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update java jdk/jre list, make icedtea a bit more prominent, address ACCEPT_LICENSE, misc fixes. bug 366261 and bug 366257.

1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/java.xml,v 1.49 2010/07/06 11:51:28 jkt Exp $ -->
4
5 <guide>
6 <title>Gentoo Java Guide</title>
7
8 <author title="Author">
9 <mail link="nichoj@gentoo.org">Joshua Nichols</mail>
10 </author>
11 <author title="Author">
12 <mail link="karltk@gentoo.org">Karl Trygve Kalleberg</mail>
13 </author>
14 <author title="Editor">
15 <mail link="nightmorph@gentoo.org">Joshua Saddler</mail>
16 </author>
17
18 <abstract>
19 This guide will introduce you to Java and explain how to use Java with Gentoo
20 Linux.
21 </abstract>
22
23 <!-- The content of this document is licensed under the CC-BY-SA license -->
24 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
25 <license/>
26
27 <version>1</version>
28 <date>2011-05-09</date>
29
30 <chapter>
31 <title>What is Java?</title>
32 <section>
33 <title>Overview</title>
34 <body>
35
36 <p>
37 Java is a programming language developed by engineers of Sun Microsystems. The
38 language is object-oriented and designed to run on multiple platforms without
39 the need of recompiling code for each platform. Although Java can be compiled
40 as a native program, much of Java's popularity can be attributed to its
41 portability, along with other features such as garbage collection. To make
42 platform independence possible the Java compiler compiles the Java code to an
43 intermediate representation called "Java bytecode" that runs on a JRE (Java
44 Runtime Environment) and not directly on the operating system.
45 </p>
46
47 <p>
48 In order to run Java bytecode, one needs to have a JRE (Java Runtime
49 Environment) installed. A JRE provides core libraries, a platform dependent
50 Java Virtual Machine, plugins for browsers, among other things. A JDK (Java
51 Development Kit) adds programming tools, such as a bytecode compiler and a
52 debugger.
53 </p>
54
55 </body>
56 </section>
57 </chapter>
58
59 <chapter>
60 <title>Before You Begin</title>
61 <section>
62 <title>Existing installs</title>
63 <body>
64
65 <p>
66 For existing installs, regardless of if you have installed anything Java
67 before, make sure you have followed the <uri
68 link="/proj/en/java/java-upgrade.xml">Java Upgrade Guide</uri>.
69 </p>
70
71 </body>
72 </section>
73 <section>
74 <title>New installs</title>
75 <body>
76
77 <p>
78 New installs should require no further preparation.
79 </p>
80
81 </body>
82 </section>
83 </chapter>
84
85 <chapter>
86 <title>Installing a Virtual Machine</title>
87 <section>
88 <title>The choices</title>
89 <body>
90
91 <p>
92 Gentoo provides numerous Runtime Environments (JREs) and Development Kits
93 (JDKs). Among the current choices, we have:
