Part 3 of creating the siark.com Gallery involves adding the keywords. This requires a new domain object, Keyword and a many to many relationship between the gallery object and the keyword object with the gallery object being the ‘owner’ or the relationship.
The Keyword class.
package com.siark.igallery.domain;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
@Entity
@Table(name = "keyword")
public class Keyword extends DomainBase {
private static final long serialVersionUID = 3747792588358317008L;
private String text;
private Set<Gallery> galleries = new HashSet<Gallery>();
/**
*
*/
public Keyword() {
}
/**
* Construct a new keyword with the keyword text. A keyword can include spaces.
* The keyword text is not case sensitive and blank spaces are removed.
*
* @param text the keyword
*/
public Keyword(String text) {
this.text = text.toLowerCase().trim();
}
/**
* Get the text of the keyword.
*
* @return the keyword text
*/
@Column(name="text")
public String getText() {
return text;
}
/**
* Set the text of the keyword. A keyword can include spaces.
* The keyword text is not case sensitive and blank spaces at the end are removed.
*
* @param text the keyword text
*/
public void setText(String text) {
this.text = text;
}
/**
* Get the galleries associated with this keyword.
*
* @return galleries associated with this keyword
*/
@ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE},
mappedBy = "keywords",
targetEntity = Gallery.class)
public Set<Gallery> getGalleries() {
return galleries;
}
/**
* Set the galleries associated with this keyword.
*
* @param galleries the galleries associated with this keyword.
*/
public void setGalleries(Set<Gallery> galleries) {
this.galleries = galleries;
}
/**
*
*/
@Override
public String toString() {
StringBuffer buffer = new StringBuffer();
buffer.append(super.toString());
buffer.append("Text: " + text + ";");
return buffer.toString();
}
/**
*
*/
@Override
public boolean equals(Object o) {
if (o == this) return true;
if (!(o instanceof Keyword)) return false;
Keyword keyword = (Keyword) o;
if ((this.id == keyword.getId())
&& (this.text == null) ? (keyword.getText() == null) : keyword.getText().equals(this.text)) {
return true;
} else {
return false;
}
}
/**
*
*/
@Override
public int hashCode() {
int result = 17;
result = 31 * result + this.id;
result = 31 * result + (this.text == null ? 0 : this.text.hashCode());
return result;
}
}
The Gallery class must now be updated to include keywords. I am also including the notion of a gallery being a leaf. That is a leaf gallery may not be the parent of any other galleries.
package com.siark.igallery.domain;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.ForeignKey;
import org.hibernate.validator.constraints.NotEmpty;
@Entity
@Table(name = "gallery")
public class Gallery extends DomainBase {
private static final long serialVersionUID = -3449742178300288206L;
private String title;
private Gallery parent;
private List<Gallery> children = new ArrayList<Gallery>();
private Set<Keyword> keywords = new HashSet<Keyword>();
boolean leaf = false;
/**
* Construct a new gallery with the display name of the gallery.
* Blank spaces at the end of the title are removed.
*
* @param title the display name of the gallery
*/
public Gallery(String title) {
this.title = title.trim();
}
/**
*
*/
public Gallery() {
}
/**
* Returns the display name of the gallery.
*
* @return title the display name of the gallery
*/
@Column(name = "title")
@NotEmpty
public String getTitle() {
return title;
}
/**
* Sets the display name of the gallery.
* Blank spaces at the end of the title are removed.
*
* @param title the display name of the gallery
*/
public void setTitle(String title) {
this.title = title.trim();
}
/**
* Returns the gallery that is the parent to this gallery.
* A gallery has only one parent.
*
* @return the gallery that is this galleries parent
*/
@ManyToOne
@JoinColumn(name="parent_fk")
@ForeignKey(name="to_parent_fk")
public Gallery getParent() {
return this.parent;
}
/**
* Sets this galleries parent.
*
* @param the parent gallery
*/
public void setParent(Gallery parent) {
this.parent = parent;
}
/**
* If this gallery is a non-leaf gallery it can have zero or more child galleries.
