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過去4小時我正在處理此JPA問題。最後我放棄了，所以我要求你的幫助。到目前爲止，我嘗試了幾乎所有建議的解決方案。JPA：重複輸入主鍵
我嘗試，
1）映射改變（@ManyToOne，@OneToOne，@OneToMany）
2）級聯選項（持續，MERGE，ALL ..）
3）禁用緩存
3）許多其他嘗試，不像1,2和3 spesific。只是希望。 :)
的TestClass
public class testClass {
public static void main(String[] args) {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("CSE_482_Project_4_-_PersistencePU");
EntityManager em = emf.createEntityManager();
EntityTransaction tx = em.getTransaction();
File parentFile = new File("cleardata");
File[] allFiles = parentFile.listFiles();
File myFile;
int k = 1;
for(int f =0; f<allFiles.length; f++){
try {
myFile=allFiles[f];
BufferedReader br = new BufferedReader(new FileReader(myFile));
String tempDate = br.readLine();
tempDate = tempDate.substring(17);
String[] tempDateArr = tempDate.split(" ");
int day = Integer.parseInt(tempDateArr[0]);
int month = Integer.parseInt(tempDateArr[1]);
int year = Integer.parseInt(tempDateArr[2]);
Date leavingDate = new Date(year, month, day);
String studentNumber = br.readLine().substring(13);
boolean minor = true;
if (br.readLine().contains("false")) {
minor = false;
}
Student stu = new Student(studentNumber, leavingDate);
stu.setMinorDegree(minor);
tx.begin();
em.persist(stu);
tx.commit();
String currentLine;
Slot s;
Course c;
SlotAndCourse sc;
int semester = 0;
String courseCode = "";
String slotName = "";
int credit = 0;
String termTaken = "";
int yearTaken = 0;
String grade = "";
boolean semesterSet = false;
boolean courseSet = false;
boolean gradesSet = false;
int count = 0;
while ((currentLine = br.readLine()) != null) {
String[] arr = currentLine.split(" ");
if (arr[0].equals("semester")) {
semester = Integer.parseInt(arr[1]);
semesterSet = true;
} else if (arr[0].matches("^([0-9]+[a-zA-Z]+|[a-zA-Z]+[0-9]+)[0-9a-zA-Z]*$")) { // contains both latters and digits CS112
courseCode = arr[0];
slotName = arr[1];
credit = Integer.parseInt(arr[2]);
courseSet = true;
} else if (arr[0].equals("numberofattempts")) {
int n = Integer.parseInt(arr[1]);
for (int i = 0; i < n; i++) {
currentLine = br.readLine();
System.out.println(currentLine);
arr = currentLine.split(" ");
yearTaken = Integer.parseInt(arr[0]);
termTaken = arr[1];
grade = arr[2];
}
gradesSet = true;
}
if (gradesSet && courseSet && semesterSet) {
s = new Slot();
c = new Course(courseCode);
s.setCredit(credit);
s.setSemester(semester);
s.setSlotName(slotName);
s.setSlotCode("" + k);
c.setCourseCode(courseCode);
sc = new SlotAndCourse(s,c,yearTaken,termTaken);
sc.setCourse(c);
sc.setSlot(s);
sc.setGrade(grade);
tx.begin();
em.clear(); // just a try, but didn't work
em.persist(sc);
tx.commit();
courseSet = false;
semesterSet = false;
gradesSet = false;
k++;
}
}
} catch (Exception ex) {
System.out.println(ex.toString());
ex.printStackTrace();
}
}
em.close();
}
}
學生班級
@Entity
@Cacheable(false)
public class Student implements Serializable {
@Id
private String studentNumber;
@Temporal(TemporalType.DATE)
private Date leavIngDate;
private boolean mInorDegree;
public Student() {
}
public Student(String studentNumber, Date leavingDate) {
this.studentNumber = studentNumber;
this.leavIngDate = leavingDate;
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof Slot)) {
return false;
}
Student other = (Student) obj;
if ((this.studentNumber == null && other.studentNumber != null) || (this.studentNumber != null && !this.studentNumber.equals(other.studentNumber))) {
return false;
}
return true;
}
@Override
public int hashCode() {
int hash = 0;
hash += (studentNumber != null ? studentNumber.hashCode() : 0);
return hash;
}
// setters and getters
課程班
@Entity
@Cacheable(false)
public class Course implements Serializable {
@Id
private String courseCode;
public Course() {
}
public Course(String courseCode) {
this.courseCode = courseCode;
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof Course)) {
return false;
}
Course other = (Course) obj;
if ((this.courseCode == null && other.courseCode != null) || (this.courseCode != null && !this.courseCode.equals(other.courseCode))) {
return false;
}
return true;
}
@Override
public int hashCode() {
int hash = 0;
hash += (courseCode != null ? courseCode.hashCode() : 0);
return hash;
}
//setters and getters
時隙等級
@Entity
@Cacheable(false)
