filehandler2.java

关于文件处理的类

//**************************************
// Name: Universal File Handler
// Description:There is a lot you can do with this class! See the code to see the exact methods and how they work. You can delete files, copy files, insert a line into a file (alphabetically or append at end), search for a line, retrieve the nth line as a String, count the number of lines in the files, and more!
// By: Jennica Jane Humphrey
//
//
// Inputs:None
//
// Returns:None
//
//Assumes:Simply paste the code below into a file, UniversalFileHandler.java... you have to configure two variables to make sure the files will to go to the directory you want them to go to. To use the code, create a new instance in another class... like UniversalFileHandler uFileHandler = new UniversalFileHandler();
//
//Side Effects:None
//This code is copyrighted and has limited warranties.
//Please see http://www.Planet-Source-Code.com/xq/ASP/txtCodeId.2417/lngWId.2/qx/vb/scripts/ShowCode.htm
//for details.
//**************************************

import java.io.*;


    class UniversalFileHandler {
    /**********************************************************
    *
    * UNIVERSAL FILE HANDLER
    * UniversalFileHandler.java
    *
    * The goal here is to be as encapsulated as possible.
    * This class should be reuseable for a wide variety of
    * purposes and have no "specialization" whatsoever
    * for my particular applications.
    *
    * Does various things with files. Like, delete,
    * create, insert a line into a file in lexiconial
    * order and all that.
    *
    *********************************************************
    *
    * CUSTOMIZING IT FOR YOUR USE
    *
    * All you need to do is modify the filePath and
    * the fileSlash variables at the end of the class.
    *
    * FILEPATH: The directory you want to place the
    * files in.
    *
    * FILESLASH: Windows users should
    * keep the fileSlash variable unchanged at "\\".
    * Linux probably should change the variable to
    * "/".
    *
    *********************************************************
    *
    * METHODS INCLUDED IN THIS CLASS
    *
    * There is a lot you can do with this class! Here are
    * the methods, as they appear in this class (see the
    * actual methods themselves to find out how to use them):
    *
    * deleteFile: Deletes a file.
    *
    * createFile: Creates a (blank) file.
    *
    * fileExists: Checks to see if a file exists.
    *
    * copyFile: Copies the original file into a new file.
    *
    * searchForString: Searches for a partial string in the
    * file at the beginning of a new line.
    *
    * numberOfLines: Returns the number of lines in a given
    * file.
    *
    * returnFullString: Returns the full line of a partial
    * string at the beginning of a line (ie, if you search for
    * "ABC", you'll get "ABCDEFGHIJKLMNOPQRSTUVWXYZ" returned)
    *
    * retrieveEndLineChar: Returns the last character in a
    * specified line in the file.
    *
    * writeIntoFile: Writes a line at the end of the file.
    *
    * insertIntoFile: Inserts a line in the file in
    * alphabetical order.
    *
    * deleteFromFile: Deletes a single line from the file.
    *
    * getLine: Returns the nth line from the file.
    *
    ***********************************************************
    *
    * If you see any errors in this code, please contact
    * me at [e-mail]. Please keep the comments
    * on this java file unchanged and keep my name and email.
    *
    * I created this class for a school project and it just
    * kept growing and growing... I hope people will get as
    * much use out of this as I have.
    *
    * Feel free to use this class in whatever way you want.
    * I've used it with almost all of my applications that
    * relate to file manipulation... it has been a great
    * timesaver. My java knowledge is largely self-taught,
    * so please pardon any gaffes I make.
    *
    * @seeRandomAccessFile
    * @seeFile
    * @author Jennica Humphrey ([e-mail])
    * @version %I%, %G%
    * @since JDK1.3
    *
    */
    /**
    * Deletes the file if it does already exist.
    *
    * @param fileName Name of the file to be deleted.
    * @seeFile
    * @sinceJDK1.3
    */


        public void deleteFile(String fileName) {
        String path = new String();
        path = filePath; // uses the filePath directory
        File f1 = new File( path, fileName);
        if (f1.exists())
        f1.delete();
    } // Ends deleteFile
    /**
    * Creates the file if it does already exist.
    *
    * @param fileName Name of the file to be deleted.
    * @returnTRUE if file is successfully created,
    *FALSE if it already exists or if some
    * other error happens.
    * @seeFile
    * @sinceJDK1.3
    */


