org.apache.fop.apps.FOURIResolver Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of fop Show documentation
Show all versions of fop Show documentation
Apache FOP (Formatting Objects Processor) is the world's first print formatter driven by XSL formatting objects (XSL-FO) and the world's first output independent formatter. It is a Java application that reads a formatting object (FO) tree and renders the resulting pages to a specified output. Output formats currently supported include PDF, PCL, PS, AFP, TIFF, PNG, SVG, XML (area tree representation), Print, AWT and TXT. The primary output target is PDF.
/*
* 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.
*/
/* $Id: FOURIResolver.java 772672 2009-05-07 15:08:30Z cbowditch $ */
package org.apache.fop.apps;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLConnection;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.URIResolver;
import javax.xml.transform.stream.StreamSource;
import org.apache.commons.io.FileUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.xmlgraphics.util.io.Base64EncodeStream;
import org.apache.xmlgraphics.util.uri.CommonURIResolver;
/**
* Provides FOP specific URI resolution. This is the default URIResolver
* {@link FOUserAgent} will use unless overridden.
*
* @see javax.xml.transform.URIResolver
*/
public class FOURIResolver implements javax.xml.transform.URIResolver {
// log
private Log log = LogFactory.getLog("FOP");
/** Common URIResolver */
private CommonURIResolver commonURIResolver = new CommonURIResolver();
/** A user settable URI Resolver */
private URIResolver uriResolver = null;
/** true if exceptions are to be thrown if the URIs cannot be resolved. */
private boolean throwExceptions = false;
/**
* Checks if the given base URL is acceptable. It also normalizes the URL.
* @param base the base URL to check
* @return the normalized URL
* @throws MalformedURLException if there's a problem with a file URL
*/
public String checkBaseURL(String base) throws MalformedURLException {
// replace back slash with forward slash to ensure windows file:/// URLS are supported
base = base.replace('\\', '/');
if (!base.endsWith("/")) {
// The behavior described by RFC 3986 regarding resolution of relative
// references may be misleading for normal users:
// file://path/to/resources + myResource.res -> file://path/to/myResource.res
// file://path/to/resources/ + myResource.res -> file://path/to/resources/myResource.res
// We assume that even when the ending slash is missing, users have the second
// example in mind
base += "/";
}
File dir = new File(base);
if (dir.isDirectory()) {
return dir.toURI().toASCIIString();
} else {
URI baseURI;
try {
baseURI = new URI(base);
String scheme = baseURI.getScheme();
boolean directoryExists = true;
if ("file".equals(scheme)) {
dir = FileUtils.toFile(baseURI.toURL());
directoryExists = dir.isDirectory();
}
if (scheme == null || !directoryExists) {
String message = "base " + base + " is not a valid directory";
if (throwExceptions) {
throw new MalformedURLException(message);
}
log.error(message);
}
return baseURI.toASCIIString();
} catch (URISyntaxException e) {
//TODO not ideal: our base URLs are actually base URIs.
throw new MalformedURLException(e.getMessage());
}
}
}
/**
* Default constructor
*/
public FOURIResolver() {
this(false);
}
/**
* Additional constructor
*
* @param throwExceptions
* true if exceptions are to be thrown if the URIs cannot be
* resolved.
*/
public FOURIResolver(boolean throwExceptions) {
this.throwExceptions = throwExceptions;
}
/**
* Handles resolve exceptions appropriately.
*
* @param e
* the exception
* @param errorStr
* error string
* @param strict
* strict user config
*/
private void handleException(Exception e, String errorStr, boolean strict)
throws TransformerException {
if (strict) {
throw new TransformerException(errorStr, e);
}
log.error(e.getMessage());
}
/**
* Called by the processor through {@link FOUserAgent} when it encounters an
* uri in an external-graphic element. (see also
* {@link javax.xml.transform.URIResolver#resolve(String, String)} This
* resolver will allow URLs without a scheme, i.e. it assumes 'file:' as the
* default scheme. It also allows relative URLs with scheme, e.g.
* file:../../abc.jpg which is not strictly RFC compliant as long as the
* scheme is the same as the scheme of the base URL. If the base URL is null
* a 'file:' URL referencing the current directory is used as the base URL.
* If the method is successful it will return a Source of type
* {@link javax.xml.transform.stream.StreamSource} with its SystemID set to
* the resolved URL used to open the underlying InputStream.
*
* @param href
* An href attribute, which may be relative or absolute.
* @param base
* The base URI against which the first argument will be made
* absolute if the absolute URI is required.
* @return A {@link javax.xml.transform.Source} object, or null if the href
* cannot be resolved.
* @throws javax.xml.transform.TransformerException
* Never thrown by this implementation.
