/*******************************************************************************
* Copyright (c) 2000, 2004 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.webdav.internal.kernel;
import java.io.IOException;
import java.io.StreamTokenizer;
import org.eclipse.webdav.IResponse;
/**
* An EntityTag is a ConditionFactor describing some state of a resource represented
* as an opaque string. See section 3.11 of the HTTP/1.1 spec.
*/
public class EntityTag extends ConditionFactor {
private static int bcnt = 0;
private static String basetime = Long.toHexString(new java.util.Date().getTime());
private String eTag = null;
// represents some state of a resource expressed as a ETag
private boolean weak = false;
/**
* Construct a EntityTag. Should never be called.
*/
private EntityTag() {
super();
}
/**
* Construct a EntityTag with the given opaque string tag.
*
* @param tag the opaque string defining the entity tag
*/
public EntityTag(String tag) {
this.eTag = tag;
}
/**
* Create an EntityTag by parsing the given If header as defined by
* section 3.11 of the HTTP/1.1 spec.
*
* @param tokenizer a StreamTokenizer on the contents of a WebDAV If header
* @return the parsed ConditionFactor (EntityTag)
* @exception WebDAVException thrown if there is a syntax error in the If header
*/
public static ConditionFactor create(StreamTokenizer tokenizer) throws WebDAVException {
EntityTag entityTag = new EntityTag();
try {
int token = tokenizer.ttype;
if (token == '[')
token = tokenizer.nextToken();
else
throw new WebDAVException(IResponse.SC_BAD_REQUEST, Policy.bind("error.parseMissing", String.valueOf(token), "[")); //$NON-NLS-1$ //$NON-NLS-2$
if (token == '"') { //$NON-NLS-1$
entityTag.setETag(tokenizer.sval);
token = tokenizer.nextToken();
} else
throw new WebDAVException(IResponse.SC_BAD_REQUEST, Policy.bind("error.parseMissingQuotedString", String.valueOf(token))); //$NON-NLS-1$
if (token == ']')
token = tokenizer.nextToken();
else
throw new WebDAVException(IResponse.SC_BAD_REQUEST, Policy.bind("error.parseMissing", String.valueOf(token), "]")); //$NON-NLS-1$ //$NON-NLS-2$
} catch (IOException exc) {
// ignore or log?
}
return entityTag;
}
/**
* Compare with another EntityTag.
*
* @param etag the entity tag to compare
* @return true if the tags are equal, false otherwise
*/
public boolean equals(Object etag) {
return etag != null && etag instanceof EntityTag && getETag().equals(((EntityTag) etag).getETag());
}
/**
* Construct a unique EntityTag. The tag is constructed by concatening the
* current time with the current thread's hash code.
*
* @return a unique entity tag that servers may use for any purpose
*/
public static EntityTag generateEntityTag() {
String xx = basetime + ":" + Integer.toHexString(Thread.currentThread().hashCode()); //$NON-NLS-1$
bcnt++;
xx += ":" + bcnt; //$NON-NLS-1$
return new EntityTag(xx);
}
/**
* Get the ETag of this EntityTag. The ETag represents some state of the
* resource in the containing Condition.
*
* @return the etag
*/
public String getETag() {
return eTag;
}
/**
* Is this a weak EntityTag?
*
* @return true if this is a weak entity tag
*/
public boolean isWeak() {
return weak;
}
/**
* Set the ETag of this EntityTag. The ETag represents some state of the
* resource in the containing Condition, for example, the lock token.
*
* @value the etag to set
*/
public void setETag(String value) {
eTag = value;
}
/**
* Set the strength of this EntityTag.
* value true indicates this is a weak entity tag
*/
public void setWeak(boolean value) {
weak = value;
}
/**
* Return a String representation of this EntityTag as defined by the If
* header in section 9.4 of the WebDAV spec.
*
* @return a string representation of this entity tag
*/
public String toString() {
StringBuffer buffer = new StringBuffer();
if (not())
buffer.append("Not "); //$NON-NLS-1$
if (isWeak())
buffer.append("W/"); //$NON-NLS-1$
buffer.append("[\""); //$NON-NLS-1$
buffer.append(getETag());
buffer.append("\"]"); //$NON-NLS-1$
return buffer.toString();
}
}
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