我构建了 Spring Boot Web 应用程序并运行它，我得到了一个异常 java.sql.SQLException, String

Question

我的主要课程如下

package com.student;

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

@SpringBootApplication
public class StudentManagementSystemApplication {

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

}

我的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 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>3.3.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.student</groupId>
    <artifactId>Student-Management-System</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Student-Management-System</name>
    <description>Spring boot project for student management </description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

我的application.properties文件

spring.application.name=Student-Management-System

#Datasource property
spring.datasource.url=jdbc:mysql://localhost:/3306/Student_Management
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=Ashish

#Hibernate 
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQLDialect
spring.jpa.show-sql=true

我的项目结构

我的控制台错误

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/

[32m :: Spring Boot :: [39m              [2m (v3.3.0)[0;39m

[2m2024-05-27T12:16:22.817+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mc.s.StudentManagementSystemApplication  [0;39m [2m:[0;39m Starting StudentManagementSystemApplication using Java 17.0.10 with PID 2748 (C:\Users\ashis\eclipse-workspace\microservices\spring\boot\Student-Management-System\target\classes started by ashis in C:\Users\ashis\eclipse-workspace\microservices\spring\boot\Student-Management-System)
[2m2024-05-27T12:16:22.819+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mc.s.StudentManagementSystemApplication  [0;39m [2m:[0;39m No active profile set, falling back to 1 default profile: "default"
[2m2024-05-27T12:16:22.883+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36m.e.DevToolsPropertyDefaultsPostProcessor[0;39m [2m:[0;39m Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
[2m2024-05-27T12:16:22.883+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36m.e.DevToolsPropertyDefaultsPostProcessor[0;39m [2m:[0;39m For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
[2m2024-05-27T12:16:23.737+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36m.s.d.r.c.RepositoryConfigurationDelegate[0;39m [2m:[0;39m Bootstrapping Spring Data JPA repositories in DEFAULT mode.
[2m2024-05-27T12:16:23.770+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36m.s.d.r.c.RepositoryConfigurationDelegate[0;39m [2m:[0;39m Finished Spring Data repository scanning in 25 ms. Found 0 JPA repository interfaces.
[2m2024-05-27T12:16:24.422+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat initialized with port 8080 (http)
[2m2024-05-27T12:16:24.433+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.apache.catalina.core.StandardService  [0;39m [2m:[0;39m Starting service [Tomcat]
[2m2024-05-27T12:16:24.433+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.apache.catalina.core.StandardEngine   [0;39m [2m:[0;39m Starting Servlet engine: [Apache Tomcat/10.1.24]
[2m2024-05-27T12:16:24.488+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.a.c.c.C.[Tomcat].[localhost].[/]      [0;39m [2m:[0;39m Initializing Spring embedded WebApplicationContext
[2m2024-05-27T12:16:24.488+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mw.s.c.ServletWebServerApplicationContext[0;39m [2m:[0;39m Root WebApplicationContext: initialization completed in 1604 ms
[2m2024-05-27T12:16:24.741+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mcom.zaxxer.hikari.HikariDataSource      [0;39m [2m:[0;39m HikariPool-1 - Starting...
[2m2024-05-27T12:16:26.457+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.hibernate.jpa.internal.util.LogHelper [0;39m [2m:[0;39m HHH000204: Processing PersistenceUnitInfo [name: default]
[2m2024-05-27T12:16:26.530+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36morg.hibernate.Version                   [0;39m [2m:[0;39m HHH000412: Hibernate ORM core version 6.5.2.Final
[2m2024-05-27T12:16:26.574+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.h.c.internal.RegionFactoryInitiator   [0;39m [2m:[0;39m HHH000026: Second-level cache disabled
[2m2024-05-27T12:16:26.859+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.s.o.j.p.SpringPersistenceUnitInfo     [0;39m [2m:[0;39m No LoadTimeWeaver setup: ignoring JPA class transformer
[2m2024-05-27T12:16:26.891+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mcom.zaxxer.hikari.HikariDataSource      [0;39m [2m:[0;39m HikariPool-1 - Starting...
[2m2024-05-27T12:16:27.915+05:30[0;39m [33m WARN[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.h.e.j.e.i.JdbcEnvironmentInitiator    [0;39m [2m:[0;39m HHH000342: Could not obtain connection to query metadata

