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我有一个Java Server Faces项目使用Hibernate将数据存储到PostgreSQL数据库。休眠不使用PostgreSQL序列来生成主键
我遇到的问题是，Hibernate不考虑现有序列（fifo_id_seq），同时将数据保存到数据库中;它保存着id = 0;
答案可能非常明显，因为我是Hibernate的新手。
对于大量的代码，我很抱歉，但我想发布一切可能相关的内容。
FIFO表：
Table "public.fifo"
Column | Type | Modifiers
---------------------+------------------+---------------------------------------------------
id | integer | not null default nextval('fifo_id_seq'::regclass)
number_of_processes | integer |
total_time | integer |
average_time | double precision |
average_wait_time | double precision |
total_wait_time | integer |
Indexes:
"fifo_pkey" PRIMARY KEY, btree (id)
的fifo_id_seq序列：
Sequence "public.fifo_id_seq"
Column | Type | Value
---------------+---------+---------------------
sequence_name | name | fifo_id_seq
last_value | bigint | 1
start_value | bigint | 1
increment_by | bigint | 1
max_value | bigint | 9223372036854775807
min_value | bigint | 1
cache_value | bigint | 1
log_cnt | bigint | 0
is_cycled | boolean | f
is_called | boolean | f
FifoEntity.java： *注：构造函数和由我添加@Id注释，产生
休息@Entity
@Table(name = "fifo", schema = "public", catalog = "processmanagement")
public class FifoEntity {
private int id;
private Integer numberOfProcesses;
private Integer totalTime;
private Double averageTime;
private Double averageWaitTime;
private Integer totalWaitTime;
public FifoEntity()
{
// empty
}
public FifoEntity(int numberOfProcesses, int totalTime, double averageTime, double averageWaitTime, int totalWaitTime)
{
this.numberOfProcesses = numberOfProcesses;
this.totalTime = totalTime;
this.averageTime = averageTime;
this.averageWaitTime = averageWaitTime;
this.totalWaitTime = totalWaitTime;
}
@Id
@SequenceGenerator(name="fifo_pkey", sequenceName="fifo_id_seq", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator="fifo_pkey")
@Column(name = "id", unique = true, nullable = false)
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@Basic
@Column(name = "number_of_processes")
public Integer getNumberOfProcesses() {
return numberOfProcesses;
}
public void setNumberOfProcesses(Integer numberOfProcesses) {
this.numberOfProcesses = numberOfProcesses;
}
@Basic
@Column(name = "total_time")
public Integer getTotalTime() {
return totalTime;
}
public void setTotalTime(Integer totalTime) {
this.totalTime = totalTime;
}
@Basic
@Column(name = "average_time")
public Double getAverageTime() {
return averageTime;
}
public void setAverageTime(Double averageTime) {
this.averageTime = averageTime;
}
@Basic
@Column(name = "average_wait_time")
public Double getAverageWaitTime() {
return averageWaitTime;
}
public void setAverageWaitTime(Double averageWaitTime) {
this.averageWaitTime = averageWaitTime;
}
@Basic
@Column(name = "total_wait_time")
public Integer getTotalWaitTime() {
return totalWaitTime;
}
public void setTotalWaitTime(Integer totalWaitTime) {
this.totalWaitTime = totalWaitTime;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
FifoEntity that = (FifoEntity) o;
if (id != that.id) return false;
if (averageTime != null ? !averageTime.equals(that.averageTime) : that.averageTime != null) return false;
if (averageWaitTime != null ? !averageWaitTime.equals(that.averageWaitTime) : that.averageWaitTime != null)
return false;
if (numberOfProcesses != null ? !numberOfProcesses.equals(that.numberOfProcesses) : that.numberOfProcesses != null)
return false;
if (totalTime != null ? !totalTime.equals(that.totalTime) : that.totalTime != null) return false;
if (totalWaitTime != null ? !totalWaitTime.equals(that.totalWaitTime) : that.totalWaitTime != null)
return false;
return true;
}
@Override
public int hashCode() {
int result = id;
result = 31 * result + (numberOfProcesses != null ? numberOfProcesses.hashCode() : 0);
result = 31 * result + (totalTime != null ? totalTime.hashCode() : 0);
result = 31 * result + (averageTime != null ? averageTime.hashCode() : 0);
result = 31 * result + (averageWaitTime != null ? averageWaitTime.hashCode() : 0);
result = 31 * result + (totalWaitTime != null ? totalWaitTime.hashCode() : 0);
return result;
}
}
FifoEntity映射到hbm.xml中： *
<class name="com.processmanagement.hibernate.entities.FifoEntity" table="fifo" schema="public" catalog="processmanagement">
<id name="id" column="id">
<generator class="sequence-identity">
<param name="sequence">fifo_id_seq</param>
</generator>
</id>
<property name="numberOfProcesses" column="number_of_processes"/>
<property name="totalTime" column="total_time"/>
<property name="averageTime" column="average_time"/>
<property name="averageWaitTime" column="average_wait_time"/>
<property name="totalWaitTime" column="total_wait_time"/>
</class>
这就是我怎样，我尝试使用Hibernate来保存数据到数据库：试图保存一个连续的对象时
FifoEntity fifoEntity = new FifoEntity(processList.size(), totalTime,
averageProcessTime, averageWaitTime, totalWaitTime);
databaseHelper.saveOutcomeToDatabase(fifoEntity);
.
.
.
public void saveOutcomeToDatabase(Object object)
{
// session.beginTransaction();
// session.save(object);
// session.getTransaction().commit();
Transaction transaction = session.beginTransaction();
session.persist(object);
transaction.commit();
session.clear();
}
当然，错误：
org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "fifo_pkey"
Detail: Key (id)=(0) already exists.