public class Slot implements Serializable {
@Id
private String slotCode;
private String slotName;
private int credIt;
private int semester;
public Slot() {
}
public Slot(String slotCode, String slotName) {
this.slotCode = slotCode;
this.slotName = slotName;
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof Slot)) {
return false;
}
Slot other = (Slot) obj;
if ((this.slotCode == null && other.slotCode != null) || (this.slotCode != null && !this.slotCode.equals(other.slotCode))) {
return false;
}
return true;
}
@Override
public int hashCode() {
int hash = 0;
hash += (slotCode != null ? slotCode.hashCode() : 0);
return hash;
//setters getters
SlotAndCourse類
@Entity
@Cacheable(false)
public class SlotAndCourse implements Serializable {
@EmbeddedId
protected SlotAndCoursePK slotAndCoursePK;
@JoinColumn(name = "SLOTCODE", referencedColumnName = "SLOTCODE", insertable = false, updatable = false)
@ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.ALL})
private Slot slot;
@JoinColumn(name = "COURSECODE", referencedColumnName = "COURSECODE", insertable = false, updatable = false)
@ManyToOne(cascade = CascadeType.PERSIST)
private Course course;
private String grade;
public SlotAndCourse() {
}
public SlotAndCourse(SlotAndCoursePK slotAndCoursePK) {
this.slotAndCoursePK = slotAndCoursePK;
}
public SlotAndCourse(String slotCode, String courseCode, int yearTaken, String termTaken) {
this.slotAndCoursePK = new SlotAndCoursePK(slotCode, courseCode, yearTaken, termTaken);
}
public SlotAndCourse(Slot s, Course c, int yearTaken, String termTaken) {
this.slot = s;
this.course = c;
this.slotAndCoursePK = new SlotAndCoursePK(s.getSlotCode(), c.getCourseCode(),yearTaken,termTaken);
}
@Override
public boolean equals(Object obj) {
if(obj instanceof SlotAndCourse){
SlotAndCourse arg = (SlotAndCourse)obj;
return this.slotAndCoursePK.equals(arg.slotAndCoursePK);
}
else if(obj instanceof SlotAndCoursePK){
SlotAndCoursePK arg = (SlotAndCoursePK)obj;
return this.slotAndCoursePK.equals(arg);
}
return false;
}
@Override
public int hashCode() {
int hash = 0;
hash += (slotAndCoursePK != null ? slotAndCoursePK.hashCode() : 0);
return hash;
}
SlontAndCoursePK類
@Embeddable
public class SlotAndCoursePK implements Serializable{
protected String slotCode;
protected String courseCode;
protected int yearTaken;
protected String termTaken;
public SlotAndCoursePK() {
}
public SlotAndCoursePK(String slotCode, String courseCode, int yearTaken, String termTaken) {
this.slotCode = slotCode;
this.courseCode = courseCode;
this.yearTaken = yearTaken;
this.termTaken = termTaken;
}
@Override
public int hashCode() {
int hash = 0;
hash += (slotCode != null ? slotCode.hashCode() : 0);
hash += (courseCode != null ? courseCode.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 SlotAndCoursePK)) {
return false;
}
SlotAndCoursePK other = (SlotAndCoursePK) object;
if ((this.slotCode == null && other.slotCode != null) || (this.slotCode != null && !this.slotCode.equals(other.slotCode))) {
return false;
}
if ((this.courseCode == null && other.courseCode != null) || (this.courseCode != null && !this.courseCode.equals(other.courseCode))) {
return false;
}
return true;
}
// setters and getters
我覺得應對和粘貼在這裏所有的代碼那麼糟糕。我希望有人能幫助我瞭解我失蹤的事情。 testClass的第一部分是從現有結構良好的文本文件中讀取數據並填充相關的數據字段。
當我運行調試時會發生什麼; 首先一切都很好，它將學生，課程，slotAndCourses添加到數據庫按預期，但是當一個slotAndCourse實例與現有的數據庫中的courseCode創建和特林持久（不知道它是否是正確的詞）數據庫它給了我重複在課程表中的主鍵項目。
錯誤看起來是這樣的：
javax.persistence.RollbackException：異常[的EclipseLink-4002]（Eclipse持久服務 - 2.5.2.v20140319-9ad6abd）：org.eclipse.persistence.exceptions.DatabaseException javax.persistence.RollbackException：異常[EclipseLink-4002]（Eclipse持久性服務 - 2.5.2.v20140319-9ad6abd）：org.eclipse.persistence.exceptions.DatabaseException 內部異常：com.mysql.jdbc.exceptions.jdbc4。 MySQLIntegrityConstraintViolationException：重複項'cse110'爲'PRIMARY'鍵' 內部異常：com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationEx ception：重複鍵'cse110'鍵'PRIMARY' 錯誤代碼：1062 錯誤代碼：1062 調用：INSERT INTO COURSE（COURSECODE）VALUES（？） 調用：INSERT INTO COURSE（COURSECODE）VALUES（？）
現在我更好地瞭解你在做什麼，刪除我的答案。它與你的問題沒有關係，所以我將發表評論，如果變量聲明在何處，而不是在沒有其他變量使用的更高範圍中，那麼讀取代碼會更容易。在你擁有它的形式中，讀者只需要閱讀每個變量的所有內容，看看它是否在其他地方使用。更重要的是，你可能會這樣找到自己的問題。 –
開始之前數據庫是否爲空？ – gfelisberto
持久性設置設置爲「拖放和創建」，因此每次首次刪除所有模式並重新創建。這只是我現在的一個模板，它有點混亂。我會盡量讓它更容易閱讀:) – user2949556