Java CharsetEncoder.maxBytesPerChar方法代碼示例

import java.nio.charset.CharsetEncoder; //導入方法依賴的package包/類
protected final void setEncoding(final String encoding)
throws UnsupportedEncodingException {

    final Charset charSet = charsetForName(encoding);
    final CharsetEncoder encoder = charSet.newEncoder().onMalformedInput(
        CodingErrorAction.REPLACE).onUnmappableCharacter(
        CodingErrorAction.REPLACE);
    final float maxBytesPerChar     = encoder.maxBytesPerChar();
    final float averageBytesPerChar = encoder.averageBytesPerChar();
    final boolean fixedWidthCharset =
        (maxBytesPerChar == Math.round(maxBytesPerChar))
        && (maxBytesPerChar == averageBytesPerChar);

    //
    m_fixedWidthCharset = fixedWidthCharset;
    m_maxCharWidth      = Math.round(maxBytesPerChar);
    m_charset           = charSet;
    m_encoder           = encoder;
    m_encoding          = m_charset.name();
}
 

import java.nio.charset.CharsetEncoder; //導入方法依賴的package包/類
byte[] getBytes(String s) {
    CharsetEncoder ce = encoder().reset();
    char[] ca = s.toCharArray();
    int len = (int)(ca.length * ce.maxBytesPerChar());
    byte[] ba = new byte[len];
    if (len == 0)
        return ba;
    ByteBuffer bb = ByteBuffer.wrap(ba);
    CharBuffer cb = CharBuffer.wrap(ca);
    CoderResult cr = ce.encode(cb, bb, true);
    if (!cr.isUnderflow())
        throw new IllegalArgumentException(cr.toString());
    cr = ce.flush(bb);
    if (!cr.isUnderflow())
        throw new IllegalArgumentException(cr.toString());
    if (bb.position() == ba.length)  // defensive copy?
        return ba;
    else
        return Arrays.copyOf(ba, bb.position());
}
 

import java.nio.charset.CharsetEncoder; //導入方法依賴的package包/類
byte[] getBytes(String s) {
    CharsetEncoder ce = encoder().reset();
    char[] ca = s.toCharArray();
    int len = (int)(ca.length * ce.maxBytesPerChar());
    byte[] ba = new byte[len];
    if (len == 0)
        return ba;
    // UTF-8 only for now. Other ArrayDeocder only handles
    // CodingErrorAction.REPLACE mode.
    if (isUTF8 && ce instanceof ArrayEncoder) {
        int blen = ((ArrayEncoder)ce).encode(ca, 0, ca.length, ba);
        if (blen == -1)    // malformed
            throw new IllegalArgumentException("MALFORMED");
        return Arrays.copyOf(ba, blen);
    }
    ByteBuffer bb = ByteBuffer.wrap(ba);
    CharBuffer cb = CharBuffer.wrap(ca);
    CoderResult cr = ce.encode(cb, bb, true);
    if (!cr.isUnderflow())
        throw new IllegalArgumentException(cr.toString());
    cr = ce.flush(bb);
    if (!cr.isUnderflow())
        throw new IllegalArgumentException(cr.toString());
    if (bb.position() == ba.length)  // defensive copy?
        return ba;
    else
        return Arrays.copyOf(ba, bb.position());
}
 

import java.nio.charset.CharsetEncoder; //導入方法依賴的package包/類
/**
 * 指定したバイト數で文字列をカットする
 *
 * @param obj 対象オブジェクト
 * @param capacity カットするバイト數
 * @return String
 * @throws CharacterCodingException
 * @throws UnsupportedEncodingException
 */
private String getSubstringByte(final Object obj, final int capacity) throws CharacterCodingException,
		UnsupportedEncodingException {

	String str = obj == null ? "null" : obj.toString();
	if (capacity < 1) {
		return str;
	}

