我一直在寻找解决此问题的解决方案。我使用 Spring data JPA 从 MySQL 数据库服务器检索数据。
下面是实体：
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package com.parko.timebestilling.database.entity;
import java.io.Serializable;
import java.util.Collection;
import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlTransient;
/**
*
* @author Christian
*/
@Entity
@Table(name = "customer")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Customer.findAll", query = "SELECT c FROM Customer c"),
@NamedQuery(name = "Customer.findByCID", query = "SELECT c FROM Customer c WHERE c.cID = :cID"),
@NamedQuery(name = "Customer.findByCAdress", query = "SELECT c FROM Customer c WHERE c.cAdress = :cAdress"),
@NamedQuery(name = "Customer.findByCEpost", query = "SELECT c FROM Customer c WHERE c.cEpost = :cEpost"),
@NamedQuery(name = "Customer.findByCLastName", query = "SELECT c FROM Customer c WHERE c.cLastName = :cLastName"),
@NamedQuery(name = "Customer.findByCName", query = "SELECT c FROM Customer c WHERE c.cName = :cName"),
@NamedQuery(name = "Customer.findByCNote", query = "SELECT c FROM Customer c WHERE c.cNote = :cNote"),
@NamedQuery(name = "Customer.findByCPhonenumber", query = "SELECT c FROM Customer c WHERE c.cPhonenumber = :cPhonenumber"),
})
public class Customer implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "cID")
private Integer cID;
@Size(max = 255)
@Column(name = "cAdress")
private String cAdress;
@Size(max = 255)
@Column(name = "cEpost")
private String cEpost;
@Size(max = 255)
@Column(name = "cLastName")
private String cLastName;
@Size(max = 255)
@Column(name = "cName")
private String cName;
@Size(max = 255)
@Column(name = "cNote")
private String cNote;
@Size(max = 255)
@Column(name = "cPhonenumber")
private String cPhonenumber;
/*
@OneToMany(cascade = CascadeType.ALL, mappedBy = "cid")
private Collection<SmsHistory> smsHistoryCollection;
@OneToMany(cascade = CascadeType.ALL, mappedBy = "customer")
private Collection<SmsReceivers> smsReceiversCollection;
@OneToMany(mappedBy = "cid")
private Collection<Reservation> reservationCollection;
*/
public Customer() {
}
public Customer(Integer cID) {
this.cID = cID;
}
public Customer(Integer cID, String cAdress1, String cEpost1, String cLastName1, String cName1, String cPhonenumber1) {
this.cID = cID;
this.cAdress = cAdress1;
this.cEpost = cEpost1;
this.cLastName = cLastName1;
this.cName = cName1;
this.cPhonenumber = cPhonenumber1;
}
public Integer getCID() {
return cID;
}
public void setCID(Integer cID) {
this.cID = cID;
}
public String getCAdress() {
return cAdress;
}
public void setCAdress(String cAdress) {
this.cAdress = cAdress;
}
public String getCEpost() {
return cEpost;
}
public void setCEpost(String cEpost) {
this.cEpost = cEpost;
}
public String getCLastName() {
return cLastName;
}
public void setCLastName(String cLastName) {
this.cLastName = cLastName;
}
public String getCName() {
return cName;
}
public void setCName(String cName) {
this.cName = cName;
}
public String getCNote() {
return cNote;
}
public void setCNote(String cNote) {
this.cNote = cNote;
}
public String getCPhonenumber() {
return cPhonenumber;
}
public void setCPhonenumber(String cPhonenumber) {
this.cPhonenumber = cPhonenumber;
}
/*
@XmlTransient
public Collection<SmsHistory> getSmsHistoryCollection() {
return smsHistoryCollection;
}
public void setSmsHistoryCollection(Collection<SmsHistory> smsHistoryCollection) {
this.smsHistoryCollection = smsHistoryCollection;
}
@XmlTransient
public Collection<SmsReceivers> getSmsReceiversCollection() {
return smsReceiversCollection;
}
public void setSmsReceiversCollection(Collection<SmsReceivers> smsReceiversCollection) {
this.smsReceiversCollection = smsReceiversCollection;
}
@XmlTransient
public Collection<Reservation> getReservationCollection() {
return reservationCollection;
}
public void setReservationCollection(Collection<Reservation> reservationCollection) {
this.reservationCollection = reservationCollection;
}
*/
@Override
public int hashCode() {
int hash = 0;
hash += (cID != null ? cID.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Customer)) {
return false;
}
Customer other = (Customer) object;
if ((this.cID == null && other.cID != null) || (this.cID != null && !this.cID.equals(other.cID))) {
return false;
}
return true;
}
@Override
public String toString() {
return "com.parko.timebestilling.database.entity.Customer[ cID=" + cID + " ]";
}
}
存储库类：
package com.parko.timebestilling.database.beans;
import com.parko.timebestilling.database.entity.Customer;
import org.springframework.data.repository.CrudRepository;
/**
* Created by christian on 15.03.2017.
*/
public interface CustomerRepository extends CrudRepository<Customer, Integer>{
}
服务等级：
package com.parko.timebestilling.database.beans;
import com.parko.timebestilling.database.entity.Customer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.ArrayList;
import java.util.List;
/**
* Created by christian on 15.03.2017.
*/
@Service
public class CustomerService {
@Autowired
private CustomerRepository customerRepo;
public List<Customer> getAllCustomers() {
List<Customer> customers = new ArrayList<>();
customerRepo.findAll().forEach(customers::add);
return customers;
}
public Customer getTest() {
return customerRepo.findOne(1);
}
}
最后我称之为..
public class Welcome extends CssLayout implements View {
public static final String VIEW_NAME = "Hjem";
@Autowired
CustomerService customerServ;
public Welcome() {
System.out.println(customerServ.getTest().getcName());
}
这是我的 application.properties
# ===============================
# = DATA SOURCE
# ===============================
# Set here configurations for the database connection
# Connection url for the database "Parko"
spring.datasource.url = jdbc:mysql://localhost:3306/parko?useSSL=false
# Username and password
spring.datasource.username = root
spring.datasource.password = root
# Keep the connection alive if idle for a long time (needed in production)
spring.datasource.testWhileIdle = true
spring.datasource.validationQuery = SELECT 1
# ===============================
# = JPA / HIBERNATE
# ===============================
# Use spring.jpa.properties.* for Hibernate native properties (the prefix is
# stripped before adding them to the entity manager).
# Show or not log for each sql query
spring.jpa.show-sql = true
# Hibernate ddl auto (create, create-drop, update): with "update" the database
# schema will be automatically updated accordingly to java entities found in
# the project
spring.jpa.hibernate.ddl-auto = update
# Naming strategy
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy
spring.data.jpa.repositories.enabled=true
# Allows Hibernate to generate SQL optimized for a particular DBMS
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
spring.jpa.database=mysql
# ===============================
# = SESSION
# ===============================
spring.session.store-type=none
# ===============================
# = VAADIN
# ===============================
vaadin.servlet.productionMode=true
但是，当我的程序调用 findOne 方法时，它会返回 null。数据库中确实有一条主键为 1 的客户记录，所以情况并非如此。我希望我已经包含了你们发现问题所需的所有内容。我使用 Vaadin 来创建我的内容。如果那是要看的东西..