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java/org/apache/tomcat/util/http/fileupload/FileItem.java

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+/*
+ * 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.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
+
+/**
+ * <p> This class represents a file or form item that was received within a
+ * <code>multipart/form-data</code> POST request.
+ *
+ * <p> After retrieving an instance of this class from a {@link
+ * org.apache.tomcat.util.http.fileupload.FileUpload FileUpload} instance (see
+ * {@link org.apache.tomcat.util.http.fileupload.FileUpload
+ * #parseRequest(RequestContext)}), you may
+ * either request all contents of the 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.
+ *
+ * <p> While this interface does not extend
+ * <code>javax.activation.DataSource</code> per se (to avoid a seldom used
+ * dependency), several of the defined methods are specifically defined with
+ * the same signatures as methods in that interface. This allows an
+ * implementation of this interface to also implement
+ * <code>javax.activation.DataSource</code> with minimal additional work.
+ *
+ * @since 1.3 additionally implements FileItemHeadersSupport
+ */
+public interface FileItem extends FileItemHeadersSupport {
+
+    // ------------------------------- 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.
+     *
+     * @throws IOException if an error occurs.
+     */
+    InputStream getInputStream() throws IOException;
+
+    /**
+     * 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.
+     */
+    String getContentType();
+
+    /**
+     * Returns the original file name in the client's file system, as provided by
+     * the browser (or other client software). In most cases, this will be the
+     * base file name, without path information. However, some clients, such as
+     * the Opera browser, do include path information.
+     *
+     * @return The original file name in the client's file system.
+     * @throws InvalidFileNameException The file name contains a NUL character,
+     *   which might be an indicator of a security attack. If you intend to
+     *   use the file name anyways, catch the exception and use
+     *   InvalidFileNameException#getName().
+     */
+    String getName();
+
+    // ------------------------------------------------------- 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.
+     */
+    boolean isInMemory();
+
+    /**
+     * Returns the size of the file item.
+     *
+     * @return The size of the file item, in bytes.
+     */
+    long getSize();
+
+    /**
+     * Returns the contents of the file item as an array of bytes.
+     *
+     * @return The contents of the file item as an array of bytes.
+     */
+    byte[] get();
+
+    /**
+     * Returns the contents of the file item as a String, using the specified
+     * encoding.  This method uses {@link #get()} to retrieve the
+     * contents of the item.
+     *
+     * @param encoding The character encoding to use.
+     *
+     * @return The contents of the item, as a string.
+     *
+     * @throws UnsupportedEncodingException if the requested character
+     *                                      encoding is not available.
+     */
+    String getString(String encoding) throws UnsupportedEncodingException;
+
+    /**
+     * Returns the contents of the file item as a String, using the default
+     * character encoding.  This method uses {@link #get()} to retrieve the
+     * contents of the item.
+     *
+     * @return The contents of the item, as a string.
+     */
+    String getString();
+
+    /**
+     * 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 method is not guaranteed to succeed if called more than once for
+     * the same item. This allows a particular implementation to use, for
+     * example, file renaming, where possible, rather than copying all of the
+     * underlying data, thus gaining a significant performance benefit.
+     *
+     * @param file The <code>File</code> into which the uploaded item should
+     *             be stored.
+     *
+     * @throws Exception if an error occurs.
+     */
+    void write(File file) throws Exception;
+
+    /**
+     * 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</code> instance is garbage
+     * collected, this method can be used to ensure that this is done at an
+     * earlier time, thus preserving system resources.
+     */
+    void delete();
+
+    /**
+     * Returns the name of the field in the multipart form corresponding to
+     * this file item.
+     *
+     * @return The name of the form field.
+     */
+    String getFieldName();
+
+    /**
+     * Sets the field name used to reference this file item.
+     *
+     * @param name The name of the form field.
+     */
+    void setFieldName(String name);
+
+    /**
+     * Determines whether or not a <code>FileItem</code> instance represents
+     * a simple form field.
+     *
+     * @return <code>true</code> if the instance represents a simple form
+     *         field; <code>false</code> if it represents an uploaded file.
+     */
+    boolean isFormField();
+
+    /**
+     * Specifies whether or not a <code>FileItem</code> instance represents
+     * a simple form field.
+     *
+     * @param state <code>true</code> if the instance represents a simple form
+     *              field; <code>false</code> if it represents an uploaded file.
+     */
+    void setFormField(boolean 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.
+     *
+     * @throws IOException if an error occurs.
+     */
+    OutputStream getOutputStream() throws IOException;
+
+}