我希望能够将我的程序连接到数据库.但是因为我在遵循这里找到的教程之前从未使用过数据库：
https://www.javacodegeeks.com/2016/03/springboot-working-jdbctemplate.html.在完成本教程的所有步骤(据我所知)后,我得到以下堆栈跟踪：
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]
有人熟悉这种类型的错误吗？这可能非常简单.我使用的IDE是IntelliJ.我把我的代码放在下面：
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>
<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","john@gmail.com");
User savedUser = userRepository.create(user);
User newUser = userRepository.findUserById(savedUser.getId());
Assert.assertNotNull(newUser);
Assert.assertEquals("John",newUser.getName());
Assert.assertEquals("john@gmail.com",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,newUser.getEmail());
}
}
解决方法
是的,在你的pom中,你对h2有依赖性
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</dependency>
并且你想使用mysql.要么改变它,要么只是添加MysqL如果你也使用h2,to
<dependency>
<groupId>MysqL</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>