* @see javax.xml.transform.URIResolver#resolve(String, String)
*/
public Source resolve(String href, String base) throws TransformerException {
Source source = null;
// data URLs can be quite long so evaluate early and don't try to build a File
// (can lead to problems)
source = commonURIResolver.resolve(href, base);
// Custom uri resolution
if (source == null && uriResolver != null) {
source = uriResolver.resolve(href, base);
}
// Fallback to default resolution mechanism
if (source == null) {
URL absoluteURL = null;
int hashPos = href.indexOf('#');
String fileURL, fragment;
if (hashPos >= 0) {
fileURL = href.substring(0, hashPos);
fragment = href.substring(hashPos);
} else {
fileURL = href;
fragment = null;
}
File file = new File(fileURL);
if (file.canRead() && file.isFile()) {
try {
if (fragment != null) {
absoluteURL = new URL(file.toURI().toURL().toExternalForm() + fragment);
} else {
absoluteURL = file.toURI().toURL();
}
} catch (MalformedURLException mfue) {
handleException(mfue, "Could not convert filename '" + href
+ "' to URL", throwExceptions);
}
} else {
// no base provided
if (base == null) {
// We don't have a valid file protocol based URL
try {
absoluteURL = new URL(href);
} catch (MalformedURLException mue) {
try {
// the above failed, we give it another go in case
// the href contains only a path then file: is
// assumed
absoluteURL = new URL("file:" + href);
} catch (MalformedURLException mfue) {
handleException(mfue, "Error with URL '" + href
+ "'", throwExceptions);
}
}
// try and resolve from context of base
} else {
URL baseURL = null;
try {
baseURL = new URL(base);
} catch (MalformedURLException mfue) {
handleException(mfue, "Error with base URL '" + base
+ "'", throwExceptions);
}
/*
* This piece of code is based on the following statement in
* RFC2396 section 5.2:
*
* 3) If the scheme component is defined, indicating that
* the reference starts with a scheme name, then the
* reference is interpreted as an absolute URI and we are
* done. Otherwise, the reference URI's scheme is inherited
* from the base URI's scheme component.
*
* Due to a loophole in prior specifications [RFC1630], some
* parsers allow the scheme name to be present in a relative
* URI if it is the same as the base URI scheme.
* Unfortunately, this can conflict with the correct parsing
* of non-hierarchical URI. For backwards compatibility, an
* implementation may work around such references by
* removing the scheme if it matches that of the base URI
* and the scheme is known to always use the
* syntax.
*
* The URL class does not implement this work around, so we
* do.
*/
assert (baseURL != null);
String scheme = baseURL.getProtocol() + ":";
if (href.startsWith(scheme) && "file:".equals(scheme)) {
href = href.substring(scheme.length());
int colonPos = href.indexOf(':');
int slashPos = href.indexOf('/');
if (slashPos >= 0 && colonPos >= 0
&& colonPos < slashPos) {
href = "/" + href; // Absolute file URL doesn't
// have a leading slash
}
}
try {
absoluteURL = new URL(baseURL, href);
} catch (MalformedURLException mfue) {
handleException(mfue, "Error with URL; base '" + base
+ "' " + "href '" + href + "'", throwExceptions);
}
}
}
if (absoluteURL != null) {
String effURL = absoluteURL.toExternalForm();
try {
URLConnection connection = absoluteURL.openConnection();
connection.setAllowUserInteraction(false);
connection.setDoInput(true);
updateURLConnection(connection, href);
connection.connect();
return new StreamSource(connection.getInputStream(), effURL);
} catch (FileNotFoundException fnfe) {
// Note: This is on "debug" level since the caller is
// supposed to handle this
log.debug("File not found: " + effURL);
} catch (java.io.IOException ioe) {
log.error("Error with opening URL '" + effURL + "': "
+ ioe.getMessage());
}
}
}
return source;
}
/**
* This method allows you to set special values on a URLConnection just
* before the connect() method is called. Subclass FOURIResolver and
* override this method to do things like adding the user name and password
* for HTTP basic authentication.
*
* @param connection
* the URLConnection instance
* @param href
* the original URI
*/
protected void updateURLConnection(URLConnection connection, String href) {
// nop
}
/**
* This is a convenience method for users who want to override
* updateURLConnection for HTTP basic authentication. Simply call it using
* the right username and password.
*
* @param connection
* the URLConnection to set up for HTTP basic authentication
* @param username
* the username
* @param password
* the password
*/
protected void applyHttpBasicAuthentication(URLConnection connection,
String username, String password) {
String combined = username + ":" + password;
try {
ByteArrayOutputStream baout = new ByteArrayOutputStream(combined
.length() * 2);
Base64EncodeStream base64 = new Base64EncodeStream(baout);
// TODO Not sure what charset/encoding can be used with basic
// authentication
base64.write(combined.getBytes("UTF-8"));
base64.close();
connection.setRequestProperty("Authorization", "Basic "
+ new String(baout.toByteArray(), "UTF-8"));
} catch (IOException e) {
// won't happen. We're operating in-memory.
throw new RuntimeException(
"Error during base64 encodation of username/password");
}
}
/**
* Sets the custom URI Resolver. It is used for resolving factory-level URIs like
* hyphenation patterns and as backup for URI resolution performed during a
* rendering run.
*
* @param resolver
* the new URI resolver
*/
public void setCustomURIResolver(URIResolver resolver) {
this.uriResolver = resolver;
}
/**
* Returns the custom URI Resolver.
*
* @return the URI Resolver or null, if none is set
*/
public URIResolver getCustomURIResolver() {
return this.uriResolver;
}
/**
* @param throwExceptions
* Whether or not to throw exceptions on resolution error
*/
public void setThrowExceptions(boolean throwExceptions) {
this.throwExceptions = throwExceptions;
}
}