搜索
搜索

JPA存储库抛出空指针异常

Jyoti Ranjan Singh 发表于 Java
165
Jyoti Ranjan Singh：

我对Spring Boot和JPA相当陌生。我正在做一个小项目以达到我的学习目的。

实体类

package com.jranjanacademy.currencyexchangeservice.service;

import java.math.BigDecimal;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class ExchangeService {

    @Id
    private long id;

    @Column(name="currency_from")
    private String from;

    @Column(name="currency_to")
    private String to;

    private BigDecimal conversionMultiple;

    private int port;

    // == Constructors ==

    // == No arg Constructors ==
      public ExchangeService() {

      }

    // == Parametrised Constructors ==
    public ExchangeService(long id, String from, String to, BigDecimal conversionMultiple) {
        super();
        this.id = id;
        this.from = from;
        this.to = to;
        this.conversionMultiple = conversionMultiple;
    }

    /**
     * @return the id
     */
    public long getId() {
        return id;
    }

    /**
     * @param id the id to set
     */
    public void setId(long id) {
        this.id = id;
    }

    /**
     * @return the from
     */
    public String getFrom() {
        return from;
    }

    /**
     * @param from the from to set
     */
    public void setFrom(String from) {
        this.from = from;
    }

    /**
     * @return the to
     */
    public String getTo() {
        return to;
    }

    /**
     * @param to the to to set
     */
    public void setTo(String to) {
        this.to = to;
    }

    /**
     * @return the conversionMultiple
     */
    public BigDecimal getConversionMultiple() {
        return conversionMultiple;
    }

    /**
     * @param conversionMultiple the conversionMultiple to set
     */
    public void setConversionMultiple(BigDecimal conversionMultiple) {
        this.conversionMultiple = conversionMultiple;
    }

    /**
     * @return the port
     */
    public int getPort() {
        return port;
    }

    /**
     * @param port the port to set
     */
    public void setPort(int port) {
        this.port = port;
    }
}

控制器类别：

package com.jranjanacademy.currencyexchangeservice.controller;

    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.core.env.Environment;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RestController;

    import com.jranjanacademy.currencyexchangeservice.service.ExchangeService;
    import com.jranjanacademy.currencyexchangeservice.service.ExchangeServiceRepository;

    @RestController
    public class ExchangeServiceController {

        @Autowired
        private Environment environment;

        @Autowired
        private ExchangeServiceRepository exchangeServiceRepository;

        @GetMapping("/currency-exchange/from/{from}/to/{to}")
        public ExchangeService retrieveExchangeValue(@PathVariable String from, @PathVariable String to){
            ExchangeService exchangeValue =
                    exchangeServiceRepository.findByFromAndTo(from, to);
        exchangeValue.setPort(
                    Integer.parseInt(environment.getProperty("local.server.port")));
        return exchangeValue;
        }
    }

JPAR存储库

package com.jranjanacademy.currencyexchangeservice.service;

import org.springframework.data.jpa.repository.JpaRepository;

public interface ExchangeServiceRepository extends JpaRepository<ExchangeService, Long>{

    ExchangeService findByFromAndTo(String from, String to);
}

data.sql如下所示，我可以在h2控制台中看到该表

insert into exchange_service(id,currency_from,currency_to,conversion_multiple,port)
values(1001,'USD','INR',75,0);
insert into exchange_service(id,currency_from,currency_to,conversion_multiple,port)
values(1002,'AUD','INR',42,0);
insert into exchange_service(id,currency_from,currency_to,conversion_multiple,port)
values(1003,'EUR','INR',65,0);
insert into exchange_service(id,currency_from,currency_to,conversion_multiple,port)
values(1004,'POUND','INR',51,0);

当我尝试使用URL“ http：// localhost：8000 / currency-exchange / from / INR / to / USD ” 时，出现以下异常

2020-05-21 21:14:58.229 ERROR 9384 --- [nio-8000-exec-8] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause

    java.lang.NullPointerException: null
        at com.jranjanacademy.currencyexchangeservice.controller.ExchangeServiceController.retrieveExchangeValue(ExchangeServiceController.java:25) ~[classes/:na]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_91]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_91]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_91]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_91]
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:93) ~[spring-boot-actuator-2.3.0.RELEASE.jar:2.3.0.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.35.jar:9.0.35]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_91]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_91]
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.35.jar:9.0.35]

Application.properties

spring.application.name=currency-exchange-service
server.port=8000
spring.jpa.show-sql=true
spring.h2.console.enabled=true

