tutorial.po

hibernate 开源框架的代码 jar包希望大家能喜欢

#. Tag: programlisting
#: tutorial.xml:494
#, no-c-format
msgid ""
"<![CDATA[private List listEvents() {\n"
"\n"
"    Session session = HibernateUtil.getSessionFactory().getCurrentSession"
"();\n"
"\n"
"    session.beginTransaction();\n"
"\n"
"    List result = session.createQuery(\"from Event\").list();\n"
"\n"
"    session.getTransaction().commit();\n"
"\n"
"    return result;\n"
"}]]>"
msgstr ""

#. Tag: para
#: tutorial.xml:496
#, no-c-format
msgid ""
"What we do here is use an HQL (Hibernate Query Language) query to load all "
"existing <literal>Event</literal> objects from the database. Hibernate will "
"generate the appropriate SQL, send it to the database and populate "
"<literal>Event</literal> objects with the data. You can create more complex "
"queries with HQL, of course."
msgstr ""
"我们在这里是用一个HQL（Hibernate Query Language－Hibernate查询语言）查询语句"
"来从数据库中加载所有存在的<literal>Event</literal>对象。Hibernate会生成适当的"
"SQL，把它发送到数据库，并操作从查询得到数据的<literal>Event</literal>对象。当"
"然，你可以使用HQL来创建更加复杂的查询。"

#. Tag: para
#: tutorial.xml:503
#, no-c-format
msgid "Now, to execute and test all of this, follow these steps:"
msgstr "现在，根据以下步骤来执行并测试以上各项："

#. Tag: para
#: tutorial.xml:509
#, no-c-format
msgid ""
"Run <literal>ant run -Daction=store</literal> to store something into the "
"database and, of course, to generate the database schema before through "
"hbm2ddl."
msgstr ""
"运行<literal>ant run -Daction=store</literal>来保存一些内容到数据库。当然，先"
"得用hbm2ddl来生成数据库schema。"

#. Tag: para
#: tutorial.xml:515
#, no-c-format
msgid ""
"Now disable hbm2ddl by commenting out the property in your "
"<literal>hibernate.cfg.xml</literal> file. Usually you only leave it turned "
"on in continous unit testing, but another run of hbm2ddl would "
"<emphasis>drop</emphasis> everything you have stored - the <literal>create</"
"literal> configuration setting actually translates into \"drop all tables "
"from the schema, then re-create all tables, when the SessionFactory is build"
"\"."
msgstr ""
"现在把<literal>hibernate.cfg.xml</literal>文件中hbm2ddl属性注释掉，这样我们就"
"取消了在启动时用hbm2ddl来生成数据库schema。通常只有在不断重复进行单元测试的时"
"候才需要打开它，但再次运行hbm2ddl会把你保存的一切都删掉（<emphasis>drop</"
"emphasis>）——<literal>create</literal>配置的真实含义是：“在创建SessionFactory"
"的时候，从schema 中drop 掉所有的表，再重新创建它们”。"

#. Tag: para
#: tutorial.xml:525
#, no-c-format
msgid ""
"If you now call Ant with <literal>-Daction=list</literal>, you should see "
"the events you have stored so far. You can of course also call the "
"<literal>store</literal> action a few times more."
msgstr ""
"如果你现在使用命令行参数<literal>-Daction=list</literal>运行Ant，你会看到那些"
"至今为止我们所储存的events。当然，你也可以多调用几次<literal>store</literal>"
"以保存更多的envents。"

#. Tag: para
#: tutorial.xml:531
#, no-c-format
msgid ""
"Note: Most new Hibernate users fail at this point and we see questions about "
"<emphasis>Table not found</emphasis> error messages regularly. However, if "
"you follow the steps outlined above you will not have this problem, as "
"hbm2ddl creates the database schema on the first run, and subsequent "
"application restarts will use this schema. If you change the mapping and/or "
"database schema, you have to re-enable hbm2ddl once again."
msgstr ""
"注意，很多Hibernate新手在这一步会失败，我们不时看到关于<emphasis>Table not "
"found</emphasis>错误信息的提问。但是，只要你根据上面描述的步骤来执行，就不会"
"有这个问题，因为hbm2ddl会在第一次运行的时候创建数据库schema，后继的应用程序重"
"起后还能继续使用这个schema。假若你修改了映射，或者修改了数据库schema，你必须"
"把hbm2ddl重新打开一次。"

