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167 lines
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167 lines
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<div class="header">
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<h1 class="title" title="Package">Package javax.management.monitor</h1>
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<div class="docSummary">
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提供监视器类的定义。
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<p>See: <a href="#package.description">描述</a></p>
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<ul class="blockList">
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<table border="0" cellpadding="3" cellspacing="0" class="typeSummary" summary="Interface Summary table, listing interfaces, and an explanation">
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<caption>
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<span>接口摘要</span>
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<span class="tabEnd"> </span>
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</caption>
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<tbody>
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<th class="colFirst" scope="col">接口</th>
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<th class="colLast" scope="col">描述</th>
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<tbody>
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<td class="colFirst"><a href="../../../javax/management/monitor/CounterMonitorMBean.html" title="interface in javax.management.monitor">CounterMonitorMBean</a></td>
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<div class="block">
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暴露计数器监视器MBean的远程管理界面。
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</div> </td>
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<td class="colFirst"><a href="../../../javax/management/monitor/GaugeMonitorMBean.html" title="interface in javax.management.monitor">GaugeMonitorMBean</a></td>
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暴露量规监视器MBean的远程管理界面。
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</div> </td>
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<td class="colFirst"><a href="../../../javax/management/monitor/MonitorMBean.html" title="interface in javax.management.monitor">MonitorMBean</a></td>
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<div class="block">
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暴露监视器MBean的远程管理界面。
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</div> </td>
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<td class="colFirst"><a href="../../../javax/management/monitor/StringMonitorMBean.html" title="interface in javax.management.monitor">StringMonitorMBean</a></td>
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<td class="colLast">
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暴露字符串监视器MBean的远程管理界面。
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</div> </td>
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</tr>
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</tbody>
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</table> </li>
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<li class="blockList">
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<table border="0" cellpadding="3" cellspacing="0" class="typeSummary" summary="Class Summary table, listing classes, and an explanation">
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<caption>
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<span>类摘要</span>
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<span class="tabEnd"> </span>
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</caption>
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<tbody>
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<tr>
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<th class="colFirst" scope="col">类</th>
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<th class="colLast" scope="col">描述</th>
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</tr>
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</tbody>
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<tbody>
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<tr class="altColor">
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<td class="colFirst"><a href="../../../javax/management/monitor/CounterMonitor.html" title="class in javax.management.monitor">CounterMonitor</a></td>
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<td class="colLast">
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<div class="block">
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定义监视器MBean，用于观察计数器属性的值。
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</div> </td>
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</tr>
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<tr class="rowColor">
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<td class="colFirst"><a href="../../../javax/management/monitor/GaugeMonitor.html" title="class in javax.management.monitor">GaugeMonitor</a></td>
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<div class="block">
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定义一个监视器MBean，用于观察仪表属性的值。
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</div> </td>
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</tr>
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<td class="colFirst"><a href="../../../javax/management/monitor/Monitor.html" title="class in javax.management.monitor">Monitor</a></td>