94 </p>
95
96 <table>
97 <tr>
98 <th>Vendor</th>
99 <th>JDK</th>
100 <th>JRE</th>
101 </tr>
102 <tr>
103 <ti>Sun's Java Kit</ti>
104 <ti>dev-java/sun-jdk</ti>
105 <ti>dev-java/sun-jre-bin</ti>
106 </tr>
107 <tr>
108 <ti>The IBM Java Kit</ti>
109 <ti>dev-java/ibm-jdk-bin</ti>
110 <ti>dev-java/ibm-jre-bin</ti>
111 </tr>
112 <tr>
113 <ti>BEA WebLogic's J2SE Development Kit</ti>
114 <ti>dev-java/jrockit-jdk-bin</ti>
115 </tr>
116 <tr>
117 <ti>The IcedTea Open Java Kit</ti>
118 <ti>dev-java/icedtea</ti>
119 <ti>dev-java/icedtea6-bin</ti>
120 </tr>
121 </table>
122
123 <!--
124 TODO: list free implementations?
125 note about not drop-in replacements
126 kaffe/sablevm/gcj/jamvm
127 -->
128 </body>
129 </section>
130 <section>
131 <title>Installing a JRE/JDKs</title>
132 <body>
133
134 <p>
135 To install your profile's default JDK, you can run <c>emerge virtual/jdk</c>.
136 Or to install your profile's default JRE, you can <c>emerge virtual/jre</c>.
137 </p>
138
139 <p>
140 Some JDKs and JREs, including the Sun packages, require accepting an End User
141 License Agreement, or EULA. If its license (such as dlj-1.1) is not listed in
142 ACCEPT_LICENSE in <path>/etc/make.conf</path>, then you won't be able to install
143 the JDK/JRE. For more information on how to add acceptable licenses to
144 <path>make.conf</path>, please read the <uri
145 link="/doc/en/handbook/handbook-x86.xml?part=2&amp;chap=1#doc_chap4">Portage
146 Handbook</uri>.
147 </p>
148
149 <p>
150 To avoid any restrictive license hassle, consider installing <c>icedtea6-bin</c>
151 or <c>icedtea</c>, which are more open Java implementations from the OpenJDK
152 project.
153 </p>
154
155 <note>
156 A JDK also includes a JRE, so if you install a JDK you shouldn't have to also
157 have to install a JRE.
158 </note>
159
160 </body>
161 </section>
162 <section>
163 <title>Installing fetch-restricted virtual machines</title>
164 <body>
165
166 <p>
167 Some of the JDKs and JREs require you to jump through a few hoops before
168 installing. Simply emerge the packages as you normally would. The ebuilds will
169 then instruct you where to go and what to download.
170 </p>
171
172 <p>
173 You should download the indicated file(s) into
174 <path>/usr/portage/distfiles</path>. Once there, you can rerun the emerge
175 command, at which point the JRE/JDK will be begin to install.
176 </p>
177
178 </body>
179 </section>
180 </chapter>
181
182 <chapter>
183 <title>Configuring your virtual machine</title>
184 <section>
185 <title>Overview</title>
186 <body>
187
188 <p>
189 Gentoo has the ability to have multiple JDKs and JREs installed without causing
190 conflicts.
191 </p>
192
193 <p>
194 Using the <c>java-config</c> tool, you can set the system-wide default
195 (provided you have root access). Users can also use <c>java-config</c> to set
196 up their own personal default.
197 </p>
198
199 <note>
200 You can also use <e>eselect</e> to change the system and user vm. See
201 <c>eselect java-vm help</c>.
202 </note>
203
204 </body>
205 </section>
206 <section>
207 <title>Setting a default virtual machine</title>
208 <body>
209
210 <p>
211 Running the command <c>java-config --list-available-vms</c> will give you a
212 list of all JREs and JDKs installed on your system. Here is an example of
213 output:
214 </p>
215
216 <pre caption="Listing available VMs">
217 # <i>java-config --list-available-vms</i>
218 The following VMs are available for generation-2:
219 1) IcedTea6-bin 1.4.1 [icedtea6-bin]
220 2) Sun JDK 1.5.0.20 [sun-jdk-1.5] <comment>(Build Only)</comment>
221 *) Sun JDK 1.6.0.16 [sun-jdk-1.6]
222 </pre>
223
224 <note>
225 VMs marked as Build Only may contain security vulnerabilities and/or be EOL.
226 Gentoo recommends not setting these VMs as either your system or user VM.
227 Please see <uri link="java.xml#build-only">Build Only VM</uri> for more
228 information.
229 </note>
230
231 <p>
232 The <e>*</e> indicates this is the current active vm (system-vm or user-vm when
233 set). The name in the brackets (<e>[]</e>) is the handle or ID for that
234 particular VM. You use the handle or the number to <c>java-config
235 --set-system-vm</c>. Here is an example of how to set the system VM.
