Java Archive File:::::::::: .jar in java

من طرف **صانع برامج** الثلاثاء أبريل 20, 2010 3:58 pm

بسم الله الرحمن الرحيم
وبعد السلام عليكم والرحمه

إسمحو لي أن أضيف هذه الصفحه إلى سلسله الصفحات والدروس في هذا القسم
وهي
الـــ Jar files
هي عباره عن Java Archive Files
وبها يتم عمل البرامج التنفيذيه الخاصه بالجافا
بحيث يتم تجميع جميع العناصر الضررويه والتي قد يحتاجها النظام.

وكذالك لهذا النوع من الأرشفه مميزات أخرى، فبواسطته
قللنا عدد requests عند التعامل مع Applets
وذالك في التعامل مع الويب

القدره على تجميع الكلاسات المفسره مسبقا في مكان واحد
وإستخدامها كمكتبه

له دور كبير في تكوين beans والتي تستند على مبدأ إعادة الإستخدام،....

ولكن هذا النوع من الأرشفه ليس جيدا بمستوى جودة ZIP

لنكمل الحديث
و ليكن الكلام مقتبس من
From Thinking in Java Book www.BruceEckel.com

اقتباس:

From Thinking in Java Book www.BruceEckel.com

Java ARchives (JARs)
The Zip format is also used in the JAR (Java ARchive) file format, which
is a way to collect a group of files into a single compressed file, just like
Zip. However, like everything else in Java, JAR files are cross-platform so
you don’t need to worry about platform issues. You can also include audio
and image files as well as class files.
JAR files are particularly helpful when you deal with the Internet. Before
JAR files, your Web browser would have to make repeated requests of a
Web server in order to download all of the files that make up an applet. In
addition, each of these files was uncompressed. By combining all of the
files for a particular applet into a single JAR file, only one server request
is necessary and the transfer is faster because of compression. And each
entry in a JAR file can be digitally signed for security (refer to the Java
documentation for details).
A JAR file consists of a single file containing a collection of zipped files
along with a “manifest” that describes them. (You can create your own
manifest file; otherwise the jar program will do it for you.) You can find
out more about JAR manifests in the JDK HTML documentation.
The jar utility that comes with Sun’s JDK automatically compresses the
files of your choice. You invoke it on the command line:
jar [options] destination [manifest] inputfile(s)

The options are simply a collection of letters (no hyphen or any other
indicator is necessary). Unix/Linux users will note the similarity to the
tar options. These are:
c :::::::::::Creates a new or empty archive.
t :::::::::::Lists the table of contents.
x :::::::::::Extracts all files.
xfile :::::::::::Extracts the named file.
f :::::::::::Says: “I’m going to give you the name of the file.” If you
don’t use this, jar assumes that its input will come from
standard input, or, if it is creating a file, its output will go
to standard output.
m ::::::::::: Says that the first argument will be the name of the user-
created manifest file.
v :::::::::::Generates verbose output describing what jar is doing.
0 :::::::::::Only store the files; doesn’t compress the files (use to
create a JAR file that you can put in your classpath).
M :::::::::::Don’t automatically create a manifest file.

If a subdirectory is included in the files to be put into the JAR file, that
subdirectory is automatically added, including all of its subdirectories,
etc. Path information is also preserved.
Here are some typical ways to invoke jar:

jar cf myJarFile.jar *.class

This creates a JAR file called myJarFile.jar that contains all of the class
files in the current directory, along with an automatically generated
manifest file.
jar cmf myJarFile.jar myManifestFile.mf *.class

Like the previous example, but adding a user-created manifest file called
myManifestFile.mf.
jar tf myJarFile.jar

Produces a table of contents of the files in myJarFile.jar.
jar tvf myJarFile.jar

Adds the “verbose” flag to give more detailed information about the files
in myJarFile.jar.
jar cvf myApp.jar audio classes image

وهذا من
From Complate Refernces

اقتباس:

The java.util.jar Package

The java.util.jar package provides the ability to read and write Java Archive (JAR)
files. You will see in Chapter 25 that JAR files are used to contain software components
known as Java Beans and any associated files.
==
==

A JAR file allows you to efficiently deploy a set of classes and their associated
resources. For example, a developer may build a multimedia application that uses
various sound and image files. A set of Beans can control how and when this
information is presented. All of these pieces can be placed into one JAR file.JAR technology makes it much easier to deliver and install software. Also, the
elements in a JAR file are compressed, which makes downloading a JAR file much
faster than separately downloading several uncompressed files. Digital signatures may
also be associated with the individual elements in a JAR file. This allows a consumer to be sure that these elements were produced by a specific organization or individual.
The package java.util.zip contains classes that read and write JAR files.

Manifest Files

A developer must provide a manifest file to indicate which of the components in a JAR file.

"I am this words adding now we indicate the class which include the main method"

A manifest file may reference several .class files. If a .class file is a Java Bean, its
entry must be immediately followed by the line “Java-Bean: True”.
The JAR Utility
A utility is used to generate a JAR file. Its syntax is shown here:
jar options files
Table [Option Description " Table 25-1. JAR Command Options "]
lists the possible options and their meanings. The following examples show how to use this utility
Creating a JAR File

The following command creates a JAR file named Xyz.jar that contains all of the .class and .gif files in the current directory:

jar cf Xyz.jar *.class *.gif

If a manifest file such as Yxz.mf is available, it can be used with the following command:

jar cfm Xyz.jar Yxz.mf *.class *.gif

The following command lists the contents of Xyz.jar:

jar tf Xyz.jar

Extracting Files from a JAR File
The following command extracts the contents of Xyz.jar and places those files in the
current directory:

jar xf Xyz.jar

Option Description
C:::::::::::A new archive is to be created.
C:::::::::::Change directories during command execution.
f :::::::::::The first element in the file list is the name of the archive that is to be
created or accessed.
i :::::::::::Index information should be provided.
m :::::::::::The second element in the file list is the name of the external manifest file.
M :::::::::::Manifest file not created.
T::::::::::: The archive contents should be tabulated.
u :::::::::::Update existing JAR file.
v :::::::::::Verbose output should be provided by the utility as it executes.
x :::::::::::Files are to be extracted from the archive. (If there is only one file, that
is the name of the archive, and all files in it are extracted. Otherwise,
the first element in the file list is the name of the archive, and the
remaining elements in the list are the files that should be extracted
from the archive.)
0 :::::::::::Do not use compression.

