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#79399 - Java guide update (finally :)

1 neysx 1.11 <?xml version="1.0" encoding="UTF-8"?>
2 swift 1.13 <!-- $Header: /home/cvsroot/gentoo/xml/htdocs/doc/en/java.xml,v 1.12 2003/11/22 10:01:56 neysx Exp $ -->
3 swift 1.8 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
4 zhen 1.4
5 neysx 1.11 <guide link="/doc/en/java.xml">
6     <title>Gentoo Java Guide</title>
7    
8     <author title="Author and Editor">
9     <mail link="karltk@gentoo.org">Karl Trygve Kalleberg</mail>
10     </author>
11     <author title="Editor">
12     <mail link="swift@gentoo.org">Sven Vermeulen</mail>
13     </author>
14 swift 1.13 <author title="Editor">
15     <mail link="marcelogoes@gmail.com">Marcelo Góes</mail>
16     </author>
17 neysx 1.11
18     <abstract>
19 swift 1.13 This guide will introduce users and developers to Java and explain how to use
20     Java with Gentoo Linux.
21 neysx 1.11 </abstract>
22    
23     <license/>
24    
25 swift 1.13 <version>0.1.5</version>
26     <date>2005-02-07</date>
27 neysx 1.11
28     <chapter>
29 swift 1.13 <title>What is Java?</title>
30 neysx 1.11 <section>
31     <title>Overview</title>
32     <body>
33    
34     <p>
35 swift 1.13 Java is a programming language developed by engineers of Sun Microsystems.
36     The language is object-oriented and designed to run on multiple platforms
37     without the need of recompiling code for each platform. Although Java can
38     be compiled as a native program, much of Java's popularity can be attributed
39     to its portability, along with other features such as garbage collection.
40     The ability to compile once and run in various platforms is achieved through
41     the use of just-in-time compilers (JIT), which compile Java bytecodes into
42     native code when a given program is run.
43     </p>
44    
45     <p>
46     In order to run Java bytecodes, one needs to have a JRE (Java Runtime Environment)
47     installed. A JRE provides core libraries, a platform dependent Java Virtual Machine,
48     plug-ins for browsers, among other things. A JDK (Java Development Kit) adds
49     programming tools, such as a bytecode compiler and a debugger.
50     </p>
51    
52     </body>
53     </section>
54     </chapter>
55    
56     <chapter>
57     <title>Installing a JRE/JDK</title>
58     <section>
59     <title>The choices</title>
60     <body>
61    
62     <p>
63     Gentoo provides numerous JREs and JDKs. Among the current alternatives, we have:
64     </p>
65    
66     <ul>
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>
72     </ul>
73    
74     <p>
75     The default is the Blackdown JRE/JDK
76 neysx 1.11 pair, as it is freely (beer) available without any registration fuss.
77     </p>
78    
79     <p>
80 swift 1.13 Both the Sun JRE/JDK and the IBM JRE/JDK are generally faster, but getting them
81 neysx 1.11 is a bit more work, as you are required to read and accept their license before
82     downloading (IBM additionally requires you to register).
83     </p>
84    
85     <p>
86 swift 1.13 Our ebuilds for the Sun and IBM JRE/JDKs will notify you of where to go to
87 neysx 1.11 download them.
88     </p>
89    
90     </body>
91     </section>
92    
93     <section>
94 swift 1.13 <title>Installing the Sun/IBM JRE/JDKs</title>
95 neysx 1.11 <body>
96    
97     <p>
98 swift 1.13 If you run <c>emerge =sun-jdk-1.4.2.06</c> or <c>=ibm-jdk-bin-1.4.2</c>, you will
99 neysx 1.11 be notified that you are required to download the actual tarballs yourself. This
100 swift 1.13 has to do with license restrictions for the Sun JRE/JDK (online click-wrap
101     license) and registration issues with the IBM JRE/JDK.
102 neysx 1.11 </p>
103    
104     <note>
105 swift 1.13 ibm-jdk-bin is currently masked, you may have to unmask it to use it.
106 neysx 1.11 </note>
107    
108     <p>
109     You should download the indicated file(s) into
110     <path>/usr/portage/distfiles</path>. Once that is done, you can rerun the emerge
111 swift 1.13 command, then the JRE/JDK will be installed properly into <path>/opt</path>.