236 </p>
237
238 <pre caption="Setting the System VM">
239 <comment>(By handle (preferred))</comment>
240 # <i>java-config --set-system-vm sun-jdk-1.6</i>
241 Now using sun-jdk-1.6 as your generation-2 system JVM
242 <comment>(By number)</comment>
243 # <i>java-config --set-system-vm 3</i>
244 Now using sun-jdk-1.6 as your generation-2 system JVM
245 </pre>
246
247 <p>
248 As a regular user, you can use <c>java-config --set-user-vm</c>.
249 </p>
250
251 <note>
252 You no longer have to <c>source</c> the profile for updates to the user/system
253 VM take place.
254 </note>
255
256 </body>
257 </section>
258 <section id="build-only">
259 <title>Build Only VM</title>
260 <body>
261
262 <p>
263 Some virtual machines are flagged as build-only due to being EOL and/or
264 containing security vulnerabilities. These virtual machines will not
265 automatically be used by Gentoo for the running of applications using Gentoo
266 launchers but will still be available for use by Gentoo's build environment as
267 some packages may require them for building. The setting of these virtual
268 machines as either your system or user VM is strongly discouraged as these VMs
269 will then be used when running the <path>/usr/bin/{java,javac,..}</path>
270 executables and will also be used by any packages not using Gentoo's launcher
271 scripts.
272 </p>
273
274 </body>
275 </section>
276 <section id="preferred-vm">
277 <title>Preferred Build VM</title>
278 <body>
279
280 <p>
281 While merging Java packages, the VM used for building can sometimes be different
282 from the one currently set as the system VM.
283 </p>
284
285 <p>
286 This merge time VM switching is needed when, for example, your system-vm is
287 set to a 1.6 VM and the package you are merging requires a 1.5 VM. While merging
288 it will select and use a 1.5 VM, leaving your system-vm choice intact.
289 </p>
290
291 <p>
292 To define which VM is selected when a switch is needed, we have created a list of <e>default/supported
293 VMs</e> per arch. You can find them in
294 <path>/usr/share/java-config-2/config/jdk-defaults.conf</path>.
295 </p>
296
297 <p>
298 You can override these defaults (and even your selected system VM) in
299 <path>/etc/java-config-2/build/jdk.conf</path> and have complete control over
300 which VM will get used for merging. Some examples:
301 </p>
302
303 <pre caption="Example /etc/java-config-2/build/jdk.conf">
304 <comment>(I always want it to use a sun-jdk, ie sun-jdk-1.4 for 1.4, sun-jdk-1.5 for 1.5, etc)</comment>
305 *=sun-jdk
306 </pre>
307
308 <pre caption="Example /etc/java-config-2/build/jdk.conf">
309 <comment>(Always use sun-jdk-1.5 wherever possible, except for when a 1.4 or 1.3 VM is explicitly required)</comment>
310 *=sun-jdk-1.5
311 </pre>
312
313 <pre caption="Example /etc/java-config-2/build/jdk.conf">
314 <comment># For 1.3 I prefer sun-jdk 1.4 but when it is not available, use ibm-jdk-bin,
315 # For 1.5, use sun-jdk </comment>
316 1.3=sun-jdk-1.4 ibm-jdk-bin
317 1.5=sun-jdk
318 </pre>
319
320 <warn>
321 You do not <e>have</e> to edit this file. If you change these options to use a
322 unsupported VM, things could possibly break. Because of the wide variety of
323 available VMs, we do not have the resources to test and verify every package
324 works on all of them. Bugs reported with a unsupported VM won't be prioritized
325 as much as bugs present within supported VMs.
326 </warn>
327
328 </body>
329 </section>
330 </chapter>
331
332 <chapter>
333 <title>Compilers</title>
334 <section>
335 <body>
336
337 <p>
338 The standard Java compiler used for building is <c>javac</c>, which comes with
339 each JDK. In addition to configuring the VM used at build time, it is also
340 possible configure which compiler is used. Essentially, you define a list your
341 preference for which compiler to use in
342 <path>/etc/java-config-2/build/compilers.conf</path>.
