java - DAO 和 Spring Autowired

Question

我尝试创建一个抽象的 Dao。我使用 Spring + Hibernate。这是我的代码。
具有配置的主类:

package ru.makaek.growbox.api;

import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.core.env.Environment;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;

@ComponentScan(value = "ru.makaek.growbox")
@EnableAutoConfiguration(exclude = HibernateJpaAutoConfiguration.class)
@EnableTransactionManagement
@SpringBootApplication
public class Application {

    @Autowired
    private Environment env;

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


    @Bean
    public DataSource getDataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(env.getRequiredProperty("datasource.driver"));
        dataSource.setUrl(env.getRequiredProperty("datasource.url"));
        dataSource.setUsername(env.getRequiredProperty("datasource.username"));
        dataSource.setPassword(env.getRequiredProperty("datasource.password"));
        return dataSource;
    }

    @Bean
    public LocalSessionFactoryBean getSessionFactory() {
        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
        sessionFactory.setDataSource(getDataSource());
        sessionFactory.setPackagesToScan(new String[]{"ru.makaek.growbox"});
        return sessionFactory;
    }

    @Bean
    public HibernateTransactionManager getTransactionManager(SessionFactory sessionFactory) {
        HibernateTransactionManager txManager = new HibernateTransactionManager();
        txManager.setSessionFactory(sessionFactory);
        return txManager;
    }

}

休息 Controller

package ru.makaek.growbox.api.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import ru.makaek.growbox.api.model.data.entities.Device;
import ru.makaek.growbox.api.service.IStructureService;

@RestController
public class DeviceController extends AbstractController {

    @Autowired
    IStructureService structureService;

    @RequestMapping(value = "/devices", method = RequestMethod.POST)
    public Answer addDevice(@RequestBody Device device) {
        structureService.addDevice(device);
        return ok("Device has been added");
    }

    @RequestMapping(value = "/devices", method = RequestMethod.GET)
    public Answer getDevices() {
        return ok(structureService.getDevices());
    }

    @RequestMapping(value = "/devices/{deviceId}", method = RequestMethod.GET)
    public Answer getDevice(@PathVariable Long deviceId) {
        return ok(structureService.getDevice(deviceId));
    }

}

服务层。界面

package ru.makaek.growbox.api.service;

import ru.makaek.growbox.api.model.data.entities.Device;

import java.util.List;

public interface IStructureService {

    void addDevice(Device device);

    List<Device> getDevices();

    Device getDevice(Long deviceId);
}

服务层。实现

package ru.makaek.growbox.api.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import ru.makaek.growbox.api.model.data.dao.base.IDao;
import ru.makaek.growbox.api.model.data.entities.Device;

import java.util.List;

@Service
@Transactional
public class StructureService implements IStructureService {

    IDao<Device> deviceDao;

    @Autowired
    public void setDao(IDao<Device> dao) {
        deviceDao = dao;
        dao.setClazz(Device.class);
    }

    @Override
    public void addDevice(Device device) {
        deviceDao.create(device);
    }

    @Override
    public List<Device> getDevices() {
        return deviceDao.findAll();
    }

    @Override
    public Device getDevice(Long deviceId) {
        return deviceDao.findOne(deviceId);
    }
}

实体

package ru.makaek.growbox.api.model.data.entities;

import lombok.Data;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity(name = "devices")
@Data public class Device extends BaseEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
}

DAO。界面

package ru.makaek.growbox.api.model.data.dao.base;

import ru.makaek.growbox.api.model.data.entities.BaseEntity;

import java.util.List;

public interface IDao<T extends BaseEntity> {

    T findOne(final long id);

    void setClazz(Class<T> clazz);

    List<T> findAll();

    void create(final T entity);

    T update(final T entity);

    void delete(final T entity);

    void deleteById(final long entityId);

}

抽象 DAO

package ru.makaek.growbox.api.model.data.dao.base;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import ru.makaek.growbox.api.model.data.entities.BaseEntity;
import ru.makaek.growbox.api.util.GBException;

import java.util.List;

public abstract class AbstractDao<T extends BaseEntity> implements IDao<T> {

    private Class<T> clazz;

    @Autowired
    private SessionFactory sessionFactory;

    public final void setClazz(Class<T> clazz) {
        this.clazz = clazz;
    }

    public T findOne(long id) {
        try {
            return (T) getCurrentSession().get(clazz, id);
        } catch (Exception e) {
            throw new GBException.InternalError(e.getMessage());
        }
    }

    public List<T> findAll() {
        try {
            return getCurrentSession().createQuery("from " + clazz.getName()).list();
        } catch (Exception e) {
            throw new GBException.InternalError(e.getMessage());
        }
    }

    public void create(T entity) {
        try {
            getCurrentSession().persist(entity);
        } catch (Exception e) {
            throw new GBException.InternalError(e.getMessage());
        }
    }

    public T update(T entity) {
        try {
            return (T) getCurrentSession().merge(entity);
        } catch (Exception e) {
            throw new GBException.InternalError(e.getMessage());
        }
    }

    public void delete(T entity) {
        try {
            getCurrentSession().delete(entity);
        } catch (Exception e) {
            throw new GBException.InternalError(e.getMessage());
        }
    }

    public void deleteById(long entityId) {
        try {
            T entity = findOne(entityId);
            delete(entity);
        } catch (Exception e) {
            throw new GBException.InternalError(e.getMessage());
        }
    }

    protected final Session getCurrentSession() {
        return sessionFactory.getCurrentSession();
    }


}

DAO。实现

package ru.makaek.growbox.api.model.data.dao;

import org.springframework.stereotype.Repository;
import ru.makaek.growbox.api.model.data.dao.base.AbstractDao;
import ru.makaek.growbox.api.model.data.entities.Device;

@Repository
public class DeviceDao extends AbstractDao<Device> {
}

我有一个麻烦。当我调用GET http://host:port/devices时 API 方法 我在 AbstractDao.findAll() 方法的 clazz 变量中有 null。当我调试代码时，我发现了一件有趣的事情:在服务层方法 deviceDao.getClazz() 中返回了所需的 clazz (不为空)。但在方法 AbstractDao.findAll() 中，我的 clazz 变量中有 null 。为什么？请帮忙。
抱歉我的英语和表述。我是这个网站的新人，Spring 和英语

Answer 1

你把事情搞得太复杂了。因为您使用的是 Spring Boot，所以可以只创建扩展 CrudRepository 的通用接口(interface)并添加您需要的但尚未存在于其中的方法。

看这里 https://docs.spring.io/spring-data/data-commons/docs/1.6.1.RELEASE/reference/html/repositories.html