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2010-06-01T05:20:14Z

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в 17:44, 31 мая 2010

2010-05-31T17:44:27Z

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== Check the class version ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
DataInputStream in = new DataInputStream(new FileInputStream("Main.class"));
int start = in.readInt();
if (start != 0xcafebabe) {
System.out.println("not valid");
}
in.close();
System.out.println(in.readUnsignedShort()+"/"+in.readUnsignedShort());

}
}</source>



== Create a compressed data file by using a DeflaterOutputStream and then read that data through an InflaterInputStream. ==



<source lang="java">
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.InflaterInputStream;
public class Main {
public static void main(String[] argv) throws Exception {
double data[] = { 1.1, 2.2, 3.3, 4.4, 5.5, 6.6 };
DataOutputStream fout = new DataOutputStream(new DeflaterOutputStream(new FileOutputStream(
"data.dat")));
fout.writeInt(data.length);
for (double d : data)
fout.writeDouble(d);
DataInputStream fin = new DataInputStream(new InflaterInputStream(new FileInputStream(
"data.dat")));
int num = fin.readInt();
double avg = 0.0;
double d;
for (int i = 0; i < num; i++) {
d = fin.readDouble();
avg += d;
System.out.print(d + " ");
}
fin.close();
fout.close();
}
}</source>



== Create DataInputStream from BufferedInputStream and FileInputStream ==



<source lang="java">
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
public class MainClass {
public static void main(String[] args) throws IOException {
DataInputStream dis = new DataInputStream(new BufferedInputStream(new FileInputStream(
"temp.tmp")));
for (int i = 0; i < 10; i++)
dis.readInt();
dis.close();
}
}</source>



== Create DataInputStream from ByteArrayInputStream ==



<source lang="java">
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.IOException;
public class MainClass {
public static void main(String[] args) throws IOException {
try {
DataInputStream in3 = new DataInputStream(
new ByteArrayInputStream("a dbcde".getBytes()));
while(true)
System.out.print((char)in3.readByte());
} catch(EOFException e) {
System.err.println("End of stream");
}

}
}//</source>



<pre class=codeResult>a dbcdeEnd of stream</pre>

== Create DataInputStream from FileInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.IOException;
public class MainClass {
public static void main(String[] args) throws Exception {
DataInputStream din = null;
try {
FileInputStream fin = new FileInputStream("myfile.dat");
din = new DataInputStream(fin);
while (true) {
int theNumber = din.readInt();
System.out.println(theNumber);
}
} catch (EOFException ex) {
din.close();
} catch (IOException ex) {
System.err.println(ex);
}
}
}</source>



== Read boolean from file using DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/n.txt");
DataInputStream din = new DataInputStream(fin);
boolean b = din.readBoolean();
System.out.println("boolean : " + b);
din.close();
}
}</source>



== Read byte array from file using DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Array.txt");
DataInputStream din = new DataInputStream(fin);
byte b[] = new byte[10];
din.read(b);
din.close();
}
}</source>



== Read byte from file using DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Byte.txt");
DataInputStream din = new DataInputStream(fin);
byte b = din.readByte();
System.out.println("byte : " + b);
din.close();
}
}</source>



== Read char from file using DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception{
FileInputStream fin = new FileInputStream("C:/Char.txt");
DataInputStream din = new DataInputStream(fin);
char ch = din.readChar();
System.out.println("Char : " + ch);
din.close();
}
}</source>



== Read double and UTF from DataInputStream with BufferedInputStream backended ==



<source lang="java">
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class MainClass {
public static void main(String[] args) throws IOException {
DataOutputStream out2 = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(
"Data.txt")));
out2.writeDouble(3.14159);
out2.writeUTF("Square root of 2");
out2.close();
DataInputStream in5 = new DataInputStream(new BufferedInputStream(new FileInputStream(
"Data.txt")));
System.out.println(in5.readDouble());
System.out.println(in5.readUTF());
}
}</source>



== Read double from DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.IOException;
public class MainClass {
public static void main(String[] args) {
try {
FileInputStream fin = new FileInputStream("myFile.dat");
DataInputStream din = new DataInputStream(fin);
while (true) {
double theNumber = din.readDouble();
System.out.println(theNumber);
}
} catch (EOFException e) {
} catch (IOException e) {
// abnormal termination
System.err.println(e);
}
}
}</source>



== Read float from file using DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Float.txt");
DataInputStream din = new DataInputStream(fin);
float f = din.readFloat();
System.out.println("float : " + f);
din.close();
}
}</source>



== Read int from DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.IOException;
public class MainClass {
public static void main(String[] args) throws Exception {
DataInputStream din = null;
try {
FileInputStream fin = new FileInputStream("myfile.dat");
din = new DataInputStream(fin);
while (true) {
int theNumber = din.readInt();
System.out.println(theNumber);
}
} catch (EOFException ex) {
din.close();
} catch (IOException ex) {
System.err.println(ex);
}
}
}</source>