        public boolean createFile(String fileName) {
        String path = new String();
        path = filePath; // uses the filePath directory
        boolean fileCreated = false;
        File f1 = new File( path, fileName);


            if ( !f1.exists() ) {


                try {
                f1.createNewFile();
                fileCreated = true;
            }


                catch( IOException e ) {
            }
        }
        return fileCreated;
    } // Ends createFile
    /**
    * Checks to see if a file exists.
    *
    * @param fileName Name of the file to be deleted.
    * @returnTRUE if the file exists, FALSE if the file
    *does not exist.
    * @seeFile
    * @sinceJDK1.3
    */


        public boolean fileExists(String fileName) {
        // Makes sure file exists
        String path = new String();
        path = filePath; // Uses the filePath dir
        boolean fileFound = false;
        File f1 = new File(path, fileName);
        if (f1.exists())
        fileFound = true;
        return fileFound;
    } // ends fileExists
    /**
    * Copies a file (assuming it exists) into a new file.
    *
    * @param fileNameName of the file to be copied.
    * @param copiedFileName Name of the file to be written into.
    * @see RandomAccessFile
    * @see#fileExists
    * @see#createFile
    * @sinceJDK1.3
    */


        public void copyFile(String fileName, String copiedFileName) {
        // Copies one file into a new file (if that file doesn't exist )
        if ( fileExists(fileName) ) // Creates new file if original file does exist
        createFile( copiedFileName );
        if ( fileExists(fileName) ) { // If original file exists, copy file into new file


            try {
            fileName = filePath + fileSlash + fileName;
            copiedFileName = filePath + fileSlash + copiedFileName;
            RandomAccessFile raf = new RandomAccessFile(fileName, "r");
            RandomAccessFile raf2 = new RandomAccessFile(copiedFileName, "rw");
            raf.seek( 0 );
            raf2.seek( 0 );
            Long lengthFile = new Long( raf.length() );
            byte[] b = new byte[ lengthFile.intValue() ];
            raf.readFully(b);
            raf2.write(b);
            raf.close();
        }


            catch (IOException e) {
            System.out.println("Error opening file: " + e);
        }
    }
} // Ends copyFile
/**
* Searches for a partial string at the beginning of a new line
* in a file name. For instance, searching for "ABC" in a file
* with the line "ABCDEFGHIJKL" will return TRUE, but searching
* for "BCD" will not return TRUE.
*
* Does not assume lines are in alphabetical order.
*
* @param fileName Name of the file to be searched
* @param searchString Partial string to be searching for.
* @returnTRUE if there is a match for the string being
*searched for, FALSE if there is no match.
* @see RandomAccessFile
* @sinceJDK1.3
*/


    public boolean searchForString(String fileName, String searchString) {
    int i;
    long filePointer;
    boolean stringFound = false;
    fileName = filePath + fileSlash + fileName;


        try {
        RandomAccessFile raf = new RandomAccessFile(fileName, "rw");
        raf.seek( 0 ); // Starts at the beginning of the file
        String thisString = new String();


            do {
            thisString = raf.readLine();
            if ( thisString.length() > searchString.length() )
            thisString = thisString.substring( 0, searchString.length() );
            i = searchString.compareToIgnoreCase( thisString );
            if ( i == 0 )
            stringFound = true;
        } while ( raf.getFilePointer() < raf.length() );
        raf.close();
    }


        catch (IOException e) {
        System.out.println("Error opening file: " + e);
    }
    return stringFound;
} // ends searchForString
/**
* Returns the number of lines in a given file.
*
* @param fileName File to check for.
* @returnThe number of lines within a file.
* @seeRandomAccessFile
* @sinceJDK1.3
*/


    public int numberOfLines( String fileName ) {
    int lineCount = 0;
    fileName = filePath + fileSlash + fileName;


        try {
        RandomAccessFile raf = new RandomAccessFile(fileName, "rw");
        raf.seek( 0 );


            if ( raf.length() > 0 ) {


                do {
                lineCount++;
                raf.readLine();
            } while ( raf.getFilePointer() < raf.length() );
        }
        raf.close();
    }


        catch (IOException e) {
        System.out.println("Error opening file: " + e);
    }
    return lineCount;
} // end lineCount
/**
* Returns the full string of a partial search. For example
* returnFullString( "jjh0901.txt", "abc" ) will return
* "abcFullLine".