/*
* @(#)DataInputStream.java 1.27 95/08/15 Arthur van Hoff
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package java.io;
/**
* A data input stream that lets you read primitive Java data types
* from a stream in a portable way. Primitive data types are well
* understood types with associated operations. For example,
* Integers are considered primitive data types.
*
* @see DataOutputStream
* @version 1.27, 15 Aug 1995
* @author Arthur van Hoff
*/
public
class DataInputStream extends FilterInputStream implements DataInput {
/**
* Creates a new DataInputStream.
* @param in the input stream
*/
public DataInputStream(InputStream in) {
super(in);
}
/**
* Reads data into an array of bytes.
* This method blocks until some input is available.
* @param b the buffer into which the data is read
* @return the actual number of bytes read, -1 is
* returned when the end of the stream is reached.
* @exception IOException If an I/O error has occurred.
*/
public final int read(byte b[]) throws IOException {
return in.read(b, 0, b.length);
}
/**
* Reads data into an array of bytes.
* This method blocks until some input is available.
* @param b the buffer into which the data is read
* @param off the start offset of the data
* @param len the maximum number of bytes read
* @return the actual number of bytes read, -1 is
* returned when the end of the stream is reached.
* @exception IOException If an I/O error has occurred.
*/
public final int read(byte b[], int off, int len) throws IOException {
return in.read(b, off, len);
}
/**
* Reads bytes, blocking until all bytes are read.
* @param b the buffer into which the data is read
* @exception IOException If an I/O error has occurred.
* @exception EOFException If EOF reached before all bytes are read.
*/
public final void readFully(byte b[]) throws IOException {
readFully(b, 0, b.length);
}
/**
* Reads bytes, blocking until all bytes are read.
* @param b the buffer into which the data is read
* @param off the start offset of the data
* @param len the maximum number of bytes read
* @exception IOException If an I/O error has occurred.
* @exception EOFException If EOF reached before all bytes are read.
*/
public final void readFully(byte b[], int off, int len) throws IOException {
InputStream in = this.in;
int n = 0;
while (n < len) {
int count = in.read(b, off + n, len - n);
if (count < 0)
throw new EOFException();
n += count;
}
}
/**
* Skips bytes, block until all bytes are skipped.
* @param n the number of bytes to be skipped
* @return the actual number of bytes skipped.
* @exception IOException If an I/O error has occurred.
*/
public final int skipBytes(int n) throws IOException {
InputStream in = this.in;
for (int i = 0 ; i < n ; i += (int)in.skip(n - i));
return n;
}
/**
* Reads in a boolean.
* @return the boolean read.
*/
public final boolean readBoolean() throws IOException {
int ch = in.read();
if (ch < 0)
throw new EOFException();
return (ch != 0);
}
/**
* Reads an 8 bit byte.
* @return the 8 bit byte read.
*/
public final byte readByte() throws IOException {
int ch = in.read();
if (ch < 0)
throw new EOFException();
return (byte)(ch);
}
/**
* Reads an unsigned 8 bit byte.
* @return the 8 bit byte read.
*/
public final int readUnsignedByte() throws IOException {
int ch = in.read();
if (ch < 0)
throw new EOFException();
return ch;
}
/**
* Reads 16 bit short.
* @return the read 16 bit short.
*/
public final short readShort() throws IOException {
InputStream in = this.in;
int ch1 = in.read();
int ch2 = in.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (short)((ch1 << 8) + (ch2 << 0));
}
/**
* Reads 16 bit short.
* @return the read 16 bit short.
*/
public final int readUnsignedShort() throws IOException {
InputStream in = this.in;
int ch1 = in.read();
int ch2 = in.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (ch1 << 8) + (ch2 << 0);
}
/**
* Reads a 16 bit char.
* @return the read 16 bit char.
*/
public final char readChar() throws IOException {
InputStream in = this.in;
int ch1 = in.read();
int ch2 = in.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (char)((ch1 << 8) + (ch2 << 0));
}
/**
* Reads a 32 bit int.
* @return the read 32 bit integer.
*/
public final int readInt() throws IOException {
InputStream in = this.in;
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));
}
/**
* Reads a 64 bit long.
* @return the read 64 bit long.
*/
public final long readLong() throws IOException {
InputStream in = this.in;
return (readInt() << 32L) + (readInt() & 0xFFFFFFFFL);
}
/**
* Reads a 32 bit float.
* @return the read 32 bit float.
*/
public final float readFloat() throws IOException {
return Float.intBitsToFloat(readInt());
}
/**
* Reads a 64 bit double.
* @return the read 64 bit double.
*/
public final double readDouble() throws IOException {
return Double.longBitsToDouble(readLong());
}
private char lineBuffer[];
/**
* Reads in a line that has been terminated by a \n, \r,
* \r\n or EOF.
* @return a String copy of the line.
*/
public final String readLine() throws IOException {
InputStream in = this.in;
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') {
if (!(in instanceof PushbackInputStream)) {
in = 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);
}
/**
* Reads a UTF format String.
* @return the String.
*/
public final String readUTF() throws IOException {
return readUTF(this);
}
/**
* Reads a UTF format String from the given input stream.
* @return the String.
*/
public final static String readUTF(DataInput in) throws IOException {
int utflen = in.readUnsignedShort();
char str[] = new char[utflen];
int count = 0;
int strlen = 0;
while (count < utflen) {
int c = in.readUnsignedByte();
int char2, char3;
switch (c >> 4) {
case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
// 0xxxxxxx
count++;
str[strlen++] = (char)c;
break;
case 12: case 13:
// 110x xxxx 10xx xxxx
count += 2;
if (count > utflen)
throw new UTFDataFormatException();
char2 = in.readUnsignedByte();
if ((char2 & 0xC0) != 0x80)
throw new UTFDataFormatException();
str[strlen++] = (char)(((c & 0x1F) << 6) | (char2 & 0x3F));
break;
case 14:
// 1110 xxxx 10xx xxxx 10xx xxxx
count += 3;
if (count > utflen)
throw new UTFDataFormatException();
char2 = in.readUnsignedByte();
char3 = in.readUnsignedByte();
if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80))
throw new UTFDataFormatException();
str[strlen++] = (char)(((c & 0x0F) << 12) |
((char2 & 0x3F) << 6) |
((char3 & 0x3F) << 0));
break;
default:
// 10xx xxxx, 1111 xxxx
throw new UTFDataFormatException();
}
}
return new String(str, 0, strlen);
}
}