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<li class="toctree-l2 current"><a class="current reference internal" href="#">classloader</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#">参数说明</a></li>
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<li class="toctree-l4"><a class="reference internal" href="#">按类加载类型查看统计信息</a></li>
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<li class="toctree-l4"><a class="reference internal" href="#urlclassloaderurls">查看URLClassLoader实际的urls</a></li>
<li class="toctree-l4"><a class="reference internal" href="#classloaderresource">使用ClassLoader去查找resource</a></li>
<li class="toctree-l4"><a class="reference internal" href="#classloader">使用ClassLoader去加载类</a></li>
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<div class="section" id="classloader">
<span id="classloader"></span><h1>classloader<a class="headerlink" href="#classloader" title="永久链接至标题">¶</a></h1>
<blockquote>
<div>查看classloader的继承树，urls，类加载信息</div></blockquote>
<p><tt class="docutils literal">classloader</tt> 命令将 JVM 中所有的classloader的信息统计出来，并可以展示继承树，urls等。</p>
<p>可以让指定的classloader去getResources，打印出所有查找到的resources的url。对于<tt class="docutils literal">ResourceNotFoundException</tt>比较有用。</p>
<div class="section" id="">
<span id="id1"></span><h2>参数说明<a class="headerlink" href="#" title="永久链接至标题">¶</a></h2>
<table border="1" class="docutils">
<thead>
<tr>
<th align="right">参数名称</th>
<th align="left">参数说明</th>
</tr>
</thead>
<tbody>
<tr>
<td align="right">[l]</td>
<td align="left">按类加载实例进行统计</td>
</tr>
<tr>
<td align="right">[t]</td>
<td align="left">打印所有ClassLoader的继承树</td>
</tr>
<tr>
<td align="right">[a]</td>
<td align="left">列出所有ClassLoader加载的类，请谨慎使用</td>
</tr>
<tr>
<td align="right"><code>[c:]</code></td>
<td align="left">ClassLoader的hashcode</td>
</tr>
<tr>
<td align="right"><code>[c: r:]</code></td>
<td align="left">用ClassLoader去查找resource</td>
</tr>
<tr>
<td align="right"><code>[c: load:]</code></td>
<td align="left">用ClassLoader去加载指定的类</td>
</tr>
</tbody>
</table></div>
<div class="section" id="">
<span id="id2"></span><h2>使用参考<a class="headerlink" href="#" title="永久链接至标题">¶</a></h2>
<div class="section" id="">
<span id="id3"></span><h3>按类加载类型查看统计信息<a class="headerlink" href="#" title="永久链接至标题">¶</a></h3>
<div class="highlight-bash notranslate"><div class="highlight hljs"><pre class="bash">$ classloader
name numberOfInstances loadedCountTotal
com.taobao.arthas.agent.ArthasClassloader 1 2115
BootstrapClassLoader 1 1861
sun.reflect.DelegatingClassLoader 5 5
sun.misc.Launcher$AppClassLoader 1 4
sun.misc.Launcher$ExtClassLoader 1 1
Affect(row-cnt:5) cost in 3 ms.
</pre></div>
</div>
</div>
<div class="section" id="">
<span id="id4"></span><h3>按类加载实例查看统计信息<a class="headerlink" href="#" title="永久链接至标题">¶</a></h3>
<div class="highlight-bash notranslate"><div class="highlight hljs"><pre class="bash">$ classloader -l
name loadedCount hash parent
BootstrapClassLoader 1861 null null
com.taobao.arthas.agent.ArthasClassloader@68b31f0a 2115 68b31f0a sun.misc.Launcher$ExtClassLoader@66350f69
sun.misc.Launcher$AppClassLoader@3d4eac69 4 3d4eac69 sun.misc.Launcher$ExtClassLoader@66350f69
sun.misc.Launcher$ExtClassLoader@66350f69 1 66350f69 null
Affect(row-cnt:4) cost in 2 ms.
</pre></div>
</div>
</div>
<div class="section" id="classloader">
<span id="id5"></span><h3>查看ClassLoader的继承树<a class="headerlink" href="#classloader" title="永久链接至标题">¶</a></h3>
<div class="highlight-bash notranslate"><div class="highlight hljs"><pre class="bash">$ classloader -t
+-BootstrapClassLoader
+-sun.misc.Launcher$ExtClassLoader@66350f69
+-com.taobao.arthas.agent.ArthasClassloader@68b31f0a
+-sun.misc.Launcher$AppClassLoader@3d4eac69
Affect(row-cnt:4) cost in 3 ms.
</pre></div>
</div>
</div>
<div class="section" id="urlclassloaderurls">
<span id="urlclassloaderurls"></span><h3>查看URLClassLoader实际的urls<a class="headerlink" href="#urlclassloaderurls" title="永久链接至标题">¶</a></h3>
<div class="highlight-bash notranslate"><div class="highlight hljs"><pre class="bash">$ classloader -c 3d4eac69
file:/private/tmp/arthas-demo.jar
file:/Users/hengyunabc/.arthas/lib/3.0.5/arthas/arthas-agent.jar
Affect(row-cnt:9) cost in 3 ms.
</pre></div>
</div>
</div>
<div class="section" id="classloaderresource">
<span id="classloaderresource"></span><h3>使用ClassLoader去查找resource<a class="headerlink" href="#classloaderresource" title="永久链接至标题">¶</a></h3>
<div class="highlight-bash notranslate"><div class="highlight hljs"><pre class="bash">$ classloader -c 3d4eac69 -r META-INF/MANIFEST.MF
jar:file:/System/Library/Java/Extensions/MRJToolkit.jar!/META-INF/MANIFEST.MF
jar:file:/private/tmp/arthas-demo.jar!/META-INF/MANIFEST.MF
jar:file:/Users/hengyunabc/.arthas/lib/3.0.5/arthas/arthas-agent.jar!/META-INF/MANIFEST.MF
</pre></div>
</div>
<p>也可以尝试查找类的class文件：</p>
<div class="highlight-bash notranslate"><div class="highlight hljs"><pre class="bash">$ classloader -c 1b6d3586 -r java/lang/String.class
jar:file:/Library/Java/JavaVirtualMachines/jdk1.8.0_60.jdk/Contents/Home/jre/lib/rt.jar!/java/lang/String.class
</pre></div>
</div>
</div>
<div class="section" id="classloader">
<span id="id6"></span><h3>使用ClassLoader去加载类<a class="headerlink" href="#classloader" title="永久链接至标题">¶</a></h3>
<div class="highlight-bash notranslate"><div class="highlight hljs"><pre class="bash">$ classloader -c 3d4eac69 --load demo.MathGame
load class success.
class-info demo.MathGame
code-source /private/tmp/arthas-demo.jar
name demo.MathGame
isInterface false
isAnnotation false
isEnum false
isAnonymousClass false
isArray false
isLocalClass false
isMemberClass false
isPrimitive false
isSynthetic false
simple-name MathGame
modifier public
annotation
interfaces
super-class +-java.lang.Object
class-loader +-sun.misc.Launcher$AppClassLoader@3d4eac69
+-sun.misc.Launcher$ExtClassLoader@66350f69
classLoaderHash 3d4eac69
</pre></div>
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