+ * DataInputStream is not necessarily safe for multithreaded access.
+ * Thread safety is optional and is the responsibility of users of
+ * methods in this class.
+ *
+ * @author Arthur van Hoff
+ * @see java.io.DataOutputStream
+ * @since JDK1.0
+ */
+public
+class DataInputStream extends FilterInputStream implements DataInput {
+
+ /**
+ * Creates a DataInputStream that uses the specified
+ * underlying InputStream.
+ *
+ * @param in the specified input stream
+ */
+ public DataInputStream(InputStream in) {
+ super(in);
+ }
+
+ /**
+ * working arrays initialized on demand by readUTF
+ */
+ private byte bytearr[] = new byte[80];
+ private char chararr[] = new char[80];
+
+ /**
+ * Reads some number of bytes from the contained input stream and
+ * stores them into the buffer array b. The number of
+ * bytes actually read is returned as an integer. This method blocks
+ * until input data is available, end of file is detected, or an
+ * exception is thrown.
+ *
+ *
If b is null, a NullPointerException is
+ * thrown. If the length of b is zero, then no bytes are
+ * read and 0 is returned; otherwise, there is an attempt
+ * to read at least one byte. If no byte is available because the
+ * stream is at end of file, the value -1 is returned;
+ * otherwise, at least one byte is read and stored into b.
+ *
+ *
The first byte read is stored into element b[0], the
+ * next one into b[1], and so on. The number of bytes read
+ * is, at most, equal to the length of b. Let k
+ * be the number of bytes actually read; these bytes will be stored in
+ * elements b[0] through b[k-1], leaving
+ * elements b[k] through b[b.length-1]
+ * unaffected.
+ *
+ *
The read(b) method has the same effect as:
+ *
+ * + * @param b the buffer into which the data is read. + * @return the total number of bytes read into the buffer, or + *+ * read(b, 0, b.length) + *
-1 if there is no more data because the end
+ * of the stream has been reached.
+ * @exception IOException if the first byte cannot be read for any reason
+ * other than end of file, the stream has been closed and the underlying
+ * input stream does not support reading after close, or another I/O
+ * error occurs.
+ * @see java.io.FilterInputStream#in
+ * @see java.io.InputStream#read(byte[], int, int)
+ */
+ public final int read(byte b[]) throws IOException {
+ return in.read(b, 0, b.length);
+ }
+
+ /**
+ * Reads up to len bytes of data from the contained
+ * input stream into an array of bytes. An attempt is made to read
+ * as many as len bytes, but a smaller number may be read,
+ * possibly zero. The number of bytes actually read is returned as an
+ * integer.
+ *
+ * This method blocks until input data is available, end of file is + * detected, or an exception is thrown. + * + *
If len is zero, then no bytes are read and
+ * 0 is returned; otherwise, there is an attempt to read at
+ * least one byte. If no byte is available because the stream is at end of
+ * file, the value -1 is returned; otherwise, at least one
+ * byte is read and stored into b.
+ *
+ *
The first byte read is stored into element b[off], the
+ * next one into b[off+1], and so on. The number of bytes read
+ * is, at most, equal to len. Let k be the number of
+ * bytes actually read; these bytes will be stored in elements
+ * b[off] through b[off+k-1],
+ * leaving elements b[off+k] through
+ * b[off+len-1] unaffected.
+ *
+ *
In every case, elements b[0] through
+ * b[off] and elements b[off+len] through
+ * b[b.length-1] are unaffected.
+ *
+ * @param b the buffer into which the data is read.
+ * @param off the start offset in the destination array b
+ * @param len the maximum number of bytes read.
+ * @return the total number of bytes read into the buffer, or
+ * -1 if there is no more data because the end
+ * of the stream has been reached.
+ * @exception NullPointerException If b is null.
+ * @exception IndexOutOfBoundsException If off is negative,
+ * len is negative, or len is greater than
+ * b.length - off
+ * @exception IOException if the first byte cannot be read for any reason
+ * other than end of file, the stream has been closed and the underlying
+ * input stream does not support reading after close, or another I/O
+ * error occurs.
+ * @see java.io.FilterInputStream#in
+ * @see java.io.InputStream#read(byte[], int, int)
+ */
+ public final int read(byte b[], int off, int len) throws IOException {
+ return in.read(b, off, len);
+ }
+
+ /**
+ * See the general contract of the readFully
+ * method of DataInput.
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @param b the buffer into which the data is read.
+ * @exception EOFException if this input stream reaches the end before
+ * reading all the bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final void readFully(byte b[]) throws IOException {
+ readFully(b, 0, b.length);
+ }
+
+ /**
+ * See the general contract of the readFully
+ * method of DataInput.