343 </p>
344
345 <pre caption="/etc/java-config-2/build/compilers.conf">
346 # If the ebuild supports it
347 # it will check the COMPILERS var front to back and
348 # use the first compiler that is installed
349
350 COMPILERS="ecj-X.Y jikes javac"
351 </pre>
352
353 <p>
354 Some compilers don't support all possible -target and -source arguments.
355 Therefore, each compiler in the list is checked to see if it can support the
356 desired -source/-target. javac will work in all cases, so if no other suitable
357 compiler is found, it will be used instead.
358 </p>
359
360 <p>
361 More details about each compiler are provided below:
362 </p>
363
364 <table>
365 <tr>
366 <th>Name</th>
367 <th>Handle</th>
368 <th>Package</th>
369 <th>Description</th>
370 </tr>
371 <tr>
372 <ti>javac</ti>
373 <ti>javac</ti>
374 <ti>N/A</ti>
375 <ti>
376 This is the default compiler that will be used, and comes with each JDK.
377 </ti>
378 </tr>
379 <tr>
380 <ti>jikes</ti>
381 <ti>jikes</ti>
382 <ti>dev-java/jikes</ti>
383 <ti>
384 Jikes was originally developed by IBM. Anecdotally, it is generally quicker
385 than javac. Note however, that it is more pedantic, and will fail under a
386 few circumstances where javac has no issue. It also does not support Java
387 1.5 syntax yet.
388 </ti>
389 </tr>
390 <tr>
391 <ti>Eclipse Compiler for Java</ti>
392 <ti>ecj</ti>
393 <ti>dev-java/eclipse-ecj</ti>
394 <ti>
395 ECJ is the compiler used by the Eclipse software development kit. It is
396 very full featured, and is pretty fast. It does support Java 1.5 syntax.
397 </ti>
398 </tr>
399 </table>
400
401 </body>
402 </section>
403 </chapter>
404
405 <chapter>
406 <title>Setting a default CLASSPATH</title>
407 <section>
408 <body>
409
410 <warn>
411 The options explained in this section should be considered deprecated and will
412 most likely be removed in the future. We strongly recommend against using
413 these, because your Java projects or application should ideally manage their
414 own classpaths. If you choose to specify a default CLASSPATH, some applications
415 may behave unexpectedly, because classes they weren't expecting would be on the
416 classpath.
417 </warn>
418
419 <p>
420 <c>java-config</c> can also be used to set a system-wide default CLASSPATH, as
421 well a user-specific default CLASSPATH.
422 </p>
423
424 <p>
425 First, you will want to list available Java libraries installed on your system
426 that might want to be put in your CLASSPATH. Here is an example of output:
427 </p>
428
429 <pre caption="Listing classes">
430 # <i>java-config --list-available-packages</i>
431 [xerces-2] The next generation of high performance, fully compliant XML parsers in the Apache Xerces family (/usr/share/xerces-2/package.env)
432 [junit] Simple framework to write repeatable tests (/usr/share/junit/package.env)
433 [bsh] BeanShell: A small embeddable Java source interpreter (/usr/share/bsh/package.env)
434 [bcel] The Byte Code Engineering Library: analyze, create, manipulate Java class files (/usr/share/bcel/package.env)
435 [log4j] A low-overhead robust logging package for Java (/usr/share/log4j/package.env)
436 ...
437 </pre>
438
439 <p>
440 Again, the names in brackets (<e>[]</e>) are the IDs that you have to pass to
441 <c>java-config --set-system-classpath</c>. Here is an example:
442 </p>
443
444 <pre caption="Setting classpaths">
445 # <i>java-config --set-system-classpath log4j,xerces-2</i>
446 </pre>
447
448 <note>
449 The current directory (<path>.</path>) will not be part of the system
450 classpath, as that should be added in your system's login profile.
451 </note>
452
453 <p>
454 You will have to update your environment by logging out, then in again or
455 sourcing <path>/etc/profile</path>.
456 </p>
457
458 <p>
459 For users, <c>java-config --set-user-classpath</c> will create
460 <path>~/.gentoo/java-env-classpath</path>, which you should then source from
461 your shell's profile.