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<div class="block">
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定义所有监视器MBean的通用部分。
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</div> </td>
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<td class="colFirst"><a href="../../../javax/management/monitor/MonitorNotification.html" title="class in javax.management.monitor">MonitorNotification</a></td>
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<div class="block">
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提供监视器MBean发送的通知的定义。
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</div> </td>
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</tr>
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<tr class="altColor">
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<td class="colFirst"><a href="../../../javax/management/monitor/StringMonitor.html" title="class in javax.management.monitor">StringMonitor</a></td>
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<td class="colLast">
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<div class="block">
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定义一个监视器MBean，用于观察字符串属性的值。
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</div> </td>
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</tr>
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</tbody>
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</table> </li>
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<li class="blockList">
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<table border="0" cellpadding="3" cellspacing="0" class="typeSummary" summary="Exception Summary table, listing exceptions, and an explanation">
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<caption>
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<span>异常摘要</span>
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<span class="tabEnd"> </span>
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</caption>
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<tbody>
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<tr>
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<th class="colFirst" scope="col">异常</th>
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<th class="colLast" scope="col">描述</th>
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</tr>
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</tbody>
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<tbody>
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<tr class="altColor">
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<td class="colFirst"><a href="../../../javax/management/monitor/MonitorSettingException.html" title="class in javax.management.monitor">MonitorSettingException</a></td>
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<td class="colLast">
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<div class="block">
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监视器设置在监视器运行时无效时由监视器抛出异常。
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</div> </td>
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</tr>
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</tbody>
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</table> </li>
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</ul>
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<a name="package.description">
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<!-- --> </a>
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<h2 title="Package javax.management.monitor Description">Package javax.management.monitor Description</h2>
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<div class="block">
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<p> <span>提供监视器类的定义。</span> <span>监视器是一个MBean，它定期地观察一个或多个其他MBean中属性的值。</span> <span>如果属性满足某个条件，则监视器将发出<a href="../../../javax/management/monitor/MonitorNotification.html" title="javax.management.monitor中的类"><code>MonitorNotification</code></a> 。</span> <span>当监视器MBean周期性地调用<a href="../../../javax/management/MBeanServer.html#getAttribute-javax.management.ObjectName-java.lang.String-"><code>getAttribute</code></a>来检索被监视的属性的值时，它将在<a href="../../../javax/management/monitor/Monitor.html#start--"><code>Monitor.start()</code></a>调用者的访问控制上下文中执行。</span> </p>
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<p id="complex"> <span>被监视的值可以是复杂类型中包含的简单值。</span> <span>例如， <a href="../../../java/lang/management/MemoryMXBean.html" title="java.lang.management中的接口">java.lang.management中</a>定义的<tt><code>MemoryMXBean</code></tt>具有<tt><code>MemoryUsage</code></tt>类型的<a href="../../../java/lang/management/MemoryUsage.html" title="java.lang.management中的类">属性HeapMemoryUsage</a> 。</span> <span>要监控MemoryUsage的<tt>used</tt>属性描述的<tt>已</tt> <i>用</i>内存量，您可以监视“ <tt>HeapMemoryUsage.used</tt> ”。</span> <span>那个字符串是<a href="../../../javax/management/monitor/MonitorMBean.html#setObservedAttribute-java.lang.String-"><code>setObservedAttribute</code></a>的参数。</span> </p>
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<p> <span>用于解释<tt>ObservedAttribute（</tt>如<tt>"HeapMemoryUsage.used"）</tt>的规则如下。</span> <span>假设字符串是<i>Ae</i> （所以<i>A</i>将为<tt>"HeapMemoryUsage"</tt> ， <i>e</i>将在<tt>示例</tt>中为<tt>"used"</tt> ）。</span> </p>
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<p> <span>首先得到属性<i>A</i>的值。</span> <span>叫它<i>v</i> 。</span> <span>从<i>v</i>中提取值<i>x</i> ，如下所示：</span> </p>
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<ul>
