/**
* 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.nutch.protocol.file;
import java.net.URL;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.nutch.crawl.CrawlDatum;
import org.apache.nutch.net.protocols.Response;
import org.apache.nutch.protocol.Content;
import org.apache.nutch.protocol.Protocol;
import org.apache.nutch.protocol.ProtocolOutput;
import org.apache.nutch.protocol.ProtocolStatus;
import org.apache.nutch.protocol.RobotRulesParser;
import org.apache.nutch.util.NutchConfiguration;
import crawlercommons.robots.BaseRobotRules;
/**
* This class is a protocol plugin used for file: scheme.
* It creates {@link FileResponse} object and gets the content of the url from it.
* Configurable parameters are {@code file.content.limit} and {@code file.crawl.parent}
* in nutch-default.xml defined under "file properties" section.
*
* @author John Xing
*/
public class File implements Protocol {
public static final Logger LOG = LoggerFactory.getLogger(File.class);
static final int MAX_REDIRECTS = 5;
int maxContentLength;
boolean crawlParents;
private Configuration conf;
public File() {}
/**
* Set the {@link Configuration} object
*/
public void setConf(Configuration conf) {
this.conf = conf;
this.maxContentLength = conf.getInt("file.content.limit", 64 * 1024);
this.crawlParents = conf.getBoolean("file.crawl.parent", true);
}
/**
* Get the {@link Configuration} object
*/
public Configuration getConf() {
return this.conf;
}
/**
* Set the length after at which content is truncated.
*/
public void setMaxContentLength(int maxContentLength) {
this.maxContentLength = maxContentLength;
}
/**
* Creates a {@link FileResponse} object corresponding to the url and
* return a {@link ProtocolOutput} object as per the content received
*
* @param url Text containing the url
* @param datum The CrawlDatum object corresponding to the url
*
* @return {@link ProtocolOutput} object for the content of the file indicated by url
*/
public ProtocolOutput getProtocolOutput(Text url, CrawlDatum datum) {
String urlString = url.toString();
try {
URL u = new URL(urlString);
int redirects = 0;
while (true) {
FileResponse response;
response = new FileResponse(u, datum, this, getConf()); // make a request
int code = response.getCode();
if (code == 200) { // got a good response
return new ProtocolOutput(response.toContent()); // return it
} else if (code == 304) { // got not modified
return new ProtocolOutput(response.toContent(), ProtocolStatus.STATUS_NOTMODIFIED);
} else if (code == 401) { // access denied / no read permissions
return new ProtocolOutput(response.toContent(), new ProtocolStatus(ProtocolStatus.ACCESS_DENIED));
} else if (code == 404) { // no such file
return new ProtocolOutput(response.toContent(), ProtocolStatus.STATUS_NOTFOUND);
} else if (code >= 300 && code < 400) { // handle redirect
if (redirects == MAX_REDIRECTS)
throw new FileException("Too many redirects: " + url);
u = new URL(response.getHeader("Location"));
redirects++;
if (LOG.isTraceEnabled()) {
LOG.trace("redirect to " + u);
}
} else { // convert to exception
throw new FileError(code);
}
}
} catch (Exception e) {
e.printStackTrace();
return new ProtocolOutput(null, new ProtocolStatus(e));
}
}
/**
* Quick way for running this class. Useful for debugging.
*/
public static void main(String[] args) throws Exception {
int maxContentLength = Integer.MIN_VALUE;
String logLevel = "info";
boolean dumpContent = false;
String urlString = null;
String usage = "Usage: File [-logLevel level] [-maxContentLength L] [-dumpContent] url";
if (args.length == 0) {
System.err.println(usage);
System.exit(-1);
}
for (int i = 0; i < args.length; i++) {
if (args[i].equals("-logLevel")) {
logLevel = args[++i];
} else if (args[i].equals("-maxContentLength")) {
maxContentLength = Integer.parseInt(args[++i]);
} else if (args[i].equals("-dumpContent")) {
dumpContent = true;
} else if (i != args.length-1) {
System.err.println(usage);
System.exit(-1);
} else
urlString = args[i];
}
File file = new File();
file.setConf(NutchConfiguration.create());
if (maxContentLength != Integer.MIN_VALUE) // set maxContentLength
file.setMaxContentLength(maxContentLength);
// set log level
//LOG.setLevel(Level.parse((new String(logLevel)).toUpperCase()));
Content content = file.getProtocolOutput(new Text(urlString), new CrawlDatum()).getContent();
System.err.println("Content-Type: " + content.getContentType());
System.err.println("Content-Length: " +
content.getMetadata().get(Response.CONTENT_LENGTH));
System.err.println("Last-Modified: " +
content.getMetadata().get(Response.LAST_MODIFIED));
if (dumpContent) {
System.out.print(new String(content.getContent()));
}
file = null;
}
/**
* No robots parsing is done for file protocol.
* So this returns a set of empty rules which will allow every url.
*/
public BaseRobotRules getRobotRules(Text url, CrawlDatum datum) {
return RobotRulesParser.EMPTY_RULES;
}
}