462 </p>
463
464 <pre caption="Sourcing user specific classpath">
465 <i>if [[ -f "${HOME}/.gentoo/java-env-classpath" ]]; then
466 source ${HOME}/.gentoo/java-env-classpath
467 fi</i>
468 </pre>
469
470 <p>
471 If you really want a system wide or user default classpath you can add
472 something like the following to your shell's profile. But we would advise
473 against it.
474 </p>
475
476 <pre caption="Setting classpath">
477 # <i>export CLASSPATH="${CLASSPATH}:$(java-config --classpath log4j,xerces-2)"</i>
478 </pre>
479
480 </body>
481 </section>
482 </chapter>
483
484 <chapter>
485 <title>Java Browser Plugins</title>
486 <section>
487 <title>Installing a plugin</title>
488 <body>
489
490 <p>
491 You can install a Java plugin for your web browser by emerging a Java VM with
492 the <c>nsplugin</c> USE flag set.
493 </p>
494
495 <note>
496 <c>nsplugin</c> is not available for all architectures. Check for available
497 plugins on your arch before trying to install a VM by running <c>emerge -pv
498 &lt;java-vm&gt;</c>.
499 </note>
500
501 <p>
502 Portage will allow you to install multiple versions of Java plugins, though
503 only one will be used by your browser. You can check the list of available
504 plugins by running:
505 </p>
506
507 <pre caption="Viewing available plugins">
508 # <i>eselect java-nsplugin list</i>
509 [1] sun-jre-bin-1.6
510 [2] icedtea6-bin
511 </pre>
512
513 <p>
514 In this example, <c>sun-jre-bin</c> is selected for the browser plugin.
515 </p>
516
517 <pre caption="Selecting a plugin">
518 # <i>eselect java-nsplugin set sun-jre-bin-1.6</i>
519 </pre>
520
521 <p>
522 Verify that the correct plugin was selected:
523 </p>
524
525 <pre caption="Verifying the correct plugin">
526 # <i>eselect java-nsplugin list</i>
527 [1] sun-jre-bin-1.6 current
528 [2] icedtea6-bin
529 </pre>
530
531 <p>
532 Java.com also provides a link to <uri
533 link="http://java.com/en/download/installed.jsp">verify your installed
534 plugin</uri>. Additionally, if you are using a Mozilla-based browser, you can
535 verify your Java plugin by typing <c>about:plugins</c> into the address bar.
536 </p>
537
538 </body>
539 </section>
540 <section>
541 <title>Plugins on multilib systems</title>
542 <body>
543
544 <p>
545 If you are running a mixed 64-bit and 32-bit multilib system (for example, on
546 AMD64), you can use 64-bit and 32-bit Java plugins. Unless you have a pressing
547 need to run 32-bit Java applications, we recommend using native 64-bit plugins
548 on 64-bit web browsers.
549 </p>
550
551 <p>
552 There are several native 64-bit browser plugins available. The default JDK/JRE
553 pair, <c>sun-jdk</c> and <c>sun-jre-bin</c>, both include browser plugins. Just
554 emerge one of them with the <c>nsplugin</c> USE flag enabled.
555 </p>
556
557 <pre caption="Installing a 64-bit plugin">
558 # <i>echo "dev-java/sun-jre-bin nsplugin" >> /etc/portage/package.use</i>
559 # <i>emerge sun-jre-bin</i>
560 </pre>
561
562 <p>
563 To use a 32-bit plugin on a 32-bit browser, you will need to emerge
564 <c>emul-linux-x86-java</c> with the <c>nsplugin</c> USE flag enabled.
