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Struts example source code file (DefaultStaticContentLoader.java)
This example Struts source code file (DefaultStaticContentLoader.java) is included in the DevDaily.com
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The Struts DefaultStaticContentLoader.java source code
/*
* $Id$
*
* 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.struts2.dispatcher;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.StringTokenizer;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.StrutsConstants;
import org.apache.struts2.dispatcher.ng.HostConfig;
import org.apache.struts2.util.ClassLoaderUtils;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.ClassLoaderUtil;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
public class DefaultStaticContentLoader implements StaticContentLoader {
/**
* Provide a logging instance.
*/
private Logger log;
/**
* Store set of path prefixes to use with static resources.
*/
protected String[] pathPrefixes;
/**
* Store state of StrutsConstants.STRUTS_SERVE_STATIC_CONTENT setting.
*/
protected boolean serveStatic;
/**
* Store state of StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE setting.
*/
protected boolean serveStaticBrowserCache;
/**
* Provide a formatted date for setting heading information when caching static content.
*/
protected final Calendar lastModifiedCal = Calendar.getInstance();
/**
* Store state of StrutsConstants.STRUTS_I18N_ENCODING setting.
*/
protected String encoding;
/**
* Modify state of StrutsConstants.STRUTS_SERVE_STATIC_CONTENT setting.
*
* @param val
* New setting
*/
@Inject(StrutsConstants.STRUTS_SERVE_STATIC_CONTENT)
public void setServeStaticContent(String val) {
serveStatic = "true".equals(val);
}
/**
* Modify state of StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE
* setting.
*
* @param val
* New setting
*/
@Inject(StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE)
public void setServeStaticBrowserCache(String val) {
serveStaticBrowserCache = "true".equals(val);
}
/**
* Modify state of StrutsConstants.STRUTS_I18N_ENCODING setting.
* @param val New setting
*/
@Inject(StrutsConstants.STRUTS_I18N_ENCODING)
public void setEncoding(String val) {
encoding = val;
}
/*
* (non-Javadoc)
*
* @see org.apache.struts2.dispatcher.StaticResourceLoader#setHostConfig(javax.servlet.FilterConfig)
*/
public void setHostConfig(HostConfig filterConfig) {
String param = filterConfig.getInitParameter("packages");
String packages = getAdditionalPackages();
if (param != null) {
packages = param + " " + packages;
}
this.pathPrefixes = parse(packages);
initLogging(filterConfig);
}
protected String getAdditionalPackages() {
return "org.apache.struts2.static template org.apache.struts2.interceptor.debugging static";
}
/**
* Create a string array from a comma-delimited list of packages.
*
* @param packages
* A comma-delimited String listing packages
* @return A string array of packages
*/
protected String[] parse(String packages) {
if (packages == null) {
return null;
}
List<String> pathPrefixes = new ArrayList();
StringTokenizer st = new StringTokenizer(packages, ", \n\t");
while (st.hasMoreTokens()) {
String pathPrefix = st.nextToken().replace('.', '/');
if (!pathPrefix.endsWith("/")) {
pathPrefix += "/";
}
pathPrefixes.add(pathPrefix);
}
return pathPrefixes.toArray(new String[pathPrefixes.size()]);
}
/*
* (non-Javadoc)
*
* @see org.apache.struts2.dispatcher.StaticResourceLoader#findStaticResource(java.lang.String,
* javax.servlet.http.HttpServletRequest,
* javax.servlet.http.HttpServletResponse)
*/
public void findStaticResource(String path, HttpServletRequest request, HttpServletResponse response)
throws IOException {
String name = cleanupPath(path);
for (String pathPrefix : pathPrefixes) {
URL resourceUrl = findResource(buildPath(name, pathPrefix));
if (resourceUrl != null) {
InputStream is = null;
try {
//check that the resource path is under the pathPrefix path
String pathEnding = buildPath(name, pathPrefix);
if (resourceUrl.getFile().endsWith(pathEnding))
is = resourceUrl.openStream();
} catch (IOException ex) {
// just ignore it
continue;
}
//not inside the try block, as this could throw IOExceptions also
if (is != null) {
process(is, path, request, response);
return;
}
}
}
response.sendError(HttpServletResponse.SC_NOT_FOUND);
}
protected void process(InputStream is, String path, HttpServletRequest request, HttpServletResponse response) throws IOException {
if (is != null) {
Calendar cal = Calendar.getInstance();
// check for if-modified-since, prior to any other headers
