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1<?xml version='1.0'?> 1<?xml version="1.0" encoding="UTF-8"?>
2<?xml-stylesheet href="/xsl/guide.xsl" type="text/xsl"?> 2<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/java.xml,v 1.17 2005/09/29 18:27:31 rane Exp $ -->
3<guide> 3<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
5<guide link="/doc/en/java.xml">
4<title>Gentoo Java Guide</title> 6<title>Gentoo Java Guide</title>
5<author title="Author and Editor"> 8<author title="Author and Editor">
6<mail link="karltk@gentoo.org">Karl Trygve Kalleberg</mail> 9 <mail link="karltk@gentoo.org">Karl Trygve Kalleberg</mail>
7</author> 10</author>
11<author title="Editor">
12 <mail link="swift@gentoo.org">Sven Vermeulen</mail>
14<author title="Editor">
15 <mail link="vanquirius@gentoo.org">Marcelo Góes</mail>
8 17
9<abstract> 18<abstract>
10Users' and Developers' Guide to Java in Gentoo 19This guide will introduce users and developers to Java and explain how to use
20Java with Gentoo Linux.
11</abstract> 21</abstract>
12 22
13<version>0.1.1</version> 25<version>0.1.7</version>
14<date>June 25, 2002</date> 26<date>2005-09-29</date>
15 27
16<chapter> 28<chapter>
17 29<title>What is Java?</title>
18<title>Installing a JDK/JRE</title>
19<section> 30<section>
20<title>Overview</title> 31<title>Overview</title>
21<body> 32<body>
22<p>Gentoo provides numerous JDKs and JREs. The default is the
23Blackdown JDK/JRE pair, as it is freely (beer) available without any
24registration fuss.</p>
25 33
26<note>As kaffe becomes a JRE/JDK drop-in replacement, that will most 34<p>
27likely become our default.</note> 35Java is a programming language developed by engineers of Sun Microsystems.
36The language is object-oriented and designed to run on multiple platforms
37without the need of recompiling code for each platform. Although Java can
38be compiled as a native program, much of Java's popularity can be attributed
39to its portability, along with other features such as garbage collection.
40The ability to compile once and run in various platforms is achieved through
41the use of just-in-time compilers (JIT), which compile Java bytecodes into
42native code when a given program is run.
28 44
29<p>Both the Sun JDK/JRE and the IBM JDK/JRE are generally faster, but 45<p>
30getting them is a bit more work, as you are required to read and 46In order to run Java bytecodes, one needs to have a JRE (Java Runtime Environment)
31accept their license before downloading (IBM additionally requires you 47installed. A JRE provides core libraries, a platform dependent Java Virtual Machine,
32to register).</p> 48plug-ins for browsers, among other things. A JDK (Java Development Kit) adds
49programming tools, such as a bytecode compiler and a debugger.
33 51
34<p>Our ebuilds for the Sun and IBM JDK/JREs will notify you of where
35to go to download them.</p>
36</body> 52</body>
39<section> 53</section>
40<title>Installing the Sun/IBM JDK/JREs</title> 54</chapter>
57<title>Installing a JRE/JDK</title>
59<title>The choices</title>
63Gentoo provides numerous JREs and JDKs. Among the current alternatives, we have:
67 <li>blackdown-jre and blackdown-jdk, the Blackdown Java Kit</li>
68 <li>sun-jre-bin and sun-jdk, Sun's Java Kit </li>
69 <li>ibm-jre-bin and ibm-jdk-bin, the IBM Java Kit</li>
70 <li>compaq-jre and compaq-jdk, the Compaq Java Kit for Alpha/Linux/GNU</li>
71 <li>jrockit-jdk-bin, BEA WebLogic's J2SE Development Kit</li>
75The default is the Blackdown JRE/JDK
76pair, as it is freely ("free as in beer") available without any registration
81Both the Sun JRE/JDK and the IBM JRE/JDK are generally faster, but getting them
82is a bit more work, as you are required to read and accept their license before
83downloading (IBM additionally requires you to register).
