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/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package java.io;

import com.jtransc.JTranscBits;
import com.jtransc.io.JTranscIoTools;

import java.nio.charset.StandardCharsets;
import java.nio.internal.SizeOf;

/**
 * Wraps an existing {@link InputStream} and reads big-endian typed data from it.
 * Typically, this stream has been written by a DataOutputStream. Types that can
 * be read include byte, 16-bit short, 32-bit int, 32-bit float, 64-bit long,
 * 64-bit double, byte strings, and strings encoded in
 * {@link DataInput modified UTF-8}.
 *
 * @see DataOutputStream
 */
public class DataInputStream extends FilterInputStream implements DataInput {

	private final byte[] scratch = new byte[8];

	/**
	 * Constructs a new DataInputStream on the InputStream {@code in}. All
	 * reads are then filtered through this stream. Note that data read by this
	 * stream is not in a human readable format and was most likely created by a
	 * DataOutputStream.
	 * 

*

Warning: passing a null source creates an invalid * {@code DataInputStream}. All operations on such a stream will fail. * * @param in the source InputStream the filter reads from. * @see DataOutputStream * @see RandomAccessFile */ public DataInputStream(InputStream in) { super(in); } // overridden to add 'final' @Override public final int read(byte[] buffer) throws IOException { return super.read(buffer); } @Override public final int read(byte[] buffer, int byteOffset, int byteCount) throws IOException { return in.read(buffer, byteOffset, byteCount); } public final boolean readBoolean() throws IOException { int temp = in.read(); if (temp < 0) { throw new EOFException(); } return temp != 0; } public final byte readByte() throws IOException { int temp = in.read(); if (temp < 0) { throw new EOFException(); } return (byte) temp; } public final char readChar() throws IOException { return (char) readShort(); } public final double readDouble() throws IOException { return Double.longBitsToDouble(readLong()); } public final float readFloat() throws IOException { return Float.intBitsToFloat(readInt()); } public final void readFully(byte[] dst) throws IOException { readFully(dst, 0, dst.length); } public final void readFully(byte[] dst, int offset, int byteCount) throws IOException { JTranscIoTools.readFully(in, dst, offset, byteCount); } public final int readInt() throws IOException { JTranscIoTools.readFully(in, scratch, 0, SizeOf.INT); return JTranscBits.readInt32BE(scratch, 0); } /** * @deprecated This method cannot be trusted to convert bytes to characters correctly. * Wrap this stream with a {@link BufferedReader} instead. */ @Deprecated public final String readLine() throws IOException { StringBuilder line = new StringBuilder(80); // Typical line length boolean foundTerminator = false; while (true) { int nextByte = in.read(); switch (nextByte) { case -1: if (line.length() == 0 && !foundTerminator) { return null; } return line.toString(); case (byte) '\r': if (foundTerminator) { ((PushbackInputStream) in).unread(nextByte); return line.toString(); } foundTerminator = true; /* Have to be able to peek ahead one byte */ if (!(in.getClass() == PushbackInputStream.class)) { in = new PushbackInputStream(in); } break; case (byte) '\n': return line.toString(); default: if (foundTerminator) { ((PushbackInputStream) in).unread(nextByte); return line.toString(); } line.append((char) nextByte); } } } public final long readLong() throws IOException { JTranscIoTools.readFully(in, scratch, 0, SizeOf.LONG); return JTranscBits.readInt64BE(scratch, 0); } public final short readShort() throws IOException { JTranscIoTools.readFully(in, scratch, 0, SizeOf.SHORT); return JTranscBits.readInt16BE(scratch, 0); } public final int readUnsignedByte() throws IOException { int temp = in.read(); if (temp < 0) { throw new EOFException(); } return temp; } public final int readUnsignedShort() throws IOException { return ((int) readShort()) & 0xffff; } public final String readUTF() throws IOException { return decodeUTF(readUnsignedShort()); } String decodeUTF(int utfSize) throws IOException { return decodeUTF(utfSize, this); } private static String decodeUTF(int utfSize, DataInput in) throws IOException { byte[] buf = new byte[utfSize]; in.readFully(buf, 0, utfSize); return new String(buf, 0, utfSize, StandardCharsets.UTF_8); } public static final String readUTF(DataInput in) throws IOException { return decodeUTF(in.readUnsignedShort(), in); } /** * Skips {@code count} number of bytes in this stream. Subsequent {@code * read()}s will not return these bytes unless {@code reset()} is used. *

* This method will not throw an {@link EOFException} if the end of the * input is reached before {@code count} bytes where skipped. * * @param count the number of bytes to skip. * @return the number of bytes actually skipped. * @throws IOException if a problem occurs during skipping. * @see #mark(int) * @see #reset() */ public final int skipBytes(int count) throws IOException { int skipped = 0; long skip; while (skipped < count && (skip = in.skip(count - skipped)) != 0) { skipped += skip; } return skipped; } }





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