java.lang.NullPointerException: Cannot invoke "org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(java.sql.SQLException, String)" because the return value of "org.hibernate.resource.transaction.backend.jdbc.internal.JdbcIsolationDelegate.sqlExceptionHelper()" is null
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcIsolationDelegate.delegateWork(JdbcIsolationDelegate.java:116) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.getJdbcEnvironmentUsingJdbcMetadata(JdbcEnvironmentInitiator.java:290) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:123) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:77) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:130) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:238) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:215) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.boot.model.relational.Database.<init>(Database.java:45) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.getDatabase(InFlightMetadataCollectorImpl.java:221) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:189) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:171) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1431) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1502) ~[hibernate-core-6.5.2.Final.jar:6.5.2.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:75) ~[spring-orm-6.1.8.jar:6.1.8]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:390) ~[spring-orm-6.1.8.jar:6.1.8]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:409) ~[spring-orm-6.1.8.jar:6.1.8]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:396) ~[spring-orm-6.1.8.jar:6.1.8]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:366) ~[spring-orm-6.1.8.jar:6.1.8]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1835) ~[spring-beans-6.1.8.jar:6.1.8]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1784) ~[spring-beans-6.1.8.jar:6.1.8]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:600) ~[spring-beans-6.1.8.jar:6.1.8]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:522) ~[spring-beans-6.1.8.jar:6.1.8]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:337) ~[spring-beans-6.1.8.jar:6.1.8]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-6.1.8.jar:6.1.8]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:335) ~[spring-beans-6.1.8.jar:6.1.8]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:205) ~[spring-beans-6.1.8.jar:6.1.8]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:952) ~[spring-context-6.1.8.jar:6.1.8]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:624) ~[spring-context-6.1.8.jar:6.1.8]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:146) ~[spring-boot-3.3.0.jar:3.3.0]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) ~[spring-boot-3.3.0.jar:3.3.0]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:456) ~[spring-boot-3.3.0.jar:3.3.0]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:335) ~[spring-boot-3.3.0.jar:3.3.0]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1363) ~[spring-boot-3.3.0.jar:3.3.0]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1352) ~[spring-boot-3.3.0.jar:3.3.0]
    at com.student.StudentManagementSystemApplication.main(StudentManagementSystemApplication.java:10) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:50) ~[spring-boot-devtools-3.3.0.jar:3.3.0]

[2m2024-05-27T12:16:27.942+05:30[0;39m [33m WARN[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36morg.hibernate.orm.deprecation           [0;39m [2m:[0;39m HHH90000025: MySQLDialect does not need to be specified explicitly using 'hibernate.dialect' (remove the property setting and it will be selected by default)
[2m2024-05-27T12:16:28.286+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.h.e.t.j.p.i.JtaPlatformInitiator      [0;39m [2m:[0;39m HHH000489: No JTA platform available (set 'hibernate.transaction.jta.platform' to enable JTA platform integration)
[2m2024-05-27T12:16:28.291+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mj.LocalContainerEntityManagerFactoryBean[0;39m [2m:[0;39m Initialized JPA EntityManagerFactory for persistence unit 'default'
[2m2024-05-27T12:16:28.370+05:30[0;39m [33m WARN[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mJpaBaseConfiguration$JpaWebConfiguration[0;39m [2m:[0;39m spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
[2m2024-05-27T12:16:28.710+05:30[0;39m [33m WARN[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mion$DefaultTemplateResolverConfiguration[0;39m [2m:[0;39m Cannot find template location: classpath:/templates/ (please add some templates, check your Thymeleaf configuration, or set spring.thymeleaf.check-template-location=false)
[2m2024-05-27T12:16:29.136+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.s.b.d.a.OptionalLiveReloadServer      [0;39m [2m:[0;39m LiveReload server is running on port 35729
[2m2024-05-27T12:16:29.147+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.s.b.a.e.web.EndpointLinksResolver     [0;39m [2m:[0;39m Exposing 1 endpoint beneath base path '/actuator'
[2m2024-05-27T12:16:29.221+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat started on port 8080 (http) with context path '/'
[2m2024-05-27T12:16:29.239+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [  restartedMain][0;39m [2m[0;39m[36mc.s.StudentManagementSystemApplication  [0;39m [2m:[0;39m Started StudentManagementSystemApplication in 6.751 seconds (process running for 7.271)
[2m2024-05-27T12:16:29.830+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [on(4)-127.0.0.1][0;39m [2m[0;39m[36mo.a.c.c.C.[Tomcat].[localhost].[/]      [0;39m [2m:[0;39m Initializing Spring DispatcherServlet 'dispatcherServlet'
[2m2024-05-27T12:16:29.831+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [on(4)-127.0.0.1][0;39m [2m[0;39m[36mo.s.web.servlet.DispatcherServlet       [0;39m [2m:[0;39m Initializing Servlet 'dispatcherServlet'
[2m2024-05-27T12:16:29.833+05:30[0;39m [32m INFO[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [on(4)-127.0.0.1][0;39m [2m[0;39m[36mo.s.web.servlet.DispatcherServlet       [0;39m [2m:[0;39m Completed initialization in 2 ms
[2m2024-05-27T12:55:24.976+05:30[0;39m [33m WARN[0;39m [35m2748[0;39m [2m---[0;39m [2m[Student-Management-System] [n(14)-127.0.0.1][0;39m [2m[0;39m[36mjavax.management.remote.misc            [0;39m [2m:[0;39m The server has decided to close this client connection.

我到处尝试但无法得到正确的答案

我找到了答案，但无法得到正确的答案为什么发生此异常。 文字

1. 我尝试取消注释某些属性，但它不起作用。
2. 我尝试 maven clean-install 但遇到了同样的异常。

问题

我想知道为什么会出现这个异常？

Answer 1

您的连接字符串错误。删除 localhost 后面的正斜杠

spring.datasource.url=jdbc:mysql://localhost:3306/Student_Management