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @param b the buffer into which the data is read.
+ * @param off the start offset of the data.
+ * @param len the number of bytes to read.
+ * @exception EOFException if this input stream reaches the end before
+ * reading all the bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final void readFully(byte b[], int off, int len) throws IOException {
+ if (len < 0)
+ throw new IndexOutOfBoundsException();
+ int n = 0;
+ while (n < len) {
+ int count = in.read(b, off + n, len - n);
+ if (count < 0)
+ throw new EOFException();
+ n += count;
+ }
+ }
+
+ /**
+ * See the general contract of the skipBytes
+ * method of DataInput.
+ *
+ * Bytes for this operation are read from the contained
+ * input stream.
+ *
+ * @param n the number of bytes to be skipped.
+ * @return the actual number of bytes skipped.
+ * @exception IOException if the contained input stream does not support
+ * seek, or the stream has been closed and
+ * the contained input stream does not support
+ * reading after close, or another I/O error occurs.
+ */
+ public final int skipBytes(int n) throws IOException {
+ int total = 0;
+ int cur = 0;
+
+ while ((total
+ * Bytes for this operation are read from the contained
+ * input stream.
+ *
+ * @return the
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next byte of this input stream as a signed 8-bit
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next byte of this input stream, interpreted as an
+ * unsigned 8-bit number.
+ * @exception EOFException if this input stream has reached the end.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final int readUnsignedByte() throws IOException {
+ int ch = in.read();
+ if (ch < 0)
+ throw new EOFException();
+ return ch;
+ }
+
+ /**
+ * See the general contract of the
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next two bytes of this input stream, interpreted as a
+ * signed 16-bit number.
+ * @exception EOFException if this input stream reaches the end before
+ * reading two bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final short readShort() throws IOException {
+ int ch1 = in.read();
+ int ch2 = in.read();
+ if ((ch1 | ch2) < 0)
+ throw new EOFException();
+ return (short)((ch1 << 8) + (ch2 << 0));
+ }
+
+ /**
+ * See the general contract of the
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next two bytes of this input stream, interpreted as an
+ * unsigned 16-bit integer.
+ * @exception EOFException if this input stream reaches the end before
+ * reading two bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final int readUnsignedShort() throws IOException {
+ int ch1 = in.read();
+ int ch2 = in.read();
+ if ((ch1 | ch2) < 0)
+ throw new EOFException();
+ return (ch1 << 8) + (ch2 << 0);
+ }
+
+ /**
+ * See the general contract of the
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next two bytes of this input stream, interpreted as a
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next four bytes of this input stream, interpreted as an
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next eight bytes of this input stream, interpreted as a
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next four bytes of this input stream, interpreted as a
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return the next eight bytes of this input stream, interpreted as a
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @deprecated This method does not properly convert bytes to characters.
+ * As of JDK 1.1, the preferred way to read lines of text is via the
+ *
+ * Bytes
+ * for this operation are read from the contained
+ * input stream.
+ *
+ * @return a Unicode string.
+ * @exception EOFException if this input stream reaches the end before
+ * reading all the bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @exception UTFDataFormatException if the bytes do not represent a valid
+ * modified UTF-8 encoding of a string.
+ * @see java.io.DataInputStream#readUTF(java.io.DataInput)
+ */
+ public final String readUTF() throws IOException {
+ return readUTF(this);
+ }
+
+ /**
+ * Reads from the
+ * stream readBoolean
+ * method of DataInput.
+ * boolean value read.
+ * @exception EOFException if this input stream has reached the end.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final boolean readBoolean() throws IOException {
+ int ch = in.read();
+ if (ch < 0)
+ throw new EOFException();
+ return (ch != 0);
+ }
+
+ /**
+ * See the general contract of the readByte
+ * method of DataInput.
+ * byte.
+ * @exception EOFException if this input stream has reached the end.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final byte readByte() throws IOException {
+ int ch = in.read();
+ if (ch < 0)
+ throw new EOFException();
+ return (byte)(ch);
+ }
+
+ /**
+ * See the general contract of the readUnsignedByte
+ * method of DataInput.
+ * readShort
+ * method of DataInput.
+ * readUnsignedShort
+ * method of DataInput.
+ * readChar
+ * method of DataInput.
+ * char.
+ * @exception EOFException if this input stream reaches the end before
+ * reading two bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final char readChar() throws IOException {
+ int ch1 = in.read();
+ int ch2 = in.read();
+ if ((ch1 | ch2) < 0)
+ throw new EOFException();
+ return (char)((ch1 << 8) + (ch2 << 0));
+ }
+
+ /**
+ * See the general contract of the readInt
+ * method of DataInput.
