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具有不同的行爲啊，我知道，標題是有點混亂，但這裏的情況是：JPA在一個項目中插入觸發前執行，並在另一個
我有兩個項目，即應工作方式相同。他們都訪問Oracle數據庫。 Oracle數據庫上的每個表都有一個TABLENAME_ID列，它是主鍵，它與BEFORE INSERT觸發器相關聯，該觸發器執行TABLENAME_SEQ nextval（）以插入到TABLENAME_ID列中。 （瞭解？）。在這種環境下，通過SQL插入工作正常。
這就是說讓我們去的問題：
我有一個使用其中從數據庫表生成實體JPA一個PROJECT1。在這個項目上生成的實體工作正常，完成CRUD和搜索。實體與SequenceGenerator註釋相關聯，DOES不會在插入時執行數據庫觸發器，因此無論使用何種通道（系統或SQL DML語句），都會順序生成id行。
現在我必須創建第二個項目，該項目的行爲方式應該是相同的，但不是。在這個項目上，當我創建一個實體時，它會檢索我。即ID = 3，但實際上在數據庫上寫入ID = 4。所以，如果我得到這個相同的實體並嘗試對它進行更新，JPA會嘗試再次插入它，並給我一個錯誤。
任何線索？一些代碼如下波紋管：
實體實例（從Project 1）：
@Entity
public class Category implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@SequenceGenerator(name = "CATEGORY_CATEGORYID_GENERATOR", sequenceName = "CATEGORY_SEQ", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "CATEGORY_CATEGORYID_GENERATOR")
@Column(name = "CATEGORY_ID", unique = true, nullable = false, precision = 10)
private long categoryId;
@Column(name = "IS_ACTIVE", nullable = false, precision = 3)
private boolean isActive;
@Column(name = "LONG_TITLE", nullable = false, length = 250)
private String longTitle;
public Category() {
}
public long getCategoryId() {
return this.categoryId;
}
public boolean getIsActive() {
return this.isActive;
}
public String getLongTitle() {
return this.longTitle;
}
public void setCategoryId(long categoryId) {
this.categoryId = categoryId;
}
public void setIsActive(boolean isActive) {
this.isActive = isActive;
}
public void setLongTitle(String longTitle) {
this.longTitle = longTitle;
}
}
實體實例（從Project 2）：
@Entity
public class Author implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@SequenceGenerator(name = "AUTHOR_AUTHORID_GENERATOR", sequenceName = "AUTHOR_AUTHOR_ID_SEQ", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "AUTHOR_AUTHORID_GENERATOR")
@Column(name = "AUTHOR_ID", unique = true, nullable = false, precision = 10)
private long authorId;
@Column(name = "ADDRESS_COMPLEMENT")
private String addressComplement;
@Column(name = "AUTHOR_KIND")
private int authorKind;
@Column(name = "BUILDING_NUMBER")
private String buildingNumber;
private String city;
// bi-directional many-to-one association to Product
@OneToMany(mappedBy = "author")
private List<Product> products;
public Author() {
}
public String getAddressComplement() {
return addressComplement;
}
public long getAuthorId() {
return authorId;
}
public int getAuthorKind() {
return authorKind;
}
public String getBuildingNumber() {
return buildingNumber;
}
public String getCity() {
return city;
}
public List<Product> getProducts() {
return products;
}
public void setAddressComplement(String addressComplement) {
this.addressComplement = addressComplement;
}
public void setAuthorId(long authorId) {
this.authorId = authorId;
}
public void setAuthorKind(int authorKind) {
this.authorKind = authorKind;
}
public void setBuildingNumber(String buildingNumber) {
this.buildingNumber = buildingNumber;
}
public void setCity(String city) {
this.city = city;
}
public void setProducts(List<Product> products) {
this.products = products;
}
}
EDIT
如JScoobyCed問這裏遵循如何使用第二實體代碼：
// ...
Author author = new Author();
// Here follows setters
// Code below returns, ie, author_id = 3, but saves author_id = 4 on database
author = authotEjb.create(author);
// ...
product.setAuthor(author);
// Don't find author_id = 3 on database and tries to insert author again
// or complains about PERSIST cascade on Product entitiy.
product = productEjb.update(product)
EJB在create（）方法上使用EntityManager.persist（），在update方法上使用EntityManager.merge（）。
編輯2
添加的順序和觸發碼。每個表都有它自己的序列和它自己的觸發遵循相同的模式TABLENAME_SEQ和TABLENAME_TRG：
序列碼：
CREATE SEQUENCE AUTHOR_SEQ MINVALUE 1 MAXVALUE 9999999999999999999999999999 INCREMENT BY 1 START WITH 1 NOCACHE ORDER NOCYCLE;
觸發代碼：
create or replace
trigger author_trg before insert on author
for each row
begin
select author_seq.nextval into :new.author_id from dual;
end;
你能發表關於你如何使用這些實體的代碼，特別是你的第二個項目。也許你的實體沒有（不再）由JPA在你想更新的時候管理。 – JScoobyCed
嗨JScoobyCed，編輯。 –
兩個表上的觸發器是否相同？如果在設置之前已經設置了id，是否觸發類別檢查？ – Nemanja