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File » ByteArrayOutputStream

import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class FileByteArrayOutputStream { private static final Logger LOG = LoggerFactory.getLogger("ByteArrayOutputStream"); public static void main(String args[]) throws IOException { final String s = "This is a test."; new FileByteArrayOutputStream().demo(s); } private void demo(String s) { final ByteArrayOutputStream outStream = new ByteArrayOutputStream(); for (int i = 0; i < s.length(); ++i) { outStream.write(s.charAt(i)); } LOG.info("Outstream: " + outStream); LOG.info("Size: " + outStream.size()); final ByteArrayInputStream inStream = new ByteArrayInputStream(outStream.toByteArray()); final int inBytes = inStream.available(); LOG.info("InStream has available bytes: " + inBytes); final byte inBuf[] = new byte[inBytes]; final int bytesRead = inStream.read(inBuf, 0, inBytes); LOG.info("Bytes Read: " + bytesRead); LOG.info("They are: " + new String(inBuf)); } }

#java File

File » ByteArrayInputStream

import java.io.ByteArrayInputStream; import java.io.InputStream; public class FileByteArrayInputStream { public static void main(String[] args)throws Exception { final String text = "Converting String to InputStream Example"; final InputStream is = new ByteArrayInputStream(text.getBytes("UTF-8")); } }

#java File

File » PipedInputStream

import java.io.IOException; import java.io.PipedInputStream; import java.io.PipedOutputStream; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class FilePipedInputStream { public static void main(String args[]) { final Thread thread1 = new Thread(new PipeOutput("Producer")); final Thread thread2 = new Thread(new PipeInput("Consumer")); thread1.start(); thread2.start(); boolean thread1IsAlive = true; boolean thread2IsAlive = true; do { if (thread1IsAlive && !thread1.isAlive()) { thread1IsAlive = false; } if (thread2IsAlive && !thread2.isAlive()) { thread2IsAlive = false; } } while (thread1IsAlive || thread2IsAlive); } } class PipeIO { private static final Logger LOG = LoggerFactory.getLogger("PipeIO"); static PipedOutputStream outputPipe = new PipedOutputStream(); static PipedInputStream inputPipe = new PipedInputStream(); static { try { outputPipe.connect(inputPipe); } catch (IOException ex) { LOG.error("IOException in static initializer"); } } private String name; public PipeIO(String id) { name = id; } public String getName() { return name; } } class PipeOutput extends PipeIO implements Runnable { private static final Logger LOG = LoggerFactory.getLogger("PipeOutput"); public PipeOutput(String id) { super(id); } public void run() { final String s = "This is a test."; try { for (int i = 0; i < s.length(); ++i) { outputPipe.write(s.charAt(i)); LOG.info(getName() + " wrote " + s.charAt(i)); } outputPipe.write('!'); } catch (IOException ex) { LOG.error("IOException in PipeOutput"); } } } class PipeInput extends PipeIO implements Runnable { private static final Logger LOG = LoggerFactory.getLogger("PipeIO"); public PipeInput(String id) { super(id); } public void run() { boolean eof = false; try { while (!eof) { final int inChar = inputPipe.read(); if (inChar != -1) { final char ch = (char) inChar; if (ch == '!') { eof = true; break; } else LOG.info(getName() + " read " + ch); } } } catch (IOException ex) { LOG.error("IOException in PipeOutput"); } } }

#java File

File » PrintStream

import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.PrintStream; public class FilePrintStream { public static void main(String[] argv) throws Exception { try { final int i = 500/0; } catch (Exception e) { e.printStackTrace(getErrorLoggerPrintStream()); } } public static PrintStream getErrorLoggerPrintStream() { try { PrintStream s = new PrintStream(new FileOutputStream(new File( "d:\\log.txt"), true)); return s; } catch (FileNotFoundException e) { e.printStackTrace(); } return null; } }

#java File

File » Encoding

import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class FileEncoding { private static final Logger LOG = LoggerFactory.getLogger("ByteArrayOutputStream"); public static void main(String[] args) { LOG.info(System.getProperty("file.encoding")); } }

