Java 为什么hibernate无法保存？

我正在使用Flyway尝试创建一个数据库，然后在SpringBootWeb应用程序启动时为其种子。Flyway在第一次迁移中成功创建了数据库表，但在第二次迁移中由于NullPointerException而无法填充它们

以下是迁移代码V2_seed_database.java，位于包db.migration中：

package db.migration;

import org.flywaydb.core.api.migration.BaseJavaMigration;
import org.flywaydb.core.api.migration.Context;

import net.tekknow.medaverter.db.seeds.AppointmentSeeder;

public class V2__seed_database extends BaseJavaMigration {
    public void migrate(Context context) {
        AppointmentSeeder appointmentSeeder = new AppointmentSeeder();
        appointmentSeeder.seed();
    }
}

以下是任命播种机代码：

package net.tekknow.medaverter.db.seeds;

import org.json.JSONArray; 
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import net.tekknow.medaverter.domain.Appointment;
import net.tekknow.medaverter.service.AppointmentService;

@Service
public class AppointmentSeeder {
    @Autowired
    AppointmentService appointmentService;

    @PostConstruct
    public void seed() {
        String json = "[" +
            "{\"id\":1,\"patient_id\":1,\"dateTime\":\"10/29/2010\",\"physician_id\":1,\"lab_id\":1,\"note_id\":0}" +
        "]";
        org.json.JSONArray appointments = new JSONArray(json);

        for (int i=0; i<appointments.length(); i++) {
            JSONObject appointment = appointments.getJSONObject(i);
            Appointment dbAppointment = new Appointment();
            dbAppointment.setId(appointment.getInt("id"));
            dbAppointment.setPatientId(appointment.getInt("patient_id"));
            dbAppointment.setDateTime(appointment.getString("dateTime"));
            dbAppointment.setPhysicianId(appointment.getInt("physician_id"));
            dbAppointment.setLabId(appointment.getInt("lab_id"));
            dbAppointment.setNoteId(appointment.getInt("note_id"));
            appointmentService.save(dbAppointment);
        }
    }
}   

以下是预约bean：

package net.tekknow.medaverter.domain;

import javax.persistence.*;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Size;

@Entity
@Table(name = "appointments")
public class Appointment {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    @NotBlank
    @Column(unique = true)
    private int patient_id;
    @Size(max = 32)
    private String date_time;
    private int physician_id;
    private int lab_id;
    private int note_id;

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
... other getters and setters, truncated for brevity

当我运行程序时，迁移开始，但在这一行失败：

    repo.save(appointment);  //its failing here

显示以下错误消息：

原因：java.lang.NullPointerException:null net.teknow.medverter.service.AppointmentService.save（AppointmentService.java:32） ~[classes/：na]

就在失败的代码行之前，我输出了表示为null的对象的内容，以及表示为notnull的对象的内容：

AppointmentService.save:appointment=id:1，patient\u id:1， 日期时间：2010年10月29日，医师id:1，实验室id:1，备注id:0

---

有什么建议吗？

也许您应该将JSON文件中**note\u id**的值更改为1

这与hibernate无关，您使用spring依赖项注入的方式不正确：您试图自动连接静态字段，这是不允许的

看

更新

现在你有了

AppointmentService appointmentService = new AppointmentService();

而不是将这片土地注入播种机

如果您想要依赖注入工作，Seeder需要是一个Spring管理的bean（

@Service

）。另请参见

@PostConstruct

，您可以使用它在bean初始化后调用方法

更新2

您仍然使用

new

自己实例化Springbean，因此没有注入依赖项

AppointmentSeeder appointmentSeeder = new AppointmentSeeder();

然而，您已经成功地将问题推向了Flyway。现在的问题是Flyway迁移不是SpringBean：它们是由Flyway而不是Spring创建的，因此它们的依赖项不会由Spring自动连接