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect

有线索吗？

阿维：

从问题中可以看到两件事

  1. 插入的项目是 
id,  | currency_from | currency_to | conversion_multiple |port
1001 |    'USD'      |    'INR'    |     75.             |0
1002 |    'AUD'      |    'INR'    |     42              |0
1003 |    'EUR'      |    'INR'    |     65              |0
1004 |    'POUND'    |    'INR'    |     51              |0
  1. 要求 http://localhost:8000/currency-exchange/from/INR/to/USD
From : INR, TO : USD

所以我怀疑在下面的行中您必须具有NULL值，因为表中不存在FROM :INRtoTO: USD

ExchangeService exchangeValue = exchangeServiceRepository.findByFromAndTo(from, to);

所以解决办法是

  • 检查exchangeValue是null处理前。

（要么）

  • 将Employee作为Optional数据返回，请参考此（上面的sol更简单，以提高代码质量）

本文收集自互联网，转载请注明来源。

如有侵权，请联系 [email protected] 删除。

编辑于
0

我来说两句

0 条评论
登录 后参与评论

相关文章

服务注解类抛出空指针异常上的存储库调用

NullPointer异常存储库Spring Boot Jpa

Spring Data JPA存储库抛出空指针

Spring Data JPA的findById无法调用；空指针异常

android设计库gradle空指针异常

resttemplate.exchange抛出空指针异常

JOOQ“ IN”查询抛出空指针异常

liquibase：diff命令抛出空指针异常

在存储库空指针异常中使用AsyncTask的Android Room查询

KeyedProcessFunction实现抛出空指针异常？

尽管使用when和then，模拟存储库功能仍会导致空指针异常

ListView项目长按侦听器抛出空指针异常

简单的记录器类，但是抛出空指针异常？

运行ArrayList <checkbox>时抛出空指针异常

模拟抛出空指针异常。Mockito的新手

定时函数抛出空指针异常

mClustermanager.additem（）谷歌地图抛出空指针异常android

Mockito方法为使用的变量抛出空指针异常

NPE Navigation Drawer listView 抛出空指针异常

片段中的工具栏不断抛出空指针异常

JPA 存储库在抛出异常之前在 Catch 子句中调用时不执行更新

JPG 处理器 Java 代码抛出空指针异常

为什么这段代码会抛出空指针异常

ViewModel 类在尝试显示存储库中的结果时抛出空指针

Spring Boot Data Jpa中的空指针异常

声纳立方体“可能抛出空指针异常”：误报？

Edittext 字段未检测到。抛出空指针异常

尝试使用 JPA 将数据插入 MySQL 数据库时，抛出异常：列“billing_address”不能为空

JPA 存储库布尔查询 - 返回空指针异常

TOP 榜单

  1. 1

    Qt Creator Windows 10 - “使用 jom 而不是 nmake”不起作用

  2. 2

    使用next.js时出现服务器错误，错误：找不到react-redux上下文值；请确保组件包装在<Provider>中

  3. 3

    SQL Server中的非确定性数据类型

  4. 4

    Swift 2.1-对单个单元格使用UITableView

  5. 5

    如何避免每次重新编译所有文件？

  6. 6

    在同一Pushwoosh应用程序上Pushwoosh多个捆绑ID

  7. 7

    Hashchange事件侦听器在将事件处理程序附加到事件之前进行侦听

  8. 8

    应用发明者仅从列表中选择一个随机项一次

  9. 9

    在 Avalonia 中是否有带有柱子的 TreeView 或类似的东西？

  10. 10

    HttpClient中的角度变化检测

  11. 11

    在Wagtail管理员中，如何禁用图像和文档的摘要项？

  12. 12

    如何了解DFT结果

  13. 13

    Camunda-根据分配的组过滤任务列表

  14. 14

    错误：找不到存根。请确保已调用spring-cloud-contract：convert

  15. 15

    为什么此后台线程中未处理的异常不会终止我的进程？

  16. 16

    构建类似于Jarvis的本地语言应用程序

  17. 17

    使用分隔符将成对相邻的数组元素相互连接

  18. 18

    您如何通过 Nativescript 中的 Fetch 发出发布请求？

  19. 19

    通过iwd从Linux系统上的命令行连接到wifi（适用于Linux的无线守护程序）

  20. 20

    使用React / Javascript在Wordpress API中通过ID获取选择的多个帖子/页面

  21. 21

    使用 text() 獲取特定文本節點的 XPath

热门标签

归档