Utente:Amux/Java Inspection

List all the classes in a jar file

jar tf <file.jar>

Result:

META-INF/MANIFEST.MF
META-INF/JBOSSCOD.SF
META-INF/JBOSSCOD.RSA
META-INF/
org/
org/apache/
org/apache/log4j/
org/apache/log4j/chainsaw/
[...]
org/apache/log4j/Appender.class
org/apache/log4j/AppenderSkeleton.class
org/apache/log4j/AsyncAppender$DiscardSummary.class
org/apache/log4j/AsyncAppender$Dispatcher.class
[...]
org/apache/log4j/spi/LoggingEvent.class
[...]

List all the public members of a set of classes in a jar file

javap -classpath log4j-boot.jar org.apache.log4j.spi.LoggingEvent

If you want protected and private members, or more informations, you can use additional options.

Result:

Compiled from "LoggingEvent.java"
public class org.apache.log4j.spi.LoggingEvent extends java.lang.Object implements java.io.Serializable{
    public final transient java.lang.String fqnOfCategoryClass;
    public final java.lang.String categoryName;
    public transient org.apache.log4j.Priority level;
    public final long timeStamp;
    static final long serialVersionUID;
    static final java.lang.Integer[] PARAM_ARRAY;
    static final java.lang.String TO_LEVEL;
    static final java.lang.Class[] TO_LEVEL_PARAMS;
    static final java.util.Hashtable methodCache;
    static java.lang.Class class$org$apache$log4j$Level;
    public org.apache.log4j.spi.LoggingEvent(java.lang.String, org.apache.log4j.Category, org.apache.log4j.Priority, java.lang.Object, java.lang.Throwable);
    public org.apache.log4j.spi.LoggingEvent(java.lang.String, org.apache.log4j.Category, long, org.apache.log4j.Priority, java.lang.Object, java.lang.Throwable);
    public org.apache.log4j.spi.LocationInfo getLocationInformation();
    public org.apache.log4j.Level getLevel();
[...]
    static {};
}

List all the members of all the classes in a jar file

To list all the members (even private) of all the classes in a jar you can use this command:

JARNAME=<jarname.jar> sh -c 'jar tf "${JARNAME}" | egrep "\.class$" | sed "s/\.class//g; s/\//\./g" | xargs javap -private -classpath "${JARNAME}"'

Result:

// JARNAME=nashorn.jar sh -c 'jar tf "${JARNAME}" | egrep "\.class$" | sed "s/\.class//g; s/\//\./g" | xargs javap -private -classpath "${JARNAME}"'
Compiled from "ScriptObjectMirror.java"
public final class jdk.nashorn.api.scripting.ScriptObjectMirror extends jdk.nashorn.api.scripting.AbstractJSObject implements javax.script.Bindings {
  private static final java.security.AccessControlContext GET_CONTEXT_ACC_CTXT;
  private final jdk.nashorn.internal.runtime.ScriptObject sobj;
  private final jdk.nashorn.internal.objects.Global global;
  private final boolean strict;
  private final boolean jsonCompatible;
  static final boolean $assertionsDisabled;
  private static java.security.AccessControlContext getContextAccCtxt();
  public boolean equals(java.lang.Object);
  public int hashCode();
  public java.lang.String toString();
  public java.lang.Object call(java.lang.Object, java.lang.Object...);
[...]
}

Look for potential memory leaks monitoring the GC

To monitor the garbage collection on <pid> every 5 seconds:

jstat -gc <pid> 5s

Proof-of-concept of a script for visualizing it in the command line (requires gnuplot):

#!/bin/bash

set -eu
set -o pipefail

FILENAME="jstat.txt"
NUMBER_OF_LINES=10

cat <(head -n 1 "${FILENAME}") <(tail -n +2 "${FILENAME}" | tail -n "${NUMBER_OF_LINES}") | \
    (
        cat > /dev/shm/mytempfile && trap 'rm /dev/shm/mytempfile' EXIT && \
        gnuplot -e "set terminal dumb; set key autotitle columnhead; plot for[col=1:17] '/dev/shm/mytempfile' using 0:col with lines"
    )

Create a memory dump

jmap -dump:format=b,file=<filename.hprof> <pid>

The memory dump can be analyzed using Eclipse Memory Analyzer