Java/File Input Output/Data Input Output
Содержание
- 1 Controlling serialization by adding your own writeObject() and readObject() methods
- 2 Data IO Demo
- 3 Data IO Test
- 4 Data IO Test 2
- 5 IO demo: DataOutputStream and DataInputStream
- 6 ProgressMonitorInputStream Demo
- 7 Read Write Lock Test
- 8 ScanStreamTok - show scanning a file with StringTokenizer
- 9 Some simple file I-O primitives reimplemented in Java
- 10 The use of DataOutputStream and DataInputStream:
- 11 Typical I/O stream configurations
- 12 Using transferTo() between channels
- 13 Write some data in binary
Controlling serialization by adding your own writeObject() and readObject() methods
// : c12:SerialCtl.java
// Controlling serialization by adding your own
// writeObject() and readObject() methods.
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
public class SerialCtl implements Serializable {
private String a;
private transient String b;
public SerialCtl(String aa, String bb) {
a = "Not Transient: " + aa;
b = "Transient: " + bb;
}
public String toString() {
return a + "\n" + b;
}
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(b);
}
private void readObject(ObjectInputStream stream) throws IOException,
ClassNotFoundException {
stream.defaultReadObject();
b = (String) stream.readObject();
}
public static void main(String[] args) throws IOException,
ClassNotFoundException {
SerialCtl sc = new SerialCtl("Test1", "Test2");
System.out.println("Before:\n" + sc);
ByteArrayOutputStream buf = new ByteArrayOutputStream();
ObjectOutputStream o = new ObjectOutputStream(buf);
o.writeObject(sc);
// Now get it back:
ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(
buf.toByteArray()));
SerialCtl sc2 = (SerialCtl) in.readObject();
System.out.println("After:\n" + sc2);
}
} ///:~
Data IO Demo
/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution 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 Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class DataIODemo {
public static void main(String[] args) throws IOException {
// write the data out
DataOutputStream out = new DataOutputStream(new FileOutputStream(
"invoice1.txt"));
double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
int[] units = { 12, 8, 13, 29, 50 };
String[] descs = { "Java T-shirt", "Java Mug", "Duke Juggling Dolls",
"Java Pin", "Java Key Chain" };
for (int i = 0; i < prices.length; i++) {
out.writeDouble(prices[i]);
out.writeChar("\t");
out.writeInt(units[i]);
out.writeChar("\t");
out.writeChars(descs[i]);
out.writeChar("\n");
}
out.close();
// read it in again
DataInputStream in = new DataInputStream(new FileInputStream(
"invoice1.txt"));
double price;
int unit;
StringBuffer desc;
double total = 0.0;
try {
while (true) {
price = in.readDouble();
in.readChar(); // throws out the tab
unit = in.readInt();
in.readChar(); // throws out the tab
char chr;
desc = new StringBuffer(20);
char lineSep = System.getProperty("line.separator").charAt(0);
while ((chr = in.readChar()) != lineSep)
desc.append(chr);
System.out.println("You"ve ordered " + unit + " units of "
+ desc + " at $" + price);
total = total + unit * price;
}
} catch (EOFException e) {
}
System.out.println("For a TOTAL of: $" + total);
in.close();
}
}
Data IO Test
/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution 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 Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class DataIOTest {
public static void main(String[] args) throws IOException {
// write the data out
DataOutputStream out = new DataOutputStream(new FileOutputStream(
"invoice1.txt"));
double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
int[] units = { 12, 8, 13, 29, 50 };
String[] descs = { "Java T-shirt", "Java Mug", "Duke Juggling Dolls",
"Java Pin", "Java Key Chain" };
for (int i = 0; i < prices.length; i++) {
out.writeDouble(prices[i]);
out.writeChar("\t");
out.writeInt(units[i]);
out.writeChar("\t");
out.writeChars(descs[i]);
out.writeChar("\n");
}
out.close();
// read it in again
DataInputStream in = new DataInputStream(new FileInputStream(
"invoice1.txt"));
double price;
int unit;
StringBuffer desc;
double total = 0.0;
try {
while (true) {
price = in.readDouble();
in.readChar(); // throws out the tab
unit = in.readInt();