	CharsetEncoder ce = Charset.forName(ENCODING_SHIFT_JIS).newEncoder()
			.onMalformedInput(CodingErrorAction.REPLACE).onUnmappableCharacter(CodingErrorAction.REPLACE).reset();
	if (capacity >= ce.maxBytesPerChar() * str.length()) {
		return str;
	}
	CharBuffer cb = CharBuffer.wrap(new char[Math.min(str.length(), capacity)]);
	str.getChars(0, Math.min(str.length(), cb.length()), cb.array(), 0);

	if (capacity >= ce.maxBytesPerChar() * cb.limit()) {
		return cb.toString();
	}
	ByteBuffer out = ByteBuffer.allocate(capacity);
	ce.reset();
	CoderResult cr = null;
	if (cb.hasRemaining()) {
		cr = ce.encode(cb, out, true);
	} else {
		cr = CoderResult.UNDERFLOW;
	}
	if (cr.isUnderflow()) {
		cr = ce.flush(out);
	}
	return cb.flip().toString();
}
 

import java.nio.charset.CharsetEncoder; //導入方法依賴的package包/類
protected MockCharsetEncoder(Charset cs, CharsetEncoder raw){
    super(cs, raw.averageBytesPerChar(), raw.maxBytesPerChar());
    this.raw = raw;
}
 

import java.nio.charset.CharsetEncoder; //導入方法依賴的package包/類
private ProxyEncoder (final CharsetEncoder defaultEncoder) {
    super (ProxyCharset.this, defaultEncoder.averageBytesPerChar(), defaultEncoder.maxBytesPerChar(), defaultEncoder.replacement());
    this.currentEncoder = defaultEncoder;
    this.initialized = true;
}
 

import java.nio.charset.CharsetEncoder; //導入方法依賴的package包/類
/**
 * Creates a ReversedLinesFileReader with the given block size and encoding.
 *
 * @param file
 *            the file to be read
 * @param blockSize
 *            size of the internal buffer (for ideal performance this should
 *            match with the block size of the underlying file system).
 * @param encoding
 *            the encoding of the file
 * @throws IOException  if an I/O error occurs
 * @since 2.3
 */
public ReversedLinesFileReader(final File file, final int blockSize, final Charset encoding) throws IOException {
    this.blockSize = blockSize;
    this.encoding = encoding;

    randomAccessFile = new RandomAccessFile(file, "r");
    totalByteLength = randomAccessFile.length();
    int lastBlockLength = (int) (totalByteLength % blockSize);
    if (lastBlockLength > 0) {
        totalBlockCount = totalByteLength / blockSize + 1;
    } else {
        totalBlockCount = totalByteLength / blockSize;
        if (totalByteLength > 0) {
            lastBlockLength = blockSize;
        }
    }
    currentFilePart = new FilePart(totalBlockCount, lastBlockLength, null);

    // --- check & prepare encoding ---
    Charset charset = Charsets.toCharset(encoding);
    CharsetEncoder charsetEncoder = charset.newEncoder();
    float maxBytesPerChar = charsetEncoder.maxBytesPerChar();
    if(maxBytesPerChar==1f) {
        // all one byte encodings are no problem
        byteDecrement = 1;
    } else if(charset == Charset.forName("UTF-8")) {
        // UTF-8 works fine out of the box, for multibyte sequences a second UTF-8 byte can never be a newline byte
        // http://en.wikipedia.org/wiki/UTF-8
        byteDecrement = 1;
    } else if(charset == Charset.forName("Shift_JIS")) {
        // Same as for UTF-8
        // http://www.herongyang.com/Unicode/JIS-Shift-JIS-Encoding.html
        byteDecrement = 1;
    } else if(charset == Charset.forName("UTF-16BE") || charset == Charset.forName("UTF-16LE")) {
        // UTF-16 new line sequences are not allowed as second tuple of four byte sequences,
        // however byte order has to be specified
        byteDecrement = 2;
    } else if(charset == Charset.forName("UTF-16")) {
        throw new UnsupportedEncodingException(
                "For UTF-16, you need to specify the byte order (use UTF-16BE or UTF-16LE)");
    } else {
        throw new UnsupportedEncodingException(
                "Encoding "+encoding+" is not supported yet (feel free to submit a patch)");
    }
    // NOTE: The new line sequences are matched in the order given, so it is important that \r\n is BEFORE \n
    newLineSequences = new byte[][] { "\r\n".getBytes(encoding), "\n".getBytes(encoding), "\r".getBytes(encoding) };