87Our ebuilds for the Sun and IBM JRE/JDKs will notify you of where to go to
88download them.
41<body> 91</body>
42<p>If you run <c>emerge dev-java/sun-jdk-1.3.1</c> or <c>emerge 92</section>
43dev-java/ibm-jdk-1.3.1</c>, you will be notified that you are required 93<section>
44to download the actual tarballs yourself. This has to do with license 94<title>Installing the Sun/IBM JRE/JDKs</title>
45restrictions for the Sun JDK/JRE (online click-wrap license) and 95<body>
46registration issues with the IBM JDK/JRE.</p>
47 96
48<note>There is also a dev-java/sun-jdk-1.4.0, but not all packages 97<p>
49work nicely with Java 1.4, so you're on your own if you use the 1.4.0 98If you run <c>emerge =sun-jdk-</c> or <c>=ibm-jdk-bin-1.4.2</c>, you will
99be notified that you are required to download the actual tarballs yourself. This
100has to do with license restrictions for the Sun JRE/JDK (online click-wrap
101license) and registration issues with the IBM JRE/JDK.
105ibm-jdk-bin is currently masked, you may have to unmask it to use it.
50JDK.</note> 106</note>
51 107
52<p>You should download the indicated file(s) into 109You should download the indicated file(s) into
53<path>/usr/portage/distfiles</path>. Once that is done, you can rerun 110<path>/usr/portage/distfiles</path>. Once that is done, you can rerun the emerge
54the emerge command, then the JDK/JRE will be installed properly into 111command, then the JRE/JDK will be installed properly into <path>/opt</path>.
55<path>/opt</path>.</p> 112</p>
59 113
60<chapter> 116</chapter>
61<title>Configuring your JDK/JRE</title> 119<title>Configuring your JRE/JDK</title>
62<section> 120<section>
63<title>Overview</title> 121<title>Overview</title>
64<body> 122<body>
65<p>Gentoo has the ability to have multiple JDKs and JREs installed 125Gentoo has the ability to have multiple JDKs and JREs installed without them
66without them conflicting. There are a few caveats to this, as noted 126conflicting.
67below.</p> 127</p>
68 128
69<p>Using the <c>java-config</c> tool, you can set the system-wide 130Using the <c>java-config</c> tool, you can set the system-wide default if you
70default if you have root access. Users can also use <c>java-config</c> 131have root access. Users can also use <c>java-config</c> to set up their own
71to set up their own personal default, that is different from the 132personal default, that is different from the system-wide default.
72system-wide default.</p> 133</p>
75 134
76<section> 136</section>
77<title>Setting a default JDK/JRE</title> 139<title>Setting a default JRE/JDK</title>
78<body> 140<body>
79<p>Running the command <c>java-config --list-available-vms</c> will 143Running the command <c>java-config --list-available-vms</c> will give you a list
80give you a list of all availble JREs and JDKs on your system, thus:</p> 144of all available JREs and JDKs on your system. Here is an example of output:
81<pre> 145</p>
147<pre caption="Listing available VMs">
82[%1 ~] java-config --list-available-vms 148# <i>java-config --list-available-vms</i>
83[blackdown-jdk-1.3.1] Blackdown JDK 1.3.1 (/etc/env.d/java/20blackdown-jdk-1.3.1) 149[blackdown-jdk-1.3.1] Blackdown JDK 1.3.1 (/etc/env.d/java/20blackdown-jdk-1.3.1)
84[blackdown-jre-1.3.1] Blackdown JRE 1.3.1 (/etc/env.d/java/20blackdown-jre-1.3.1) 150[blackdown-jre-1.3.1] Blackdown JRE 1.3.1 (/etc/env.d/java/20blackdown-jre-1.3.1)
85[ibm-jdk-1.3.0] IBM JDK 1.3.0 (/etc/env.d/java/20ibm-jdk-1.3.0) 151[ibm-jdk-1.3.0] IBM JDK 1.3.0 (/etc/env.d/java/20ibm-jdk-1.3.0)
86[ibm-jdk-1.3.1] IBM JDK 1.3.1 (/etc/env.d/java/20ibm-jdk-1.3.1) 152[ibm-jdk-1.3.1] IBM JDK 1.3.1 (/etc/env.d/java/20ibm-jdk-1.3.1)