+ * int.
+ * @exception EOFException if this input stream reaches the end before
+ * reading four bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final int readInt() throws IOException {
+ int ch1 = in.read();
+ int ch2 = in.read();
+ int ch3 = in.read();
+ int ch4 = in.read();
+ if ((ch1 | ch2 | ch3 | ch4) < 0)
+ throw new EOFException();
+ return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
+ }
+
+ private byte readBuffer[] = new byte[8];
+
+ /**
+ * See the general contract of the readLong
+ * method of DataInput.
+ * long.
+ * @exception EOFException if this input stream reaches the end before
+ * reading eight bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ public final long readLong() throws IOException {
+ readFully(readBuffer, 0, 8);
+ return (((long)readBuffer[0] << 56) +
+ ((long)(readBuffer[1] & 255) << 48) +
+ ((long)(readBuffer[2] & 255) << 40) +
+ ((long)(readBuffer[3] & 255) << 32) +
+ ((long)(readBuffer[4] & 255) << 24) +
+ ((readBuffer[5] & 255) << 16) +
+ ((readBuffer[6] & 255) << 8) +
+ ((readBuffer[7] & 255) << 0));
+ }
+
+ /**
+ * See the general contract of the readFloat
+ * method of DataInput.
+ * float.
+ * @exception EOFException if this input stream reaches the end before
+ * reading four bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.DataInputStream#readInt()
+ * @see java.lang.Float#intBitsToFloat(int)
+ */
+ public final float readFloat() throws IOException {
+ return Float.intBitsToFloat(readInt());
+ }
+
+ /**
+ * See the general contract of the readDouble
+ * method of DataInput.
+ * double.
+ * @exception EOFException if this input stream reaches the end before
+ * reading eight bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @see java.io.DataInputStream#readLong()
+ * @see java.lang.Double#longBitsToDouble(long)
+ */
+ public final double readDouble() throws IOException {
+ int hi = readInt();
+ int low = readInt();
+ return toDouble(hi, low);
+ }
+
+ @JavaScriptBody(args={ "hi", "low" },
+ body=
+ "if (low == 0) {\n"
+ + " if (hi === 0x7ff00000) return Number.POSITIVE_INFINITY;\n"
+ + " if (hi === 0xfff00000) return Number.NEGATIVE_INFINITY;\n"
+ + "}\n"
+ + "if (hi >= 0x7ff00000 && hi <= 0x7fffffff) return Number.NaN;\n"
+ + "if (hi >= 0xfff00000 && hi <= 0xffffffff) return Number.NaN;\n"
+ + "var s = (hi & 0x80000000) === 0 ? 1 : -1;\n"
+ + "var e = (hi >> 20) & 0x7ff;\n"
+ + "var to32 = low >> 0;\n"
+ + "if (e === 0) {\n"
+ + " if (to32 & 0x80000000) {\n"
+ + " hi = hi << 1 + 1; low = low << 1;\n"
+ + " } else {\n"
+ + " hi = hi << 1; low = low << 1;\n"
+ + " }\n"
+ + "} else {\n"
+ + " hi = (hi & 0xfffff) | 0x100000;\n"
+ + "}\n"
+ + "to32 = low >> 0;\n"
+ + "var m = Math.pow(2.0, 32) * hi + to32;\n"
+ + "var r = s * m * Math.pow(2.0, e - 1075);\n"
+ + "//throw 'exp: ' + e + ' sign: ' + s + ' hi:' + hi + ' low: ' + low + ' m: ' + m + ' r: ' + r;\n"
+ + "return r;\n"
+ )
+ private static double toDouble(int hi, int low) {
+ long both = hi;
+ both = (both << 32) & low;
+ return Double.doubleToLongBits(both);
+ }
+
+ private char lineBuffer[];
+
+ /**
+ * See the general contract of the readLine
+ * method of DataInput.
+ * BufferedReader.readLine() method. Programs that use the
+ * DataInputStream class to read lines can be converted to use
+ * the BufferedReader class by replacing code of the form:
+ *
+ * with:
+ *
+ * DataInputStream d = new DataInputStream(in);
+ *
+ *
+ * @return the next line of text from this input stream.
+ * @exception IOException if an I/O error occurs.
