defaultfileitem.java

业界著名的tomcat服务器的最新6.0的源代码。

/*
 * 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:[e-mail]">Rafal Krzewski</a>
 * @author <a href="mailto:[e-mail]">Sean Legassick</a>
 * @author <a href="mailto:[e-mail]">Jason van Zyl</a>
 * @author <a href="mailto:[e-mail]">John McNally</a>
 * @author <a href="mailto:[e-mail]">Martin Cooper</a>
 * @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</code> 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</code> instance.
     *
     * @param fieldName     The name of the form field.
     * @param contentType   The content type passed by the browser or
     *                      <code>null</code> 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</code> 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</code> if
     * not defined.
     *
     * @return The content type passed by the browser or <code>null</code> 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</code> if the file contents will be read
     *         from memory; <code>false</code> 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);
    }