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Tomcat example source code file (DefaultFileItem.java)

This example Tomcat source code file (DefaultFileItem.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

bufferedinputstream, bufferedoutputstream, bytearrayinputstream, defaultfileitem, deferredfileoutputstream, file, file, fileinputstream, fileoutputstream, fileoutputstream, io, ioexception, ioexception, string, string

The Tomcat DefaultFileItem.java source code

/*
 * 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.
 */


package org.apache.tomcat.util.http.fileupload;


import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;


/**
 * <p> The default implementation of the
 * {@link org.apache.tomcat.util.http.fileupload.FileItem FileItem} interface.
 *
 * <p> After retrieving an instance of this class from a {@link
 * org.apache.tomcat.util.http.fileupload.DiskFileUpload DiskFileUpload} instance (see
 * {@link org.apache.tomcat.util.http.fileupload.DiskFileUpload
 * #parseRequest(javax.servlet.http.HttpServletRequest)}), you may
 * either request all contents of file at once using {@link #get()} or
 * request an {@link java.io.InputStream InputStream} with
 * {@link #getInputStream()} and process the file without attempting to load
 * it into memory, which may come handy with large files.
 *
 * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski
 * @author <a href="mailto:sean@informage.net">Sean Legassick
 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl
 * @author <a href="mailto:jmcnally@apache.org">John McNally
 * @author <a href="mailto:martinc@apache.org">Martin Cooper
 * @author Sean C. Sullivan
 *
 * @version $Id: DefaultFileItem.java 467222 2006-10-24 03:17:11Z markt $
 */
public class DefaultFileItem
    implements FileItem
{

    // ----------------------------------------------------------- Data members


    /**
     * Counter used in unique identifier generation.
     */
    private static int counter = 0;


    /**
     * The name of the form field as provided by the browser.
     */
    private String fieldName;


    /**
     * The content type passed by the browser, or <code>null if
     * not defined.
     */
    private String contentType;


    /**
     * Whether or not this item is a simple form field.
     */
    private boolean isFormField;


    /**
     * The original filename in the user's filesystem.
     */
    private String fileName;


    /**
     * The threshold above which uploads will be stored on disk.
     */
    private int sizeThreshold;


    /**
     * The directory in which uploaded files will be stored, if stored on disk.
     */
    private File repository;


    /**
     * Cached contents of the file.
     */
    private byte[] cachedContent;


    /**
     * Output stream for this item.
     */
    private DeferredFileOutputStream dfos;


    // ----------------------------------------------------------- Constructors


    /**
     * Constructs a new <code>DefaultFileItem instance.
     *
     * @param fieldName     The name of the form field.
     * @param contentType   The content type passed by the browser or
     *                      <code>null if not specified.
     * @param isFormField   Whether or not this item is a plain form field, as
     *                      opposed to a file upload.
     * @param fileName      The original filename in the user's filesystem, or
     *                      <code>null if not specified.
     * @param sizeThreshold The threshold, in bytes, below which items will be
     *                      retained in memory and above which they will be
     *                      stored as a file.
     * @param repository    The data repository, which is the directory in
     *                      which files will be created, should the item size
     *                      exceed the threshold.
     */
    DefaultFileItem(String fieldName, String contentType, boolean isFormField,
                    String fileName, int sizeThreshold, File repository)
    {
        this.fieldName = fieldName;
        this.contentType = contentType;
        this.isFormField = isFormField;
        this.fileName = fileName;
        this.sizeThreshold = sizeThreshold;
        this.repository = repository;
    }


    // ------------------------------- Methods from javax.activation.DataSource


    /**
     * Returns an {@link java.io.InputStream InputStream} that can be
     * used to retrieve the contents of the file.
     *
     * @return An {@link java.io.InputStream InputStream} that can be
     *         used to retrieve the contents of the file.
     *
     * @exception IOException if an error occurs.
     */
    public InputStream getInputStream()
        throws IOException
    {
        if (!dfos.isInMemory())
        {
            return new FileInputStream(dfos.getFile());
        }

        if (cachedContent == null)
        {
            cachedContent = dfos.getData();
        }
        return new ByteArrayInputStream(cachedContent);
    }


    /**
     * Returns the content type passed by the browser or <code>null if
     * not defined.
     *
     * @return The content type passed by the browser or <code>null if
     *         not defined.
     */
    public String getContentType()
    {
        return contentType;
    }


