425 lines
11 KiB
XML
425 lines
11 KiB
XML
<chapter id="example-weblog">
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<title>示例：Weblog 应用程序</title>
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<sect1 id="example-weblog-classes">
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<title>持久化类</title>
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<para> 下面的持久化类表示一个weblog和在其中张贴的一个贴子。他们是标准的父/子关系模型，但是我们会用一个有序包（ordered bag)而非集合(set)。
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</para>
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<programlisting><![CDATA[package eg;
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import java.util.List;
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public class Blog {
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private Long _id;
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private String _name;
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private List _items;
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public Long getId() {
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return _id;
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}
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public List getItems() {
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return _items;
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}
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public String getName() {
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return _name;
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}
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public void setId(Long long1) {
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_id = long1;
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}
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public void setItems(List list) {
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_items = list;
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}
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public void setName(String string) {
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_name = string;
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}
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}]]></programlisting>
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<programlisting><![CDATA[package eg;
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import java.text.DateFormat;
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import java.util.Calendar;
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public class BlogItem {
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private Long _id;
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private Calendar _datetime;
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private String _text;
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private String _title;
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private Blog _blog;
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public Blog getBlog() {
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return _blog;
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}
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public Calendar getDatetime() {
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return _datetime;
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}
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public Long getId() {
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return _id;
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}
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public String getText() {
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return _text;
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}
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public String getTitle() {
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return _title;
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}
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public void setBlog(Blog blog) {
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_blog = blog;
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}
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public void setDatetime(Calendar calendar) {
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_datetime = calendar;
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}
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public void setId(Long long1) {
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_id = long1;
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}
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public void setText(String string) {
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_text = string;
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}
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public void setTitle(String string) {
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_title = string;
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}
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}]]></programlisting>
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</sect1>
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<sect1 id="example-weblog-mappings">
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<title>Hibernate 映射</title>
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<para>
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下列的XML映射应该是很直白的。
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</para>
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<programlisting><![CDATA[<?xml version="1.0"?>
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<!DOCTYPE hibernate-mapping PUBLIC
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"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
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"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
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<hibernate-mapping package="eg">
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<class
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name="Blog"
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table="BLOGS" >
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<id
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name="id"
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column="BLOG_ID">
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<generator class="native"/>
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</id>
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<property
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name="name"
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column="NAME"
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not-null="true"
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unique="true"/>
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<bag
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name="items"
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inverse="true"
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order-by="DATE_TIME"
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cascade="all">
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<key column="BLOG_ID"/>
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<one-to-many class="BlogItem"/>
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</bag>
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</class>
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</hibernate-mapping>]]></programlisting>
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<programlisting><![CDATA[<?xml version="1.0"?>
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<!DOCTYPE hibernate-mapping PUBLIC
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"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
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"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
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<hibernate-mapping package="eg">
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<class
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name="BlogItem"
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table="BLOG_ITEMS"
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dynamic-update="true">
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<id
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name="id"
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column="BLOG_ITEM_ID">
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<generator class="native"/>
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</id>
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<property
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name="title"
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column="TITLE"
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not-null="true"/>
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<property
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name="text"
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column="TEXT"
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not-null="true"/>
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<property
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name="datetime"
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column="DATE_TIME"
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not-null="true"/>
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<many-to-one
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name="blog"
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column="BLOG_ID"
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not-null="true"/>
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</class>
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</hibernate-mapping>]]></programlisting>
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</sect1>
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<sect1 id="example-weblog-code">
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<title>Hibernate 代码</title>
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<para>
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下面的类演示了我们可以使用Hibernate对这些类进行的一些操作。
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</para>
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<programlisting><![CDATA[package eg;
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import java.util.ArrayList;
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import java.util.Calendar;
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import java.util.Iterator;
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import java.util.List;
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import org.hibernate.HibernateException;
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import org.hibernate.Query;
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import org.hibernate.Session;
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import org.hibernate.SessionFactory;
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import org.hibernate.Transaction;
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import org.hibernate.cfg.Configuration;
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import org.hibernate.tool.hbm2ddl.SchemaExport;
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public class BlogMain {
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private SessionFactory _sessions;
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public void configure() throws HibernateException {
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_sessions = new Configuration()
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.addClass(Blog.class)
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.addClass(BlogItem.class)
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.buildSessionFactory();
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}
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public void exportTables() throws HibernateException {
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Configuration cfg = new Configuration()
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.addClass(Blog.class)
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.addClass(BlogItem.class);
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new SchemaExport(cfg).create(true, true);
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}
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public Blog createBlog(String name) throws HibernateException {
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Blog blog = new Blog();
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blog.setName(name);
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blog.setItems( new ArrayList() );
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Session session = _sessions.openSession();
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Transaction tx = null;
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try {
