48 lines
2.9 KiB
XML
48 lines
2.9 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!-- ============================================================================= -->
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<!-- Copyright © 2009 Red Hat, Inc. and others. -->
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<!-- -->
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<!-- The text of and illustrations in this document are licensed by Red Hat under -->
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<!-- a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). -->
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<!-- -->
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<!-- An explanation of CC-BY-SA is available at -->
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<!-- -->
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<!-- http://creativecommons.org/licenses/by-sa/3.0/. -->
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<!-- -->
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<!-- In accordance with CC-BY-SA, if you distribute this document or an adaptation -->
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<!-- of it, you must provide the URL for the original version. -->
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<!-- -->
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<!-- Red Hat, as the licensor of this document, waives the right to enforce, -->
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<!-- and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent -->
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<!-- permitted by applicable law. -->
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<!-- ============================================================================= -->
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<chapter id="scheduled-messages">
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<title>定期消息</title>
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<para>与普通消息不同，定期消息是在未来某个指定时间发送的消息。</para>
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<para>为了创建定期消息，需要设定一个特殊的参数.</para>
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<section>
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<title>定期传递参数</title>
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<para>用来标识一个定期消息的参数是<literal
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>"_HQ_SCHED_DELIVERY"</literal> （相当于常量<literal
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>Message.HDR_SCHEDULED_DELIVERY_TIME</literal>）。</para>
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<para>这个参数的值必须是一个大于零的长整型，单位是毫秒。下面例子给出了使用JMS接口创建定期消息的方法：</para>
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<programlisting>
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TextMessage message =
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session.createTextMessage("This is a scheduled message message which will be delivered
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in 5 sec.");
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message.setLongProperty("_HQ_SCHED_DELIVERY", System.currentTimeMillis() + 5000);
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producer.send(message);
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...
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// message will not be received immediately but 5 seconds later
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TextMessage messageReceived = (TextMessage) consumer.receive();
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</programlisting>
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<para>也可以使用核心接口来发送定期消息。它只需要将同样的参数设定到核心消息上即可。</para>
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</section>
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<section>
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<title>例子</title>
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<para>参见<xref linkend="examples.scheduled-message"/>，它是一个JMS使用定期消息的例子。</para>
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</section>
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</chapter>
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