112 neysx 1.11 </p>
113    
114     </body>
115     </section>
116     </chapter>
117    
118     <chapter>
119 swift 1.13 <title>Configuring your JRE/JDK</title>
120 neysx 1.11 <section>
121     <title>Overview</title>
122     <body>
123    
124     <p>
125     Gentoo has the ability to have multiple JDKs and JREs installed without them
126     conflicting.
127     </p>
128    
129     <p>
130     Using the <c>java-config</c> tool, you can set the system-wide default if you
131     have root access. Users can also use <c>java-config</c> to set up their own
132     personal default, that is different from the system-wide default.
133     </p>
134    
135     </body>
136     </section>
137    
138     <section>
139 swift 1.13 <title>Setting a default JRE/JDK</title>
140 neysx 1.11 <body>
141    
142     <p>
143     Running the command <c>java-config --list-available-vms</c> will give you a list
144 swift 1.13 of all available JREs and JDKs on your system. Here is an example of output:
145 neysx 1.11 </p>
146    
147     <pre caption="Listing available VMs">
148 neysx 1.12 # <i>java-config --list-available-vms</i>
149 drobbins 1.1 [blackdown-jdk-1.3.1] Blackdown JDK 1.3.1 (/etc/env.d/java/20blackdown-jdk-1.3.1)
150     [blackdown-jre-1.3.1] Blackdown JRE 1.3.1 (/etc/env.d/java/20blackdown-jre-1.3.1)
151     [ibm-jdk-1.3.0] IBM JDK 1.3.0 (/etc/env.d/java/20ibm-jdk-1.3.0)
152     [ibm-jdk-1.3.1] IBM JDK 1.3.1 (/etc/env.d/java/20ibm-jdk-1.3.1)
153     [ibm-jre-1.3.1] IBM JRE 1.3.1 (/etc/env.d/java/20ibm-jre-1.3.1)
154     [sun-jdk-1.4.0] Sun JDK 1.4.0 (/etc/env.d/java/20sun-jdk-1.4.0)
155 neysx 1.11 </pre>
156    
157     <p>
158     The name in the brackets <path>"[]"</path> is the handle or ID for that
159 swift 1.13 particular VM. You use pass that ID to <c>java-config --set-system-vm</c>. Here is
160     an example of how to set the system VM.
161 neysx 1.11 </p>
162 zhen 1.4
163 neysx 1.11 <pre caption="Setting the System VM">
164 neysx 1.12 # <i>java-config --set-system-vm=ibm-jdk-1.3.1</i>
165 drobbins 1.1 Now using IBM JDK 1.3.1 (/etc/env.d/java/20ibm-jdk-1.3.1)
166 neysx 1.11 </pre>
167 drobbins 1.1
168 neysx 1.11 <note>
169     You will have to be root to run --set-system-vm.
170     </note>
171    
172     <p>
173     Once you have issued <c>java-config --set-system-vm</c> with a particular VM ID,
174 swift 1.13 you will need to regenerate your /etc/profile.env. You can do it like this:
175 neysx 1.11 </p>
176 drobbins 1.1
177 neysx 1.11 <pre caption="Regenerating /etc/profile.env" >
178 neysx 1.12 # <i>env-update</i>
179 neysx 1.11 </pre>
180 drobbins 1.1
181 neysx 1.11 <p>
182     After this, you will either want to relogin, or resource
183     <path>/etc/profile</path> into your environment.
184     </p>
185    
186     <p>
187     As a regular user, you can use <c>java-config --set-user-vm</c>, which will
188 swift 1.13 create <path>~/.gentoo/java-env</path> with all required env vars. You would
189 neysx 1.11 normally source this from your shell's startup script
190 swift 1.13 (generally <path>~/.bashrc</path>).
191 neysx 1.11 </p>
192    
193     </body>
194     </section>
195    
196     <section>
197     <title>Setting a default CLASSPATH</title>
198     <body>
199    
200     <p>
201     <c>java-config</c> can also be used to set a system-wide default CLASSPATH, and
202     of course a user-specific default CLASSPATH.
