session_api.po

hibernate-distribution-3.3.1.GA-dist.zip源码

"use the JDBC <literal>Connection</literal> directly. If you chose to use the "
"Hibernate API, you must enclose SQL aliases in braces:"
msgstr ""
"你可以使用<literal>createSQLQuery()</literal>方法，用SQL来描述查询，并由"
"Hibernate将结果集转换成对象。 请注意，你可以在任何时候调用<literal>session."
"connection()</literal>来获得并使用JDBC <literal>Connection</literal>对象。 如"
"果你选择使用Hibernate的API, 你必须把SQL别名用大括号包围起来:"

#. Tag: programlisting
#: session_api.xml:492
#, no-c-format
msgid ""
"<![CDATA[List cats = session.createSQLQuery(\"SELECT {cat.*} FROM CAT {cat} "
"WHERE ROWNUM<10\")\n"
"    .addEntity(\"cat\", Cat.class)\n"
".list();]]>"
msgstr ""

#. Tag: programlisting
#: session_api.xml:494
#, no-c-format
msgid ""
"<![CDATA[List cats = session.createSQLQuery(\n"
"    \"SELECT {cat}.ID AS {cat.id}, {cat}.SEX AS {cat.sex}, \" +\n"
"           \"{cat}.MATE AS {cat.mate}, {cat}.SUBCLASS AS {cat.class}, ... \" "
"+\n"
"    \"FROM CAT {cat} WHERE ROWNUM<10\")\n"
"    .addEntity(\"cat\", Cat.class)\n"
".list()]]>"
msgstr ""

#. Tag: para
#: session_api.xml:496
#, no-c-format
msgid ""
"SQL queries may contain named and positional parameters, just like Hibernate "
"queries. More information about native SQL queries in Hibernate can be found "
"in <xref linkend=\"querysql\"/>."
msgstr ""
"和Hibernate查询一样，SQL查询也可以包含命名参数和占位参数。 可以在<xref "
"linkend=\"querysql\"/>找到更多关于Hibernate中原生SQL(native SQL)的信息。"

#. Tag: title
#: session_api.xml:507
#, no-c-format
msgid "Modifying persistent objects"
msgstr "修改持久对象"

#. Tag: para
#: session_api.xml:509
#, no-c-format
msgid ""
"<emphasis>Transactional persistent instances</emphasis> (ie. objects loaded, "
"saved, created or queried by the <literal>Session</literal>) may be "
"manipulated by the application and any changes to persistent state will be "
"persisted when the <literal>Session</literal> is <emphasis>flushed</"
"emphasis> (discussed later in this chapter). There is no need to call a "
"particular method (like <literal>update()</literal>, which has a different "
"purpose) to make your modifications persistent. So the most straightforward "
"way to update the state of an object is to <literal>load()</literal> it, and "
"then manipulate it directly, while the <literal>Session</literal> is open:"
msgstr ""
"<emphasis>事务中的持久实例</emphasis>（就是通过<literal>session</literal>装"
"载、保存、创建或者查询出的对象） 被应用程序操作所造成的任何修改都会在"
"<literal>Session</literal>被<emphasis>刷出（flushed）</emphasis>的时候被持久"
"化（本章后面会详细讨论）。 这里不需要调用某个特定的方法（比如<literal>update"
"()</literal>，设计它的目的是不同的）将你的修改持久化。 所以最直接的更新一个对"
"象的方法就是在<literal>Session</literal>处于打开状态时<literal>load()</"
"literal>它，然后直接修改即可："

#. Tag: programlisting
#: session_api.xml:520
#, no-c-format
msgid ""
"<![CDATA[DomesticCat cat = (DomesticCat) sess.load( Cat.class, new Long"
"(69) );\n"
"cat.setName(\"PK\");\n"
"sess.flush();  // changes to cat are automatically detected and persisted]]>"
msgstr ""

#. Tag: para
#: session_api.xml:522
#, no-c-format
msgid ""
"Sometimes this programming model is inefficient since it would require both "
"an SQL <literal>SELECT</literal> (to load an object) and an SQL "
"<literal>UPDATE</literal> (to persist its updated state) in the same "
"session. Therefore Hibernate offers an alternate approach, using detached "
"instances."
msgstr ""
"有时这种程序模型效率低下，因为它在同一Session里需要一条SQL <literal>SELECT</"
"literal>语句（用于加载对象） 以及一条SQL <literal>UPDATE</literal>语句(持久化"
"更新的状态)。 为此Hibernate提供了另一种途径，使用脱管(detached)实例。"

