Java Web Applications in Fedora

Fedora and Debian play the role where many chaotic projects get a degree of charm school: they learn to play nice with a lot of other projects. In Fedora, as near as I can tell, there is only one Java based web application packages as part of the distribution: Dogtag, the Public Key Infrastructure server. As we look at how PKI should look in the future, the dearth of comparable applications packaged for Fedora leaves us with the opportunity for defining a logical and simple standard packing scheme. While I am not there yet, this post is the start of my attempts to organize my thoughts on the subject. I’m looking for input.

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Finding Java Classes

I’m back on a Java project. Been a while, and I want to capture some of the tricks I’m using.

Right now, I’m just trying to import the project into eclipse.  Seems that the current team members don’t use it.  I’m an IDE kind of guy, at least when it comes to Java.

Building the .classpath file can be tricky.  However, since I know that I have a good build, and that this project it a good participant in the Fedora build process, I have the advantage of knowing that my packages reside in /usr/share/java.  Still, all eclipse gives me is a set of classes that it can’t find.  how to find them?

This project uses CMake.  I could look for all of the Jar files in the CMakeLists.txt files, and I might do that in the future.  However, a trick I’ve developed in the past has come in handy.

 

class2path(){
echo $1 | sed 's!\.!\/!g'
}

JDIR=/usr/share/java

make_alljars(){
for JAR in `find /usr/share/java -name \*.jar -type f ` 
	do for CLASS in `jar -tf $JAR |  grep \.class` 
		do echo $JAR $CLASS  
	done 
done > /tmp/alljars.txt
}

 

First, the make_alljars function creates a map in (value key) order. The value is the Jar file name, and the key is the class name. To fine a Jar file that contains a given class (in this example netscape.ldap.LDAPConnection) , run:

 

grep `class2path  netscape.ldap.LDAPConnection` /tmp/alljars.txt

And the output is

/usr/share/java/ldapjdk.jar netscape/ldap/LDAPConnection$ResponseControls.class
/usr/share/java/ldapjdk.jar netscape/ldap/LDAPConnection.class


This works really well with eclipse, in that the error messages have the name of the class. You can then just highlight the class name, paste it into the command line in place of the class I have above, and when you get the Jar file name, you can highlight to save to the clipboard. From The right click context menu pick Java Build Path and then Add External Archive and then paste the whole path in.

What Jar File

When working a with a new project, I often find I am searching for the Jar files that fulfill a dependency. Sometimes they come from maven, sometimes from the Fedora RPMS. My approach has been to make a cache of the Jar files in the directories that I care about that contains a map from jar file name to class name:

#!/bin/bash

CACHE_FILE=/tmp/jarcache

echo > $CACHE_FILE

for DIR in /usr/share/java /usr/lib/java
do
    for JAR in `find $DIR -name \*.jar`
    do
        #only do the non-symlinked versions
        if [ -f $JAR ]
        then
            for CLASS_FILE in `jar -tf $JAR | grep \.class`
            do
                CLASS=`echo $CLASS_FILE | sed 's!/!.!g'`
                echo $JAR $CLASS >> $CACHE_FILE
            done
        fi
    done
done

Then call it this way:

grep "org.mozilla.jss.ssl" /tmp/jarcache