87[ibm-jre-1.3.1] IBM JRE 1.3.1 (/etc/env.d/java/20ibm-jre-1.3.1) 153[ibm-jre-1.3.1] IBM JRE 1.3.1 (/etc/env.d/java/20ibm-jre-1.3.1)
88[sun-jdk-1.4.0] Sun JDK 1.4.0 (/etc/env.d/java/20sun-jdk-1.4.0) 154[sun-jdk-1.4.0] Sun JDK 1.4.0 (/etc/env.d/java/20sun-jdk-1.4.0)
89</pre> 155</pre>
90<p>The name in the brackets <path>"[]"</path> is the handle or ID for 158The name in the brackets <path>"[]"</path> is the handle or ID for that
91that particular VM. You use pass that ID to <c>java-config 159particular VM. You use pass that ID to <c>java-config --set-system-vm</c>. Here is
92--set-system-vm</c>, thus:</p> 160an example of how to set the system VM.
93<pre> 161</p>
163<pre caption="Setting the System VM">
94[#1 ~] java-config --set-system-vm=ibm-jdk-1.3.1 164# <i>java-config --set-system-vm=ibm-jdk-1.3.1</i>
95Now using IBM JDK 1.3.1 (/etc/env.d/java/20ibm-jdk-1.3.1) 165Now using IBM JDK 1.3.1 (/etc/env.d/java/20ibm-jdk-1.3.1)
96</pre> 166</pre>
97 167
98<note>You will have to be root to run --set-system-vm</note> 169You will have to be root to run --set-system-vm.
99 171
100<p>Once you have issued <c>java-config --set-system-vm</c> with a 173Once you have issued <c>java-config --set-system-vm</c> with a particular VM
101particular VM ID, you will need to regenerate your /etc/profile.env, 174ID, you will need to regenerate your <path>/etc/profile.env</path>. You can do
102thus:</p> 175it like this:
103<pre> 176</p>
104[#1 ~] env-update 177
178<pre caption="Regenerating /etc/profile.env" >
179# <i>env-update</i>
105</pre> 180</pre>
106 181
107<p>After this, you will either want to relogin, or resource 183After this, you will either want to relogin, or resource
108<path>/etc/profile</path> into your environment.</p> 184<path>/etc/profile</path> into your environment.
109 186
110<p>As a regular user, you can use <c>java-config --set-user-vm</c>, 188As a regular user, you can use <c>java-config --set-user-vm</c>, which will
111which will create <path>$HOME/.gentoo/java-env</path> with all 189create <path>~/.gentoo/java-env</path> with all required env vars. You would
112required env vars. You would normally source this from your shell's 190normally source this from your shell's startup script (generally
113startup script (<path>$HOME/.zshenv</path> in my case).</p> 191<path>~/.bashrc</path>).
114</body> 192</p>
116 193
117<section> 195</section>
118<title>Setting a default CLASSPATH</title> 196</chapter>
199<title>USE flags for use with Java</title>
201<title>Setting USE flags</title>
205For more information regarding USE flags, refer to the <uri
206link="/doc/en/handbook/handbook-x86.xml?part=2&amp;chap=2">USE flags</uri>
207chapter from the Gentoo Handbook.
119<body> 210</body>
120<p><c>java-config</c> can also be used to set a system-wide default 211</section>
121CLASSPATH, and of course a user-specific default CLASSPATH.</p> 212<section>
213<title>The flags</title>
122 215
123<p>First you want to list available java libraries that might be 216<ul>
124interesting to put in your CLASSPATH, thus:</p> 217 <li>The <b>java</b> flag adds support for Java in a variety of programs.</li>
125<pre> 218 <li>
126[%1 ~] java-config --list-available-packages 219 The <b>browserplugin</b> flag adds support for Mozilla-like browsers
127[ant] No description (/usr/share/ant/classpath.env) 220 (including Firefox) if you are using blackdown's Java kit. You will need
128[java-gnome] No description (/usr/share/java-gnome/classpath.env) 221 this for viewing Java applets in your Mozilla-like browser.