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tx = session.beginTransaction();
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session.persist(blog);
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tx.commit();
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}
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catch (HibernateException he) {
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if (tx!=null) tx.rollback();
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throw he;
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}
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finally {
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session.close();
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}
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return blog;
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}
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public BlogItem createBlogItem(Blog blog, String title, String text)
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throws HibernateException {
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BlogItem item = new BlogItem();
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item.setTitle(title);
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item.setText(text);
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item.setBlog(blog);
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item.setDatetime( Calendar.getInstance() );
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blog.getItems().add(item);
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Session session = _sessions.openSession();
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Transaction tx = null;
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try {
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tx = session.beginTransaction();
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session.update(blog);
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tx.commit();
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}
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catch (HibernateException he) {
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if (tx!=null) tx.rollback();
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throw he;
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}
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finally {
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session.close();
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}
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return item;
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}
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public BlogItem createBlogItem(Long blogid, String title, String text)
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throws HibernateException {
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BlogItem item = new BlogItem();
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item.setTitle(title);
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item.setText(text);
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item.setDatetime( Calendar.getInstance() );
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Session session = _sessions.openSession();
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Transaction tx = null;
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try {
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tx = session.beginTransaction();
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Blog blog = (Blog) session.load(Blog.class, blogid);
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item.setBlog(blog);
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blog.getItems().add(item);
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tx.commit();
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}
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catch (HibernateException he) {
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if (tx!=null) tx.rollback();
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throw he;
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}
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finally {
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session.close();
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}
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return item;
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}
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public void updateBlogItem(BlogItem item, String text)
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throws HibernateException {
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item.setText(text);
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Session session = _sessions.openSession();
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Transaction tx = null;
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try {
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tx = session.beginTransaction();
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session.update(item);
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tx.commit();
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}
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catch (HibernateException he) {
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if (tx!=null) tx.rollback();
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throw he;
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}
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finally {
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session.close();
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}
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}
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public void updateBlogItem(Long itemid, String text)
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throws HibernateException {
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Session session = _sessions.openSession();
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Transaction tx = null;
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try {
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tx = session.beginTransaction();
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BlogItem item = (BlogItem) session.load(BlogItem.class, itemid);
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item.setText(text);
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tx.commit();
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}
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catch (HibernateException he) {
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if (tx!=null) tx.rollback();
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throw he;
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}
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finally {
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session.close();
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}
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}
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public List listAllBlogNamesAndItemCounts(int max)
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throws HibernateException {
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Session session = _sessions.openSession();
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Transaction tx = null;
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List result = null;
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try {
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tx = session.beginTransaction();
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Query q = session.createQuery(
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"select blog.id, blog.name, count(blogItem) " +
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"from Blog as blog " +
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"left outer join blog.items as blogItem " +
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"group by blog.name, blog.id " +
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"order by max(blogItem.datetime)"
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);
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q.setMaxResults(max);
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result = q.list();
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tx.commit();
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}
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catch (HibernateException he) {
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if (tx!=null) tx.rollback();
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throw he;
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}
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finally {
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session.close();
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}
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return result;
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}
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public Blog getBlogAndAllItems(Long blogid)
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throws HibernateException {
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Session session = _sessions.openSession();
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Transaction tx = null;
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Blog blog = null;
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try {
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tx = session.beginTransaction();
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Query q = session.createQuery(
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"from Blog as blog " +
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"left outer join fetch blog.items " +
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"where blog.id = :blogid"
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);
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q.setParameter("blogid", blogid);
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blog = (Blog) q.uniqueResult();
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tx.commit();
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}
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catch (HibernateException he) {
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if (tx!=null) tx.rollback();
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throw he;
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}
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finally {
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session.close();
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}
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return blog;
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}
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public List listBlogsAndRecentItems() throws HibernateException {
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Session session = _sessions.openSession();
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Transaction tx = null;
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List result = null;
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try {
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tx = session.beginTransaction();
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Query q = session.createQuery(
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"from Blog as blog " +
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"inner join blog.items as blogItem " +
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"where blogItem.datetime > :minDate"
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);
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Calendar cal = Calendar.getInstance();
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cal.roll(Calendar.MONTH, false);
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q.setCalendar("minDate", cal);
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result = q.list();
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tx.commit();
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}
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catch (HibernateException he) {
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if (tx!=null) tx.rollback();
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throw he;
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}
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finally {
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session.close();
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}
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return result;
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}
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}]]></programlisting>
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</sect1>
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</chapter>
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