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1DEVFEST NANTES 16
Jigsawest prêt à tuer le
classpath
@AlexisHassler février 2017
"Classpath is dead!"
Mark ReinholdJavaOne 2009
3
Classpath Classloader
SuccessionJigsaw
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Alexis Hassler
Développeur
Formateur
Indépendant
Fondateur
Préparateur de
Classpath
https://www.flickr.com/photos/summonedbyfells/15007676965
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String hello = "Salut à vous tous les zazous";
Chercher les classes
CLASSPATH
Hello var = new Hello();
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-classpath
java -cp hello-lib.jar HelloWorld
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Erreurs
java.lang.NoClassDefFoundError
java.lang.ClassNotFoundException
https://www.flickr.com/photos/rocketboom/2816790116
Class Loader
https://www.flickr.com/photos/15574096@N00/12119344725/
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java.lang.ClassLoader
loadClass(String name) : Class<?>
getResource(String name) : URLgetResourceAsStream(String name) : InputStream
getParent() : ClassLoader
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Classloader
sun.misc.Launcher$AppClassLoader CLASSPATH
Hello.class.getClassLoader()
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Classloader
null
Hello.class.getClassLoader()
.getClass().getClassLoader()
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Bootstrap Classloader
BootstrapClassLoader
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Délégation
BootstrapClassLoader
Parent first
System ClassLoader
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Délégation
System ClassLoader
java -cp hello-lib.jar ...
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bootclasspath
java -Xbootclasspath/p:hello-lib.jar ...
java -Xbootclasspath:hello-rt.jar ...
java -Xbootclasspath/a:hello-lib.jar ...
BootstrapClassLoader
https://github.com/hasalex/classpath-demo
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DémonstrationBootstrapClassLoader
java -cp example.jar fr.sewatech.classpath.Count
System ClassLoader
java.lang.Integer
example.jar
java.lang.Integer
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example.jar
Démonstration
java -Xbootclasspath/p:example.jar fr.sewatech.classpath.Count
BootstrapClassLoader
java.lang.Integer
java.lang.Integer
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URLClassloader
java.net.URLClassLoader
sun.misc.Launcher$AppClassLoader
URLURLURL
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URLClassloader
System ClassLoader
Bootstrap ClassLoader
URL ClassLoader
URL ClassLoader
URL ClassLoader
Parentfirst
Parentfirst
Parentfirst
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DIY Classloader
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Usages
Application Servers JRebel Javassist, CGLib,...
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Tomcat
System
Bootstrap
Common
Webapp1
Webapp2
Webapp3
Local First
message-launcher
message-main
message-common
message-printer
message-service
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Démonstration
message-launcher
message-common
message-printer
message-service
message-service
System ClassLoader ParentFirst ClassLoader
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Démonstration
message-launcher
message-common
message-printer
message-service
message-service
System ClassLoader LocalFirst ClassLoader
https://www.flickr.com/photos/delete08/5971235700/
29http://www.ironmaidenwallpaper.com/
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Dépendances
Maven, Gradle,...
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Dépendances
Classpath
https://github.com/hasalex/classpath-demo
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Démonstration
slf4j-api 1.5.11
slf4j-api 1.7.2
message-launcher
message-main
message-common
message-printer
message-service
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Granularité
SécuritéApache commons-collections
https://foxglovesecurity.com/
Succession
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Modularité
Dépendance Exposition
Lecture
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1999
Java embarquéJava SEJava serveur
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Bundle-Name = Hello Service
Bundle-SymbolicName = hello-service
Bundle-Description = Hello Service Bundle
Bundle-Version = 1.0.1
Export-Package = fr.sewatech.classpath
Import-Package = fr.sewatech.classpath.print;version=1.3
OSGi
Bundle
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OSGi
OS + Hardware
Java Runtime
Module
Life Cycle Services
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JBoss Modules
java -jar jboss-modules.jar -mp path/to/modules
my.main.module.name
Base de JBoss OSGi
Java SE
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JBoss Modules
module.xml
resource dependency slot
dependency slot
dependency slot
name slot
resource
resource
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Jigsaw
9 (2016)8 (2012)
(2017)
Projet
Intégré au JDK 7 (2008)
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Jigsaw
Modularité du JDK
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Jigsaw
Modularité des applications// module-info.java
module message.service {
requires java.xml.bind;
requires message.common;
exports fr.sewatech.message;
}
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Jigsaw
Compilation
javac --module-path modules \
-d target/classes/ \
$(find src/main/java/ -name "*.java")
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Jigsaw
Exécution
java --module-path jigsaw-modules \
-m misc.examples/fr.sewatech.example.Main
https://github.com/hasalex/classpath-demo
Jigsaw ++
https://www.flickr.com/photos/intvgene/370973576
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Classpath mode
java -classpath lib/* fr.sewatech.example.Main
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Modular JDK
rt.jar tools.jar
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Modular JDK
https://github.com/hasalex/classpath-demo
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Dependencies
module message.service {
requires message.printer;
requires slf4j.api;
}
module message.printer {
requires transitive message.common;
}
message.printer
message.service
message.common
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module message.service {
requires message.printer;
requires slf4j.api;
}
Dependencies
Automatic modules slf4j-api-1.5.2.
