com.sun.enterprise.admin.servermgmt.stringsubs.impl.LargeFileSubstitutionHandler Maven / Gradle / Ivy

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package com.sun.enterprise.admin.servermgmt.stringsubs.impl;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.util.logging.Level;

/**
 * Creates {@link Reader} and {@link Writer} for the String substitution file.
 * Implementation is useful for large files which cann't be read entirely in a
 *  memory or need a substantial amount of memory.
 * 
 * To perform substitution it take helps of temporary file to write output, after
 * substitution, temporary file renamed to input file.
 *  
 */
public class LargeFileSubstitutionHandler extends FileSubstitutionHandler {
    private static final String BACKUP_FILE_PREFIX = ".bkp";
    private static final String TEMP_FILE_PREFIX = ".tmp";
    private File outputFile;

    public LargeFileSubstitutionHandler(File file) throws FileNotFoundException {
        super(file);
    }

    @Override
    public Reader getReader() {
        try {
            reader = new BufferedReader(new InputStreamReader(new FileInputStream(inputFile)));
        } catch (FileNotFoundException e) {
            LOGGER.log(Level.INFO, STRINGS.get("invalidFileLocation", inputFile.getAbsolutePath()) 
                    , e);
        }
        return reader;
    }

    @Override
    public Writer getWriter() {
        outputFile = new File(inputFile.getAbsolutePath() + TEMP_FILE_PREFIX);
        try {
            if (!outputFile.exists()) {
                if (!outputFile.createNewFile()) {
                    throw new IOException();
                }
            }
            writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(outputFile)));
        } catch (IOException e) {
            LOGGER.log(Level.INFO, STRINGS.get("failureTempFileCreation",
                    outputFile.getAbsolutePath(), e));
        }
        return writer;
    }

    @Override
    public void finish() {
        super.finish();
        String inputFileName = inputFile.getName();
        File inputBackUpfile = new File(inputFile.getAbsolutePath() + BACKUP_FILE_PREFIX);
        if (inputFile.renameTo(inputBackUpfile)) {
            if (outputFile.renameTo(new File(inputFile.getAbsolutePath()))) {
                if (!inputBackUpfile.delete()) {
                    LOGGER.log(Level.INFO, STRINGS.get("failureInBackUpFileDeletion", 
                            inputBackUpfile.getAbsolutePath()));
                }
            } else {
                LOGGER.log(Level.INFO, STRINGS.get("failureInFileRename", outputFile.getAbsolutePath(),
                        inputFileName));
            }
        } else {
            LOGGER.log(Level.WARNING,  STRINGS.get("failureInFileRename", inputFile.getAbsolutePath(),
                   inputBackUpfile.getName()));
        }
    }
}