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2010-06-01T05:19:40Z

1 версия

в 17:44, 31 мая 2010

2010-05-31T17:44:27Z

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== Append output to file using FileOutputStream ==



<source lang="java">
import java.io.FileOutputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileOutputStream fos = new FileOutputStream("C:/demo.txt", true);
fos.write("Appended".getBytes());
fos.close();
}
}</source>



== Copy a file with FileInputStream and FileOutputStream ==



<source lang="java">
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
class CopyFile {
public static void main(String args[]) throws IOException {
int i;
FileInputStream fin;
FileOutputStream fout;
fin = new FileInputStream(args[0]);
fout = new FileOutputStream(args[1]);
do {
i = fin.read();
if (i != -1)
fout.write(i);
} while (i != -1);
fin.close();
fout.close();
}
}</source>



== Create a file output stream directly from the file name ==



<source lang="java">
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
public class MainClass {
public static void main(String[] a) {
FileOutputStream outputFile = null; // Place to store the stream reference
try {
outputFile = new FileOutputStream("myFile.txt");
} catch (FileNotFoundException e) {
e.printStackTrace(System.err);
}
}
}</source>



== Create DataOutputStream from FileOutputStream ==



<source lang="java">
import java.io.DataOutputStream;
import java.io.FileOutputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileOutputStream fos = new FileOutputStream("C:/demo.txt");
DataOutputStream dos = new DataOutputStream(fos);
}
}</source>



== Create FileOutputStream object from File object ==



<source lang="java">
import java.io.File;
import java.io.FileOutputStream;
public class Main {
public static void main(String[] args) throws Exception {
File file = new File("C:/demo.txt");
FileOutputStream fos = new FileOutputStream(file);
}
}</source>



== Create FileOutputStream object from String file path ==



<source lang="java">
import java.io.FileOutputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileOutputStream fos = new FileOutputStream("C:/demo.txt");
}
}</source>



== File IO ==



<source lang="java">
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class FileIOApp {
public static void main(String args[]) throws IOException {
FileOutputStream outStream = new FileOutputStream("test.txt");
String s = "This is a test.";
for (int i = 0; i < s.length(); ++i)
outStream.write(s.charAt(i));
outStream.close();
FileInputStream inStream = new FileInputStream("test.txt");
int inBytes = inStream.available();
System.out.println("inStream has " + inBytes + " available bytes");
byte inBuf[] = new byte[inBytes];
int bytesRead = inStream.read(inBuf, 0, inBytes);
System.out.println(bytesRead + " bytes were read");
System.out.println("They are: " + new String(inBuf));
inStream.close();
File f = new File("test.txt");
f.delete();
}
}</source>



== FileOutputStream ==

<OL><LI>The FileOutputStream class is a subclass of OutputStream.</LI><LI>You can construct a FileOutputStream object by passing a string containing a path name or a File object.</LI><LI>You can also specify whether you want to append the output to an existing file.</LI></OL>



<source lang="java">
public FileOutputStream (String path)
public FileOutputStream (String path, boolean append)
public FileOutputStream (File file)
public FileOutputStream (File file, boolean append)</source>



== Forcing Updates to a File to the Disk ==



<source lang="java">
import java.io.FileDescriptor;
import java.io.FileOutputStream;
public class Main {
public static void main(String[] argv) throws Exception {
FileOutputStream os = new FileOutputStream("outfilename");
FileDescriptor fd = os.getFD();
os.write(1);
os.flush();
fd.sync();
}
}</source>



== Get FileChannel from FileOutputStream ==



<source lang="java">
// Getting channels from streams
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
public class MainClass {
private static final int BSIZE = 1024;
public static void main(String[] args) throws Exception {
FileChannel fc = new FileOutputStream("data.txt").getChannel();
fc.write(ByteBuffer.wrap("Some text ".getBytes()));
fc.close();
}
}</source>



== serializes an object to an output stream. ==



<source lang="java">
/*
* 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.
*/
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;

public class Main {

/**
* This method serializes an object to an output stream.
*
* @param file The output file
* @param object The object to be serialized
* @exception IOException IOError
*/
public static void serializeObject(File file, Object object)
throws IOException {
FileOutputStream fos = new FileOutputStream(file);
try {
ObjectOutputStream oos = new ObjectOutputStream(new BufferedOutputStream(fos));
oos.writeObject(object);
oos.flush();
} finally {
fos.close();
}
}
}</source>



== Use FileOutputStream to read integers ==



<source lang="java">
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class MainClass {
public static void main(String args[]) throws IOException {
int howMany = 20;
// To avoid resizing the buffer, calculate the size of the
// byte array in advance.
ByteArrayOutputStream bout = new ByteArrayOutputStream(howMany * 4);
DataOutputStream dout = new DataOutputStream(bout);
for (int i = 0; i <= 20; i++) {
dout.writeInt(i);
}
FileOutputStream fout = new FileOutputStream("fibonacci.dat");
try {
bout.writeTo(fout);
fout.flush();
} finally {
fout.close();
}
}
}</source>



== Use FileOutputStream to write the bytes to a file. ==



<source lang="java">
import java.io.FileOutputStream;
public class Main {
public static void main(String[] argv) throws Exception {
byte[] vals = { 65, 66, 67, 68, 69, 70, 71, 72, 73, 74 };
FileOutputStream fout = new FileOutputStream("Test.dat");
for (int i = 0; i < vals.length; i += 2)
fout.write(vals[i]);
fout.close();
}
}</source>



== Write byte array to a file using FileOutputStream ==



<source lang="java">
import java.io.FileOutputStream;
public class Main {
public static void main(String[] args) throws Exception {
String strFilePath = "C://demo.txt";
FileOutputStream fos = new FileOutputStream(strFilePath);
String strContent = "Write File using Java FileOutputStream example !";
fos.write(strContent.getBytes());
fos.close();
}
}</source>



== Write double to a file using DataOutputStream ==



<source lang="java">
import java.io.DataOutputStream;
import java.io.FileOutputStream;
public class Main {
public static void main(String[] args) throws Exception {
String strFilePath = "C:/Double.txt";
FileOutputStream fos = new FileOutputStream(strFilePath);
DataOutputStream dos = new DataOutputStream(fos);
double d = 1;
dos.writeDouble(d);
dos.close();
}
}</source>



== Write file using FileOutputStream ==



<source lang="java">
import java.io.FileOutputStream;
public class Main {
public static void main(String[] args) throws Exception {
FileOutputStream fos = new FileOutputStream("C:/demo.txt");
byte b = 01;
fos.write(b);
fos.close();
}
}</source>



== Write UTF String, integer and double with DataOutputStream ==



<source lang="java">
import java.io.BufferedOutputStream;
import java.io.DataOutputStream;
import java.io.FileOutputStream;
public class Main {
public static void main(String[] argv) throws Exception {
FileOutputStream fileOut = new FileOutputStream("data.txt");
BufferedOutputStream buffer = new BufferedOutputStream(fileOut);
DataOutputStream dataOut = new DataOutputStream(buffer);
dataOut.writeUTF("Hello!");
dataOut.writeInt(4);
dataOut.writeDouble(100.0);
dataOut.close();
buffer.close();
fileOut.close();
}
}</source>

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Admin: 1 версия

в 17:44, 31 мая 2010