我在Maven的JEE项目上很长时间以来一直在处理问题;
我的EntityManager.createQuery()。getResultList()始终返回一个空列表。
数据库连接正常,我的表中有数据,并且仅使用JDBC即可很好地工作。我想我尝试了几乎在互联网上看到的所有内容,只是有点遗漏了……
[我也尝试使用和不使用EJB,并且如果Tomcat无法识别库,则将库移动到WEB-INF目录。
我尝试过如下所示的JPQL请求,但也使用了NamedQuery注释,结果仍然相同。
这是我的代码(DAO):
public List<Conge> getLeaves(String username) {
EntityManagerFactory entityManagerFactory = null;
EntityManager entityManager = null;
List<Conge> listLeaves = new ArrayList<Conge>();
try {
entityManagerFactory = Persistence.createEntityManagerFactory("ProjetJEE");
entityManager = entityManagerFactory.createEntityManager();
List<Employe> a = entityManager.createQuery("select c.login from Employe c").getResultList();
System.out.println("a" + a); //always empty
} finally {
if ( entityManager != null ) entityManager.close();
if ( entityManagerFactory != null ) entityManagerFactory.close();
}
return listLeaves;
}
My Employe.java(Entity):
package org.gdc.models;
import java.io.Serializable;
import javax.persistence.*;
import java.util.List;
/**
* The persistent class for the Employe database table.
*
*/
@Entity
@NamedQuery(name="Employe.findAll", query="SELECT e FROM Employe e")
public class Employe implements Serializable {
private static final long serialVersionUID = 1L;
@Id
private String login;
private String adresse;
@Column(name="code_postal")
private String codePostal;
private String mail;
private String nom;
private String pnom;
@Column(name="solde_congés")
private int soldeCongés;
private String ville;
//bi-directional one-to-one association to Authentification
@OneToOne(mappedBy="employe")
private Authentification authentification;
//bi-directional many-to-one association to Conge
@OneToMany(mappedBy="employe")
private List<Conge> conges;
//bi-directional many-to-one association to Ref_Equipe
@ManyToOne
@JoinColumn(name="equipe")
private Ref_Equipe refEquipe;
//bi-directional many-to-one association to Ref_Fonction
@ManyToOne
@JoinColumn(name="fonction")
private Ref_Fonction refFonction;
//bi-directional many-to-one association to Rendez_vous
@OneToMany(mappedBy="employe")
private List<Rendez_vous> rendezVouses;
public Employe() {
}
public String getLogin() {
return this.login;
}
public void setLogin(String login) {
this.login = login;
}
public String getAdresse() {
return this.adresse;
}
public void setAdresse(String adresse) {
this.adresse = adresse;
}
public String getCodePostal() {
return this.codePostal;
}
public void setCodePostal(String codePostal) {
this.codePostal = codePostal;
}
public String getMail() {
return this.mail;
}
public void setMail(String mail) {
this.mail = mail;
}
public String getNom() {
return this.nom;
}
public void setNom(String nom) {
this.nom = nom;
}
public String getPnom() {
return this.pnom;
}
public void setPnom(String pnom) {
this.pnom = pnom;
}
public int getSoldeCongés() {
return this.soldeCongés;
}
public void setSoldeCongés(int soldeCongés) {
this.soldeCongés = soldeCongés;
}
public String getVille() {
return this.ville;
}
public void setVille(String ville) {
this.ville = ville;
}
public Authentification getAuthentification() {
return this.authentification;
}
public void setAuthentification(Authentification authentification) {
this.authentification = authentification;
}
public List<Conge> getConges() {
return this.conges;
}
public void setConges(List<Conge> conges) {
this.conges = conges;
}
public Conge addConge(Conge conge) {
getConges().add(conge);
conge.setEmploye(this);
return conge;
}
public Conge removeConge(Conge conge) {
getConges().remove(conge);
conge.setEmploye(null);
return conge;
}
public Ref_Equipe getRefEquipe() {
return this.refEquipe;
}
public void setRefEquipe(Ref_Equipe refEquipe) {
this.refEquipe = refEquipe;
}
public Ref_Fonction getRefFonction() {
return this.refFonction;
}
public void setRefFonction(Ref_Fonction refFonction) {
this.refFonction = refFonction;
}
public List<Rendez_vous> getRendezVouses() {
return this.rendezVouses;
}
public void setRendezVouses(List<Rendez_vous> rendezVouses) {
this.rendezVouses = rendezVouses;
}
public Rendez_vous addRendezVous(Rendez_vous rendezVous) {
getRendezVouses().add(rendezVous);
rendezVous.setEmploye(this);
return rendezVous;
}
public Rendez_vous removeRendezVous(Rendez_vous rendezVous) {
getRendezVouses().remove(rendezVous);
rendezVous.setEmploye(null);
return rendezVous;
}
}
我的pom.xml:
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>ProjetJEE</groupId>
<artifactId>ProjetJEE</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<name>Leave Management System</name>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.18</version>
</dependency>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>eclipselink</artifactId>
<version>2.7.5</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.10</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.persistence</groupId>
<artifactId>persistence-api</artifactId>
<version>1.0.2</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.ejb</groupId>
<artifactId>ejb-api</artifactId>
<version>3.0</version>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<sourceDirectory>src</sourceDirectory>
<resources>
<resource>
<directory>src</directory>
<excludes>
<exclude>**/*.java</exclude>
</excludes>
</resource>
</resources>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
<configuration>
<release>12</release>
</configuration>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.1</version>
<configuration>
<warSourceDirectory>WebContent</warSourceDirectory>
</configuration>
</plugin>
</plugins>
</build>
</project>
还有我的persistence.xml:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1"
xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="ProjetJEE"
transaction-type="RESOURCE_LOCAL">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>org.gdc.models.Authentification</class>
<class>org.gdc.models.Conge</class>
<class>org.gdc.models.CongePK</class>
<class>org.gdc.models.Employe</class>
<class>org.gdc.models.Ref_Equipe</class>
<class>org.gdc.models.Ref_Etat_Conge</class>
<class>org.gdc.models.Ref_Fonction</class>
<class>org.gdc.models.Ref_Motif_Conge</class>
<class>org.gdc.models.Ref_Type_Conge</class>
<class>org.gdc.models.Rendez_vous</class>
<class>org.gdc.models.Rendez_vousPK</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/ProjetJEE" />
<property name="javax.persistence.jdbc.user" value="root" />
<property name="javax.persistence.jdbc.password" value="mysql" />
<property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver" />
<!-- <property name="eclipselink.logging.level" value="FINE" />
<property name="eclipselink.ddl-generation" value="create-tables" /> -->
</properties>
</persistence-unit>
</persistence>
在带有JEE,Maven,Mysql,Tomcat9,JPA的Eclipse上
如果您需要其他帮助我的人,请告诉我...
提前感谢
我唯一的观察结果是您正在从工厂创建EntityManager
,而没有注入上下文。这样,我认为您会在应用程序生命周期中发现问题。您必须自己处理事务(提交,回滚)。我看到您正在关闭决赛中的连接,但是我不知道您是否有交易或需要打开一个新交易。请参阅:PersistenceUnit vs PersistenceContext和https://www.logicbig.com/tutorials/java-ee-tutorial/jpa/entity-context.html