    /**
     * Returns the original filename in the client's filesystem.
     *
     * @return The original filename in the client's filesystem.
     */
    public String getName()
    {
        return fileName;
    }


    // ------------------------------------------------------- FileItem methods


    /**
     * Provides a hint as to whether or not the file contents will be read
     * from memory.
     *
     * @return <code>true if the file contents will be read
     *         from memory; <code>false otherwise.
     */
    public boolean isInMemory()
    {
        return (dfos.isInMemory());
    }


    /**
     * Returns the size of the file.
     *
     * @return The size of the file, in bytes.
     */
    public long getSize()
    {
        if (cachedContent != null)
        {
            return cachedContent.length;
        }
        else if (dfos.isInMemory())
        {
            return dfos.getData().length;
        }
        else
        {
            return dfos.getFile().length();
        }
    }


    /**
     * Returns the contents of the file as an array of bytes.  If the
     * contents of the file were not yet cached in memory, they will be
     * loaded from the disk storage and cached.
     *
     * @return The contents of the file as an array of bytes.
     */
    public byte[] get()
    {
        if (dfos.isInMemory())
        {
            if (cachedContent == null)
            {
                cachedContent = dfos.getData();
            }
            return cachedContent;
        }

        byte[] fileData = new byte[(int) getSize()];
        FileInputStream fis = null;

        try
        {
            fis = new FileInputStream(dfos.getFile());
            fis.read(fileData);
        }
        catch (IOException e)
        {
            fileData = null;
        }
        finally
        {
            if (fis != null)
            {
                try
                {
                    fis.close();
                }
                catch (IOException e)
                {
                    // ignore
                }
            }
        }

        return fileData;
    }


    /**
     * Returns the contents of the file as a String, using the specified
     * encoding.  This method uses {@link #get()} to retrieve the
     * contents of the file.
     *
     * @param encoding The character encoding to use.
     *
     * @return The contents of the file, as a string.
     *
     * @exception UnsupportedEncodingException if the requested character
     *                                         encoding is not available.
     */
    public String getString(String encoding)
        throws UnsupportedEncodingException
    {
        return new String(get(), encoding);
    }


    /**
     * Returns the contents of the file as a String, using the default
     * character encoding.  This method uses {@link #get()} to retrieve the
     * contents of the file.
     *
     * @return The contents of the file, as a string.
     */
    public String getString()
    {
        return new String(get());
    }


    /**
     * A convenience method to write an uploaded item to disk. The client code
     * is not concerned with whether or not the item is stored in memory, or on
     * disk in a temporary location. They just want to write the uploaded item
     * to a file.
     * <p>
     * This implementation first attempts to rename the uploaded item to the
     * specified destination file, if the item was originally written to disk.
     * Otherwise, the data will be copied to the specified file.
     * <p>
     * This method is only guaranteed to work <em>once, the first time it
     * is invoked for a particular item. This is because, in the event that the
     * method renames a temporary file, that file will no longer be available
     * to copy or rename again at a later time.
     *
     * @param file The <code>File into which the uploaded item should
     *             be stored.
     *
     * @exception Exception if an error occurs.
     */
    public void write(File file) throws Exception
    {
        if (isInMemory())
        {
            FileOutputStream fout = null;
            try
            {
                fout = new FileOutputStream(file);
                fout.write(get());
            }
            finally
            {
                if (fout != null)
                {
                    fout.close();
                }
            }
        }
        else
        {
            File outputFile = getStoreLocation();
            if (outputFile != null)
            {
                /*
                 * The uploaded file is being stored on disk
                 * in a temporary location so move it to the
                 * desired file.
                 */
                if (!outputFile.renameTo(file))
                {
                    BufferedInputStream in = null;
                    BufferedOutputStream out = null;
                    try
                    {
                        in = new BufferedInputStream(
                            new FileInputStream(outputFile));
                        out = new BufferedOutputStream(
                                new FileOutputStream(file));
                        byte[] bytes = new byte[2048];
                        int s = 0;
                        while ((s = in.read(bytes)) != -1)
                        {
                            out.write(bytes, 0, s);
                        }
                    }
                    finally
                    {
                        try
                        {
                            in.close();
                        }
                        catch (IOException e)
                        {
                            // ignore
                        }
                        try
                        {
                            out.close();
                        }
                        catch (IOException e)
                        {
                            // ignore
                        }
                    }
                }
            }
            else
            {
                /*
                 * For whatever reason we cannot write the
                 * file to disk.
                 */
                throw new FileUploadException(
                    "Cannot write uploaded file to disk!");
            }
        }
    }


