jad en

2024-12-02 20:28:05 +08:00 · 2018-09-21 01:11:23 +08:00 · 2018-09-21 01:11:23 +08:00 · b8040c551b
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+jad
+===
+
+De-compile specified loaded classes.
+
+`jad` helps to *de-compile* the byte code in JVM to the source code to assist you to better understand the logic behind.
+
+F.Y.I
+* the de-compiled code will be grammatically highlighted for readability in Arthas Console;
+* you have to understand there might be some trivial grammar errors but it won't affect the logic understanding.
+
+### Options
+
+|Name|Specification|
+|---:|:---|
+|*class-pattern*|pattern for the class name|
+|`[c:]`|hashcode of the class loader that loaded the class|
+|[E]|turn on regx matching while the default is wildcards matching|
+
+### Usage
+
+When several class loaders loaded the same class:
+1. `jad` to get the hashcode of the class loader;
+2. `jad -c <hashcode>` to get the de-compiled class loaded by the class loader.
+
+```java
+$ jad org.apache.log4j.Logger
+
+ Found more than one class for: org.apache.log4j.Logger, Please use jad -c hashcode org.apache.log4j.Logger
+ HASHCODE  CLASSLOADER
+ 69dcaba4  +-monitor's ModuleClassLoader
+ 6e51ad67  +-java.net.URLClassLoader@6e51ad67
+             +-sun.misc.Launcher$AppClassLoader@6951a712
+               +-sun.misc.Launcher$ExtClassLoader@6fafc4c2
+ 2bdd9114  +-pandora-qos-service's ModuleClassLoader
+ 4c0df5f8  +-pandora-framework's ModuleClassLoader
+
+Affect(row-cnt:0) cost in 38 ms.
+$ jad org.apache.log4j.Logger -c 69dcaba4
+
+ClassLoader:
+-monitor's ModuleClassLoader
+
+Location:
+/Users/zhuyong/Downloads/taobao-hsf.sar/plugins/monitor/lib/log4j-1.2.14.jar
+
+package org.apache.log4j;
+
+import org.apache.log4j.spi.*;
+
+public class Logger extends Category
+{
+    private static final String FQCN;
+
+    protected Logger(String name)
+    {
+        super(name);
+    }
+
+    public static Logger getLogger(String name)
+    {
+        return LogManager.getLogger(name);
+    }
+
+    public static Logger getLogger(Class clazz)
+    {
+        return LogManager.getLogger(clazz.getName());
+    }
+
+    public static Logger getRootLogger()
+    {
+        return LogManager.getRootLogger();
+    }
+
+    public static Logger getLogger(String name, LoggerFactory factory)
+    {
+        return LogManager.getLogger(name, factory);
+    }
+
+    public void trace(Object message)
+    {
+        if (repository.isDisabled(5000))
+        {
+            return;
+        }
+        if (Level.TRACE.isGreaterOrEqual(getEffectiveLevel()))
+        {
+            forcedLog(Logger.FQCN, Level.TRACE, message, null);
+        }
+    }
+
+    public void trace(Object message, Throwable t)
+    {
+        if (repository.isDisabled(5000))
+        {
+            return;
+        }
+        if (Level.TRACE.isGreaterOrEqual(getEffectiveLevel()))
+        {
+            forcedLog(Logger.FQCN, Level.TRACE, message, t);
+        }
+    }
+
+    public boolean isTraceEnabled()
+    {
+        if (repository.isDisabled(5000))
+        {
+            return false;
+        }
+        return Level.TRACE.isGreaterOrEqual(getEffectiveLevel());
+    }
+
+    static
+    {
+        Logger.FQCN = Logger.class.getName();
+    }
+
+}
+
+Affect(row-cnt:1) cost in 190 ms.
+```
+
+De-compile the specified method:
+
+```sh
+$ jad com.taobao.container.web.arthas.rest.MetricsController directMetrics
+
+ClassLoader:
+-com.taobao.pandora.boot.loader.ReLaunchURLClassLoader@1817d444
+  +-sun.misc.Launcher$AppClassLoader@14dad5dc
+    +-sun.misc.Launcher$ExtClassLoader@a38d7a3
+
+Location:
+/Users/zhuyong/middleware/tomcat-web/tomcat-web-web/target/classes/
+
+private Map<String, Object> directMetrics(String ip, String[] metrics) {
+    JSONObject obj;
+    HashMap<String, Object> result = new HashMap<String, Object>();
+    result.put("success", false);
+    String metricUrl = "http://" + ip + ":8006/metrics/specific";
+    String postBody = Arrays.stream(metrics).map(metric -> "metric=" + metric).collect(Collectors.joining("&"));
+    HttpClientUtils.Response resp = HttpClientUtils.sendPostRequest((String)metricUrl, (String)postBody);
+    if (resp.isSuccess() && (obj = JSON.parseObject(resp.getContent())).containsKey("success") && obj.getBoolean("success").booleanValue() && obj.containsKey("data")) {
+        JSONArray dataArray = obj.getJSONArray("data");
+        HashMap<String, Object> metricMap = new HashMap<String, Object>();
+        for (Object aDataArray : dataArray) {
+            JSONObject o = (JSONObject)aDataArray;
+            metricMap.put(o.getString("metric"), o.get("value"));
+        }
+        result.put("data", metricMap);
+        result.put("success", true);
+        return result;
+    }
+    return result;
+}
+
+Affect(row-cnt:1) cost in 1508 ms.
+```