#java File

File » FileReader

The FileReader class is a subclass of InputStreamReader The FileReader class is a convenient class to read characters from a file. The FileReader class uses an encoding other than the default one. To construct a FileReader object: public FileReader (File file) public FileReader (FileDescriptor fileDescriptor) public FileReader (String filePath)

import java.io.BufferedReader; import java.io.File; import java.io.FileReader; import java.io.IOException; import java.util.LinkedList; import java.util.List; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class FileFileReader { private static final Logger LOG = LoggerFactory.getLogger("FileFileReader"); private String listToString(final List l) { final StringBuilder builder = new StringBuilder(l.size()); for (Character ch : l) { builder.append(ch); } return builder.toString(); } public static void main(String[] argv) throws Exception { final File dd = new File("D:\\", "text.txt"); FileFileReader ffr = new FileFileReader(); LOG.info(ffr.a(dd)); LOG.info(ffr.b(dd)); LOG.info(ffr.d(dd)); LOG.info(ffr.c(dd)); } public String a(final File dd) throws IOException { final FileReader fr = new FileReader(dd); final List l = new LinkedList(); int ch; do { ch = fr.read(); if (ch != -1) l.add((char) ch); } while (ch != -1); fr.close(); return listToString(l); } public String b(final File dd) throws IOException { final FileReader fr = new FileReader(dd); final List l = new LinkedList(); int count; final char chrs[] = new char[80]; do { count = fr.read(chrs); for (int i = 0; i < count; i++) l.add(chrs[i]); } while (count != -1); fr.close(); return listToString(l); } public String c(final File dd) throws IOException { final FileReader fr = new FileReader(dd); final BufferedReader br = new BufferedReader(fr); final StringBuffer sb = new StringBuffer(); boolean mof = true; String eachLine = br.readLine(); while (eachLine != null) { if(mof) { mof = false; }else { sb.append("\n"); } sb.append(eachLine); eachLine = br.readLine(); } br.close(); fr.close(); return sb.toString(); } public String d(final File dd) throws IOException { final StringBuffer sb = new StringBuffer(); final FileReader fr = new FileReader(dd); final BufferedReader buff = new BufferedReader(fr); boolean eof = false; boolean mof = true; while (!eof) { if(mof) { mof = false; }else { sb.append("\n"); } String line = buff.readLine(); if (line == null) eof = true; else sb.append(line); } buff.close(); return sb.substring(0, sb.length()-1).toString(); } }

#java File

File » Temporary File

import java.io.File; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class FileTemporaryFile { private static final Logger LOG = LoggerFactory.getLogger("FileTemporaryFile"); public static void main(String[] args) throws Exception { final File f = File.createTempFile("temp_", null); final File file1 = File.createTempFile("JavaTemp1", null); final File file2 = File.createTempFile("JavaTemp2", ".java"); File dir = new File("D:/"); final File file = File.createTempFile("JavaTemp3", ".javatemp", dir); LOG.info(f.getAbsolutePath()); LOG.info(file1.getPath()); LOG.info(file2.getPath()); LOG.info(file.getPath()); f.deleteOnExit(); file1.deleteOnExit(); file2.deleteOnExit(); file.deleteOnExit(); } }

#java File

File » Stream

A stream 'is' a sequence of bytes

When writing data to a stream, the stream is called an output stream.

When reading data from a stream, the stream is called an input stream.

If a stream has a buffer in memory, it is a buffered stream.

Binary Streams contain binary data.

Character Streams have character data and are used for storing and retrieving text

ClassDescriptionInputStreamThe base class for byte stream input operations.

OutputStreamThe base class for byte stream output operations.

