/*
* Copyright (c) 1994, 2006, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
*
*
*
*
*
*
*
*
*
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*
*
*
*
*
*
*/
package java.io;
/**
* A data input stream lets an application read primitive Java data
* types from an underlying input stream in a machine-independent
* way. An application uses a data output stream to write data that
* can later be read by a data input stream.
* <p>
* 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 <code>b</code>. 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.
*
* <p>If <code>b</code> is null, a <code>NullPointerException</code> is
* thrown. If the length of <code>b</code> is zero, then no bytes are
* read and <code>0</code> 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 <code>-1</code> is returned;
* otherwise, at least one byte is read and stored into <code>b</code>.
*
* <p>The first byte read is stored into element <code>b[0]</code>, the
* next one into <code>b[1]</code>, and so on. The number of bytes read
* is, at most, equal to the length of <code>b</code>. Let <code>k</code>
* be the number of bytes actually read; these bytes will be stored in
* elements <code>b[0]</code> through <code>b[k-1]</code>, leaving
* elements <code>b[k]</code> through <code>b[b.length-1]</code>
* unaffected.
*
* <p>The <code>read(b)</code> method has the same effect as:
* <blockquote><pre>
* read(b, 0, b.length)
* </pre></blockquote>
*
* @param b the buffer into which the data is read.
* @return the total number of bytes read into the buffer, or
* <code>-1</code> 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 <code>len</code> bytes of data from the contained
* input stream into an array of bytes. An attempt is made to read
* as many as <code>len</code> bytes, but a smaller number may be read,
* possibly zero. The number of bytes actually read is returned as an
* integer.
*
* <p> This method blocks until input data is available, end of file is
* detected, or an exception is thrown.
*
* <p> If <code>len</code> is zero, then no bytes are read and
* <code>0</code> 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 <code>-1</code> is returned; otherwise, at least one
* byte is read and stored into <code>b</code>.
*
* <p> The first byte read is stored into element <code>b[off]</code>, the
* next one into <code>b[off+1]</code>, and so on. The number of bytes read
* is, at most, equal to <code>len</code>. Let <i>k</i> be the number of
* bytes actually read; these bytes will be stored in elements
* <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>,
* leaving elements <code>b[off+</code><i>k</i><code>]</code> through
* <code>b[off+len-1]</code> unaffected.
*
* <p> In every case, elements <code>b[0]</code> through
* <code>b[off]</code> and elements <code>b[off+len]</code> through
* <code>b[b.length-1]</code> are unaffected.
*
* @param b the buffer into which the data is read.
* @param off the start offset in the destination array <code>b</code>
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* <code>-1</code> if there is no more data because the end
* of the stream has been reached.
* @exception NullPointerException If <code>b</code> is <code>null</code>.
* @exception IndexOutOfBoundsException If <code>off</code> is negative,
* <code>len</code> is negative, or <code>len</code> is greater than
* <code>b.length - off</code>
* @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 <code>readFully</code>
* method of <code>DataInput</code>.
* <p>
* 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 <code>readFully</code>
* method of <code>DataInput</code>.
* <p>
* 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 <code>skipBytes</code>
* method of <code>DataInput</code>.
* <p>
* 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<
n) && ((
cur = (int)
in.
skip(
n-
total)) > 0)) {
total +=
cur;
}
return
total;
}
/**
* See the general contract of the <code>readBoolean</code>
* method of <code>DataInput</code>.
* <p>
* Bytes for this operation are read from the contained
* input stream.
*
* @return the <code>boolean</code> 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 <code>readByte</code>
* method of <code>DataInput</code>.
* <p>
* Bytes
* for this operation are read from the contained
* input stream.
*
* @return the next byte of this input stream as a signed 8-bit
* <code>byte</code>.
* @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 <code>readUnsignedByte</code>
* method of <code>DataInput</code>.
* <p>
* 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 <code>readShort</code>
* method of <code>DataInput</code>.
* <p>
* 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 <code>readUnsignedShort</code>
* method of <code>DataInput</code>.
* <p>
* 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 <code>readChar</code>
* method of <code>DataInput</code>.
* <p>
* Bytes
* for this operation are read from the contained
* input stream.
*
* @return the next two bytes of this input stream, interpreted as a
* <code>char</code>.
* @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 <code>readInt</code>
* method of <code>DataInput</code>.
* <p>
* Bytes
* for this operation are read from the contained
* input stream.
*
* @return the next four bytes of this input stream, interpreted as an
* <code>int</code>.
* @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 <code>readLong</code>
* method of <code>DataInput</code>.
* <p>
* Bytes
* for this operation are read from the contained
* input stream.
*
* @return the next eight bytes of this input stream, interpreted as a
* <code>long</code>.
* @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 <code>readFloat</code>
* method of <code>DataInput</code>.
* <p>
* Bytes
* for this operation are read from the contained
* input stream.
*
* @return the next four bytes of this input stream, interpreted as a
* <code>float</code>.
* @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 <code>readDouble</code>
* method of <code>DataInput</code>.
* <p>
* Bytes
* for this operation are read from the contained
* input stream.
*
* @return the next eight bytes of this input stream, interpreted as a
* <code>double</code>.
* @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 {
return
Double.
longBitsToDouble(
readLong());
}
private char
lineBuffer[];
/**
* See the general contract of the <code>readLine</code>
* method of <code>DataInput</code>.
* <p>
* 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
* <code>BufferedReader.readLine()</code> method. Programs that use the
* <code>DataInputStream</code> class to read lines can be converted to use
* the <code>BufferedReader</code> class by replacing code of the form:
* <blockquote><pre>
* DataInputStream d = new DataInputStream(in);
* </pre></blockquote>
* with:
* <blockquote><pre>
* BufferedReader d
* = new BufferedReader(new InputStreamReader(in));
* </pre></blockquote>
*
* @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;
System.
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 <code>readUTF</code>
* method of <code>DataInput</code>.
* <p>
* 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 <code>in</code> a representation
* of a Unicode character string encoded in
* <a href="DataInput.html#modified-utf-8">modified UTF-8</a> format;
* this string of characters is then returned as a <code>String</code>.
* The details of the modified UTF-8 representation
* are exactly the same as for the <code>readUTF</code>
* method of <code>DataInput</code>.
*
* @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);
}
}