in.readChar(); // throws out the tab
char chr;
desc = new StringBuffer(20);
char lineSep = System.getProperty("line.separator").charAt(0);
while ((chr = in.readChar()) != lineSep)
desc.append(chr);
System.out.println("You"ve ordered " + unit + " units of "
+ desc + " at $" + price);
total = total + unit * price;
}
} catch (EOFException e) {
}
System.out.println("For a TOTAL of: $" + total);
in.close();
}
}
Data IO Test 2
/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution 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 Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class DataIOTest2 {
public static void main(String[] args) throws IOException {
// write the data out
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(
"invoice1.txt"));
double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
int[] units = { 12, 8, 13, 29, 50 };
String[] descs = { "Java T-shirt", "Java Mug", "Duke Juggling Dolls",
"Java Pin", "Java Key Chain" };
for (int i = 0; i < prices.length; i++) {
out.writeDouble(prices[i]);
out.writeChar("\t");
out.writeInt(units[i]);
out.writeChar("\t");
out.writeChars(descs[i]);
out.writeChar("\n");
}
out.close();
// read it in again
ObjectInputStream in = new ObjectInputStream(new FileInputStream(
"invoice1.txt"));
double price;
int unit;
String desc;
double total = 0.0;
try {
while (true) {
price = in.readDouble();
in.readChar(); // throws out the tab
unit = in.readInt();
in.readChar(); // throws out the tab
desc = in.readLine();
System.out.println("You"ve ordered " + unit + " units of "
+ desc + " at $" + price);
total = total + unit * price;
}
} catch (EOFException e) {
}
System.out.println("For a TOTAL of: $" + total);
in.close();
}
}
IO demo: DataOutputStream and DataInputStream
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class DataIODemo1 {
public static void main(String[] args) throws IOException {
DataOutputStream out = new DataOutputStream(new FileOutputStream(
"jexp.txt"));
double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
int[] units = { 12, 8, 13, 29, 50 };
String[] descs = { "Java", "Source ", "and",
"Support."};
for (int i = 0; i < prices.length; i++) {
out.writeDouble(prices[i]);
out.writeChar("\t");
out.writeInt(units[i]);
out.writeChar("\t");
out.writeChars(descs[i]);
out.writeChar("\n");
}
out.close();
// read it in again
DataInputStream in = new DataInputStream(new FileInputStream(
"jexp.txt"));
double price;
int unit;
String desc;
double total = 0.0;
try {
while (true) {
price = in.readDouble();
in.readChar(); // throws out the tab
unit = in.readInt();
in.readChar(); // throws out the tab
desc = in.readLine();
System.out.println( unit );
System.out.println( desc );
System.out.println( desc );
total = total + unit * price;
}
} catch (EOFException e) {
}
in.close();
}
}
ProgressMonitorInputStream Demo
import java.awt.Color;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import javax.swing.JLabel;
import javax.swing.ProgressMonitorInputStream;
public class ProgressInputSample {
public static final int NORMAL = 0;
public static void main(String args[]) throws Exception {
int returnValue = NORMAL;
if (args.length != 1) {
System.err.println("Usage:");
System.err.println("java ProgressInput filename");
} else {
FileInputStream fis = new FileInputStream(args[0]);
JLabel filenameLabel = new JLabel(args[0], JLabel.RIGHT);
filenameLabel.setForeground(Color.black);
Object message[] = { "Reading:", filenameLabel };
ProgressMonitorInputStream pmis = new ProgressMonitorInputStream(null, message, fis);
InputStreamReader isr = new InputStreamReader(pmis);
BufferedReader br = new BufferedReader(isr);
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
Thread.sleep(500);
}
br.close();
}
// AWT Thread created - must exit
System.exit(returnValue);
}
}
Read Write Lock Test
/*
Software Architecture Design Patterns in Java
by Partha Kuchana
Auerbach Publications
*/
public class ReadWriteLockTest {
public static void main(String[] args) {
Item item = new Item("CompScience-I");
new MemberTransaction("Member1", item, "StatusCheck");
new MemberTransaction("Member2", item, "StatusCheck");
new MemberTransaction("Member3", item, "CheckOut");
new MemberTransaction("Member4", item, "CheckOut");
new MemberTransaction("Member5", item, "CheckOut");