slf4j.apimessage.service
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Dependencies
Classpath
message.common
message.printer
unnamed
message.service
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Dependencies
module message.service @ 1.0 {
requires message.printer @ 1.0;
requires slf4j.api @ 1.7;
}
Module version
https://github.com/hasalex/classpath-demo
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Exports
Accessibilitypublicprotectedpackageprivate
inside a module
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Exports
Accessibilitypublic for other modules
module message.service {
exports fr.sewatech.message;
}
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Exports
Accessibilitypublic for some modules
module java.base {
exports sun.reflect to
java.logging,
java.sql,
jdk.scripting.nashorn;
}
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field.setAccessible(true);
Exports
java.lang.reflect.InaccessibleObjectException
Deep reflection
module message.service {
opens java.security;
}
https://github.com/hasalex/classpath-demo
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Classloader
java.net.URLClassLoader FLTMClassLoader
java.lang.ClassLoader
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BootClassLoader
bootclasspath
java -Xbootclasspath/p:hello-lib.jar ...
java -Xbootclasspath:hello-rt.jar ...
java -Xbootclasspath/a:hello-lib.jar ...
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Patch
Compile
Run
javac -Xmodule:java.base \
-d ../patch-classes \
src/java/lang/Integer.java
java --patch-module java.base=patch.jar \
--module-path jigsaw-modules \
-m misc.examples
https://github.com/hasalex/classpath-demo
Jigsaw ++++
https://www.flickr.com/photos/foot-slogger/901793825/
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Aller plus haw avec Jigsaw
Service Providers / Loaders
jlink : custom JRE
jdeps : migration
Layers : versioning
...
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Packaging
Jar files
module-info.class
META-INF/MANIFEST.MF
fr/sewatech/message/Hello.class
...
jar --create
--file=mods/message-service.jar
-C message-service/src .
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Packaging
Mod files jmod create
--class-path mods/message-service.jar:mods/slf4j-api.jar
message-service.jmodclasses/...
conf/...
native/
...
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Packaging
Linkingjlink --module-path $JAVA_HOME/jmods:mods
--add-modules message-service.jmod
--output message-appbin
└ java
conf
└ ...
lib
└ ...
modules
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Service Provider
# META-INF/services/fr.sewatech.message.MessageService
fr.sewatech.message.impl.FullMessageService
Provider (Java 8)
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Service Provider
Consumer
ServiceLoader<MessageService> loader
= ServiceLoader.load(MessageService.class);
for (MessageService service : loader) {
...
}
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Service Provider
# module-info.java
module message.service.full {
requires message.service;
exports fr.sewatech.message.impl; // NO !
provides fr.sewatech.message.MessageService
with fr.sewatech.message.impl.FullMessageService;
}
Provider (Java 9)
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Service Provider
Consumer
# module-info.java
module message.launcher {
requires message.service;
uses fr.sewatech.message.MessageService ;
}
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Migration
java / javac arguments --add-modules --add-exports --add-opens
jdeps jdeps --jdk-internals ./
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Migration
Multi-Release JAR FilesJAR File
First.class
META-INF
Second.class
Third.class
versions
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First.class
Quand ?
https://www.flickr.com/photos/mars_/18189674562/
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Planning
Java SE 9
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Planning
Outils ?Maven, Gradle, IDE
Librairies ?SLF4J, Guava,...
Frameworks ?Spring, Hibernate,...
Runtimes ?Java EE, Tomcat,...Hadoop,...
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Essayer...
https://jdk9.java.net/download/ Exécutable d'installation
https://jdk9.java.net/jigsaw/ ArchiveDernières évolutions de Jigsaw
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Apprendre +
JavaOne, Devoxxhttp://openjdk.java.net/projects/jigsaw/talks/
Quick-Start Guidehttp://openjdk.java.net/projects/jigsaw/quick-start
The State of the Module Systemhttp://openjdk.java.net/projects/jigsaw/spec/sotms/
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Apprendre +
Oracle JDK 9 Documentation http://docs.oracle.com/javase/9/
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module-path is born
classpath is NOT dead
Conclusion
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https://www.sewatech.fr
@AlexisHassler
http://alexis-hassler.com
https://www.flickr.com/photos/a-hassler/28532230893
