org.apache.openjpa.lib.meta.ClassMetaDataIterator Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.openjpa.lib.meta;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLDecoder;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.NoSuchElementException;
import org.apache.openjpa.lib.util.ClassUtil;
import org.apache.openjpa.lib.util.J2DoPrivHelper;
import org.apache.openjpa.lib.util.MultiClassLoader;
/**
* Iterator over all metadata resources that might contain the
* metadata for a given class, starting with the most general. Assumes that
* package-level resources are named "package.<suffix>".
*
* @author Abe White
*/
public class ClassMetaDataIterator implements MetaDataIterator {
private final ClassLoader _loader;
private final List _locs;
private int _loc = -1;
private final List _urls = new ArrayList<>(3);
private int _url = -1;
/**
* Constructor; supply the class whose metadata to find, the suffix
* of metadata files, and whether to parse top-down or bottom-up.
*/
public ClassMetaDataIterator(Class cls, String suffix, boolean topDown) {
this(cls, suffix, null, topDown);
}
/**
* Constructor; supply the class whose metadata to find, the suffix
* of metadata files, and whether to parse top-down or bottom-up.
*/
public ClassMetaDataIterator(Class cls, String suffix,
ClassLoader loader, boolean topDown) {
// skip classes that can't have metadata
if (cls != null && (cls.isPrimitive()
|| cls.getName().startsWith("java.")
|| cls.getName().startsWith("javax."))) {
_loader = null;
_locs = Collections.emptyList();
return;
}
if (loader == null) {
MultiClassLoader multi = AccessController
.doPrivileged(J2DoPrivHelper.newMultiClassLoaderAction());
multi.addClassLoader(MultiClassLoader.SYSTEM_LOADER);
multi.addClassLoader(MultiClassLoader.THREAD_LOADER);
multi.addClassLoader(getClass().getClassLoader());
if (cls != null)
{
ClassLoader clsLoader = (ClassLoader)
AccessController.doPrivileged(
J2DoPrivHelper.getClassLoaderAction(cls));
if (clsLoader != null)
multi.addClassLoader(clsLoader);
}
loader = multi;
}
_loader = loader;
// collect the set of all possible metadata locations; start with
// system locations
_locs = new ArrayList<>();
_locs.add("META-INF/package" + suffix);
_locs.add("WEB-INF/package" + suffix);
_locs.add("package" + suffix);
// put this legacy location at the end regardless of whether we're
// going top down or bottom up so we don't have to parse it as often
// during testing
if (!topDown)
_locs.add("system" + suffix);
if (cls != null) {
// also check:
// 1. for each package from the top down to cls' package:
// /package
// / (legacy support)
// /../ (legacy support)
// 2. /
String pkg = ClassUtil.getPackageName(cls).replace('.', '/');
if (pkg.length() > 0) {
int idx, start = 0;
String pkgName, path, upPath = "";
do {
idx = pkg.indexOf('/', start);
if (idx == -1) {
pkgName = (start == 0) ? pkg : pkg.substring(start);
path = pkg + "/";
} else {
pkgName = pkg.substring(start, idx);
path = pkg.substring(0, idx + 1);
}
_locs.add(path + "package" + suffix);
_locs.add(path + pkgName + suffix); // legacy
_locs.add(upPath + pkgName + suffix); // legacy
if (idx == -1)
_locs.add(path + ClassUtil.getClassName(cls) + suffix);
start = idx + 1;
upPath = path;
}
while (idx != -1);
} else {
// for top-level classes
_locs.add(cls.getName() + suffix);
}
}
if (topDown)
_locs.add("system" + suffix); // legacy
else
Collections.reverse(_locs);
}
@Override
public boolean hasNext() throws IOException {
Enumeration e;
while (_url + 1 >= _urls.size()) {
if (++_loc >= _locs.size())
return false;
_url = -1;
_urls.clear();
try {
e = AccessController.doPrivileged(
J2DoPrivHelper.getResourcesAction(
_loader, _locs.get(_loc)));
} catch (PrivilegedActionException pae) {
throw (IOException) pae.getException();
}
while (e.hasMoreElements())
_urls.add(e.nextElement());
}
return true;
}
@Override
public URL next() throws IOException {
if (!hasNext())
throw new NoSuchElementException();
return _urls.get(++_url);
}
@Override
public InputStream getInputStream() throws IOException {
if (_url == -1 || _url >= _urls.size())
throw new IllegalStateException();
try {
return AccessController.doPrivileged(
J2DoPrivHelper.openStreamAction(_urls.get(_url)));
} catch (PrivilegedActionException pae) {
throw (IOException) pae.getException();
}
}
@Override
public File getFile() throws IOException {
if (_url == -1 || _url >= _urls.size())
throw new IllegalStateException();
File file = new File(URLDecoder.decode((_urls.get(_url)).getFile()));
return ((AccessController.doPrivileged(
J2DoPrivHelper.existsAction(file))).booleanValue()) ? file:null;
}
@Override
public void close() {
}
}