1. 1. Alexis Hassler Le classpath n'est pas mort... Janvier 2015 mais presque
2. 2. "Classpath is dead!" Mark Reinhold JavaOne 2009
3. 3. Classpath Classloader Mort? Succession
4. 4. Alexis Hassler Dveloppeur, formateur Java Indpendant Co-leader du
5. 5. Classpath
6. 6. String hello = "Bonjour Devoxx"; MyStuff var; Chercher les classes CLASSPATH
7. 7. -classpath java -cp hello-lib.jar HelloWorld
8. 8. Manifest Manifest-Version: 1.0 Class-Path: hello-lib.jar Main-Class: HelloWorld
9. 9. Connatre le classpath System.getProperty("java.class.path");
10. 10. Erreurs java.lang.NoClassDefFoundError java.lang.ClassNotFoundException
11. 11. Classpath Gr par des classloaders
12. 12. Classloader
13. 13. java.lang.ClassLoader loadClass(String name) : Class getResource(String name) : URL getResources(String name) : Enumeration getResourceAsStream(String name) : InputStream getParent() : ClassLoader
14. 14. Classloader sun.misc.Launcher$AppClassLoader CLASSPATH MyStuff.class.getClassLoader()
15. 15. Bootstrap Classloader null classloader.getClass().getClassLoader()
16. 16. Bootstrap Classloader BootstrapClassLoader
17. 17. ExtensionClasspath sun.misc.Launcher$ExtClassLoader sun.misc.Launcher$AppClassLoader Dlgation BootstrapClassLoader Parent first Parent first System ClassLoader Extension ClassLoader
18. 18. Dlgation java -cp hello-lib.jar ... System.getProperty("java.class.path"); ClasspathSystem ClassLoader
19. 19. Dlgation java -Djava.ext.dirs=~/.java8/ext ... System.getProperty("java.ext.dirs"); Extension Extension ClassLoader
20. 20. Dlgation java -Xbootclasspath:hello-rt.jar ... BootstrapClassLoader System.getProperty("sun.boot.class.path");
21. 21. bootclasspath java -Xbootclasspath:hello-rt.jar ... java -Xbootclasspath/a:hello-lib.jar ... java -Xbootclasspath/p:hello-lib.jar ...
22. 22. Endorsed java -Djava.endorsed.dirs=~/.java8/endorsed ... Endorsed BootstrapClassLoader
23. 23. Endorsed APIs standards hors JCP org.omg (CORBA), org.w3c.dom, org.xml.sax (XML) APIs standalone JAXP, JAXB, Scripting, Compiler API,...
24. 24. http://github.com/hasalex/classpath-demo
25. 25. classloader-demo Dmonstration BootstrapClassLoader java -cp cl-demo.jar fr.sewatech.classpath.Count System ClassLoader
26. 26. classloader-demo Dmonstration BootstrapClassLoader java -Xbootclasspath/p:cl-demo.jar fr.sewatech.classpath.Count
27. 27. URLClassloader java.net.URLClassLoader sun.misc.Launcher$AppClassLoader sun.misc.Launcher$ExtClassLoader URLURLURL
28. 28. URLClassloader System ClassLoader Bootstrap ClassLoader URL ClassLoader URL ClassLoader URL ClassLoader Parent first Parent first Parent first
29. 29. http://github.com/hasalex/classpath-demo
30. 30. Dmonstration java -cp cl-demo.jar:msg-main.jar fr.sewatech.classpath.Hello classloader-demo message-main message-common message-printer message-main
31. 31. classloader-demo message-main message-common message-printer message-main Dmonstration java -cp cl-demo.jar:msg-main.jar fr.sewatech.classpath.HelloViaUrl message-mainClasspath URLClassloader
32. 32. Dmonstration classloader-demo message-common message-printer message-main message-main System ClassLoader ParentFirst ClassLoader
33. 33. FLTM Classloader Fait Le Toi-Mme
34. 34. Usages Application Servers JRebel Javassist, CGLib,...
35. 35. Tomcat System Bootstrap Common Webapp1 Webapp2 Webapp3 Local First
36. 36. JBoss AS 5 System Bootstrap Common Web App Ent App Web Module EJB Module Local First Repo First
37. 37. Erreurs ClassCastException MyStuff cannot be cast to MyStuff W TF ?
38. 38. Erreurs URL ClassLoader URL ClassLoader MyStuff var = MyStuffFactory.build(); return new MyStuff() ;
39. 39. http://github.com/hasalex/classpath-demo
40. 40. Dmonstration classloader-demo message-common message-printer message-main message-main System ClassLoader ParentFirst ClassLoader
41. 41. Dmonstration classloader-demo message-common message-printer message-main message-main System ClassLoader LocalFirst ClassLoader
42. 42. Mort?
43. 43. http://www.ironmaidenwallpaper.com/
44. 44. Dpendances Maven, Gradle, ...
45. 45. Dpendances Classpath
46. 46. http://github.com/hasalex/classpath-demo
47. 47. message-main message-common Dmonstration message-printer classloader-demo slf4j-api 1.5.11 slf4j-api 1.7.2
48. 48. Succession
49. 49. Granularit Classpath Application
50. 50. Granularit Application Web / JavaEE Librairies partagesApplication
51. 51. Modularit Application Web / JavaEE Application
52. 52. 1999 Java embarqu Java SE Java serveur
53. 53. OSGi OS + Hardware Java Execution Environment Applications (bundles) Module Life Cycle Services
54. 54. JBoss Modules Sous-projet de Wildfly Inspir de Jigsaw Base de JBoss OSGi
55. 55. JBoss Modules java -jar jboss-modules.jar -mp path/to/modules my.main.module.name Java SE
56. 56. JBoss Modules hibernate-infinispan-4.1.6.Final.jar module.xml hibernate-core-4.1.6.Final.jar hibernate-entitymanager-4.1.6.Final.jar modules com fr org ... org hibernate main
57. 57.
58. 58. WildFly bin Scripts de dmarrage bundles Composants OSGi modules Modules JBoss standalone Profil standalone domain Profil domain
59. 59. bin Scripts de dmarrage bundles Composants OSGi modules Modules JBoss standalone Profil standalone domain Profil domain WildFly message.war
60. 60. WildFly message.war
61. 61. http://github.com/hasalex/classpath-demo
62. 62. Tomcat Classloading WEB-INF/classes, WEB-INF/lib Webapp ClassLoader $CATALINA_HOME/lib System ClassLoader Common Class Loader
63. 63. Tomcat Module? WEB-INF/classes, WEB-INF/lib System ClassLoader Common Class Loader Webapp ClassLoader $CATALINA_HOME/lib Module ClassLoader modules
64. 64. Tomcat https://github.com/hasalex/tomcat-modules
65. 65. Jigsaw Projet OpenJDK Intgr au JDK 7 9 (2016) 8 (2012) (2008) . . .
66. 66. Jigsaw JEP 200:The Modular JDK JEP 201: Modular Source Code JEP 220:The Modular Run-Time Images JEP xxx:The JDK Module System JSR 376: Java Platform Module System
67. 67. J'imagine qu'il est tentant, si le seul outil que vous avez est un marteau, de traiter tout problme comme si c'tait un clou. Abraham MaslowPaul Watzlawick
68. 68. @AlexisHassler http://alexis-hassler.com alexis.hassler@sewatech.fr http://sewatech.fr