我是Hibernate的新手。我正在尝试实现 OneToMany 和 ManyToOne 映射，同时执行卡住和SQLGrammarException。
这是Category（pojo）类。
package com.app.pojos;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.hibernate.validator.constraints.NotBlank;
//Category class will have all master categories like Adventurous, tourist destinations etc.
@Entity
@Table(name="category")
public class Category {
private Integer cid;
private String name,image,desc;
private List<SubCategory> subcategories = new ArrayList<>();
public Category() {
}
public Category(String name, String image, String desc, List<SubCategory> subcategories) {
super();
this.name = name;
this.image = image;
this.desc = desc;
this.subcategories = subcategories;
}
public Category(Integer cid, String name, String image, String desc, List<SubCategory> subcategories) {
super();
this.cid = cid;
this.name = name;
this.image = image;
this.desc = desc;
this.subcategories = subcategories;
}
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
public Integer getCid() {
return cid;
}
public void setCid(Integer cid) {
this.cid = cid;
}
//This is category name
@NotBlank(message="Name is REQUIRED....")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
//This is category image to be displayed
@NotBlank(message="Please select an image....")
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
@NotBlank(message="desc is REQUIRED....")
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
//This is an INVERSE SIDE because it is not having foreign key......
@OneToMany(targetEntity=SubCategory.class,mappedBy="category",
cascade=CascadeType.ALL,fetch=FetchType.LAZY)
public List<SubCategory> getSubcategories() {
return subcategories;
}
public void setSubcategories(List<SubCategory> subcategories) {
this.subcategories = subcategories;
}
//Convenience method sub-category into category
public void addSubCategory(SubCategory sub) {
subcategories.add(sub);
sub.setCategory(this);
}
}
这是我的SubCategory（Pojo类）类。
package com.app.pojos;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import org.hibernate.validator.constraints.NotBlank;
@Entity
@Table(name="subcategory")
public class SubCategory {
private Integer scid;
private String name,image,desc;
private Category category;
public SubCategory() {
}
public SubCategory(String name, String image, String desc, Category category) {
super();
this.name = name;
this.image = image;
this.desc = desc;
this.category = category;
}
public SubCategory(Integer scid, String name, String image, String desc, Category category) {
super();
this.scid = scid;
this.name = name;
this.image = image;
this.desc = desc;
this.category = category;
}
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
public Integer getScid() {
return scid;
}
public void setScid(Integer scid) {
this.scid = scid;
}
@NotBlank(message="Name is REQUIRED")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@NotBlank(message="Please select an image")
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
@NotBlank(message="Desc is REQUIRED")
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
//This is the OWNING SIDE because it is having foreign key.....
@ManyToOne
@JoinColumn(name="cat_id")
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category = category;
}
}
这是我的主要方法。
package com.app.test;
import java.util.Scanner;
import com.app.dao.CategoryDao;
import com.app.pojos.Category;
import com.app.pojos.SubCategory;
import static utils.HibernateUtils.*;
public class Tester {
public static void main(String[] args) {
try(Scanner sc = new Scanner(System.in)) {
getSf();
System.out.println("Enter Category details.....Name,image,desc");
Category category = new Category();
category.setName(sc.nextLine());
category.setImage(sc.nextLine());
category.setDesc(sc.nextLine());
System.out.println("Enter sub category....Name,Image,desc");
SubCategory sub = new SubCategory();
sub.setName(sc.nextLine());
sub.setImage(sc.nextLine());
sub.setDesc(sc.nextLine());
category.addSubCategory(sub);
System.out.println("ID : "+ new CategoryDao().saveCatgory(category));
} catch (Exception e) {
e.printStackTrace();
}
finally {
getSf().close();
}
}
}
这是CategoryDao类。
package com.app.dao;
import org.hibernate.*;
import com.app.pojos.Category;
import static utils.HibernateUtils.*;
public class CategoryDao {
public String saveCatgory(Category c) {
Session hs = getSf().getCurrentSession();
Transaction tx = hs.beginTransaction();
try {
hs.save(c);
tx.commit();
} catch (HibernateException e) {
if (tx != null)
tx.rollback();
throw e;
}
return "Course added with ID=" + c.getCid();
}
}
这是我的hibernate.cfg.xml文件。
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.autocommit">false</property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.password"></property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/vov</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.current_session_context_class">thread</property>
<property name="hibernate.connection.pool_size">2</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
<property name="hibernate.show_sql">true</property>
<property name="hibernate.format_sql">true</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<mapping class="com.app.pojos.Category"/>
<mapping class="com.app.pojos.SubCategory"/>
</session-factory>
</hibernate-configuration>
这些是例外，我正在接受。这是完整的控制台
log4j:WARN No appenders could be found for logger (org.jboss.logging).
log4j:WARN Please initialize the log4j system properly.
Hibernate:
create table category (
cid integer not null auto_increment,
desc varchar(255) not null,
image varchar(255) not null,
name varchar(255) not null,
primary key (cid)
)
Hibernate:
create table subcategory (
scid integer not null auto_increment,
desc varchar(255) not null,
image varchar(255) not null,
name varchar(255) not null,
cat_id integer,
primary key (scid)
)
Hibernate:
alter table subcategory
add constraint FK2umvqgly5rb2aqk8v273tk4o5
foreign key (cat_id)
references category (cid)
sf created!!!!!
Enter Category details.....Name,image,desc
hlkj
khjlgfh
hgvnb
Enter sub category....Name,Image,desc
hjgctg
gcnb
hcgv
Hibernate:
insert
into
category
(desc, image, name)
values
(?, ?, ?)
org.hibernate.exception.SQLGrammarException: could not execute statement
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:63)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:207)
at org.hibernate.dialect.identity.GetGeneratedKeysDelegate.executeAndExtract(GetGeneratedKeysDelegate.java:57)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:42)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2907)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3478)
at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:81)
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:623)
at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:277)
at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:258)
at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:303)
at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:318)
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:275)
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:182)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:113)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:682)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:674)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:669)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:355)
at com.sun.proxy.$Proxy32.save(Unknown Source)
at com.app.dao.CategoryDao.saveCatgory(CategoryDao.java:13)
at com.app.test.Tester.main(Tester.java:26)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'desc, image, name) values ('hgvnb', 'khjlgfh', 'hlkj')' at line 1
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
at com.mysql.jdbc.Util.getInstance(Util.java:387)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:942)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3966)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3902)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2526)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2673)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2549)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1861)
at com.mysql.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2073)
at com.mysql.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2009)
at com.mysql.jdbc.PreparedStatement.executeLargeUpdate(PreparedStatement.java:5098)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1994)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:204)
... 29 more
答案 0 :(得分：0)
desc是一个SQL关键字。不要将其用作列名。无论如何，description更加清晰。