*
* @return a list of this galleries children
*/
@OneToMany
@JoinColumn(name="parent_fk")
public List<Gallery> getChildren() {
return children;
}
/**
* Child galleries can only be added to this gallery if this gallery is a non-leaf gallery.
*
* @param the list of this galleries child galleries
*/
public void setChildren(List<Gallery> children) throws GalleryException {
if (!this.leaf || children.isEmpty() || (children == null)) this.children = children;
else throw new GalleryException();
}
/**
* Get the keywords associated with this gallery.
*
* @return a set of keywords
*/
@ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE},
targetEntity = Keyword.class)
@JoinTable(name = "gallery_keyword",
joinColumns = @JoinColumn(name = "gallery_fk"),
inverseJoinColumns = @JoinColumn(name="keyword_fk"))
@ForeignKey(name = "to_gallery_fk", inverseName = "to_keyword_fk")
@Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE)
public Set<Keyword> getKeywords() {
return keywords;
}
/**
* Set the keywords associated with this gallery. A gallery may have zero or more keywords,
* but no duplicate keywords.
*
* @param keywords a set of keywords
*/
public void setKeywords(Set<Keyword> keywords) {
this.keywords = keywords;
}
/**
* A leaf gallery may not be the parent of any other galleries.
*
* @return true if this gallery is a leaf otherwise false
*/
@Column(name="leaf")
public boolean isLeaf() {
return leaf;
}
/**
* The value of leaf can only be set to true if there are no children.
*
* @param leaf
*/
public void setLeaf(boolean leaf) {
this.leaf = leaf;
}
/**
*
*/
@Override
public String toString() {
StringBuffer buffer = new StringBuffer();
buffer.append(super.toString());
buffer.append("Title: " + this.title + "; ");
buffer.append(this.parent == null ? "Parent: null ; " : "Parent: " + this.parent.getId() + "; ");
buffer.append("Children: ");
for (Iterator<Gallery> i = this.children.iterator(); i.hasNext();) {
buffer.append(i.next().getTitle());
buffer.append(i.hasNext() ? ", " : "; ");
}
buffer.append("Keywords: ");
for (Iterator<Keyword> i = this.keywords.iterator(); i.hasNext();) {
buffer.append(i.next());
buffer.append(i.hasNext() ? ", " : "; ");
}
buffer.append("isLeaf: " + this.leaf + ";");
return buffer.toString();
}
/**
*
*/
@Override
public boolean equals(Object o) {
if (o == this) return true;
if (!(o instanceof Gallery)) return false;
if (getClass() != o.getClass()) return false;
Gallery gallery = (Gallery) o;
if ((this.id == gallery.getId())
&& (this.title == null) ? (gallery.getTitle() == null) : gallery.getTitle().equals(this.title)
&& (this.parent == null) ? (gallery.getParent() == null) : gallery.getParent().equals(this.parent)
&& this.children.equals(gallery.getChildren())
&& this.keywords.equals(gallery.getKeywords())
&& this.leaf == gallery.leaf) {
return true;
} else {
return false;
}
}
/**
*
*/
@Override
public int hashCode() {
int result = 17;
result = 31 * result + this.id;
result = 31 * result + (this.title == null ? 0 : this.title.hashCode());
result = 31 * result + (this.parent == null ? 0 : this.parent.hashCode());
result = 31 * result + this.children.hashCode();
result = 31 * result + this.keywords.hashCode();
result = 31 * result + (this.leaf ? 1 : 0);
return result;
}
}
I now need to create a dao for the keyword class.
package com.siark.igallery.repository;
import com.siark.igallery.domain.Keyword;
public interface KeywordDao {
public void persistKeyword(Keyword keyword);
public Keyword findKeywordByKeyword(String keyword);
public Keyword findKeywordById(int id);
}
package com.siark.igallery.repository;
import javax.inject.Inject;
import javax.inject.Named;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.SessionFactory;
import com.siark.igallery.domain.Keyword;
@Named("KeywordDao")
public class HibernateKeywordDao implements KeywordDao {
protected final Log logger = LogFactory.getLog(getClass());
private SessionFactory sessionFactory;
/**
* Save a new keyword or update an existing keyword.