#. Tag: title
#: tutorial.xml:544
#, no-c-format
msgid "Part 2 - Mapping associations"
msgstr "第二部分 － 关联映射"

#. Tag: para
#: tutorial.xml:546
#, no-c-format
msgid ""
"We mapped a persistent entity class to a table. Let's build on this and add "
"some class associations. First we'll add people to our application, and "
"store a list of events they participate in."
msgstr ""
"我们已经映射了一个持久化实体类到表上。让我们在这个基础上增加一些类之间的关"
"联。首先我们往应用程序里增加人（people）的概念，并存储他们所参与的一个Event列"
"表。（译者注：与Event一样，我们在后面将直接使用person来表示“人”而不是它的中文"
"翻译）"

#. Tag: title
#: tutorial.xml:552
#, no-c-format
msgid "Mapping the Person class"
msgstr "映射Person类"

#. Tag: para
#: tutorial.xml:554
#, no-c-format
msgid "The first cut of the <literal>Person</literal> class is simple:"
msgstr "最初简单的<literal>Person</literal>类："

#. Tag: programlisting
#: tutorial.xml:558
#, no-c-format
msgid ""
"<![CDATA[package events;\n"
"\n"
"public class Person {\n"
"\n"
"    private Long id;\n"
"    private int age;\n"
"    private String firstname;\n"
"    private String lastname;\n"
"\n"
"    public Person() {}\n"
"\n"
"    // Accessor methods for all properties, private setter for 'id'\n"
"\n"
"}]]>"
msgstr ""

#. Tag: para
#: tutorial.xml:560
#, no-c-format
msgid ""
"Create a new mapping file called <literal>Person.hbm.xml</literal> (don't "
"forget the DTD reference at the top):"
msgstr ""
"创建一个名为<literal>Person.hbm.xml</literal>的新映射文件（别忘了最上面的DTD"
"引用）："

#. Tag: programlisting
#: tutorial.xml:565
#, no-c-format
msgid ""
"<![CDATA[<hibernate-mapping>\n"
"\n"
"    <class name=\"events.Person\" table=\"PERSON\">\n"
"        <id name=\"id\" column=\"PERSON_ID\">\n"
"            <generator class=\"native\"/>\n"
"        </id>\n"
"        <property name=\"age\"/>\n"
"        <property name=\"firstname\"/>\n"
"        <property name=\"lastname\"/>\n"
"    </class>\n"
"\n"
"</hibernate-mapping>]]>"
msgstr ""

#. Tag: para
#: tutorial.xml:567
#, no-c-format
msgid "Finally, add the new mapping to Hibernate's configuration:"
msgstr "最后，把新的映射加入到Hibernate的配置中："

#. Tag: programlisting
#: tutorial.xml:571
#, no-c-format
msgid ""
"<![CDATA[<mapping resource=\"events/Event.hbm.xml\"/>\n"
"<mapping resource=\"events/Person.hbm.xml\"/>]]>"
msgstr ""

#. Tag: para
#: tutorial.xml:573
#, no-c-format
msgid ""
"We'll now create an association between these two entities. Obviously, "
"persons can participate in events, and events have participants. The design "
"questions we have to deal with are: directionality, multiplicity, and "
"collection behavior."
msgstr ""
"现在我们在这两个实体之间创建一个关联。显然，persons可以参与一系列events，而"
"events也有不同的参加者（persons）。我们需要处理的设计问题是关联方向"
"（directionality），阶数（multiplicity）和集合（collection）的行为。"

#. Tag: title
#: tutorial.xml:583
#, no-c-format
msgid "A unidirectional Set-based association"
msgstr "单向Set-based的关联"

#. Tag: para
#: tutorial.xml:585
#, no-c-format
msgid ""
"We'll add a collection of events to the <literal>Person</literal> class. "
"That way we can easily navigate to the events for a particular person, "
"without executing an explicit query - by calling <literal>aPerson.getEvents()"
"</literal>. We use a Java collection, a <literal>Set</literal>, because the "
"collection will not contain duplicate elements and the ordering is not "
"relevant for us."
msgstr ""
"我们将向<literal>Person</literal>类增加一连串的events。那样，通过调用"
"<literal>aPerson.getEvents()</literal>，就可以轻松地导航到特定person所参与的"
"events，而不用去执行一个显式的查询。我们使用Java的集合类（collection）："
"<literal>Set</literal>，因为set 不包含重复的元素及与我们无关的排序。"