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<li> <span>如果<i>v</i>是<a href="../../../javax/management/openmbean/CompositeData.html" title="javax.management.openmbean中的接口"><code>CompositeData</code></a> ，如果<i>v</i> 。</span> <span><a href="../../../javax/management/openmbean/CompositeData.html#get-java.lang.String-"><code>get</code></a> （ <i>e</i> ）返回一个值，那么<i>x</i>就是该值。</span> </li>
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<li> <span>如果<i>v</i>是数组， <i>e</i>是字符串<tt>"length"，</tt>则<i>x</i>是数组的长度。</span> </li>
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<li> <span>如果上述规则不产生一个值，并且如果自省，仿佛通过调用<a href="../../../java/beans/Introspector.html#getBeanInfo-java.lang.Class-"><code>Introspector.getBeanInfo</code></a> ，为类<i>诉</i> （ <i>诉</i> <tt>getClass()）</tt>识别与该<i>名字</i>的属性，则<i>x</i>是读取属性值的结果。</span> </li>
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</ul>
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<p> <span>第三条规则意味着例如，如果属性<tt>HeapMemoryUsage</tt>是<tt>MemoryUsage</tt> ，则监视<tt>"HeapMemoryUsage.used"</tt>将通过调用<tt>MemoryUsage.getUsed()</tt>获得观察值。</span> </p>
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<p> <span>如果<tt>ObservedAttribute</tt>包含多个周期，例如<tt>"ConnectionPool.connectionStats.length"</tt> ，则上述规则被迭代地应用。</span> <span>这里<i>，V</i>最初将所述属性<tt>ConnectionPool</tt>的值，并且<i>x</i>将由随<i>e</i>等于<tt>"connectionStats"</tt>应用上述规则来导出。</span> <span>那么<i>v</i>将被设置为该<i>x</i> ，并且通过再次应用规则得到新的<i>x</i> ， <i>e</i>等于<tt>"length"</tt> 。</span> </p>
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<p> <span>虽然建议属性名称是有效的Java标识符，但可以将属性称为<tt>HeapMemoryUsage.used</tt> 。</span> <span>这意味着一个<tt>ObservedAttribute</tt>是<tt>HeapMemoryUsage.used</tt>可能意味着要观察的值是该名称的属性，或属性<tt>used</tt>属性名为<tt>HeapMemoryUsage</tt> 。</span> <span>因此出于兼容性原因，当<tt>ObservedAttribute</tt>包含一段时间（ <tt>.</tt> ）时，监视器将检查一个属性是否存在，其名称为完整的<tt>ObservedAttribute</tt>字符串（ <tt>示例</tt>中为<tt>HeapMemoryUsage.used</tt> ）。</span> <span>它通过调用<a href="../../../javax/management/MBeanServer.html#getMBeanInfo-javax.management.ObjectName-"><code>getMBeanInfo</code></a>查看的MBean来查找<a href="../../../javax/management/MBeanAttributeInfo.html" title="javax.management中的类">包含的</a>具有给定名称的<a href="../../../javax/management/MBeanAttributeInfo.html" title="javax.management中的类"><code>MBeanAttributeInfo</code></a> 。</span> <span>如果找到了，那就是被监控的。</span> <span>如果观察到多个MBean，那么行为是未指定的，如果其中一些具有<tt>HeapMemoryUsage.used</tt>属性，而其他没有。</span> <span><tt>因此</tt> ，在这种情况下，一个实现可以在一个MBean上调用<tt>getMBeanInfo</tt> 。</span> <span>如果在显示器处于活动状态时检查结果发生变化，那么该行为也是未指定的。</span> </p>
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<p> <span>显示器的确切行为详见<a href="#spec">JMX Specification</a> 。</span> <span>以下是一个总结。</span> </p>
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<p> <span>有三种显示器：</span> </p>
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<ul>
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<li><p> <span>A <a href="../../../javax/management/monitor/CounterMonitor.html" title="javax.management.monitor中的类"><code>CounterMonitor</code></a>观察整数类型的属性。</span> <span>假设属性是非负的，并且除了在指定<em>模数</em>下可能的<em>滚转</em>之外，单调增加。</span> <span>每个观察属性都具有关联的<em>阈</em>值。</span> <span>当属性超过其阈值时，发送通知。</span> </p><p> <span>可以指定<em>偏移</em>值。</span> <span>当观测值超过其阈值时，阈值将增加偏移量，或增加足以使阈值大于新观测值的偏移量的倍数。</span> </p><p> <span>A <code>CounterMonitor</code>可以在<em>差模式下工作</em> 。</span> <span>在该模式中，与阈值比较的值是属性的两次连续观察结果之间的差异。</span> </p></li>
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<li><p> <span>A <a href="../../../javax/management/monitor/GaugeMonitor.html" title="javax.management.monitor中的类"><code>GaugeMonitor</code></a>观察数值类型的属性。</span> <span>每个观察属性具有相关联的<em>高阈值</em>和<em>低阈值</em> 。</span> </p><p> <span>当观察到的属性越过高阈值时，如果<em>通知高</em>标志为真，则发送通知。</span> <span>在阈值变得小于或等于低阈值之前，高阈值的后续交叉将不会触发进一步通知。</span> </p><p> <span>当观察到的属性越过低阈值时，如果<em>通知低</em>标志为真，则发送通知。</span> <span>在阈值变得大于或等于高阈值之前，低阈值的后续交叉将不会触发进一步通知。</span> </p><p> <span>通常，只有一个通知高和通知低标志被设置。</span> <span>另一个阈值用于提供<em>滞后</em>机制，以避免当属性围绕阈值产生小的振荡时重复触发通知。</span> </p><p> <span>A <code>GaugeMonitor</code>可以在<em>差模式下工作</em> 。</span> <span>在这种模式下，与高和低阈值比较的值是属性的两个连续观察值之间的差异。</span> </p></li>
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<li><p> <span>A <a href="../../../javax/management/monitor/StringMonitor.html" title="javax.management.monitor中的类"><code>StringMonitor</code></a>观察类型为<code>String</code> 。</span> <span>当观察到的属性变得相等和/或不等于给定的字符串时，发送通知。</span> </p></li>
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</ul>
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<p id="spec"></p>
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</div>
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<dl>
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<dt>
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<span class="simpleTagLabel">从以下版本开始：</span>
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</dt>
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<dd>
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1.5
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</dd>
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<dt>
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<span class="seeLabel">另请参见：</span>
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</dt>
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<dd>
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<a href="../../../../technotes/guides/jmx/"> Java Platform documentation on JMX technology</a>, in particular the
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<a href="../../../../technotes/guides/jmx/JMX_1_4_specification.pdf"> JMX Specification, version 1.4(pdf).</a>
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</dd>
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</dl>
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</div> |