    /**
     * Deletes the underlying storage for a file item, including deleting any
     * associated temporary disk file. Although this storage will be deleted
     * automatically when the <code>FileItem instance is garbage
     * collected, this method can be used to ensure that this is done at an
     * earlier time, thus preserving system resources.
     */
    public void delete()
    {
        cachedContent = null;
        File outputFile = getStoreLocation();
        if (outputFile != null && outputFile.exists())
        {
            outputFile.delete();
        }
    }


    /**
     * Returns the name of the field in the multipart form corresponding to
     * this file item.
     *
     * @return The name of the form field.
     *
     * @see #setFieldName(java.lang.String)
     *
     */
    public String getFieldName()
    {
        return fieldName;
    }


    /**
     * Sets the field name used to reference this file item.
     *
     * @param fieldName The name of the form field.
     *
     * @see #getFieldName()
     *
     */
    public void setFieldName(String fieldName)
    {
        this.fieldName = fieldName;
    }


    /**
     * Determines whether or not a <code>FileItem instance represents
     * a simple form field.
     *
     * @return <code>true if the instance represents a simple form
     *         field; <code>false if it represents an uploaded file.
     *
     * @see #setFormField(boolean)
     *
     */
    public boolean isFormField()
    {
        return isFormField;
    }


    /**
     * Specifies whether or not a <code>FileItem instance represents
     * a simple form field.
     *
     * @param state <code>true if the instance represents a simple form
     *              field; <code>false if it represents an uploaded file.
     *
     * @see #isFormField()
     *
     */
    public void setFormField(boolean state)
    {
        isFormField = state;
    }


    /**
     * Returns an {@link java.io.OutputStream OutputStream} that can
     * be used for storing the contents of the file.
     *
     * @return An {@link java.io.OutputStream OutputStream} that can be used
     *         for storing the contensts of the file.
     *
     * @exception IOException if an error occurs.
     */
    public OutputStream getOutputStream()
        throws IOException
    {
        if (dfos == null)
        {
            File outputFile = getTempFile();
            dfos = new DeferredFileOutputStream(sizeThreshold, outputFile);
        }
        return dfos;
    }


    // --------------------------------------------------------- Public methods


    /**
     * Returns the {@link java.io.File} object for the <code>FileItem's
     * data's temporary location on the disk. Note that for
     * <code>FileItems that have their data stored in memory,
     * this method will return <code>null. When handling large
     * files, you can use {@link java.io.File#renameTo(java.io.File)} to
     * move the file to new location without copying the data, if the
     * source and destination locations reside within the same logical
     * volume.
     *
     * @return The data file, or <code>null if the data is stored in
     *         memory.
     */
    public File getStoreLocation()
    {
        return dfos.getFile();
    }


    // ------------------------------------------------------ Protected methods


    /**
     * Removes the file contents from the temporary storage.
     */
    protected void finalize()
    {
        File outputFile = dfos.getFile();

        if (outputFile != null && outputFile.exists())
        {
            outputFile.delete();
        }
    }


    /**
     * Creates and returns a {@link java.io.File File} representing a uniquely
     * named temporary file in the configured repository path.
     *
     * @return The {@link java.io.File File} to be used for temporary storage.
     */
    protected File getTempFile()
    {
        File tempDir = repository;
        if (tempDir == null)
        {
            tempDir = new File(System.getProperty("java.io.tmpdir"));
        }

        String fileName = "upload_" + getUniqueId() + ".tmp";

        File f = new File(tempDir, fileName);
        f.deleteOnExit();
        return f;
    }


    // -------------------------------------------------------- Private methods


    /**
     * Returns an identifier that is unique within the class loader used to
     * load this class, but does not have random-like apearance.
     *
     * @return A String with the non-random looking instance identifier.
     */
    private static String getUniqueId()
    {
        int current;
        synchronized (DefaultFileItem.class)
        {
            current = counter++;
        }
        String id = Integer.toString(current);

        // If you manage to get more than 100 million of ids, you'll
        // start getting ids longer than 8 characters.
        if (current < 100000000)
        {
            id = ("00000000" + id).substring(id.length());
        }
        return id;
    }

}

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