long ifModifiedSince = 0;
try {
ifModifiedSince = request.getDateHeader("If-Modified-Since");
} catch (Exception e) {
log.warn("Invalid If-Modified-Since header value: '"
+ request.getHeader("If-Modified-Since") + "', ignoring");
}
long lastModifiedMillis = lastModifiedCal.getTimeInMillis();
long now = cal.getTimeInMillis();
cal.add(Calendar.DAY_OF_MONTH, 1);
long expires = cal.getTimeInMillis();
if (ifModifiedSince > 0 && ifModifiedSince <= lastModifiedMillis) {
// not modified, content is not sent - only basic
// headers and status SC_NOT_MODIFIED
response.setDateHeader("Expires", expires);
response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
is.close();
return;
}
// set the content-type header
String contentType = getContentType(path);
if (contentType != null) {
response.setContentType(contentType);
}
if (serveStaticBrowserCache) {
// set heading information for caching static content
response.setDateHeader("Date", now);
response.setDateHeader("Expires", expires);
response.setDateHeader("Retry-After", expires);
response.setHeader("Cache-Control", "public");
response.setDateHeader("Last-Modified", lastModifiedMillis);
} else {
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
response.setHeader("Expires", "-1");
}
try {
copy(is, response.getOutputStream());
} finally {
is.close();
}
return;
}
}
private void initLogging(HostConfig filterConfig) {
String factoryName = filterConfig.getInitParameter("loggerFactory");
if (factoryName != null) {
try {
Class cls = ClassLoaderUtils.loadClass(factoryName, this.getClass());
LoggerFactory fac = (LoggerFactory)cls.newInstance();
LoggerFactory.setLoggerFactory(fac);
} catch (InstantiationException e) {
System.err.println("Unable to instantiate logger factory: "+factoryName+", using default");
e.printStackTrace();
} catch (IllegalAccessException e) {
System.err.println("Unable to access logger factory: "+factoryName+", using default");
e.printStackTrace();
} catch (ClassNotFoundException e) {
System.err.println("Unable to locate logger factory class: "+factoryName+", using default");
e.printStackTrace();
}
}
log = LoggerFactory.getLogger(FilterDispatcher.class);
}
/**
* Look for a static resource in the classpath.
*
* @param path The resource path
* @return The inputstream of the resource
* @throws IOException If there is a problem locating the resource
*/
protected URL findResource(String path) throws IOException {
return ClassLoaderUtil.getResource(path, getClass());
}
/**
* @param name resource name
* @param packagePrefix The package prefix to use to locate the resource
* @return full path
* @throws UnsupportedEncodingException
* @throws IOException
*/
protected String buildPath(String name, String packagePrefix) throws UnsupportedEncodingException {
String resourcePath;
if (packagePrefix.endsWith("/") && name.startsWith("/")) {
resourcePath = packagePrefix + name.substring(1);
} else {
resourcePath = packagePrefix + name;
}
return URLDecoder.decode(resourcePath, encoding);
}
/**
* Determine the content type for the resource name.
*
* @param name The resource name
* @return The mime type
*/
protected String getContentType(String name) {
// NOT using the code provided activation.jar to avoid adding yet another dependency
// this is generally OK, since these are the main files we server up
if (name.endsWith(".js")) {
return "text/javascript";
} else if (name.endsWith(".css")) {
return "text/css";
} else if (name.endsWith(".html")) {
return "text/html";
} else if (name.endsWith(".txt")) {
return "text/plain";
} else if (name.endsWith(".gif")) {
return "image/gif";
} else if (name.endsWith(".jpg") || name.endsWith(".jpeg")) {
return "image/jpeg";
} else if (name.endsWith(".png")) {
return "image/png";
} else {
return null;
}
}
/**
* Copy bytes from the input stream to the output stream.
*
* @param input
* The input stream
* @param output
* The output stream
* @throws IOException
* If anything goes wrong
*/
protected void copy(InputStream input, OutputStream output) throws IOException {
final byte[] buffer = new byte[4096];
int n;
while (-1 != (n = input.read(buffer))) {
output.write(buffer, 0, n);
}
output.flush();
}
public boolean canHandle(String resourcePath) {
return serveStatic && (resourcePath.startsWith("/struts") || resourcePath.startsWith("/static"));
}
/**
* @param path requested path
* @return path without leading "/struts" or "/static"
*/
protected String cleanupPath(String path) {
//path will start with "/struts" or "/static", remove them
return path.substring(7);
}
}
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