Jpa Spring Boot 应用程序的问题

Question

我尝试运行时出现很多错误，我无法理解 到底发生了什么。 这是其中的一些：

There was an unexpected error (type=Internal Server Error, status=500).
could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet
org.springframework.dao.InvalidDataAccessResourceUsageException: could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:279)
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:253)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:527)
    at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)
    at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:153)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:144)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$ExposeRepositoryInvocationInterceptor.invoke(CrudMethodMetadataPostProcessor.java:364)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
    at com.sun.proxy.$Proxy83.findAll(Unknown Source)

我是通过一个指南完成的，但是这个指南已经很老了，也许我应该更改 JPA 依赖项，或者以不同的方式创建我的数据库？ 这是关于JPA的第二课的存储库 https://github.com/drucoder/sweater/tree/JPA_Postgres

这是我的 application.properties：

spring.datasource.username=postgres
spring.datasource.password=1506
spring.jpa.generate-ddl-auto=更新

我通过 pgadmin 创建了我的空数据库毛衣。 另外，我的 ide 告诉我 Postgresql 中有 Typo。 这是我的 pom.xml：

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.7.RELEASE</version>
    </parent>

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

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

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

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>
    </dependencies>

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

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

这是我的控制器：

@Controller
public class GreetingController {
    @Autowired
    private MessageRepo messageRepo;
    @GetMapping("/greeting")
    public String greeting(
            @RequestParam(name="name", required=false, defaultValue="World") String name,
            Map<String, Object> model
    ) {
        model.put("name", name);
        return "greeting";
    }

    @GetMapping
    public String main(Map<String, Object> model) {
       Iterable<Message> messages = messageRepo.findAll();
        model.put("messages", messages);
        return "main";
    }

    @PostMapping
    public String add(@RequestParam String text, @RequestParam String tag, Map<String, Object> model){
       Message message = new Message(text,tag);
       messageRepo.save(message);
        Iterable<Message> messages = messageRepo.findAll();
        model.put("messages", messages);
        return "main";
    }


    @PostMapping("filter")
    public String filter(@RequestParam String filter, Map<String, Object> model) {
        Iterable<Message> messages;

        if (filter != null && !filter.isEmpty()) {
            messages = messageRepo.findByTag(filter);
        } else {
            messages = messageRepo.findAll();
        }

        model.put("messages", messages);

        return "main";
    }
}

Answer 1

从

更改您的 application.properties

 spring.datasource.username=postgres
 spring.datasource.password=1506
 spring.jpa.generate-ddl-auto=update

到

 spring.datasource.username=postgres
 spring.datasource.password=1506
 spring.jpa.generate-ddl-auto=update     
 spring.datasource.url=jdbc:postgresql://localhost/{your db name}