565 </p>
566
567 <pre caption="Installing a 32-bit plugin">
568 # <i>echo "app-emulation/emul-linux-x86-java nsplugin" >> /etc/portage/package.use</i>
569 # <i>emerge emul-linux-x86-java</i>
570 </pre>
571
572 <p>
573 Next, check which plugins are available:
574 </p>
575
576 <pre caption="Viewing available plugins">
577 # <i>eselect java-nsplugin list</i>
578 Available 32-bit Java browser plugins
579 [1] emul-linux-x86-java-1.5
580 [2] emul-linux-x86-java-1.6
581 Available 64-bit Java browser plugins
582 [1] icedtea6-bin
583 [2] sun-jre-bin-1.6
584 </pre>
585
586 <p>
587 Now select the right plugin for your browsers:
588 </p>
589
590 <pre caption="Selecting plugins">
591 <comment>(Choose the plugins for 32-bit and 64-bit browsers)</comment>
592 # <i>eselect java-nsplugin set 32bit emul-linux-x86-java-1.6</i>
593 # <i>eselect java-nsplugin set 64bit sun-jre-bin-1.6</i>
594 </pre>
595
596 <p>
597 Verify the correct plugin was selected:
598 </p>
599
600 <pre caption="Verifying the correct plugin">
601 # <i>eselect java-nsplugin list</i>
602 Available 32-bit Java browser plugins
603 [1] emul-linux-x86-java-1.5
604 [2] emul-linux-x86-java-1.6 current
605 Available 64-bit Java browser plugins
606 [1] icedtea6-bin
607 [2] sun-jre-bin-1.6 current
608 </pre>
609
610 </body>
611 </section>
612 </chapter>
613
614 <chapter>
615 <title>USE flags for use with Java</title>
616 <section>
617 <title>Setting USE flags</title>
618 <body>
619
620 <p>
621 For more information regarding USE flags, refer to the <uri
622 link="/doc/en/handbook/handbook-x86.xml?part=2&amp;chap=2">USE flags</uri>
623 chapter from the Gentoo Handbook.
624 </p>
625
626 </body>
627 </section>
628 <section>
629 <title>The flags</title>
630 <body>
631
632 <ul>
633 <li>The <b>java</b> flag adds support for Java in a variety of programs</li>
634 <li>
635 The <b>nsplugin</b> flag adds support for Mozilla-like browsers (including
636 Firefox). You will need this for viewing Java applets in your Mozilla-like
637 browser.
638 </li>
639 <li>
640 The <b>source</b> flag installs a zip of the source code of a package.
641 This is traditionally used for IDEs to 'attach' source to the libraries you
642 are using.
643 </li>
644 <li>The <b>jce</b> flag adds support for the Java Cryptography Engine</li>
645 <li>
646 For Java packages, the <b>doc</b> flag will build API documentation using
647 javadoc.
648 </li>
649 </ul>
650
651 </body>
652 </section>
653 </chapter>
654
655 <chapter>
656 <title>Additional resources</title>
657 <section>
658 <title>Off-line resources</title>
659 <body>
660
661 <ul>
662 <li>java-config man page</li>
663 <li><c>java-config --help</c></li>
664 </ul>
665
666 </body>
667 </section>
668 <section>
669 <title>Online resources</title>
670 <body>
671
672 <ul>
673 <li>
674 The <uri link="http://www.gentoo.org/proj/en/java/">Java Project
675 Page</uri>
676 </li>
677 <li>
678 The <uri
679 link="http://news.gmane.org/gmane.linux.gentoo.java">gentoo-java</uri>,
680 <uri
681 link="http://news.gmane.org/gmane.linux.gentoo.user">gentoo-user</uri>, and
682 <uri
683 link="http://news.gmane.org/gmane.linux.gentoo.devel">gentoo-dev</uri>
684 mailing list archives
685 </li>
686 <li>
687 <uri link="irc://irc.gentoo.org/gentoo">#gentoo</uri> and <uri
688 link="irc://irc.gentoo.org/gentoo-java">#gentoo-java</uri> on IRC
689 </li>
690 <li>
691 <uri
692 link="http://en.wikipedia.org/wiki/Java_programming_language">Wikipedia's
693 entry for Java</uri>
694 </li>
695 <li>
696 If you have suggestions or questions regarding this document, please email
697 the Gentoo Java team: <mail>java@gentoo.org</mail>
698 </li>
699 </ul>
700
701 </body>
702 </section>
703 </chapter>
704 </guide>

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