#. Tag: para
#: tutorial.xml:592
#, no-c-format
msgid ""
"We need a unidirectional, many-valued associations, implemented with a "
"<literal>Set</literal>. Let's write the code for this in the Java classes "
"and then map it:"
msgstr ""
"我们需要用set 实现一个单向多值关联。让我们在Java类里为这个关联编码，接着映射"
"它："

#. Tag: programlisting
#: tutorial.xml:597
#, no-c-format
msgid ""
"<![CDATA[public class Person {\n"
"\n"
"    private Set events = new HashSet();\n"
"\n"
"    public Set getEvents() {\n"
"        return events;\n"
"    }\n"
"\n"
"    public void setEvents(Set events) {\n"
"        this.events = events;\n"
"    }\n"
"}]]>"
msgstr ""

#. Tag: para
#: tutorial.xml:599
#, no-c-format
msgid ""
"Before we map this association, think about the other side. Clearly, we "
"could just keep this unidirectional. Or, we could create another collection "
"on the <literal>Event</literal>, if we want to be able to navigate it bi-"
"directional, i.e. <literal>anEvent.getParticipants()</literal>. This is not "
"necessary, from a functional perspective. You could always execute an "
"explicit query to retrieve the participants for a particular event. This is "
"a design choice left to you, but what is clear from this discussion is the "
"multiplicity of the association: \"many\" valued on both sides, we call this "
"a <emphasis>many-to-many</emphasis> association. Hence, we use Hibernate's "
"many-to-many mapping:"
msgstr ""
"在映射这个关联之前，先考虑一下此关联的另外一端。很显然，我们可以保持这个关联"
"是单向的。或者，我们可以在<literal>Event</literal>里创建另外一个集合，如果希"
"望能够双向地导航，如：<literal>anEvent.getParticipants()</literal>。从功能的"
"角度来说，这并不是必须的。因为你总可以显式地执行一个查询，以获得某个特定event"
"的所有参与者。这是个在设计时需要做出的选择，完全由你来决定，但此讨论中关于关"
"联的阶数是清楚的：即两端都是“多”值的，我们把它叫做<emphasis>多对多(many-to-"
"many)</emphasis>关联。因而，我们使用Hibernate的多对多映射："

#. Tag: programlisting
#: tutorial.xml:610
#, no-c-format
msgid ""
"<![CDATA[<class name=\"events.Person\" table=\"PERSON\">\n"
"    <id name=\"id\" column=\"PERSON_ID\">\n"
"        <generator class=\"native\"/>\n"
"    </id>\n"
"    <property name=\"age\"/>\n"
"    <property name=\"firstname\"/>\n"
"    <property name=\"lastname\"/>\n"
"\n"
"    <set name=\"events\" table=\"PERSON_EVENT\">\n"
"        <key column=\"PERSON_ID\"/>\n"
"        <many-to-many column=\"EVENT_ID\" class=\"events.Event\"/>\n"
"    </set>\n"
"\n"
"</class>]]>"
msgstr ""

#. Tag: para
#: tutorial.xml:612
#, no-c-format
msgid ""
"Hibernate supports all kinds of collection mappings, a <literal>&lt;set&gt;</"
"literal> being most common. For a many-to-many association (or <emphasis>n:"
"m</emphasis> entity relationship), an association table is needed. Each row "
"in this table represents a link between a person and an event. The table "
"name is configured with the <literal>table</literal> attribute of the "
"<literal>set</literal> element. The identifier column name in the "
"association, for the person's side, is defined with the <literal>&lt;key&gt;"
"</literal> element, the column name for the event's side with the "
"<literal>column</literal> attribute of the <literal>&lt;many-to-many&gt;</"
"literal>. You also have to tell Hibernate the class of the objects in your "
"collection (correct: the class on the other side of the collection of "
"references)."
msgstr ""
"Hibernate支持各种各样的集合映射，<literal>&lt;set&gt;</literal>使用的最