org.apache.pdfbox.cos.COSString Maven / Gradle / Ivy
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/*
* 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.pdfbox.cos;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Arrays;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pdfbox.util.Charsets;
import org.apache.pdfbox.util.Hex;
/**
* A string object, which may be a text string, a PDFDocEncoded string, ASCII string, or byte string.
*
* Text strings are used for character strings that contain information intended to be
* human-readable, such as text annotations, bookmark names, article names, document information,
* and so forth.
*
*
PDFDocEncoded strings are used for characters that are represented in a single byte.
*
*
ASCII strings are used for characters that are represented in a single byte using ASCII
* encoding.
*
*
Byte strings are used for binary data represented as a series of bytes, but the encoding is
* not known. The bytes of the string need not represent characters.
*
* @author Ben Litchfield
* @author John Hewson
*/
public final class COSString extends COSBase
{
private static final Log LOG = LogFactory.getLog(COSString.class);
// legacy behaviour for old PDFParser
public static final boolean FORCE_PARSING =
Boolean.getBoolean("org.apache.pdfbox.forceParsing");
/**
* This will create a COS string from a string of hex characters.
*
* @param hex A hex string.
* @return A cos string with the hex characters converted to their actual bytes.
* @throws IOException If there is an error with the hex string.
*/
public static COSString parseHex(String hex) throws IOException
{
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
StringBuilder hexBuffer = new StringBuilder(hex.trim());
// if odd number then the last hex digit is assumed to be 0
if (hexBuffer.length() % 2 != 0)
{
hexBuffer.append('0');
}
int length = hexBuffer.length();
for (int i = 0; i < length; i += 2)
{
try
{
bytes.write(Integer.parseInt(hexBuffer.substring(i, i + 2), 16));
}
catch (NumberFormatException e)
{
if (FORCE_PARSING)
{
LOG.warn("Encountered a malformed hex string");
bytes.write('?'); // todo: what does Acrobat do? Any example PDFs?
}
else
{
throw new IOException("Invalid hex string: " + hex, e);
}
}
}
return new COSString(bytes.toByteArray());
}
private byte[] bytes;
private boolean forceHexForm;
/**
* Creates a new PDF string from a byte array. This method can be used to read a string from
* an existing PDF file, or to create a new byte string.
*
* @param bytes The raw bytes of the PDF text string or byte string.
*/
public COSString(byte[] bytes)
{
setValue(bytes);
}
/**
* Creates a new text string from a Java String.
*
* @param text The string value of the object.
*/
public COSString(String text)
{
// check whether the string uses only characters available in PDFDocEncoding
boolean isOnlyPDFDocEncoding = true;
for (char c : text.toCharArray())
{
if (!PDFDocEncoding.containsChar(c))
{
isOnlyPDFDocEncoding = false;
break;
}
}
if (isOnlyPDFDocEncoding)
{
// PDFDocEncoded string
bytes = PDFDocEncoding.getBytes(text);
}
else
{
// UTF-16BE encoded string with a leading byte order marker
byte[] data = text.getBytes(Charsets.UTF_16BE);
ByteArrayOutputStream out = new ByteArrayOutputStream(data.length + 2);
out.write(0xFE); // BOM
out.write(0xFF); // BOM
try
{
out.write(data);
}
catch (IOException e)
{
// should never happen
throw new RuntimeException(e);
}
bytes = out.toByteArray();
}
}
/**
* Sets the raw value of this string.
*
* @param value The raw bytes of the PDF text string or byte string.
*/
public void setValue(byte[] value)
{
bytes = value.clone();
}
/**
* Sets whether or not to force the string is to be written in hex form.
* This is needed when signing PDF files.
*
* @param value True to force hex.
*/
public void setForceHexForm(boolean value)
{
this.forceHexForm = value;
}
/**
* Returns true if the string is to be written in hex form.
*
* @return the hex representation of this string.
*/
public boolean getForceHexForm()
{
return forceHexForm;
}
/**
* Returns the content of this string as a PDF text string.
*
* @return the string representation of this string using the given encoding.
*/
public String getString()
{
// text string - BOM indicates Unicode
if (bytes.length >= 2)
{
if ((bytes[0] & 0xff) == 0xFE && (bytes[1] & 0xff) == 0xFF)
{
// UTF-16BE
return new String(bytes, 2, bytes.length - 2, Charsets.UTF_16BE);
}
else if ((bytes[0] & 0xff) == 0xFF && (bytes[1] & 0xff) == 0xFE)
{
// UTF-16LE - not in the PDF spec!
return new String(bytes, 2, bytes.length - 2, Charsets.UTF_16LE);
}
}
// otherwise use PDFDocEncoding
return PDFDocEncoding.toString(bytes);
}
/**
* Returns the content of this string as a PDF ASCII string.
*
* @return the ASCII representation of this string.
*/
public String getASCII()
{
// ASCII string
return new String(bytes, Charsets.US_ASCII);
}
/**
* Returns the raw bytes of the string. Best used with a PDF byte string.
*
* @return the raw bytes of this string.
*/
public byte[] getBytes()
{
return bytes;
}
/**
* This will take this string and create a hex representation of the bytes that make the string.
*
* @return A hex string representing the bytes in this string.
*/
public String toHexString()
{
return Hex.getString(bytes);
}
/**
* Visitor pattern double dispatch method.
*
* @param visitor The object to notify when visiting this object.
* @return any object, depending on the visitor implementation, or null
* @throws IOException If an error occurs while visiting this object.
*/
@Override
public Object accept(ICOSVisitor visitor) throws IOException
{
return visitor.visitFromString(this);
}
@Override
public boolean equals(Object obj)
{
if (obj instanceof COSString)
{
COSString strObj = (COSString) obj;
return getString().equals(strObj.getString()) &&
forceHexForm == strObj.forceHexForm;
}
return false;
}
@Override
public int hashCode()
{
int result = Arrays.hashCode(bytes);
return result + (forceHexForm ? 17 : 0);
}
@Override
public String toString()
{
return "COSString{" + getString() + "}";
}
}