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package com.sun.jersey.core.spi.scanning;
import com.sun.jersey.api.uri.UriComponent;
import com.sun.jersey.api.uri.UriComponent.Type;
import com.sun.jersey.core.reflection.ReflectionHelper;
import com.sun.jersey.core.spi.scanning.uri.FileSchemeScanner;
import com.sun.jersey.core.spi.scanning.uri.JarZipSchemeScanner;
import com.sun.jersey.core.spi.scanning.uri.UriSchemeScanner;
import com.sun.jersey.core.spi.scanning.uri.VfsSchemeScanner;
import com.sun.jersey.spi.service.ServiceFinder;
import java.io.IOException;
import java.lang.reflect.ReflectPermission;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
/**
* A scanner that recursively scans URI-based resources present in a set of
* package names, and sub-package names of that set.
* <p>
* The URIs for a package name are obtained, by default, by invoking
* {@link ClassLoader#getResources(java.lang.String) } with the parameter that
* is the package name with "." replaced by "/". The obtaining of the resources
* with a given name may be overridden by registering an implementation of
* {@link ResourcesProvider} using the method
* {@link #setResourcesProvider(com.sun.jersey.core.spi.scanning.PackageNamesScanner.ResourcesProvider) }.
* <p>
* Each URI is then scanned using a registered {@link UriSchemeScanner} that
* supports the URI scheme.
* <p>
* The following are registered by default.
* The {@link FileSchemeScanner} for "file" URI schemes.
* The {@link JarZipSchemeScanner} for "jar" or "zip" URI schemes to jar
* resources.
* The {@link VfsSchemeScanner} for the JBoss-based "vfsfile" and "vfszip"
* URI schemes.
* <p>
* Further schemes may be registered by registering an implementation of
* {@link UriSchemeScanner} in the META-INF/services file whose name is the
* the fully qualified class name of {@link UriSchemeScanner}.
* <p>
* If a URI scheme is not supported a {@link ScannerException} will be thrown
* and package scanning deployment will fail.
*
* @author Paul.Sandoz@Sun.Com
* @author Jakub.Podlesak@Sun.Com
*/
public class PackageNamesScanner implements Scanner {
private final String[] packages;
private final ClassLoader classloader;
private final Map<String, UriSchemeScanner> scanners;
/**
* Scan from a set of packages using the context class loader.
*
* @param packages an array of package names.
*/
public PackageNamesScanner(final String[] packages) {
this(ReflectionHelper.getContextClassLoader(), packages);
}
/**
* Scan from a set of packages using declared class loader.
*
* @param classloader the class loader to load classes from.
* @param packages an array of package names.
*/
public PackageNamesScanner(final ClassLoader classloader, final String[] packages) {
this.packages = packages;
this.classloader = classloader;
this.scanners = new HashMap<String, UriSchemeScanner>();
add(new JarZipSchemeScanner());
add(new FileSchemeScanner());
add(new VfsSchemeScanner());
for (UriSchemeScanner s : ServiceFinder.find(UriSchemeScanner.class)) {
add(s);
}
}
private void add(final UriSchemeScanner ss) {
for (final String s : ss.getSchemes()) {
scanners.put(s.toLowerCase(), ss);
}
}
@Override
public void scan(final ScannerListener cfl) {
for (final String p : packages) {
try {
final Enumeration<URL> urls = ResourcesProvider.getInstance().
getResources(p.replace('.', '/'), classloader);
while (urls.hasMoreElements()) {
try {
scan(toURI(urls.nextElement()), cfl);
} catch (URISyntaxException ex) {
throw new ScannerException("Error when converting a URL to a URI", ex);
}
}
} catch (IOException ex) {
throw new ScannerException("IO error when package scanning jar", ex);
}
}
}
/**
* Find resources with a given name and class loader.
*/
public static abstract class ResourcesProvider {
private static volatile ResourcesProvider provider;
private static ResourcesProvider getInstance() {
// Double-check idiom for lazy initialization
ResourcesProvider result = provider;
if (result == null) { // first check without locking
synchronized (ResourcesProvider.class) {
result = provider;
if (result == null) { // second check with locking
provider = result = new ResourcesProvider() {
@Override
public Enumeration<URL> getResources(String name, ClassLoader cl)
throws IOException {
return cl.getResources(name);
}
};
}
}
}
return result;
}
private static void setInstance(ResourcesProvider provider) throws SecurityException {
SecurityManager security = System.getSecurityManager();
if (security != null) {
ReflectPermission rp = new ReflectPermission("suppressAccessChecks");
security.checkPermission(rp);
}
synchronized (ResourcesProvider.class) {
ResourcesProvider.provider = provider;
}
}
/**
* Find all resources with the given name using a class loader.
*
* @param cl the class loader use to find the resources
* @param name the resource name
* @return An enumeration of URL objects for the resource.
* If no resources could be found, the enumeration will be empty.
* Resources that the class loader doesn't have access to will
* not be in the enumeration.
* @throws IOException if I/O errors occur
*/
public abstract Enumeration<URL> getResources(String name, ClassLoader cl) throws IOException;
}
/**
* Set the {@link ResourcesProvider} implementation to find resources.
* <p>
* This method should be invoked before any package scanning is performed
* otherwise the functionality method will be utilized.
*
* @param provider the resources provider.
* @throws SecurityException if the resources provider cannot be set.
*/
public static void setResourcesProvider(ResourcesProvider provider) throws SecurityException {
ResourcesProvider.setInstance(provider);
}
private void scan(final URI u, final ScannerListener cfl) {
final UriSchemeScanner ss = scanners.get(u.getScheme().toLowerCase());
if (ss != null) {
ss.scan(u, cfl);
} else {
throw new ScannerException("The URI scheme " + u.getScheme() +
" of the URI " + u +
" is not supported. Package scanning deployment is not" +
" supported for such URIs." +
"\nTry using a different deployment mechanism such as" +
" explicitly declaring root resource and provider classes" +
" using an extension of javax.ws.rs.core.Application");
}
}
private URI toURI(URL url) throws URISyntaxException {
try {
return url.toURI();
} catch (URISyntaxException e) {
// Work around bug where some URLs are incorrectly encoded.
// This can occur when certain class loaders are utilized
// to obtain URLs for resources.
return URI.create(toExternalForm(url));
}
}
private String toExternalForm(URL u) {
// pre-compute length of StringBuffer
int len = u.getProtocol().length() + 1;
if (u.getAuthority() != null && u.getAuthority().length() > 0) {
len += 2 + u.getAuthority().length();
}
if (u.getPath() != null) {
len += u.getPath().length();
}
if (u.getQuery() != null) {
len += 1 + u.getQuery().length();
}
if (u.getRef() != null) {
len += 1 + u.getRef().length();
}
StringBuffer result = new StringBuffer(len);
result.append(u.getProtocol());
result.append(":");
if (u.getAuthority() != null && u.getAuthority().length() > 0) {
result.append("//");
result.append(u.getAuthority());
}
if (u.getPath() != null) {
result.append(UriComponent.contextualEncode(u.getPath(), Type.PATH));
}
if (u.getQuery() != null) {
result.append('?');
result.append(UriComponent.contextualEncode(u.getQuery(), Type.QUERY));
}
if (u.getRef() != null) {
result.append("#");
result.append(u.getRef());
}
return result.toString();
}
}