new MemberTransaction("Member6", item, "StatusCheck");
}
}
class Item {
private String name;
private ReadWriteLock rwLock;
private String status;
public Item(String n) {
name = n;
rwLock = new ReadWriteLock();
status = "N";
}
public void checkOut(String member) {
rwLock.getWriteLock();
status = "Y";
System.out.println(member + " has been issued a write lock-ChkOut");
rwLock.done();
}
public String getStatus(String member) {
rwLock.getReadLock();
System.out.println(member + " has been issued a read lock");
rwLock.done();
return status;
}
public void checkIn(String member) {
rwLock.getWriteLock();
status = "N";
System.out.println(member + " has been issued a write lock-ChkIn");
rwLock.done();
}
}
class ReadWriteLock {
private Object lockObj;
private int totalReadLocksGiven;
private boolean writeLockIssued;
private int threadsWaitingForWriteLock;
public ReadWriteLock() {
lockObj = new Object();
writeLockIssued = false;
}
/*
* A read lock can be issued if there is no currently issued write lock and
* there is no thread(s) currently waiting for the write lock
*/
public void getReadLock() {
synchronized (lockObj) {
while ((writeLockIssued) || (threadsWaitingForWriteLock != 0)) {
try {
lockObj.wait();
} catch (InterruptedException e) {
//
}
}
//System.out.println(" Read Lock Issued");
totalReadLocksGiven++;
}
}
/*
* A write lock can be issued if there is no currently issued read or write
* lock
*/
public void getWriteLock() {
synchronized (lockObj) {
threadsWaitingForWriteLock++;
while ((totalReadLocksGiven != 0) || (writeLockIssued)) {
try {
lockObj.wait();
} catch (InterruptedException e) {
//
}
}
//System.out.println(" Write Lock Issued");
threadsWaitingForWriteLock--;
writeLockIssued = true;
}
}
//used for releasing locks
public void done() {
synchronized (lockObj) {
//check for errors
if ((totalReadLocksGiven == 0) && (!writeLockIssued)) {
System.out.println(" Error: Invalid call to release the lock");
return;
}
if (writeLockIssued)
writeLockIssued = false;
else
totalReadLocksGiven--;
lockObj.notifyAll();
}
}
}
class MemberTransaction extends Thread {
private String name;
private Item item;
private String operation;
public MemberTransaction(String n, Item i, String p) {
name = n;
item = i;
operation = p;
start();
}
public void run() {
//all members first read the status
item.getStatus(name);
if (operation.equals("CheckOut")) {
System.out.println("\n" + name + " is ready to checkout the item.");
item.checkOut(name);
try {
sleep(1);
} catch (InterruptedException e) {
//
}
item.checkIn(name);
}
}
}
ScanStreamTok - show scanning a file with StringTokenizer
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 THE AUTHOR 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.
*
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StreamTokenizer;
/**
* ScanStreamTok - show scanning a file with StringTokenizer.
*
* @author Ian Darwin, http://www.darwinsys.ru/
* @version $Id: ScanStreamTok.java,v 1.6 2004/02/17 00:17:54 ian Exp $
*/
public class ScanStreamTok {
protected StreamTokenizer tf;
public static void main(String[] av) throws IOException {
if (av.length == 0)
new ScanStreamTok(
new InputStreamReader(System.in)).process();
else
for (int i=0; i<av.length; i++)
new ScanStreamTok(av[i]).process();
}
/** Construct a file scanner by name */
public ScanStreamTok(String fileName) throws IOException {
tf = new StreamTokenizer(new FileReader(fileName));
}
/** Construct a file scanner by existing Reader */
public ScanStreamTok(Reader rdr) throws IOException {
tf = new StreamTokenizer(rdr);
}
protected void process() throws IOException {
String s = null;
int i;
while ((i = tf.nextToken()) != StreamTokenizer.TT_EOF) {
switch(i) {
case StreamTokenizer.TT_EOF:
System.out.println("End of file");
break;
case StreamTokenizer.TT_EOL:
System.out.println("End of line");
break;
case StreamTokenizer.TT_NUMBER:
System.out.println("Number " + tf.nval);
break;
case StreamTokenizer.TT_WORD:
System.out.println("Word, length " + tf.sval.length() + "->" + tf.sval);
break;
default:
System.out.println("What is it? i = " + i);
}
}
}
}
Some simple file I-O primitives reimplemented in Java
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 THE AUTHOR 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.
