Java tutorial
package org.bimserver.client; /****************************************************************************** * Copyright (C) 2009-2019 BIMserver.org * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see {@literal<http://www.gnu.org/licenses/>}. *****************************************************************************/ import java.io.DataInput; import java.io.DataInputStream; import java.io.EOFException; import java.io.FilterInputStream; import java.io.IOException; import java.io.InputStream; import com.google.common.base.Charsets; import com.google.common.io.ByteStreams; import com.google.common.primitives.Ints; import com.google.common.primitives.Longs; public final class CountingLittleEndianDataInputStream extends FilterInputStream implements DataInput { private int pos = 0; protected CountingLittleEndianDataInputStream(InputStream in) { super(in); } public void align8() throws IOException { int skip = 8 - (this.pos % 8); if (skip > 0 && skip != 8) { readFully(new byte[skip]); } } public void align4() throws IOException { int skip = 4 - (this.pos % 4); if (skip > 0 && skip != 4) { readFully(new byte[skip]); } } public int getPos() { return pos; } /** * This method will throw an {@link UnsupportedOperationException}. */ @Override public String readLine() { throw new UnsupportedOperationException("readLine is not supported"); } @Override public void readFully(byte[] b) throws IOException { ByteStreams.readFully(this, b); pos += b.length; } @Override public void readFully(byte[] b, int off, int len) throws IOException { ByteStreams.readFully(this, b, off, len); pos += len; } @Override public int skipBytes(int n) throws IOException { int skip = (int) in.skip(n); pos += skip; return skip; } @Override public int readUnsignedByte() throws IOException { int b1 = in.read(); if (0 > b1) { throw new EOFException(); } pos += 1; return b1; } /** * Reads an unsigned {@code short} as specified by * {@link DataInputStream#readUnsignedShort()}, except using little-endian * byte order. * * @return the next two bytes of the input stream, interpreted as an * unsigned 16-bit integer in little-endian byte order * @throws IOException * if an I/O error occurs */ @Override public int readUnsignedShort() throws IOException { byte b1 = readAndCheckByte(); byte b2 = readAndCheckByte(); return Ints.fromBytes((byte) 0, (byte) 0, b2, b1); } /** * Reads an integer as specified by {@link DataInputStream#readInt()}, * except using little-endian byte order. * * @return the next four bytes of the input stream, interpreted as an * {@code int} in little-endian byte order * @throws IOException * if an I/O error occurs */ @Override public int readInt() throws IOException { byte b1 = readAndCheckByte(); byte b2 = readAndCheckByte(); byte b3 = readAndCheckByte(); byte b4 = readAndCheckByte(); return Ints.fromBytes(b4, b3, b2, b1); } /** * Reads a {@code long} as specified by {@link DataInputStream#readLong()}, * except using little-endian byte order. * * @return the next eight bytes of the input stream, interpreted as a * {@code long} in little-endian byte order * @throws IOException * if an I/O error occurs */ @Override public long readLong() throws IOException { byte b1 = readAndCheckByte(); byte b2 = readAndCheckByte(); byte b3 = readAndCheckByte(); byte b4 = readAndCheckByte(); byte b5 = readAndCheckByte(); byte b6 = readAndCheckByte(); byte b7 = readAndCheckByte(); byte b8 = readAndCheckByte(); return Longs.fromBytes(b8, b7, b6, b5, b4, b3, b2, b1); } /** * Reads a {@code float} as specified by * {@link DataInputStream#readFloat()}, except using little-endian byte * order. * * @return the next four bytes of the input stream, interpreted as a * {@code float} in little-endian byte order * @throws IOException * if an I/O error occurs */ @Override public float readFloat() throws IOException { return Float.intBitsToFloat(readInt()); } /** * Reads a {@code double} as specified by * {@link DataInputStream#readDouble()}, except using little-endian byte * order. * * @return the next eight bytes of the input stream, interpreted as a * {@code double} in little-endian byte order * @throws IOException * if an I/O error occurs */ @Override public double readDouble() throws IOException { return Double.longBitsToDouble(readLong()); } @Override public String readUTF() throws IOException { String readUTF = new DataInputStream(in).readUTF(); pos += 2 + readUTF.getBytes(Charsets.UTF_8).length; return readUTF; } /** * Reads a {@code short} as specified by * {@link DataInputStream#readShort()}, except using little-endian byte * order. * * @return the next two bytes of the input stream, interpreted as a * {@code short} in little-endian byte order. * @throws IOException * if an I/O error occurs. */ @Override public short readShort() throws IOException { return (short) readUnsignedShort(); } /** * Reads a char as specified by {@link DataInputStream#readChar()}, except * using little-endian byte order. * * @return the next two bytes of the input stream, interpreted as a * {@code char} in little-endian byte order * @throws IOException * if an I/O error occurs */ @Override public char readChar() throws IOException { return (char) readUnsignedShort(); } @Override public byte readByte() throws IOException { return (byte) readUnsignedByte(); } @Override public boolean readBoolean() throws IOException { return readUnsignedByte() != 0; } /** * Reads a byte from the input stream checking that the end of file (EOF) * has not been encountered. * * @return byte read from input * @throws IOException * if an error is encountered while reading * @throws EOFException * if the end of file (EOF) is encountered. */ private byte readAndCheckByte() throws IOException, EOFException { int b1 = in.read(); pos++; if (-1 == b1) { throw new EOFException(); } return (byte) b1; } }