com.ocpsoft.pretty.faces.config.annotation.AbstractClassFinder Maven / Gradle / Ivy
/*
* Copyright 2010 Lincoln Baxter, III
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.ocpsoft.pretty.faces.config.annotation;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import javax.servlet.ServletContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Base class for implementations of the {@link ClassFinder} interface.
*
* @see ClassFinder
* @author Christian Kaltepoth
*/
public abstract class AbstractClassFinder implements ClassFinder
{
/**
* Common logger for all implementations
*/
protected final Log log = LogFactory.getLog(this.getClass());
/**
* The {@link ServletContext}
*/
protected final ServletContext servletContext;
/**
* The {@link ClassLoader} to get classes from
*/
protected final ClassLoader classLoader;
/**
* The filter for checking which classes to process
*/
protected final PackageFilter packageFilter;
/**
* The filter to check bytecode for interesting annotations
*/
private final ByteCodeAnnotationFilter byteCodeAnnotationFilter;
/**
* Initialization procedure
*
* @param servletContext
* The {@link ServletContext} of the web application.
* @param classLoader
* The {@link ClassLoader} to use for loading classes
* @param packageFilter
* The {@link PackageFilter} used to check if a package has to be
* scanned.
*/
public AbstractClassFinder(ServletContext servletContext, ClassLoader classLoader, PackageFilter packageFilter)
{
this.servletContext = servletContext;
this.classLoader = classLoader;
this.packageFilter = packageFilter;
this.byteCodeAnnotationFilter = new ByteCodeAnnotationFilter();
}
/**
* Strip everything up to and including a given prefix from a string.
*
* @param str
* The string to process
* @param prefix
* The prefix
* @return the stripped string or null if the prefix has not
* been found
*/
protected String stripKnownPrefix(String str, String prefix)
{
int startIndex = str.lastIndexOf(prefix);
if (startIndex != -1)
{
return str.substring(startIndex + prefix.length());
}
return null;
}
/**
*
* Creates a FQCN from an {@link URL} representing a .class
* file.
*
*
* @param url
* The path of the class file
* @return the FQCN of the class
*/
protected static String getClassName(String filename)
{
// end index is just before ".class"
int endIndex = filename.length() - ".class".length();
// extract relevant part of the path
String relativePath = filename.substring(0, endIndex);
// replace / by . to create FQCN
return relativePath.replace('/', '.');
}
/**
* Checks if a supplied class has to be processed by checking the package
* name against the {@link PackageFilter}.
*
* @param className
* FQCN of the class
* @return true for classes to process, false for
* classes to ignore
*/
protected boolean mustProcessClass(String className)
{
// the default package
String packageName = "";
// find last dot in class name to determine the package name
int packageEndIndex = className.lastIndexOf(".");
if (packageEndIndex != -1)
{
packageName = className.substring(0, packageEndIndex);
}
// check filter
return packageFilter.isAllowedPackage(packageName);
}
/**
*
* Handle a single class to process. This method should only be called if the
* class name is accepted by the {@link PackageFilter}.
*
*
* If classFileStream is not null the method will first
* try to check whether the class files may contain annotations by scanning
* it with the {@link ByteCodeAnnotationFilter}. If no {@link InputStream} is
* supplied, this check will be skipped. After that the method will create an
* instance of the class and then call
* {@link PrettyAnnotationHandler#processClass(Class)}.
*
*
* Please not the the called of this method is responsible to close the
* supplied {@link InputStream}!
*
*
* @param className
* The FQCN of the class
* @param classFileStream
* The Java class file of the class (may be null)
* @param handler
* the handler to notify
*/
protected void processClass(String className, InputStream classFileStream, PrettyAnnotationHandler handler)
{
// bytecode check is only performed if the InputStream is available
if (classFileStream != null)
{
// we must take care of IOExceptions thrown by ByteCodeAnnotationFilter
try
{
// call bytecode filter
boolean shouldScanClass = byteCodeAnnotationFilter.accept(classFileStream);
// No annotations -> abort
if (!shouldScanClass)
{
return;
}
// filter says we should scan the class
if (log.isDebugEnabled())
{
log.debug("Bytecode filter recommends to scan class: " + className);
}
}
catch (IOException e)
{
if (log.isDebugEnabled())
{
log.debug("Failed to parse class file: " + className, e);
}
}
}
try
{
// request this class from the ClassLoader
Class clazz = classLoader.loadClass(className);
// call handler
handler.processClass(clazz);
}
catch (NoClassDefFoundError e)
{
// reference to another class unknown to the classloader
log.debug("Could not load class '" + className + "': " + e.toString());
}
catch (ClassNotFoundException e)
{
// should no happen, because we found the class on the classpath
throw new IllegalStateException("Unable to load class: " + className, e);
}
}
}