*
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.Writer;
/**
* Some simple file I-O primitives reimplemented in Java. All methods are
* static, since there is no state.
*
* @version $Id: FileIO.java,v 1.18 2004/05/30 01:39:27 ian Exp $
*/
public class FileIO {
/** Nobody should need to create an instance; all methods are static */
private FileIO() {
// Nothing to do
}
/** Copy a file from one filename to another */
public static void copyFile(String inName, String outName)
throws FileNotFoundException, IOException {
BufferedInputStream is = new BufferedInputStream(new FileInputStream(
inName));
BufferedOutputStream os = new BufferedOutputStream(
new FileOutputStream(outName));
copyFile(is, os, true);
}
/** Copy a file from an opened InputStream to opened OutputStream */
public static void copyFile(InputStream is, OutputStream os, boolean close)
throws IOException {
byte[] b = new byte[BLKSIZ]; // the byte read from the file
int i;
while ((i = is.read(b)) != -1) {
os.write(b, 0, i);
}
is.close();
if (close)
os.close();
}
/** Copy a file from an opened Reader to opened Writer */
public static void copyFile(Reader is, Writer os, boolean close)
throws IOException {
int b; // the byte read from the file
BufferedReader bis = new BufferedReader(is);
while ((b = is.read()) != -1) {
os.write(b);
}
is.close();
if (close)
os.close();
}
/** Copy a file from a filename to a PrintWriter. */
public static void copyFile(String inName, PrintWriter pw, boolean close)
throws FileNotFoundException, IOException {
BufferedReader ir = new BufferedReader(new FileReader(inName));
copyFile(ir, pw, close);
}
/** Open a file and read the first line from it. */
public static String readLine(String inName) throws FileNotFoundException,
IOException {
BufferedReader is = new BufferedReader(new FileReader(inName));
String line = null;
line = is.readLine();
is.close();
return line;
}
/** The size of blocking to use */
protected static final int BLKSIZ = 16384;
/**
* Copy a data file from one filename to another, alternate method. As the
* name suggests, use my own buffer instead of letting the BufferedReader
* allocate and use the buffer.
*/
public void copyFileBuffered(String inName, String outName)
throws FileNotFoundException, IOException {
InputStream is = new FileInputStream(inName);
OutputStream os = new FileOutputStream(outName);
int count = 0; // the byte count
byte[] b = new byte[BLKSIZ]; // the bytes read from the file
while ((count = is.read(b)) != -1) {
os.write(b, 0, count);
}
is.close();
os.close();
}
/** Read the entire content of a Reader into a String */
public static String readerToString(Reader is) throws IOException {
StringBuffer sb = new StringBuffer();
char[] b = new char[BLKSIZ];
int n;
// Read a block. If it gets any chars, append them.
while ((n = is.read(b)) > 0) {
sb.append(b, 0, n);
}
// Only construct the String object once, here.
return sb.toString();
}
/** Read the content of a Stream into a String */
public static String inputStreamToString(InputStream is) throws IOException {
return readerToString(new InputStreamReader(is));
}
/** Write a String as the entire content of a File */
public static void stringToFile(String text, String fileName)
throws IOException {
BufferedWriter os = new BufferedWriter(new FileWriter(fileName));
os.write(text);
os.flush();
os.close();
}
/** Open a BufferedReader from a named file. */
public static BufferedReader openFile(String fileName) throws IOException {
return new BufferedReader(new FileReader(fileName));
}
}
The use of DataOutputStream and DataInputStream:
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
class DataIODemo {
public static void main(String args[]) throws IOException {
FileOutputStream fout = new FileOutputStream("Test.dat");
DataOutputStream out = new DataOutputStream(fout);
out.writeDouble(98.6);
out.writeInt(1000);
out.writeBoolean(true);
out.close();
FileInputStream fin = new FileInputStream("Test.dat");
DataInputStream in = new DataInputStream(fin);
double d = in.readDouble();
int i = in.readInt();
boolean b = in.readBoolean();
System.out.println("Here are the values: " + d + " " + i + " " + b);
in.close();
}
}
Typical I/O stream configurations
// : c12:IOStreamDemo.java
// Typical I/O stream configurations.