+ * @see java.io.BufferedReader#readLine()
+ * @see java.io.FilterInputStream#in
+ */
+ @Deprecated
+ public final String readLine() throws IOException {
+ char buf[] = lineBuffer;
+
+ if (buf == null) {
+ buf = lineBuffer = new char[128];
+ }
+
+ int room = buf.length;
+ int offset = 0;
+ int c;
+
+loop: while (true) {
+ switch (c = in.read()) {
+ case -1:
+ case '\n':
+ break loop;
+
+ case '\r':
+ int c2 = in.read();
+ if ((c2 != '\n') && (c2 != -1)) {
+ if (!(in instanceof PushbackInputStream)) {
+ this.in = new PushbackInputStream(in);
+ }
+ ((PushbackInputStream)in).unread(c2);
+ }
+ break loop;
+
+ default:
+ if (--room < 0) {
+ buf = new char[offset + 128];
+ room = buf.length - offset - 1;
+ arraycopy(lineBuffer, 0, buf, 0, offset);
+ lineBuffer = buf;
+ }
+ buf[offset++] = (char) c;
+ break;
+ }
+ }
+ if ((c == -1) && (offset == 0)) {
+ return null;
+ }
+ return String.copyValueOf(buf, 0, offset);
+ }
+
+ /**
+ * See the general contract of the
+ * BufferedReader d
+ * = new BufferedReader(new InputStreamReader(in));
+ *
readUTF
+ * method of DataInput.
+ * in a representation
+ * of a Unicode character string encoded in
+ * modified UTF-8 format;
+ * this string of characters is then returned as a String.
+ * The details of the modified UTF-8 representation
+ * are exactly the same as for the readUTF
+ * method of DataInput.
+ *
+ * @param in a data input stream.
+ * @return a Unicode string.
+ * @exception EOFException if the input stream reaches the end
+ * before all the bytes.
+ * @exception IOException the stream has been closed and the contained
+ * input stream does not support reading after close, or
+ * another I/O error occurs.
+ * @exception UTFDataFormatException if the bytes do not represent a
+ * valid modified UTF-8 encoding of a Unicode string.
+ * @see java.io.DataInputStream#readUnsignedShort()
+ */
+ public final static String readUTF(DataInput in) throws IOException {
+ int utflen = in.readUnsignedShort();
+ byte[] bytearr = null;
+ char[] chararr = null;
+ if (in instanceof DataInputStream) {
+ DataInputStream dis = (DataInputStream)in;
+ if (dis.bytearr.length < utflen){
+ dis.bytearr = new byte[utflen*2];
+ dis.chararr = new char[utflen*2];
+ }
+ chararr = dis.chararr;
+ bytearr = dis.bytearr;
+ } else {
+ bytearr = new byte[utflen];
+ chararr = new char[utflen];
+ }
+
+ int c, char2, char3;
+ int count = 0;
+ int chararr_count=0;
+
+ in.readFully(bytearr, 0, utflen);
+
+ while (count < utflen) {
+ c = (int) bytearr[count] & 0xff;
+ if (c > 127) break;
+ count++;
+ chararr[chararr_count++]=(char)c;
+ }
+
+ while (count < utflen) {
+ c = (int) bytearr[count] & 0xff;
+ switch (c >> 4) {
+ case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
+ /* 0xxxxxxx*/
+ count++;
+ chararr[chararr_count++]=(char)c;
+ break;
+ case 12: case 13:
+ /* 110x xxxx 10xx xxxx*/
+ count += 2;
+ if (count > utflen)
+ throw new UTFDataFormatException(
+ "malformed input: partial character at end");
+ char2 = (int) bytearr[count-1];
+ if ((char2 & 0xC0) != 0x80)
+ throw new UTFDataFormatException(
+ "malformed input around byte " + count);
+ chararr[chararr_count++]=(char)(((c & 0x1F) << 6) |
+ (char2 & 0x3F));
+ break;
+ case 14:
+ /* 1110 xxxx 10xx xxxx 10xx xxxx */
+ count += 3;
+ if (count > utflen)
+ throw new UTFDataFormatException(
+ "malformed input: partial character at end");
+ char2 = (int) bytearr[count-2];
+ char3 = (int) bytearr[count-1];
+ if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80))
+ throw new UTFDataFormatException(
+ "malformed input around byte " + (count-1));
+ chararr[chararr_count++]=(char)(((c & 0x0F) << 12) |
+ ((char2 & 0x3F) << 6) |
+ ((char3 & 0x3F) << 0));
+ break;
+ default:
+ /* 10xx xxxx, 1111 xxxx */
+ throw new UTFDataFormatException(
+ "malformed input around byte " + count);
+ }
+ }
+ // The number of chars produced may be less than utflen
+ return new String(chararr, 0, chararr_count);
+ }
+ static void arraycopy(char[] value, int srcBegin, char[] dst, int dstBegin, int count) {
+ while (count-- > 0) {
+ dst[dstBegin++] = value[srcBegin++];
+ }
+ }
+}