BufferedInputStreamBuffers input from another stream in memory to make the read operations more efficient.

import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.FileInputStream; public class FileStream { public static void main(String[] args) throws IOException { final File dd = new File("D:\\", "text.txt"); final FileStream fs = new FileStream(); fs.a(dd); fs.b(new File("D:\\", "na.txt")); copy("D:\\text.txt", "D:\\log.txt"); copy(System.in, System.out); } private void a(final File dd) throws IOException { final FileInputStream fin = new FileInputStream(dd); try { copy(fin, System.out); } finally { fin.close(); } } private void b(final File dd) throws IOException { InputStream in = null; try { in = dd.toURI().toURL().openStream(); for (int c = in.read(); c != -1; c = in.read()) { System.out.write(c); } System.out.flush(); in.close(); } finally { if (in != null) in.close(); } } public static void copy(final InputStream in, final OutputStream out) throws IOException { final byte[] buffer = new byte[1024]; while (true) { final int bytesRead = in.read(buffer); if (bytesRead == -1) break; out.write(buffer, 0, bytesRead); } } public static void copy(final String inFile, final String outFile) throws IOException { FileInputStream fin = null; FileOutputStream fout = null; try { fin = new FileInputStream(inFile); fout = new FileOutputStream(outFile); copy(fin, fout); } finally { if (fin != null) fin.close(); if (fout != null) fout.close(); } } }

#java File

File » BufferedInputStream

For faster reading you should use BufferedInputStream to wrap any InputStream. BufferedInputStream has two constructors that accept an InputStream:

public BufferedInputStream(InputStream in) public BufferedInput Stream (Input Stream in, int bufferSize)

For example, the following code wraps a FileInputStream with a BufferedInputStream.

FileInputStream fis = new FileInputStream(aFile); BufferedInputStream bis = new BufferedInputStream (fis);

Then, instead of calling the methods on fis, work with the BufferedInputStream bis.

import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.util.prefs.Preferences; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class FileBufferedInputStream { private static final Logger LOG = LoggerFactory.getLogger("FileBufferedInputStream"); public static void main(String[] args) throws Exception { final File file = new File("D:\\", "text.txt"); final File ofile = new File("D:\\", "log.txt"); final FileBufferedInputStream fbins =new FileBufferedInputStream(); fbins.b(file); fbins.c(file); fbins.d(file); fbins.e(file, ofile); fbins.f(new File("D:\\", "na.txt")); fbins.g(); fbins.a(); } private void a() throws IOException { final BufferedInputStream bin = new BufferedInputStream(System.in); final BufferedOutputStream bout = new BufferedOutputStream(System.out); while (true) { int datum = bin.read(); if (datum == -1) break; bout.write(datum); } bout.flush(); bin.close(); bout.close(); } private void b(final File file) throws IOException { final FileInputStream fin = new FileInputStream(file); final BufferedInputStream bin = new BufferedInputStream(fin); final byte[] buffer = new byte[1024]; int bytesRead = 0; while ((bytesRead = bin.read(buffer)) != -1) { final String chunk = new String(buffer, 0, bytesRead); LOG.info(chunk); } bin.close(); fin.close(); } private void c(final File file) throws IOException { final FileInputStream fin = new FileInputStream(file); final BufferedInputStream bin = new BufferedInputStream(fin); byte[] contents = new byte[1024]; int bytesRead = 0; String strFileContents; while ((bytesRead = bin.read(contents)) != -1) { strFileContents = new String(contents, 0, bytesRead); LOG.info(strFileContents); } bin.close(); fin.close(); } private void d(final File file) throws IOException { final FileInputStream fin = new FileInputStream(file); final BufferedInputStream bin = new BufferedInputStream(fin); while (bin.available() > 0) { LOG.info(""+(char) bin.read()); } bin.close(); fin.close(); } private void e(final File in, final File out) throws IOException { final FileInputStream fin = new FileInputStream(in); final BufferedInputStream bfin = new BufferedInputStream(fin); final FileOutputStream fop = new FileOutputStream(out); final BufferedOutputStream bfop = new BufferedOutputStream(fop); int i; do { i = bfin.read(); if (i != -1) bfop.write(i); } while (i != -1); bfop.flush(); bfin.close(); fin.close(); bfop.close(); fop.close(); } private void f(final File file) throws Exception { final FileInputStream fin = new FileInputStream(file); final BufferedInputStream bin = new BufferedInputStream(fin); Preferences.importPreferences(fin); bin.close(); fin.close(); } private void g() throws Exception { LOG.info("What is your name? "); final StringBuffer response = new StringBuffer(); final BufferedInputStream buff = new BufferedInputStream(System.in); int in = 0; char inChar; do { in = buff.read(); inChar = (char) in; if ((in != -1) & (in != '\n') & (in != '\r')) { response.append(inChar); } } while ((in != -1) & (inChar != '\n') & (in != '\r')); buff.close(); LOG.info("Hello, " + response.toString()); } }

