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International Component for Unicode for Java (ICU4J) is a mature, widely used Java library providing Unicode and Globalization support

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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/**
*******************************************************************************
* Copyright (C) 2005-2016, International Business Machines Corporation and    *
* others. All Rights Reserved.                                                *
*******************************************************************************
*/
package com.ibm.icu.text;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;


/**
 * This class represents a charset that has been identified by a CharsetDetector
 * as a possible encoding for a set of input data.  From an instance of this
 * class, you can ask for a confidence level in the charset identification,
 * or for Java Reader or String to access the original byte data in Unicode form.
 * 

* Instances of this class are created only by CharsetDetectors. *

* Note: this class has a natural ordering that is inconsistent with equals. * The natural ordering is based on the match confidence value. * * @stable ICU 3.4 */ public class CharsetMatch implements Comparable { /** * Create a java.io.Reader for reading the Unicode character data corresponding * to the original byte data supplied to the Charset detect operation. *

* CAUTION: if the source of the byte data was an InputStream, a Reader * can be created for only one matching char set using this method. If more * than one charset needs to be tried, the caller will need to reset * the InputStream and create InputStreamReaders itself, based on the charset name. * * @return the Reader for the Unicode character data. * * @stable ICU 3.4 */ public Reader getReader() { InputStream inputStream = fInputStream; if (inputStream == null) { inputStream = new ByteArrayInputStream(fRawInput, 0, fRawLength); } try { inputStream.reset(); return new InputStreamReader(inputStream, getName()); } catch (IOException e) { return null; } } /** * Create a Java String from Unicode character data corresponding * to the original byte data supplied to the Charset detect operation. * * @return a String created from the converted input data. * * @stable ICU 3.4 */ public String getString() throws java.io.IOException { return getString(-1); } /** * Create a Java String from Unicode character data corresponding * to the original byte data supplied to the Charset detect operation. * The length of the returned string is limited to the specified size; * the string will be trunctated to this length if necessary. A limit value of * zero or less is ignored, and treated as no limit. * * @param maxLength The maximum length of the String to be created when the * source of the data is an input stream, or -1 for * unlimited length. * @return a String created from the converted input data. * * @stable ICU 3.4 */ public String getString(int maxLength) throws java.io.IOException { String result = null; if (fInputStream != null) { StringBuilder sb = new StringBuilder(); char[] buffer = new char[1024]; Reader reader = getReader(); int max = maxLength < 0? Integer.MAX_VALUE : maxLength; int bytesRead = 0; while ((bytesRead = reader.read(buffer, 0, Math.min(max, 1024))) >= 0) { sb.append(buffer, 0, bytesRead); max -= bytesRead; } reader.close(); return sb.toString(); } else { String name = getName(); /* * getName() may return a name with a suffix 'rtl' or 'ltr'. This cannot * be used to open a charset (e.g. IBM424_rtl). The ending '_rtl' or 'ltr' * should be stripped off before creating the string. */ int startSuffix = name.indexOf("_rtl") < 0 ? name.indexOf("_ltr") : name.indexOf("_rtl"); if (startSuffix > 0) { name = name.substring(0, startSuffix); } result = new String(fRawInput, name); } return result; } /** * Get an indication of the confidence in the charset detected. * Confidence values range from 0-100, with larger numbers indicating * a better match of the input data to the characteristics of the * charset. * * @return the confidence in the charset match * * @stable ICU 3.4 */ public int getConfidence() { return fConfidence; } /** * Get the name of the detected charset. * The name will be one that can be used with other APIs on the * platform that accept charset names. It is the "Canonical name" * as defined by the class java.nio.charset.Charset; for * charsets that are registered with the IANA charset registry, * this is the MIME-preferred registerd name. * * @see java.nio.charset.Charset * @see java.io.InputStreamReader * * @return The name of the charset. * * @stable ICU 3.4 */ public String getName() { return fCharsetName; } /** * Get the ISO code for the language of the detected charset. * * @return The ISO code for the language or null if the language cannot be determined. * * @stable ICU 3.4 */ public String getLanguage() { return fLang; } /** * Compare to other CharsetMatch objects. * Comparison is based on the match confidence value, which * allows CharsetDetector.detectAll() to order its results. * * @param other the CharsetMatch object to compare against. * @return a negative integer, zero, or a positive integer as the * confidence level of this CharsetMatch * is less than, equal to, or greater than that of * the argument. * @throws ClassCastException if the argument is not a CharsetMatch. * @stable ICU 4.4 */ @Override public int compareTo (CharsetMatch other) { int compareResult = 0; if (this.fConfidence > other.fConfidence) { compareResult = 1; } else if (this.fConfidence < other.fConfidence) { compareResult = -1; } return compareResult; } /* * Constructor. Implementation internal */ CharsetMatch(CharsetDetector det, CharsetRecognizer rec, int conf) { fConfidence = conf; // The references to the original application input data must be copied out // of the charset recognizer to here, in case the application resets the // recognizer before using this CharsetMatch. if (det.fInputStream == null) { // We only want the existing input byte data if it came straight from the user, // not if is just the head of a stream. fRawInput = det.fRawInput; fRawLength = det.fRawLength; } fInputStream = det.fInputStream; fCharsetName = rec.getName(); fLang = rec.getLanguage(); } /* * Constructor. Implementation internal */ CharsetMatch(CharsetDetector det, CharsetRecognizer rec, int conf, String csName, String lang) { fConfidence = conf; // The references to the original application input data must be copied out // of the charset recognizer to here, in case the application resets the // recognizer before using this CharsetMatch. if (det.fInputStream == null) { // We only want the existing input byte data if it came straight from the user, // not if is just the head of a stream. fRawInput = det.fRawInput; fRawLength = det.fRawLength; } fInputStream = det.fInputStream; fCharsetName = csName; fLang = lang; } // // Private Data // private int fConfidence; private byte[] fRawInput = null; // Original, untouched input bytes. // If user gave us a byte array, this is it. private int fRawLength; // Length of data in fRawInput array. private InputStream fInputStream = null; // User's input stream, or null if the user // gave us a byte array. private String fCharsetName; // The name of the charset this CharsetMatch // represents. Filled in by the recognizer. private String fLang; // The language, if one was determined by // the recognizer during the detect operation. }





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