129[java-gtk] No description (/usr/share/java-gtk/classpath.env) 222 </li>
130[log4j] "" (/usr/share/log4j/package.env) 223</ul>
132 224
133<note>None of these packages have a proper description. That is
134something that will be implemented in the not-so-distant
137<p>Again, the name in brackets <path>"[]"</path> are the IDs that you
138have to pass to <c>java-config --set-system-classpath</c>, thus:</p>
140java-config --set-system-classpath=log4j,java-gtk,java-gnome
142<note>The current directory (.) will not be part of the system classpath,
143as that should be added in root's login profile.</note>
144<p>Again, you will want to run <c>env-update</c> to update your
145system's environment, and you might also want to relogin or resource
146the <path>/etc/profile</path>.</p>
147<p>For users, <c>java-config --set-user-classpath</c> will create
148<path>$HOME/.gentoo/java-env-classpath</path>, which is automatically
149included by <path>$HOME/.gentoo/java-env</path>.</p>
150</body> 225</body>
151</section> 226</section>
152</chapter> 227</chapter>
153 228
154<chapter> 229<chapter>
155<title>Additional resources</title> 230<title>Additional resources</title>
156<section> 231<section>
157<title>Off-line resources</title> 232<title>Off-line resources</title>
158<body> 233<body>
159<ul> 235<ul>
160<li>java-config man page</li> 236 <li>java-config man page</li>
161<li><c>java-config --help</c></li> 237 <li><c>java-config --help</c></li>
162<li>The <path>/usr/bin/java-config</path> script itself</li> 238 <li>The <path>/usr/bin/java-config</path> script itself</li>
163</ul> 239</ul>
164</body> 241</body>
165</section> 242</section>
166<section> 243<section>
167<title>Online resources</title> 244<title>Online resources</title>
168<body> 245<body>
169<ul> 246
170<li>The <uri link="http://lists.gentoo.org/pipermail/gentoo-dev/">
171gentoo-dev </uri>,
172<uri link="http://lists.gentoo.org/pipermail/gentoo-user/"> gentoo-user
173</uri> mailing list archives</li>
174<li>#gentoo on irc.openprojects.net</li>
175</ul> 247<ul>
176</body> 248 <li>
177</section> 249 The <uri
178</chapter> 250 link="http://news.gmane.org/gmane.linux.gentoo.devel">gentoo-dev</uri>,
179<chapter> 251 <uri link="http://news.gmane.org/gmane.linux.gentoo.user">gentoo-user
180<title>Caveats</title> 252 </uri> and <uri
181<section> 253 link="http://news.gmane.org/gmane.linux.gentoo.java">gentoo-java</uri>
182<title>General</title> 254 mailing list archives</li> <li>#gentoo and #gentoo-java on
183<body> 255 irc.freenode.net
184<p>If you select a JRE as your default VM, you may not have a 256 </li>
185<c>javac</c> command handy at all times, unless you have manually 257 <li>
186installed a symlink to take care of that.</p> 258 <uri
259 link="http://en.wikipedia.org/wiki/Java_programming_language">Wikipedia's
260 entry for Java</uri>
261 </li>
187 263
188<p>Jikes will be used to compile some of the largest packages, if it
189is available. With time, we hope to be able to compile all
190java-dependent packages with Jikes, so some dependencies on the JDK
191can be replaced with a dependency on the JRE.</p>
193<p>With some versions of Portage, doing an <c>emerge --world
194update</c> will install the JDK regardless if whether you have it
195installed before or not. This is a known bug addressed in later
196versions of Portage.</p>
197</body> 264</body>
198</section> 265</section>
199</chapter> 266</chapter>
200</guide> 267</guide>

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