وهذا

اقتباس:

Java Archive File [From java Documentation]
Another interesting Java technology in the works at Sun is the JAR file format, which is an archive file format aimed at grouping all the files that comprise an applet and its resources. By combining all an applet's resources into one compact file, both local storage and transfer overhead time are reduced. This is a technology that will have huge implications as Java applets gain acceptance and become more widespread because the task of managing a bunch of files over an Internet connection is something that would be nice to avoid.
The JAR file format is being designed to meet the following criteria:
• Compact
• Platform independent
• Support for Unicode
• Extensible
By being compact, JAR files can better meet their goal of minimizing the storage space and transfer times associated with Java applets and their resources. Part of the compactness of JAR files is attributable to their support for compression, which can greatly reduce the size of applet resources. Platform independence is a crucial requirement because Java applets are expected to run on a wide range of systems. Unicode support is important so that there is consistency regarding textual information stored in JAR file headers. Finally, the JAR file format must be extensible so that new features such as code signing can be easily incorporated. For more information on the JAR file format, check out JavaSoft's JAR File Format Specification Web site at http://www.javasoft.com/security/cod...ar-format.html.

==============
وبعد كل الي سبق
عندما يكون لدينا نظام من غير واجهة ،، يعني عـ الدوز
ما ينفعوش jar عشان نخله تنفيذي،، الماوس لا يشغله
لذالك نعمل ملف دفعي أو باتش لتشغيل ذالك النضام

و jar وجد ليكون إما مكتبه تحوي عدة كلاسات او حتى مكتبات متعددة ومتداخله
ومثال لهذا هي الكمتبه المستخدمه لربط الجافا بقواعد البيانات

أو ليكون أداة قابله لإعادة الإستخدام كما تستخدم البينز
مثلا واجهة إسم المستخدم وكلمة المرور
مش بالضروره كل مره نصمم من جديد ، نصممها مرة واحده ونهيئها
لتكون قابله لإعادة اللإستخدام ، ثم نضمنها في JBuider او غيره
وعند ئذ ما علينا إلا سحبها وإلقائها

أو ليكون ملف قابل لتنفيذ يحتوي على جميع الملفات المكونه لنظام
================================================
أبسط طريقه لعمل برنامج تنفيذي[بإفتراض أنه بدون إنشاء مكتبه]

1) قم بجلب أي برنامج يحتوي على واجهات
او قم يتصميم أبسط برنامج ذو واجهات [Frame وحجمه ملئ الشاشه]

2) قم بتوليد البايت كوت (الكلاسات) وقم بنقلها إلى مجلد مؤقت
وليكن مجلد جديد ولا يحتوي هذا المجلد إلا على الملفات المتعلقه بالنظام أو البرنامج
كالصور والأصوات و.....
ملاحظه : من هنا ضروري الدقه وإلا ما راح يشتغل

3)بعد ما تم تجميع جميع أجزاء النظام وضمها إلى بعض
بنفس ذالك المجلد قم بإنشاء مجلد جديد [ملاحظه التسميات هنا حساسه جدا للأحرف]
ولا بد من تسميته بــ META-INF
ثم إفتح برنامج محررالنصوص
واكتب Main-Class: your_main_class
ولا تترك فراغ في أخر السطر ،، بل عند أخر حرف إنزل سطر جديد
ثم إحفظ السابق كـــ MANIFEST.MF
بإمتداد mf لا تتركها تغيب عن بالك
ثم إنقل هذا الملف MANIFEST.MF إلى المجلد META-INF الموجود
في المجلد الؤقت والذي أستخدم فقط لتجميع أجزاء البرنامج او النظام في مكان
واحد لتسهيل عملية الضغط ثم التهيئه ليكون تنفيذي

4) بعد ما تم إنشاء META-INF والذي يحتوي على MANIFEST.MF
وهي بدورها [حاليا وفي هذا الحاله]سوف تخبر JVM أين هو الكلاس الذي
يحتوي على الداله الرئيسيه.
قم يتضليل الكل وانقر بالماوس فوق أحد العناصر المضلله [إلحذر إذا كانت هناك ملفات مخفيه غير مرئيه، الملفات المصدريه،العناصر الغير ضروريه ]
ثم إرسال إلى Compressed(Zipped) Folder
أعد تسميته وأحرص على تغيير الإمتداد إلى .jar ولكي تستطيع تغيير الإمتداد عند إعادة التسميه
إذهب إلى خيارات المجلد ـــ ثم ــــ عرض ـــ ثم ـــ أزل خيار إخفاء إمتدادات وملخقات الملفات

ولرؤيه الخطوات بالتفصيل شاهد الملحقات

some notes within this links

http://www.java-tips.org/java-se-tip...-jar-file.html
http://java.sun.com/docs/books/tutor...jar/build.html
http://www.querycat.com/faq/c78daf06...2a5f8cdb468e57
http://java.sun.com/j2se/1.4.2/docs/...ndows/jar.html
http://java.sun.com/developer/online...CBook/jar.html