Could "attach source" be made easier for popular Java libraries?

Question

I run into this obstacle when my debugger steps into some classfile without corresponding source. Finding it is often difficult:

• You have to search for the site hosting the respective project, and find its ``download source'' page (for instance, last time I searched for the JPA API, and it took me hours to obtain the sources). Or, you might be required to check it out from revision control.

• You need to know the exact version you are using. Otherwise the debugger might step into comments and empty lines :)

• There is no convention for packaging source code—some projects include it in the jar itself; some provide a separate zip file; others put it in a src/ subfolder within the zip.

I know Maven has the capability of downloading source from its repository and including it in the src paths when an IDE config file is generated. But Maven's repo is so poor in terms of content—few libs actually have their source uploaded.

Why is it so complicated when it can be made straightforward? We could have some central repo which relates a classfile (or a hash thereof) to the source file it was compiled from (or a link to it). Maybe a rather huge repo, but pretty simply structured. An IDE plugin could query it to fetch what's needed automatically.

Have you, guys, experienced the same?

How do you obtain the sources to attach?

Answer 1

Both m2eclipse and IDEA will download the sources and javadocs for any dependencies. The m2eclipse sources can be downloaded by right-clicking on a dependency (or the whole project if you want all sources) and clicking Maven->Download Sources.

On newer versions of m2eclipse you can also automatically download sources by going to Window->Preferences...->Maven, then selecting the "Download Artifact Sources" option. When you open a type in a dependency jar that there are currently no sources available for, Maven will download the sources in the background and update the source attachment in the background.

Answer 2

Haven't seen a satisfactory solution myself.

I tend to roll my own repo, without Maven (Maven is fine, but it doesn't click with me). I run something similar to the BSD ports system, that is, one big structured tree that contains little Ant build files. These build files either checkout the source of a project, pull its dependencies from somewhere else in the tree and build it (these are for the projects I want to build- i.e., mine) or pull binaries from somewhere else (which might be an external source or my own binaries repository).

The system could easily be extended to pull src jars, but I do that manually now.

Answer 3

it may be complicated but it is worth the initial effort.

i do it the following way: in my project directory i have three major directories,

• src (my own)
• lib
• suppl (sources / javadocs when no sources exist)

i put in suppl one zip file per library, containing the sources. in intellij this gives me not only debugger superpowers, but also javadocs.

you are right, obtaining the sources is a pain. sometimes the sources come deliveded in the .jar file of the lib, sometimes as a seperate download (my favorite) and sometimes i have to create a seperate cvs/svn dir where i can checkout the sources. i usually need to re-package them the way i like them, even if provided in a zip.

i am sceptical about maven. i just don't like to hand over my decisions about choosing libs to a program.

Answer 4

we do something similar to Andreas. Our lib directory has subdirectories categorizing further. One such sub dir is source or debug which has the source JAR/ZIPs of all the jars that we want to debug. Do it once and you're good. We use an IVY repository for the jars and source jars.

Answer 5

This is all done automatically if you use M2eclipse (http://m2eclipse.sonatype.org).