#. Tag: emphasis
#: session_api.xml:530
#, fuzzy, no-c-format
msgid ""
"Note that Hibernate does not offer its own API for direct execution of "
"<literal>UPDATE</literal> or <literal>DELETE</literal> statements. Hibernate "
"is a <emphasis>state management</emphasis> service, you don't have to think "
"in <emphasis>statements</emphasis> to use it. JDBC is a perfect API for "
"executing SQL statements, you can get a JDBC <literal>Connection</literal> "
"at any time by calling <literal>session.connection()</literal>. Furthermore, "
"the notion of mass operations conflicts with object/relational mapping for "
"online transaction processing-oriented applications. Future versions of "
"Hibernate may however provide special mass operation functions. See <xref "
"linkend=\"batch\"/> for some possible batch operation tricks."
msgstr ""
"请注意Hibernate本身不提供直接执行<placeholder-1/>或<placeholder-2/>语句的"
"API。 Hibernate提供的是<placeholder-3/>服务，你不必考虑要使用的<placeholder-"
"4/>。 JDBC是出色的执行SQL语句的API，任何时候调用<placeholder-5/>你都可以得到"
"一个JDBC <placeholder-6/>对象。 此外，在联机事务处理(OLTP)程序中，大量操作"
"(mass operations)与对象/关系映射的观点是相冲突的。 Hibernate的将来版本可能会"
"提供专门的进行大量操作(mass operation)的功能。 参考<xref linkend=\"batch\"/"
">，寻找一些可用的批量(batch)操作技巧。"

#. Tag: title
#: session_api.xml:545
#, no-c-format
msgid "Modifying detached objects"
msgstr "修改脱管(Detached)对象"

#. Tag: para
#: session_api.xml:547
#, no-c-format
msgid ""
"Many applications need to retrieve an object in one transaction, send it to "
"the UI layer for manipulation, then save the changes in a new transaction. "
"Applications that use this kind of approach in a high-concurrency "
"environment usually use versioned data to ensure isolation for the \"long\" "
"unit of work."
msgstr ""
"很多程序需要在某个事务中获取对象，然后将对象发送到界面层去操作，最后在一个新"
"的事务保存所做的修改。 在高并发访问的环境中使用这种方式，通常使用附带版本信息"
"的数据来保证这些“长“工作单元之间的隔离。"

#. Tag: para
#: session_api.xml:554
#, no-c-format
msgid ""
"Hibernate supports this model by providing for reattachment of detached "
"instances using the <literal>Session.update()</literal> or <literal>Session."
"merge()</literal> methods:"
msgstr ""
"Hibernate通过提供<literal>Session.update()</literal>或<literal>Session.merge"
"()</literal> 重新关联脱管实例的办法来支持这种模型。"

#. Tag: programlisting
#: session_api.xml:560
#, no-c-format
msgid ""
"<![CDATA[// in the first session\n"
"Cat cat = (Cat) firstSession.load(Cat.class, catId);\n"
"Cat potentialMate = new Cat();\n"
"firstSession.save(potentialMate);\n"
"\n"
"// in a higher layer of the application\n"
"cat.setMate(potentialMate);\n"
"\n"
"// later, in a new session\n"
"secondSession.update(cat);  // update cat\n"
"secondSession.update(mate); // update mate]]>"
msgstr ""

#. Tag: para
#: session_api.xml:562
#, no-c-format
msgid ""
"If the <literal>Cat</literal> with identifier <literal>catId</literal> had "
"already been loaded by <literal>secondSession</literal> when the application "
"tried to reattach it, an exception would have been thrown."
msgstr ""
"如果具有<literal>catId</literal>持久化标识的<literal>Cat</literal>之前已经被"
"<literal>另一Session(secondSession)</literal>装载了， 应用程序进行重关联操作"
"(reattach)的时候会抛出一个异常。"

#. Tag: para
#: session_api.xml:568
#, no-c-format
msgid ""
"Use <literal>update()</literal> if you are sure that the session does not "
"contain an already persistent instance with the same identifier, and "
"<literal>merge()</literal> if you want to merge your modifications at any "
"time without consideration of the state of the session. In other words, "
"<literal>update()</literal> is usually the first method you would call in a "
"fresh session, ensuring that reattachment of your detached instances is the "
"first operation that is executed."
msgstr ""
"如果你确定当前session没有包含与之具有相同持久化标识的持久实例，使用"
"<literal>update()</literal>。 如果想随时合并你的的改动而不考虑session的状态，"
"使用<literal>merge()</literal>。 换句话说，在一个新session中通常第一个调用的"
"是<literal>update()</literal>方法，以便保证重新关联脱管(detached)对象的操作首"
"先被执行。"

#. Tag: para
#: session_api.xml:577
#, no-c-format
msgid ""
"The application should individually <literal>update()</literal> detached "
"instances reachable from the given detached instance if and <emphasis>only</"
"emphasis> if it wants their state also updated. This can be automated of "
"course, using <emphasis>transitive persistence</emphasis>, see <xref linkend="
"\"objectstate-transitive\"/>."
msgstr ""
"如果希望相关联的脱管对象（通过引用“可到达”的脱管对象）的数据也要更新到数据库"
"时（并且也<emphasis>仅仅</emphasis>在这种情况）， 可以对该相关联的脱管对象单"
"独调用<literal>update()</literal> 当然这些可以自动完成，即通过使用<emphasis>"
"传播性持久化(transitive persistence)</emphasis>，请看<xref linkend="
"\"objectstate-transitive\"/>。"