== Read long from file using DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Long.txt");
DataInputStream din = new DataInputStream(fin);
long l = din.readLong();
System.out.println("long : " + l);
din.close();
}
}</source>



== Read short from file using DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/Short.txt");
DataInputStream din = new DataInputStream(fin);
short s = din.readShort();
System.out.println("short : " + s);
din.close();
}
}</source>



== Read unsigned byte from file using DataInputStream ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream("C:/UnsignedByte.txt");
DataInputStream din = new DataInputStream(fin);
int i = din.readUnsignedByte();
System.out.println("Unsinged byte value : " + i);
din.close();
}
}</source>



== Testing for end of file while reading a byte at a time. ==



<source lang="java">
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
public class MainClass {
public static void main(String[] args) throws IOException {
DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream(
"test.java")));
while (in.available() != 0)
System.out.print((char) in.readByte());
}
}</source>



== This class is an part implementation of DataInput. It wraps a Reader object. ==



<source lang="java">
/* Copyright (c) 2001-2009, The HSQL Development Group
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the HSQL Development Group nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

import java.io.DataInput;
import java.io.EOFException;
import java.io.IOException;
import java.io.Reader;
/**
* This class is an part implementation of DataInput. It wraps a Reader object.
*
* @author Fred Toussi (fredt@users dot sourceforge.net)
* @version 1.9.0
* @since 1.9.0
*/
public class ReaderDataInput implements DataInput {
protected Reader reader;
protected int pos;
int lastChar = -1;
public ReaderDataInput(Reader reader) {
this.reader = reader;
this.pos = 0;
}
// methods that implement java.io.DataInput
public final void readFully(byte[] b) throws IOException {
readFully(b, 0, b.length);
}
public final void readFully(byte[] bytes, int off,
int len) throws IOException {
if (len < 0) {
throw new IndexOutOfBoundsException();
}
int n = 0;
while (n < len) {
int b = read();
if (b < 0) {
throw new EOFException();
}
bytes[off + n++] = (byte) b;
}
}
public final boolean readBoolean() throws IOException {
int b = read();
if (b < 0) {
throw new EOFException();
}
return (b != 0);
}
public final byte readByte() throws IOException {
int b = read();
if (b < 0) {
throw new EOFException();
}
return (byte) b;
}
public final int readUnsignedByte() throws IOException {
int b = read();
if (b < 0) {
throw new EOFException();
}
return b;
}
public short readShort() throws IOException {
int b1 = read();
if (b1 < 0) {
throw new EOFException();
}
int b2 = read();
if (b2 < 0) {
throw new EOFException();
}
return (short) ((b1 << 8) | b2);
}
public final int readUnsignedShort() throws IOException {
int b1 = read();
int b2 = read();
if ((b1 | b2) < 0) {
throw new EOFException();
}
return ((b1 << 8) + (b2));
}
public final char readChar() throws IOException {
int b1 = read();
int b2 = read();
if ((b1 | b2) < 0) {
throw new EOFException();
}
return (char) ((b1 << 8) + (b2));
}
public int readInt() throws IOException {
throw new java.lang.RuntimeException("not implemented.");
}
public long readLong() throws IOException {
throw new java.lang.RuntimeException("not implemented.");
}
public final float readFloat() throws IOException {
throw new java.lang.RuntimeException("not implemented.");
}
public final double readDouble() throws IOException {
throw new java.lang.RuntimeException("not implemented.");
}
public int skipBytes(int n) throws IOException {
throw new java.lang.RuntimeException("not implemented.");
}
public String readLine() throws IOException {
throw new java.lang.RuntimeException("not implemented.");
}
public String readUTF() throws IOException {
throw new java.lang.RuntimeException("not implemented.");
}
public int read() throws IOException {
if (lastChar >= 0) {
int val = lastChar & 0xff;
lastChar = -1;
pos++;
return val;
}
lastChar = reader.read();
if (lastChar < 0) {
return lastChar;
}
pos++;
return lastChar >> 8;
}
}</source>



== Use DataInputStream to create double ==



<source lang="java">
import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] argv) throws Exception {
FileInputStream fileIn = new FileInputStream("data.txt");
DataInputStream dataIn = new DataInputStream(fileIn);
System.out.println(dataIn.readUTF());
int counter = dataIn.readInt();
double sum = 0.0;
for (int i = 0; i < counter; i++) {
double current = dataIn.readDouble();
System.out.println("Just read " + current);
sum += current;
}
System.out.println("\nAverage = " + sum / counter);
dataIn.close();
fileIn.close();
}
}</source>

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Admin: 1 версия

в 17:44, 31 мая 2010