Tomcat ClassLoader研究 收藏 view plain copy to clipboard print ? public final class // ------------------------------------------------------- Static Variables /** * Debugging detail level for processing the startup. */ private static int 0 ; // ----------------------------------------------------------- Main Program /** * The main program for the bootstrap. * * @param args Command line arguments to be processed */ public static void // Set the debug flag appropriately for int 0 ; i < args.length; i++) { if "-debug" .equals(args)) 1 ; } // Configure catalina.base from catalina.home if not yet set if "catalina.base" ) == null "catalina.base" , getCatalinaHome()); // Construct the class loaders we will need null null null try new 1 ]; new 1 ]; new 2 ]; ClassLoaderFactory.setDebug(debug); 0 ] = new "common" + File.separator + "classes" ); 0 ] = new "common" + File.separator + "endorsed" ); 1 ] = new "common" + File.separator + "lib" ); commonLoader = null 0 ] = new "server" + File.separator + "classes" ); 0 ] = new "server" + File.separator + "lib" ); catalinaLoader = ClassLoaderFactory.createClassLoader(unpacked, packed, commonLoader); 0 ] = new "shared" + File.separator + "classes" ); 0 ] = new "shared" + File.separator + "lib" ); sharedLoader = ClassLoaderFactory.createClassLoader(unpacked, packed, commonLoader); catch "Class loader creation threw exception" , t); 1 ); } Thread.currentThread().setContextClassLoader(catalinaLoader); // Load our startup class and call its process() method try SecurityClassLoad.securityClassLoad(catalinaLoader); // Instantiate a startup class instance if 1 ) "Loading startup class" ); Class startupClass = catalinaLoader.loadClass "org.apache.catalina.startup.Catalina" ); Object startupInstance = startupClass.newInstance(); // Set the shared extensions class loader if 1 ) "Setting startup class properties" ); "setParentClassLoader" ; new 1 ]; 0 ] = Class.forName("java.lang.ClassLoader" ); new 1 ]; 0 ] = sharedLoader; Method method = startupInstance.getClass().getMethod(methodName, paramTypes); method.invoke(startupInstance, paramValues); // Call the process() method if 1 ) "Calling startup class process() method" ); "process" ; new 1 ]; 0 ] = args.getClass(); new 1 ]; 0 ] = args; method = startupInstance.getClass().getMethod(methodName, paramTypes); method.invoke(startupInstance, paramValues); catch "Exception during startup processing" ); e.printStackTrace(System.out); 2 ); } } view plain copy to clipboard print ? public static File packed[], ClassLoader parent) throws if 1 ) "Creating new class loader" ); // Construct the "class path" for this class loader new // Add unpacked directories if null for int 0 ; i < unpacked.length; i++) { File file = unpacked; if continue if 1 ) " Including directory " + file.getAbsolutePath()); new "file" , null file.getCanonicalPath() + File.separator); list.add(url.toString()); } } // Add packed directory JAR files if null for int 0 ; i < packed.length; i++) { File directory = packed; if !directory.canRead()) continue String filenames[] = directory.list(); for int 0 ; j < filenames.length; j++) { String filename = filenames[j].toLowerCase(); if ".jar" )) continue new if 1 ) " Including jar file " + file.getAbsolutePath()); new "file" , null file.getCanonicalPath()); list.add(url.toString()); } } } // Construct the class loader itself new null if null new else new true return } view plain copy to clipboard print ? if null // (2) Required by Manager if if 1 ) "Configuring privileged default Loader" ); new this else if 1 ) "Configuring non-privileged default Loader" ); new } } view plain copy to clipboard print ? private ClassLoader oldContextClassLoader = Thread.currentThread().getContextClassLoader(); if null return Thread.currentThread().setContextClassLoader (getLoader().getClassLoader()); DirContextURLStreamHandler.bind(getResources()); if try this this catch // Silent catch, as this is a normal case during the early // startup stages } } return } view plain copy to clipboard print ? private "org.apache.catalina.loader.WebappClassLoader" ; ...... public void throws // Validate and update our current component state if throw new "webappLoader.alreadyStarted" )); if 1 ) "webappLoader.starting" )); null true if null return // Register a stream handler factory for the JNDI protocol URLStreamHandlerFactory streamHandlerFactory = new try URL.setURLStreamHandlerFactory(streamHandlerFactory); catch // Ignore the error here. } // Construct a class loader based on our current repositories list try classLoader = createClassLoader(); classLoader.setResources(container.getResources()); this this if instanceof classLoader.setAntiJARLocking(((StandardContext) container).getAntiJARLocking()); for int 0 ; i < repositories.length; i++) { classLoader.addRepository(repositories); } // Configure our repositories setRepositories(); setClassPath(); setPermissions(); if instanceof ((Lifecycle) classLoader).start(); // Binding the Webapp class loader to the directory context DirContextURLStreamHandler.bind this catch throw new "start: " , t); } // Validate that all required packages are actually available validatePackages(); // Start our background thread if we are reloadable if "webappLoader.reloading" )); try threadStart(); catch throw new } } } ...... private throws Class clazz = Class.forName(loaderClass); null if null // Will cause a ClassCast is the class does not extend WCL, but // this is on purpose (the exception will be caught and rethrown) classLoader = (WebappClassLoader) clazz.newInstance(); else class Object[] args = { parentClassLoader }; Constructor constr = clazz.getConstructor(argTypes); classLoader = (WebappClassLoader) constr.newInstance(args); } return } view plain copy to clipboard print ? Class clazz = null try if 4 ) " findClassInternal(" + name + ")" ); try clazz = findClassInternal(name); catch if throw } catch ace.printStackTrace(); throw new catch if 4 ) " -->RuntimeException Rethrown" , e); throw } if null try super catch throw new catch if 4 ) " -->RuntimeException Rethrown" , e); throw } } if null if 3 ) " --> Returning ClassNotFoundException" ); throw new } catch if 3 ) " --> Passing on ClassNotFoundException" , e); throw } 以下引自tomcat的说明文档，说明了加载类的顺序 /WEB-INF/classes of your web application/WEB-INF/lib/*.jar of your web applicationBootstrap classes of your JVM System class loader classses (described above) $CATALINA_HOME/common/classes $CATALINA_HOME/common/endorsed/*.jar $CATALINA_HOME/common/lib/*.jar $CATALINA_BASE/shared/classes $CATALINA_BASE/shared/lib/*.jar
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