// {RunByHand}
// {Clean: IODemo.out,Data.txt,rtest.dat}
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.RandomAccessFile;
import java.io.StringReader;
public class IOStreamDemo {
// Throw exceptions to console:
public static void main(String[] args) throws IOException {
// 1. Reading input by lines:
BufferedReader in = new BufferedReader(new FileReader(
"IOStreamDemo.java"));
String s, s2 = new String();
while ((s = in.readLine()) != null)
s2 += s + "\n";
in.close();
// 1b. Reading standard input:
BufferedReader stdin = new BufferedReader(new InputStreamReader(
System.in));
System.out.print("Enter a line:");
System.out.println(stdin.readLine());
// 2. Input from memory
StringReader in2 = new StringReader(s2);
int c;
while ((c = in2.read()) != -1)
System.out.print((char) c);
// 3. Formatted memory input
try {
DataInputStream in3 = new DataInputStream(new ByteArrayInputStream(
s2.getBytes()));
while (true)
System.out.print((char) in3.readByte());
} catch (EOFException e) {
System.err.println("End of stream");
}
// 4. File output
try {
BufferedReader in4 = new BufferedReader(new StringReader(s2));
PrintWriter out1 = new PrintWriter(new BufferedWriter(
new FileWriter("IODemo.out")));
int lineCount = 1;
while ((s = in4.readLine()) != null)
out1.println(lineCount++ + ": " + s);
out1.close();
} catch (EOFException e) {
System.err.println("End of stream");
}
// 5. Storing & recovering data
try {
DataOutputStream out2 = new DataOutputStream(
new BufferedOutputStream(new FileOutputStream("Data.txt")));
out2.writeDouble(3.14159);
out2.writeUTF("That was pi");
out2.writeDouble(1.41413);
out2.writeUTF("Square root of 2");
out2.close();
DataInputStream in5 = new DataInputStream(new BufferedInputStream(
new FileInputStream("Data.txt")));
// Must use DataInputStream for data:
System.out.println(in5.readDouble());
// Only readUTF() will recover the
// Java-UTF String properly:
System.out.println(in5.readUTF());
// Read the following double and String:
System.out.println(in5.readDouble());
System.out.println(in5.readUTF());
} catch (EOFException e) {
throw new RuntimeException(e);
}
// 6. Reading/writing random access files
RandomAccessFile rf = new RandomAccessFile("rtest.dat", "rw");
for (int i = 0; i < 10; i++)
rf.writeDouble(i * 1.414);
rf.close();
rf = new RandomAccessFile("rtest.dat", "rw");
rf.seek(5 * 8);
rf.writeDouble(47.0001);
rf.close();
rf = new RandomAccessFile("rtest.dat", "r");
for (int i = 0; i < 10; i++)
System.out.println("Value " + i + ": " + rf.readDouble());
rf.close();
}
} ///:~
Using transferTo() between channels
// : c12:TransferTo.java
// Using transferTo() between channels
// {Args: TransferTo.java TransferTo.txt}
// {Clean: TransferTo.txt}
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.channels.FileChannel;
public class TransferTo {
public static void main(String[] args) throws Exception {
if (args.length != 2) {
System.out.println("arguments: sourcefile destfile");
System.exit(1);
}
FileChannel in = new FileInputStream(args[0]).getChannel(), out = new FileOutputStream(
args[1]).getChannel();
in.transferTo(0, in.size(), out);
// Or:
// out.transferFrom(in, 0, in.size());
}
} ///:~
Write some data in binary
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 THE AUTHOR 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.
*
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.io.DataOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
/**
* Write some data in binary.
*
* @author Ian F. Darwin, http://www.darwinsys.ru/
* @version $Id: WriteBinary.java,v 1.3 2004/02/08 23:57:29 ian Exp $
*/
public class WriteBinary {
public static void main(String[] argv) throws IOException {
int i = 42;
double d = Math.PI;
String FILENAME = "binary.dat";
DataOutputStream os = new DataOutputStream(new FileOutputStream(
FILENAME));
os.writeInt(i);
os.writeDouble(d);
os.close();
System.out.println("Wrote " + i + ", " + d + " to file " + FILENAME);
}
}