Flyway4.1通过允许使用预先存在的Springbeans（或其他Java对象）和一些配置来解决这个问题

看

---

另请参见和javadoc。

在AppointmentSeeder中执行此操作

@Autowire
AppointmentService service;

public void seed() {
        String json = "[" +
            "{\"id\":1,\"patient_id\":1,\"dateTime\":\"10/29/2010\",\"physician_id\":1,\"lab_id\":1,\"note_id\":0}" +
        "]";
        org.json.JSONArray appointments = new JSONArray(json);

        for (int i=0; i<appointments.length(); i++) {
            JSONObject appointment = appointments.getJSONObject(i);
            Appointment dbAppointment = new Appointment();
            dbAppointment.setId(appointment.getInt("id"));
            dbAppointment.setPatientId(appointment.getInt("patient_id"));
            dbAppointment.setDateTime(appointment.getString("dateTime"));
            dbAppointment.setPhysicianId(appointment.getInt("physician_id"));
            dbAppointment.setLabId(appointment.getInt("lab_id"));
            dbAppointment.setNoteId(appointment.getInt("note_id"));
            service.save(dbAppointment);
        }
    }

@Autowire
任命服务；
公开无效种子（）{
字符串json=“[”+
“{\'id\'：1，\'patient\'U id\'：1，\'dateTime\'：\'10/29/2010\'，\'Medical\'U id\'：1，\'lab\'U id\'：1，\'note\'U id\'：0}”+
"]";
org.json.JSONArray约会=新的JSONArray（json）；
对于（inti=0；iI）最初不是这样的。Eclipse提供它作为“快速修复”错误“无法对非静态字段repo进行静态引用”。那么我应该在intead中做什么呢？您可能只有
repo
字段作为实例字段，但是
save
方法是静态的。不可能从静态方法访问实例字段（因此使用QuickFix）。您需要将字段和方法都设置为非静态，但save方法是从public interface AppointRepository Extendes JpaRepository{}继承的。JpaRepository是Spring Boot（或Hibernate？）代码，不是我的。啊，当然可以。很抱歉，我错过了。谢谢。我拿走了它，现在出现了下一个错误“org.springframework.beans.factory.BeanCreationException:创建名为'appController'的bean时出错，该bean在文件[C:\Users\Greg\Projects\MedAverter\target\classes\net\Teknow\MedAverter\controller\appController.class]中定义]：合并bean定义的后处理失败；嵌套异常为java.lang.IllegalStateException:未能内省类[net.Teknow.medaverter.controller.AppController]，原因是：java.lang.NoClassDefFoundError:Lnet/Teknow/medaverter/service/AppointmentService；“我想你解决了这个问题，所以我会给你积分。谢谢！我把它改成了1，但是@Autowired没有区别。但是这也不起作用。仍然得到相同的错误”原因是：java.lang.NullPointerException:null at net.teknow.medverter.service.AppointService.save（AppointService.java:32）~[classes/:na]”我用你的建议修改了主帖子中显示的代码。
AppointmentSeeder appointmentSeeder = new AppointmentSeeder();

ApplicationContext applicationContext = ...; // obtain a reference to Spring's ApplicationContext.

Flyway flyway = Flyway.configure()
    .dataSource(url, user, password)
    // Add all Spring-instantiated JavaMigration beans
    .javaMigrations(applicationContext.getBeansOfType(JavaMigration.class).values().toArray(new JavaMigration[0]))
    .load();
flyway.migrate();

@Autowire
AppointmentService service;

public void seed() {
        String json = "[" +
            "{\"id\":1,\"patient_id\":1,\"dateTime\":\"10/29/2010\",\"physician_id\":1,\"lab_id\":1,\"note_id\":0}" +
        "]";
        org.json.JSONArray appointments = new JSONArray(json);

        for (int i=0; i<appointments.length(); i++) {
            JSONObject appointment = appointments.getJSONObject(i);
            Appointment dbAppointment = new Appointment();
            dbAppointment.setId(appointment.getInt("id"));
            dbAppointment.setPatientId(appointment.getInt("patient_id"));
            dbAppointment.setDateTime(appointment.getString("dateTime"));
            dbAppointment.setPhysicianId(appointment.getInt("physician_id"));
            dbAppointment.setLabId(appointment.getInt("lab_id"));
            dbAppointment.setNoteId(appointment.getInt("note_id"));
            service.save(dbAppointment);
        }
    }