#java File

File » InflaterInputStream

import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream; import java.util.zip.DeflaterOutputStream; import java.util.zip.InflaterInputStream; public class FileInflaterInputStream { public static void main(String[] args) throws Exception { final File ifile = new File("D:\\", "iabc.txt"); final File ofile = new File("D:\\", "oabc.txt"); if (ofile.exists()) { ofile.delete(); } FileInputStream fis = new FileInputStream(ifile); FileOutputStream fos = new FileOutputStream(ofile); DeflaterOutputStream dos = new DeflaterOutputStream(fos); if (ifile.exists()) { ifile.delete(); } doCopy(fis, dos); FileInputStream fis2 = new FileInputStream(ofile); InflaterInputStream iis = new InflaterInputStream(fis2); FileOutputStream fos2 = new FileOutputStream(ifile); doCopy(iis, fos2); dos.flush(); fos.close(); iis.close(); fis.close(); } public static void doCopy(InputStream is, OutputStream os) throws Exception { int oneByte; while ((oneByte = is.read()) != -1) { os.write(oneByte); } os.flush(); os.close(); is.close(); } }

#java File

File » File

import java.io.File; import java.io.FilenameFilter; import java.net.URI; import org.apache.commons.io.FileUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.ArrayList; import java.util.Calendar; import java.util.Date; import java.util.List; import javax.swing.Icon; import javax.swing.ImageIcon; import javax.swing.JFrame; import javax.swing.JLabel; public class FileFile { private static final Logger LOG = LoggerFactory.getLogger("FileFile"); static File file = new File("D:\\" + File.separator); static File file1 = new File("D:" + File.separator, "text.txt"); static File file2 = new File("test.txt"); @SuppressWarnings({ "restriction", "unused" }) public static void main(String[] args) throws Exception { File remoteFile = new File(new URI("file:///index.htm")); LOG.info("getName: " + file1.getName()); LOG.info("getPath: " + file1.getPath()); LOG.info("isAbsolute: " + file1.isAbsolute()); LOG.info("getParent: " + file1.getParent()); LOG.info("file1: " + file1); LOG.info("getParentFile: " + file1.getParentFile()); LOG.info("exists: " + file1.exists()); LOG.info("isDirectory: " + file1.isDirectory()); LOG.info("isFile: " + file1.isFile()); LOG.info("isHidden: " + file1.isHidden()); LOG.info("canRead: " + file1.canRead()); LOG.info("canWrite: " + file1.canWrite()); LOG.info("getAbsolutePath: " + file1.getAbsolutePath()); LOG.info("getAbsoluteFile: " + file1.getAbsoluteFile()); LOG.info("getCanonicalPath() = " + file.getCanonicalPath()); LOG.info("getPath() = " + file.getPath()); LOG.info("" + file1.length()); long size = file1.length(); String display = FileUtils.byteCountToDisplaySize(size); LOG.info("Name = " + file1.getName()); LOG.info("size = " + size); LOG.info("Display = " + display); LOG.info("" + new Date(file1.lastModified())); for (String s : file.list()) { LOG.info(s); } for (File s : file.listFiles()) { LOG.info("" + s); } long totalSpace = file1.getTotalSpace(); LOG.info("Total space on " + file1 + " = " + totalSpace + "bytes"); long freeSpace = file1.getFreeSpace(); LOG.info("Free space on " + file1 + " = " + freeSpace + "bytes"); System.out.printf("Good url %s%n", file2.toURI().toURL()); File[] roots = File.listRoots(); for (int i = 0; i < roots.length; i++) { LOG.info("" + roots[i]); LOG.info("Free space = " + roots[i].getFreeSpace()); LOG.info("Usable space = " + roots[i].getUsableSpace()); LOG.info("Total space = " + roots[i].getTotalSpace()); LOG.info(""); } file2.createNewFile(); LOG.info("Before. canWrite?" + file2.canWrite()); file.setWritable(false); LOG.info("After. canWrite?" + file2.canWrite()); if (file2.exists()) { file2.delete(); } file2.createNewFile(); if (!file2.exists()) { LOG.info("File not found."); return; } else { if (file2.canRead()) LOG.info(" Readable"); else LOG.info(" Not Readable"); if (file2.canWrite()) LOG.info(" Writable"); else LOG.info(" Not Writable"); LOG.info(" Last modified on " + new Date(file2.lastModified())); long t = Calendar.getInstance().getTimeInMillis(); if (!file2.setLastModified(t)) LOG.info("Can’t set time."); if (!file2.setReadOnly()) LOG.info("Can’t set to read-only."); if (file2.canRead()) LOG.info(" Readable"); else LOG.info(" Not Readable"); if (file2.canWrite()) LOG.info(" Writable"); else LOG.info(" Not Writable"); LOG.info(" Last modified on " + new Date(file2.lastModified())); if (!file2.setWritable(true, false)) LOG.info("Can’t return to read/write."); if (file2.canRead()) LOG.info(" Readable"); else LOG.info(" Not Readable"); if (file2.canWrite()) LOG.info(" Writable"); else LOG.info(" Not Writable"); } if (file2.exists()) { file2.deleteOnExit(); } // getXMLFiles(file1); getFileExtensionName(file1); sun.awt.shell.ShellFolder sf = sun.awt.shell.ShellFolder .getShellFolder(file1); Icon icon = new ImageIcon(sf.getIcon(true)); LOG.info("type = " + sf.getFolderType()); JLabel label = new JLabel(icon); JFrame frame = new JFrame(); frame.getContentPane().add(label); frame.pack(); frame.setVisible(true); LOG.info("pathSeparatorChar = " + File.pathSeparatorChar); /* * file5.renameTo(hhh); file5.setReadOnly(); LOG.info("" + file5.canRead()); * File[] contents = myDir1.listFiles(select); for (File file : contents) { * LOG.info(file + " is a " + (file.isDirectory() ? "directory" : "file") + * " last modified on\n" + new Date(file.lastModified())); } * filea3.createNewFile(); * filea1.mkdir(); filea2.mkdirs(); File tmp = File.createTempFile("foo", * "tmp"); LOG.info("Your temp file is " + tmp.getCanonicalPath()); boolean * success = filea4.delete(); LOG.info("" + success); * fileb1.deleteOnExit(); * if (filec1.exists()) { file.delete(); } */ } public static File[] getXMLFiles(final File folder) { final List aList = new ArrayList(); final File[] files = folder.listFiles(); for (final File pf : files) { if (pf.isFile() && getFileExtensionName(pf).indexOf("xml") != -1) { aList.add(pf); } } return aList.toArray(new File[aList.size()]); } public static String getFileExtensionName(final File f) { if (f.getName().indexOf('.') == -1) { return ""; } else { return f.getName().substring(f.getName().length() - 3, f.getName().length()); } } } class FileListFilter implements FilenameFilter { private String name; private String extension; public FileListFilter(final String name, final String extension) { this.name = name; this.extension = extension; } public boolean accept(final File directory, final String filename) { boolean fileOK = true; if (name != null) { fileOK = filename.startsWith(name); } if (extension != null) { fileOK = filename.endsWith('.' + extension); } return fileOK; } }

#java File

File » Introduction

There are four types of streams: InputStream, OutputStream, Reader, and Writer.

Reader. A stream to read characters.

Writer. A stream to write characters.

