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Google App Engine compliant variation of FreeMarker.
FreeMarker is a "template engine"; a generic tool to generate text output based on templates.
/*
* 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 freemarker.cache;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import javax.servlet.ServletContext;
import freemarker.log.Logger;
import freemarker.template.Configuration;
import freemarker.template.utility.CollectionUtils;
import freemarker.template.utility.NullArgumentException;
import freemarker.template.utility.StringUtil;
/**
* A {@link TemplateLoader} that uses streams reachable through {@link ServletContext#getResource(String)} as its source
* of templates.
*/
public class WebappTemplateLoader implements TemplateLoader {
private static final Logger LOG = Logger.getLogger("freemarker.cache");
private final ServletContext servletContext;
private final String subdirPath;
private Boolean urlConnectionUsesCaches;
private boolean attemptFileAccess = true;
/**
* Creates a template loader that will use the specified servlet context to load the resources. It will use
* the base path of "/" meaning templates will be resolved relative to the servlet context root
* location.
*
* @param servletContext
* the servlet context whose {@link ServletContext#getResource(String)} will be used to load the
* templates.
*/
public WebappTemplateLoader(ServletContext servletContext) {
this(servletContext, "/");
}
/**
* Creates a template loader that will use the specified servlet context to load the resources. It will use the
* specified base path, which is interpreted relatively to the context root (does not mater if you start it with "/"
* or not). Path components should be separated by forward slashes independently of the separator character used by
* the underlying operating system.
*
* @param servletContext
* the servlet context whose {@link ServletContext#getResource(String)} will be used to load the
* templates.
* @param subdirPath
* the base path to template resources.
*/
public WebappTemplateLoader(ServletContext servletContext, String subdirPath) {
NullArgumentException.check("servletContext", servletContext);
NullArgumentException.check("subdirPath", subdirPath);
subdirPath = subdirPath.replace('\\', '/');
if (!subdirPath.endsWith("/")) {
subdirPath += "/";
}
if (!subdirPath.startsWith("/")) {
subdirPath = "/" + subdirPath;
}
this.subdirPath = subdirPath;
this.servletContext = servletContext;
}
public Object findTemplateSource(String name) throws IOException {
String fullPath = subdirPath + name;
if (attemptFileAccess) {
// First try to open as plain file (to bypass servlet container resource caches).
try {
String realPath = servletContext.getRealPath(fullPath);
if (realPath != null) {
File file = new File(realPath);
if (file.canRead() && file.isFile()) {
return file;
}
}
} catch (SecurityException e) {
;// ignore
}
}
// If it fails, try to open it with servletContext.getResource.
URL url = null;
try {
url = servletContext.getResource(fullPath);
} catch (MalformedURLException e) {
LOG.warn("Could not retrieve resource " + StringUtil.jQuoteNoXSS(fullPath),
e);
return null;
}
return url == null ? null : new URLTemplateSource(url, getURLConnectionUsesCaches());
}
public long getLastModified(Object templateSource) {
if (templateSource instanceof File) {
return ((File) templateSource).lastModified();
} else {
return ((URLTemplateSource) templateSource).lastModified();
}
}
public Reader getReader(Object templateSource, String encoding)
throws IOException {
if (templateSource instanceof File) {
return new InputStreamReader(
new FileInputStream((File) templateSource),
encoding);
} else {
return new InputStreamReader(
((URLTemplateSource) templateSource).getInputStream(),
encoding);
}
}
public void closeTemplateSource(Object templateSource) throws IOException {
if (templateSource instanceof File) {
// Do nothing.
} else {
((URLTemplateSource) templateSource).close();
}
}
/**
* Getter pair of {@link #setURLConnectionUsesCaches(Boolean)}.
*
* @since 2.3.21
*/
public Boolean getURLConnectionUsesCaches() {
return urlConnectionUsesCaches;
}
/**
* It does the same as {@link URLTemplateLoader#setURLConnectionUsesCaches(Boolean)}; see there.
*
* @since 2.3.21
*/
public void setURLConnectionUsesCaches(Boolean urlConnectionUsesCaches) {
this.urlConnectionUsesCaches = urlConnectionUsesCaches;
}
/**
* Show class name and some details that are useful in template-not-found errors.
*
* @since 2.3.21
*/
@Override
public String toString() {
return TemplateLoaderUtils.getClassNameForToString(this)
+ "(subdirPath=" + StringUtil.jQuote(subdirPath)
+ ", servletContext={contextPath=" + StringUtil.jQuote(getContextPath())
+ ", displayName=" + StringUtil.jQuote(servletContext.getServletContextName()) + "})";
}
/** Gets the context path if we are on Servlet 2.5+, or else returns failure description string. */
private String getContextPath() {
try {
Method m = servletContext.getClass().getMethod("getContextPath", CollectionUtils.EMPTY_CLASS_ARRAY);
return (String) m.invoke(servletContext, CollectionUtils.EMPTY_OBJECT_ARRAY);
} catch (Throwable e) {
return "[can't query before Serlvet 2.5]";
}
}
/**
* Getter pair of {@link #setAttemptFileAccess(boolean)}.
*
* @since 2.3.23
*/
public boolean getAttemptFileAccess() {
return attemptFileAccess;
}
/**
* Specifies that before loading templates with {@link ServletContext#getResource(String)}, it should try to load
* the template as {@link File}; default is {@code true}, though it's not always recommended anymore. This is a
* workaround for the case when the servlet container doesn't show template modifications after the template was
* already loaded earlier. But it's certainly better to counter this problem by disabling the URL connection cache
* with {@link #setURLConnectionUsesCaches(Boolean)}, which is also the default behavior with
* {@link Configuration#setIncompatibleImprovements(freemarker.template.Version) incompatible_improvements} 2.3.21
* and later.
*
* @since 2.3.23
*/
public void setAttemptFileAccess(boolean attemptLoadingFromFile) {
this.attemptFileAccess = attemptLoadingFromFile;
}
}