    avoidNewlineSplitBufferSize = newLineSequences[0].length;
}
 

import java.nio.charset.CharsetEncoder; //導入方法依賴的package包/類
/**
 * Creates a ReversedLinesFileReader with the given block size and encoding.
 *
 * @param file
 *            the file to be read
 * @param blockSize
 *            size of the internal buffer (for ideal performance this should
 *            match with the block size of the underlying file system).
 * @param encoding
 *            the encoding of the file
 * @throws IOException  if an I/O error occurs
 * @since 2.3
 */
@SuppressWarnings("deprecation") // unavoidable until Java 7
public ReversedLinesFileReader(final File file, final int blockSize, final Charset encoding) throws IOException {
    this.blockSize = blockSize;
    this.encoding = encoding;

    // --- check & prepare encoding ---
    final Charset charset = Charsets.toCharset(encoding);
    final CharsetEncoder charsetEncoder = charset.newEncoder();
    final float maxBytesPerChar = charsetEncoder.maxBytesPerChar();
    if (maxBytesPerChar == 1f) {
        // all one byte encodings are no problem
        byteDecrement = 1;
    } else if (charset == Charsets.UTF_8) {
        // UTF-8 works fine out of the box, for multibyte sequences a second UTF-8 byte can never be a newline byte
        // http://en.wikipedia.org/wiki/UTF-8
        byteDecrement = 1;
    } else if(charset == Charset.forName("Shift_JIS") || // Same as for UTF-8
            // http://www.herongyang.com/Unicode/JIS-Shift-JIS-Encoding.html
            charset == Charset.forName("windows-31j") || // Windows code page 932 (Japanese)
            charset == Charset.forName("x-windows-949") || // Windows code page 949 (Korean)
            charset == Charset.forName("gbk") || // Windows code page 936 (Simplified Chinese)
            charset == Charset.forName("x-windows-950")) { // Windows code page 950 (Traditional Chinese)
        byteDecrement = 1;
    } else if (charset == Charsets.UTF_16BE || charset == Charsets.UTF_16LE) {
        // UTF-16 new line sequences are not allowed as second tuple of four byte sequences,
        // however byte order has to be specified
        byteDecrement = 2;
    } else if (charset == Charsets.UTF_16) {
        throw new UnsupportedEncodingException("For UTF-16, you need to specify the byte order (use UTF-16BE or " +
                "UTF-16LE)");
    } else {
        throw new UnsupportedEncodingException("Encoding " + encoding + " is not supported yet (feel free to " +
                "submit a patch)");
    }

    // NOTE: The new line sequences are matched in the order given, so it is important that \r\n is BEFORE \n
    newLineSequences = new byte[][] { "\r\n".getBytes(encoding), "\n".getBytes(encoding), "\r".getBytes(encoding) };

    avoidNewlineSplitBufferSize = newLineSequences[0].length;

    // Open file
    randomAccessFile = new RandomAccessFile(file, "r");
    totalByteLength = randomAccessFile.length();
    int lastBlockLength = (int) (totalByteLength % blockSize);
    if (lastBlockLength > 0) {
        totalBlockCount = totalByteLength / blockSize + 1;
    } else {
        totalBlockCount = totalByteLength / blockSize;
        if (totalByteLength > 0) {
            lastBlockLength = blockSize;
        }
    }
    currentFilePart = new FilePart(totalBlockCount, lastBlockLength, null);

}