.html. After following all the steps (to the best of my knowledge) of the tutorial I get the following stack trace:

java.sql.SQLException: Unable to load class: com.mysql.jdbc.Driver from ClassLoader:sun.misc.Launcher$AppClassLoader@34a245ab;ClassLoader:sun.misc.Launcher$AppClassLoader@34a245ab
at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:283) ~[tomcat-jdbc-8.5.4.jar:na]
at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:203) ~[tomcat-jdbc-8.5.4.jar:na]
at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:716) [tomcat-jdbc-8.5.4.jar:na]
at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:648) [tomcat-jdbc-8.5.4.jar:na]
at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:468) [tomcat-jdbc-8.5.4.jar:na]
at org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:143) [tomcat-jdbc-8.5.4.jar:na]
at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:118) [tomcat-jdbc-8.5.4.jar:na]
at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:107) [tomcat-jdbc-8.5.4.jar:na]
at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:131) [tomcat-jdbc-8.5.4.jar:na]
at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:111) [spring-jdbc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77) [spring-jdbc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.jdbc.datasource.init.DatabasePopulatorUtils.execute(DatabasePopulatorUtils.java:46) [spring-jdbc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.boot.autoconfigure.jdbc.DataSourceInitializer.runScripts(DataSourceInitializer.java:176) [spring-boot-autoconfigure-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.autoconfigure.jdbc.DataSourceInitializer.runSchemaScripts(DataSourceInitializer.java:85) [spring-boot-autoconfigure-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.autoconfigure.jdbc.DataSourceInitializer.init(DataSourceInitializer.java:77) [spring-boot-autoconfigure-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_92]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_92]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_92]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_92]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:365) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:310) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:133) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:408) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1570) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:220) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:353) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:334) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.boot.autoconfigure.jdbc.DataSourceInitializerPostProcessor.postProcessAfterInitialization(DataSourceInitializerPostProcessor.java:62) [spring-boot-autoconfigure-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:422) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1583) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:207) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1214) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1054) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1019) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:835) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:189) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1143) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1046) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:372) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1123) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1018) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) [spring-beans-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1076) [spring-context-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:851) [spring-context-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541) [spring-context-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:369) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:313) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1185) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1174) [spring-boot-1.4.0.RELEASE.jar:1.4.0.RELEASE]
at edu.demo.SpringbootJdbcDemoApplication.main(SpringbootJdbcDemoApplication.java:9) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_92]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_92]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_92]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_92]
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147) [idea_rt.jar:na]

Is anyone familiar with this type of error? It's probably something pretty simple. The IDE I am using is IntelliJ. I have put my code below:

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>

    <groupId>edu.demo</groupId>
    <artifactId>SpringbootJdbcDemoApplication</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>SpringbootJdbcDemoApplication</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</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>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

SpringbootJdbcDemoApplication.java

package edu.demo;

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

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

User.java

    package edu.demo;

    public class User{
        private Integer id;
        private String name;
        private String email;

    public User(int number, String strName, String strEmail){
        id = number;
        name = strName;
        email = strEmail;
    }

    public User(){

    }
    public Integer getId() {
        return id;
    }

    public String getEmail() {
        return email;
    }

    public String getName() {
        return name;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public void setName(String name) {
        this.name = name;
    }
}

SpringbootJdbcDemoApplicationTests.java

package edu.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.SpringApplicationConfiguration;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import java.util.List;

import org.junit.*;

@org.junit.runner.RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(SpringbootJdbcDemoApplication.class)
public class SpringbootJdbcDemoApplicationTests {
        @Autowired
        private UserRepository userRepository;

        @org.junit.Test
        public void findAllUsers() {
                List<User> users = userRepository.findAll();
                Assert.assertNotNull(users);
                Assert.assertTrue(!users.isEmpty());
        }

        @Test
        public void findUserById() {
                User user = userRepository.findUserById(1);
                Assert.assertNotNull(user);
        }

        @Test
        public void createUser() {
                User user = new User(0, "John", "[email protected]");
                User savedUser = userRepository.create(user);
                User newUser = userRepository.findUserById(savedUser.getId());
                Assert.assertNotNull(newUser);
                Assert.assertEquals("John", newUser.getName());
                Assert.assertEquals("[email protected]", newUser.getEmail());
        }
}

UserRepository.java

package edu.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.SpringApplicationConfiguration;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import java.util.List;

import org.junit.*;

@org.junit.runner.RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(SpringbootJdbcDemoApplication.class)
public class SpringbootJdbcDemoApplicationTests {
        @Autowired
        private UserRepository userRepository;

        @org.junit.Test
        public void findAllUsers() {
                List<User> users = userRepository.findAll();
                Assert.assertNotNull(users);
                Assert.assertTrue(!users.isEmpty());
        }

        @Test
        public void findUserById() {
                User user = userRepository.findUserById(1);
                Assert.assertNotNull(user);
        }

        @Test
        public void createUser() {
                User user = new User(0, "John", "[email protected]");
                User savedUser = userRepository.create(user);
                User newUser = userRepository.findUserById(savedUser.getId());
                Assert.assertNotNull(newUser);
                Assert.assertEquals("John", newUser.getName());
                Assert.assertEquals("[email protected]", newUser.getEmail());
        }
}
1
  • Oh my that's a lot of code! If you take parts of it out, do you still have the same problem? stackoverflow.com/help/mcve Commented Aug 3, 2018 at 4:12

4 Answers 4

13

Yes, in your pom you have a dependency for h2 like

<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
</dependency>

and you want to use mysql. Either change it, or simply add mysql if you're also using h2, to

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency> 
Sign up to request clarification or add additional context in comments.

3 Comments

Entering that code in my pom file gives me a new error: " com.mysql.jdbc.exceptions.jdbc4.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."
That's really a different question, but now that you have the mysql jdbc driver, you need to configure it to point to your database. That's usually in your application.properties. From the link, DataSource configuration is controlled by external configuration properties in spring.datasource.*, url, username, password and driver-class-name.
Okay, I'll look into the page you linked @Elliott Frisch. Thanks for your help.
2

And my solution:

step1:delete the 'mysql-connector' maven repository:

rm -r ~/.m2/repository/mysql/mysql-connector-java

step2:add following snippet into pom.xml:

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

step3:save the project,then wait for the “Building workspace” completely,and all going well. But I don't know what happened...

Comments

2

For folks who are building a datasource manually, besides loading the mysql-connector-dependency, ensure that the driver class name is set correctly.

DataSourceFactory factory = new DataSourceFactory();
factory.setUrl("..");
factory.setUser("..");
factory.setDriverClass("com.mysql.jdbc.Driver"); //Important
...
DBI dbi = new DBI(factory.build(new MetricRegistry(), "mysql"));

Otherwise, DataSourceFactory.driverClass instance field gets set to "". When the application class loader tries to load a class with a name of "", it will throw a ClassNotFoundException

1 Comment

I also had very similar issue when I was using a dropwizard framework, I was missing configuration with values, so the error was like: Caused by: java.sql.SQLException: Unable to load class: from ClassLoader
0

if you work with netbeans and hibernate framwork add jdbc manually go to persistence.xml and go to design add jdbc connection it works fine to me good luck

Comments

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