203     </p>
204    
205     <p>
206     First you want to list available java libraries that might be interesting to put
207 swift 1.13 in your CLASSPATH. Here is an example of output:
208 neysx 1.11 </p>
209    
210     <pre caption="Listing classes">
211 neysx 1.12 # <i>java-config --list-available-packages</i>
212 swift 1.13 [bsh] BeanShell is a small, free, embeddable, Java
213     source interpreter with object scripting language
214     features. (/usr/share/bsh/package.env)
215     [oro] A set of text-processing Java classes that
216     provide Perl5 compatible regular expressions, AWK-like
217     regular expressions, glob expressions, and utility
218     classes for performing substitutions, splits, filtering
219     filenames, etc. (/usr/share/oro/package.env)
220     [bcel] The Byte Code Engineering Library: analyze, create,
221     manipulate Java class files (/usr/share/bcel/package.env)
222     [jsch] JSch is a pure Java implementation of SSH2.
223     (/usr/share/jsch/package.env)
224     ...
225 neysx 1.11 </pre>
226 zhen 1.4
227 neysx 1.11 <p>
228     Again, the name in brackets <path>"[]"</path> are the IDs that you have to pass
229 swift 1.13 to <c>java-config --set-system-classpath</c>. Here is an example:
230 neysx 1.11 </p>
231 drobbins 1.1
232 neysx 1.11 <pre caption="Setting classpaths">
233 neysx 1.12 # <i>java-config --set-system-classpath=log4j,java-gtk,java-gnome</i>
234 neysx 1.11 </pre>
235    
236     <note>
237     The current directory (.) will not be part of the system classpath, as that
238     should be added in root's login profile.
239     </note>
240    
241     <p>
242     Again, you will want to run <c>env-update</c> to update your system's
243     environment, and you might also want to relogin or resource the
244     <path>/etc/profile</path>.
245     </p>
246    
247     <p>
248     For users, <c>java-config --set-user-classpath</c> will create
249 swift 1.13 <path>~/.gentoo/java-env-classpath</path>, which is automatically included
250     by <path>~/.gentoo/java-env</path>.
251     </p>
252    
253     </body>
254     </section>
255     </chapter>
256    
257     <chapter>
258     <title>USE flags for use with Java</title>
259     <section>
260     <title>Setting USE flags</title>
261     <body>
262    
263     <p>
264     For more information regarding USE flags, refer to the
265     <uri link="/doc/en/handbook/handbook-x86.xml?part=2&amp;chap=2">USE flags</uri>
266     chapter from the Gentoo Handbook.
267 neysx 1.11 </p>
268    
269     </body>
270     </section>
271 swift 1.13 <section>
272     <title>The flags</title>
273     <body>
274    
275     <ul>
276     <li>The <b>java</b> flag adds support for Java in a variety of programs.</li>
277     <li>The <b>mozilla</b> flag adds support for Mozilla-like browsers (including Firefox)
278     if you are using blackdown's Java kit. You will need this for viewing Java applets
279     in your Mozilla-like browser.</li>
280     </ul>
281    
282     </body>
283     </section>
284 neysx 1.11 </chapter>
285    
286     <chapter>
287     <title>Additional resources</title>
288     <section>
289     <title>Off-line resources</title>
290     <body>
291    
292     <ul>
293     <li>java-config man page</li>
294     <li><c>java-config --help</c></li>
295     <li>The <path>/usr/bin/java-config</path> script itself</li>
296     </ul>
297    
298     </body>
299     </section>
300    
301     <section>
302     <title>Online resources</title>
303     <body>
304     <ul>
305     <li>The <uri link="http://news.gmane.org/gmane.linux.gentoo.devel"
306     >gentoo-dev</uri>, <uri link="http://news.gmane.org/gmane.linux.gentoo.user"
307     >gentoo-user </uri> mailing list archives</li>
308 neysx 1.12 <li>#gentoo and #gentoo-java on irc.freenode.net</li>
309 swift 1.13 <li><uri link="http://en.wikipedia.org/wiki/Java_programming_language">Wikipedia's entry for Java</uri></li>
310 neysx 1.11 </ul>
311    
312     </body>
313     </section>
314     </chapter>
315 neysx 1.12 </guide>

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