Utente:Amux/Java Inspection: differenze tra le versioni

Versione delle 15:00, 13 ago 2015

Versione attuale delle 14:03, 25 mar 2023

(16 versioni intermedie di un altro utente non mostrate)

Riga 1:

__TOC__

== ElencareList leall classithe contenuteclasses in una jar file ==

<sourcesyntaxhighlight lang="bash">

jar tf <file.jar>

</syntaxhighlight>

</source>

Result:

Risultato:

<pre>

Riga 26:

</pre>

== ElencareList iall membrithe dipublic unamembers classeof a set of classes in una jar file ==

<sourcesyntaxhighlight lang="bash">

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

</syntaxhighlight>

</source>

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

Se si vogliono anche i membri protetti o privati o ancora più dati, usare opzioni aggiuntive.

Result:

Risultato:

<sourcesyntaxhighlight lang="java">

Compiled from "LoggingEvent.java"

public class org.apache.log4j.spi.LoggingEvent extends java.lang.Object implements java.io.Serializable{

Riga 52:

public org.apache.log4j.spi.LocationInfo getLocationInformation();

public org.apache.log4j.Level getLevel();

[...]

public java.lang.String getLoggerName();

public java.lang.Object getMessage();

public java.lang.String getNDC();

public java.lang.Object getMDC(java.lang.String);

public void getMDCCopy();

public java.lang.String getRenderedMessage();

public static long getStartTime();

public java.lang.String getThreadName();

public org.apache.log4j.spi.ThrowableInformation getThrowableInformation();

public java.lang.String[] getThrowableStrRep();

static java.lang.Class class$(java.lang.String);

static {};

}

</syntaxhighlight>

</source>

== 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:

<syntaxhighlight lang="bash">

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

</syntaxhighlight>

Result:

<syntaxhighlight lang="java">

// 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 public equals(java.lang.Object getMessage();

public voidint getMDCCopyhashCode();

public java.lang.String getLoggerNametoString();

public java.lang.Object getMDCcall(java.lang.StringObject, java.lang.Object...);

[...]

}

</syntaxhighlight>

== Look for potential memory leaks monitoring the GC ==

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

<syntaxhighlight lang="bash">

jstat -gc <pid> 5s

</syntaxhighlight>

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

<syntaxhighlight lang="bash">

#!/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"

)

</syntaxhighlight>

== Create a memory dump ==

<syntaxhighlight lang="bash">

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

</syntaxhighlight>

The memory dump can be analyzed using [https://eclipse.org/mat Eclipse Memory Analyzer]