InputStream. A stream to read binary data.

OutputStream. A stream to write binary data.

For better performance, use the buffered I/O classes: BufferedInputStream, BufferedOutputStream, BufferedReader, and BufferedWriter.

Reading from and writing to a stream dictate that you do so sequentially. The java.io.RandomAccessFile is for non-sequential operations.

For object serialization and deserialization, you can use the ObjectInputStream and ObjectOutputStream classes.

You use an InputStream to read binary data.

InputStream | +-- FileInputStream | +-- BufferedInputStream

FileInputStream enables easy reading from a file.

BufferedInputStream provides data buffering that improves performance.

The ObjectInputStream class is used in object serialization.

The OutputStream abstract class represents a stream for writing binary data

OutputStream | +--FileOutputStream | +--BufferedOutputStream. | +--ObjectOutputStream

FileOutputStream provides a convenient way to write to a file.

BufferedOutputStream provides better performance.

ObjectOutputStream class plays an important role in object serialization.

The OutputStream class defines three write method overloads, which are mirrors of the read method overloads in InputStream:

public void write (int b) public void write (byte[] data) public void write (byte[] data, int offset, int length)

The first overload writes the lowest 8 bits of the integer b to this OutputStream.

The second writes the content of a byte array to this OutputStream.

The third overload writes length bytes of the data starting at offset offset.

close() method closes the OutputStream.

flush() method forces any buffered content to be written out to the sink

A File object represents a file or directory pathname. You can pass an absolute path to a file or directory like this:

File file1 = new File ("C:\\temp\\myNote.txt"); // in Windows File file2 = new File ("/tmp/myNote.txt"); // in Linux/Unix

getName(): Returns the name of the file without the path or the directory name

The java.io.File class in Mustang comes with several new features.

The java.io.File class in Mustang provides methods for checking hard disk space and the amount used.

The java.io.File class in Mustang possesses methods for changing file attributes.

Here are the new methods:

public long getFreeSpace () Returns the size, in bytes, of the partition referenced by this File object.

public long getFreeSpace () Returns the amount of free space, in bytes, in the partition referenced by this File object.

public long getUsableSpace () Returns the number of bytes available to this virtual machine on the partition referenced by this File object. The difference between getUsableSpace and getFreeSpace is that the former takes into account restrictions imposed by the operating system, such as write permissions. The latter does not.

public boolean setWritable (boolean writable, boolean ownerOnly) Sets the owner's or everybody's write permission for the path referenced by this File object.

public boolean setWritable (boolean writable) Sets the owner's write permission for the path referenced by this File object.

public boolean setReadable (boolean readable, boolean ownerOnly) Sets the owner's or everybody's read permission for the path referenced by this File object.

public boolean setReadable (boolean readable) Sets the owner's read permission for the path referenced by this File object.

public boolean setExecutable (boolean executable, boolean ownerOnly) Sets the owner's or everybody's execute permission for the path referenced by this File object.

public boolean setExecutable (boolean executable) Sets the owner's execute permission for the path referenced by this File object.

public boolean canExecute () Tests if the application has the right to execute the file referenced by this File object.

Java 6 adds canExecute plus setReadable, setWritable, and setExecutable methods to change a file’s attributes.

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#java File

Links on java exceptions

http://javarevisited.blogspot.in/2013/03/0-exception-handling-best-practices-in-Java-Programming.html

http://c2.com/cgi/wiki?ExceptionPatterns

http://codebuild.blogspot.in/2012/01/15-best-practices-about-exception.html

https://today.java.net/article/2006/04/04/exception-handling-antipatterns

http://stackoverflow.com/questions/4589750/exception-handling-pattern

http://stackoverflow.com/questions/425281/java-style-properly-handling-exceptions?rq=1

http://www.onjava.com/pub/a/onjava/2003/11/19/exceptions.html

#java exceptions

#data access

This tutorial explains how to use a DAO manager to enable connections to be used across multiple DAO instances, and transactions to span across method calls on multiple DAOs.

#data access

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