*
* @param keyword a new or existing keyword
*/
public void persistKeyword(Keyword keyword) {
this.sessionFactory.getCurrentSession()
.saveOrUpdate(keyword);
}
/**
* Find the keyword with a specific id or null if a keyword with that id does not exist.
*
* @param id the id of the keyword to find
* @return a keyword with the id specified or null
*/
public Keyword findKeywordById(int id) {
return (Keyword) this.sessionFactory.getCurrentSession()
.createQuery("from Keyword as keyword where keyword.id = :id")
.setInteger("id", id)
.uniqueResult();
}
/**
* Find the keyword with the specified text.
*
* @param text the text the keyword must contain
* @return the keyword containing the specified text
*/
public Keyword findKeywordByKeyword(String text) {
return (Keyword) this.sessionFactory.getCurrentSession()
.createQuery("from Keyword as keyword where text = :text")
.setString("text", text)
.uniqueResult();
}
/**
*
*/
@Inject
public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
}
Now I need a service.
package com.siark.igallery.service;
import java.util.Set;
import com.siark.igallery.domain.Keyword;
public interface KeywordService {
public void persistKeyword(Keyword keyword);
public Keyword getKeyword(String Keyword);
public Set<Keyword> getKeywords(Set<String> Keywords);
public Keyword findKeywordById(int id);
public Keyword findKeywordByKeyword(String keyword);
}
package com.siark.igallery.service;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import javax.inject.Inject;
import javax.inject.Named;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
import com.siark.igallery.domain.Keyword;
import com.siark.igallery.repository.KeywordDao;
@Named("KeywordService")
@Transactional(propagation=Propagation.SUPPORTS, readOnly=true)
public class KeywordServiceImpl implements KeywordService {
protected final Log logger = LogFactory.getLog(getClass());
@Inject
@Named("KeywordDao")
private KeywordDao keywordDao;
/**
*
*
* @param keyword
*/
@Transactional(propagation=Propagation.REQUIRED, readOnly=false)
public void persistKeyword(Keyword keyword) {
keywordDao.persistKeyword(keyword);
}
/**
*
*
* @param id
* @return
*/
public Keyword findKeywordById(int id) {
return keywordDao.findKeywordById(id);
}
/**
*
*
* @param keyword
* @return
*/
public Keyword findKeywordByKeyword(String keyword) {
return keywordDao.findKeywordByKeyword(keyword);
}
/**
*
*
* @param keywordStr
* @return
*/
public Keyword getKeyword(String keywordStr) {
Keyword keyword = keywordDao.findKeywordByKeyword(keywordStr);
if (keyword == null) {
keyword = new Keyword(keywordStr);
keywordDao.persistKeyword(keyword);
return keywordDao.findKeywordByKeyword(keywordStr);
}
return keyword;
}
/**
*
*
* @param keywordsStrs
* @return
*/
public Set<Keyword> getKeywords(Set<String> keywordStrs) {
Set<Keyword> keywords = new HashSet<Keyword>();
for (Iterator<String> i = keywordStrs.iterator(); i.hasNext();) {
String keywordStr = i.next();
keywords.add(getKeyword(keywordStr));
}
return keywords;
}
/**
*
*
* @param keywordDao
*/
public void setKeywordDao(KeywordDao keywordDao) {
this.keywordDao = keywordDao;
}
/**
*
*
* @return
*/
public KeywordDao getKeywordDao() {
return keywordDao;
}
}
I’ve added Spring transactions to the service classes so I have to add transactional support to the db-config.xml file.
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:jdbc.properties</value>
<value>classpath:igallery.properties</value>
</list>
</property>
</bean>
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="${jdbc.driverClassName}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
</bean>
<!-- Hibernate SessionFactory -->
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="packagesToScan" value="com.siark.igallery.domain" />
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</prop>
</props>
</property>
</bean>
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
<tx:annotation-driven />
</beans>
I have also removed the flushModeName property from the mvc-config.xml file.
siark.com blog 