#. Tag: para
#: session_api.xml:584
#, no-c-format
msgid ""
"The <literal>lock()</literal> method also allows an application to "
"reassociate an object with a new session. However, the detached instance has "
"to be unmodified!"
msgstr ""
"<literal>lock()</literal>方法也允许程序重新关联某个对象到一个新session上。不"
"过，该脱管(detached)的对象必须是没有修改过的！"

#. Tag: programlisting
#: session_api.xml:589
#, no-c-format
msgid ""
"<![CDATA[//just reassociate:\n"
"sess.lock(fritz, LockMode.NONE);\n"
"//do a version check, then reassociate:\n"
"sess.lock(izi, LockMode.READ);\n"
"//do a version check, using SELECT ... FOR UPDATE, then reassociate:\n"
"sess.lock(pk, LockMode.UPGRADE);]]>"
msgstr ""

#. Tag: para
#: session_api.xml:591
#, no-c-format
msgid ""
"Note that <literal>lock()</literal> can be used with various "
"<literal>LockMode</literal>s, see the API documentation and the chapter on "
"transaction handling for more information. Reattachment is not the only "
"usecase for <literal>lock()</literal>."
msgstr ""
"请注意，<literal>lock()</literal>可以搭配多种<literal>LockMode</literal>， 更"
"多信息请阅读API文档以及关于事务处理(transaction handling)的章节。重新关联不是"
"<literal>lock()</literal>的唯一用途。"

#. Tag: para
#: session_api.xml:598
#, no-c-format
msgid ""
"Other models for long units of work are discussed in <xref linkend="
"\"transactions-optimistic\"/>."
msgstr ""
"其他用于长时间工作单元的模型会在<xref linkend=\"transactions-optimistic\"/>中"
"讨论。"

#. Tag: title
#: session_api.xml:605
#, no-c-format
msgid "Automatic state detection"
msgstr "自动状态检测"

#. Tag: para
#: session_api.xml:607
#, no-c-format
msgid ""
"Hibernate users have requested a general purpose method that either saves a "
"transient instance by generating a new identifier or updates/reattaches the "
"detached instances associated with its current identifier. The "
"<literal>saveOrUpdate()</literal> method implements this functionality."
msgstr ""
"Hibernate的用户曾要求一个既可自动分配新持久化标识(identifier)保存瞬时"
"(transient)对象，又可更新/重新关联脱管(detached)实例的通用方法。 "
"<literal>saveOrUpdate()</literal>方法实现了这个功能。"

#. Tag: programlisting
#: session_api.xml:614
#, no-c-format
msgid ""
"<![CDATA[// in the first session\n"
"Cat cat = (Cat) firstSession.load(Cat.class, catID);\n"
"\n"
"// in a higher tier of the application\n"
"Cat mate = new Cat();\n"
"cat.setMate(mate);\n"
"\n"
"// later, in a new session\n"
"secondSession.saveOrUpdate(cat);   // update existing state (cat has a non-"
"null id)\n"
"secondSession.saveOrUpdate(mate);  // save the new instance (mate has a null "
"id)]]>"
msgstr ""

#. Tag: para
#: session_api.xml:616
#, no-c-format
msgid ""
"The usage and semantics of <literal>saveOrUpdate()</literal> seems to be "
"confusing for new users. Firstly, so long as you are not trying to use "
"instances from one session in another new session, you should not need to "
"use <literal>update()</literal>, <literal>saveOrUpdate()</literal>, or "
"<literal>merge()</literal>. Some whole applications will never use either of "
"these methods."
msgstr ""
"<literal>saveOrUpdate()</literal>用途和语义可能会使新用户感到迷惑。 首先，只"
"要你没有尝试在某个session中使用来自另一session的实例，你就应该不需要使用"
"<literal>update()</literal>， <literal>saveOrUpdate()</literal>，或"
"<literal>merge()</literal>。有些程序从来不用这些方法。"

#. Tag: para
#: session_api.xml:624
#, no-c-format
msgid ""
"Usually <literal>update()</literal> or <literal>saveOrUpdate()</literal> are "
"used in the following scenario:"
msgstr ""
"通常下面的场景会使用<literal>update()</literal>或<literal>saveOrUpdate()</"
"literal>："

#. Tag: para
#: session_api.xml:631
#, no-c-format
msgid "the application loads an object in the first session"
msgstr "程序在第一个session中加载对象"

#. Tag: para
#: session_api.xml:636
#, no-c-format
msgid "the object is passed up to the UI tier"
msgstr "该对象被传递到表现层"

#. Tag: para
#: session_api.xml:641
#, no-c-format
msgid "some modifications are made to the object"
msgstr "对象发生了一些改动"

#. Tag: para
#: session_api.xml:646
#, no-c-format
msgid "the object is passed back down to the business logic tier"
msgstr "该对象被返回到业务逻辑层"