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Tomcat example source code file (MultipartStream.java)

This example Tomcat source code file (MultipartStream.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

default_bufsize, header_separator, illegalboundaryexception, illegalboundaryexception, io, ioexception, ioexception, malformedstreamexception, malformedstreamexception, multipartstream, stream, stream_terminator, string, string, stringbuffer

The Tomcat MultipartStream.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.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;


/**
 * <p> Low level API for processing file uploads.
 *
 * <p> This class can be used to process data streams conforming to MIME
 * 'multipart' format as defined in
 * <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867. Arbitrarily
 * large amounts of data in the stream can be processed under constant
 * memory usage.
 *
 * <p> The format of the stream is defined in the following way:
* * <code> * multipart-body := preamble 1*encapsulation close-delimiter epilogue<br> * encapsulation := delimiter body CRLF<br> * delimiter := "--" boundary CRLF<br> * close-delimiter := "--" boudary "--"<br> * preamble := <ignore><br> * epilogue := <ignore><br> * body := header-part CRLF body-part<br> * header-part := 1*header CRLF<br> * header := header-name ":" header-value<br> * header-name := <printable ascii characters except ":"><br> * header-value := <any ascii characters except CR & LF><br> * body-data := <arbitrary data><br> * </code> * * <p>Note that body-data can contain another mulipart entity. There * is limited support for single pass processing of such nested * streams. The nested stream is <strong>required to have a * boundary token of the same length as the parent stream (see {@link * #setBoundary(byte[])}). * * <p>Here is an exaple of usage of this class.
* * <pre> * try { * MultipartStream multipartStream = new MultipartStream(input, * boundary); * boolean nextPart = malitPartStream.skipPreamble(); * OutputStream output; * while(nextPart) { * header = chunks.readHeader(); * // process headers * // create some output stream * multipartStream.readBodyPart(output); * nextPart = multipartStream.readBoundary(); * } * } catch(MultipartStream.MalformedStreamException e) { * // the stream failed to follow required syntax * } catch(IOException) { * // a read or write error occurred * } * * </pre> * * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski * @author <a href="mailto:martinc@apache.org">Martin Cooper * @author Sean C. Sullivan * * @version $Id: MultipartStream.java 467222 2006-10-24 03:17:11Z markt $ */ public class MultipartStream { // ----------------------------------------------------- Manifest constants /** * The maximum length of <code>header-part that will be * processed (10 kilobytes = 10240 bytes.). */ public static final int HEADER_PART_SIZE_MAX = 10240; /** * The default length of the buffer used for processing a request. */ protected static final int DEFAULT_BUFSIZE = 4096; /** * A byte sequence that marks the end of <code>header-part * (<code>CRLFCRLF). */ protected static final byte[] HEADER_SEPARATOR = {0x0D, 0x0A, 0x0D, 0x0A}; /** * A byte sequence that that follows a delimiter that will be * followed by an encapsulation (<code>CRLF). */ protected static final byte[] FIELD_SEPARATOR = { 0x0D, 0x0A }; /** * A byte sequence that that follows a delimiter of the last * encapsulation in the stream (<code>--). */ protected static final byte[] STREAM_TERMINATOR = { 0x2D, 0x2D }; // ----------------------------------------------------------- Data members /** * The input stream from which data is read. */ private InputStream input; /** * The length of the boundary token plus the leading <code>CRLF--. */ private int boundaryLength; /** * The amount of data, in bytes, that must be kept in the buffer in order * to detect delimiters reliably. */ private int keepRegion; /** * The byte sequence that partitions the stream. */ private byte[] boundary; /** * The length of the buffer used for processing the request. */ private int bufSize; /** * The buffer used for processing the request. */ private byte[] buffer; /** * The index of first valid character in the buffer. * <br> * 0 <= head < bufSize */ private int head; /** * The index of last valid characer in the buffer + 1. * <br> * 0 <= tail <= bufSize */ private int tail; /** * The content encoding to use when reading headers. */ private String headerEncoding; // ----------------------------------------------------------- Constructors /** * Default constructor. * * @see #MultipartStream(InputStream, byte[], int) * @see #MultipartStream(InputStream, byte[]) * */ public MultipartStream() { } /** * <p> Constructs a MultipartStream with a custom size buffer. * * <p> Note that the buffer must be at least big enough to contain the * boundary string, plus 4 characters for CR/LF and double dash, plus at * least one byte of data. Too small a buffer size setting will degrade * performance. * * @param input The <code>InputStream to serve as a data source. * @param boundary The token used for dividing the stream into * <code>encapsulations. * @param bufSize The size of the buffer to be used, in bytes. * * * @see #MultipartStream() * @see #MultipartStream(InputStream, byte[]) * */ public MultipartStream(InputStream input, byte[] boundary, int bufSize) { this.input = input; this.bufSize = bufSize; this.buffer = new byte[bufSize]; // We prepend CR/LF to the boundary to chop trailng CR/LF from // body-data tokens. this.boundary = new byte[boundary.length + 4]; this.boundaryLength = boundary.length + 4; this.keepRegion = boundary.length + 3; this.boundary[0] = 0x0D; this.boundary[1] = 0x0A; this.boundary[2] = 0x2D; this.boundary[3] = 0x2D; System.arraycopy(boundary, 0, this.boundary, 4, boundary.length); head = 0; tail = 0; } /** * <p> Constructs a MultipartStream with a default size buffer. * * @param input The <code>InputStream to serve as a data source. * @param boundary The token used for dividing the stream into * <code>encapsulations. * * @exception IOException when an error occurs. * * @see #MultipartStream() * @see #MultipartStream(InputStream, byte[], int) * */ public MultipartStream(InputStream input, byte[] boundary) throws IOException { this(input, boundary, DEFAULT_BUFSIZE); } // --------------------------------------------------------- Public methods /** * Retrieves the character encoding used when reading the headers of an * individual part. When not specified, or <code>null, the platform * default encoding is used. * * @return The encoding used to read part headers. */ public String getHeaderEncoding() { return headerEncoding; } /** * Specifies the character encoding to be used when reading the headers of * individual parts. When not specified, or <code>null, the platform * default encoding is used. * * @param encoding The encoding used to read part headers. */ public void setHeaderEncoding(String encoding) { headerEncoding = encoding; } /** * Reads a byte from the <code>buffer, and refills it as * necessary. * * @return The next byte from the input stream. * * @exception IOException if there is no more data available. */ public byte readByte() throws IOException { // Buffer depleted ? if (head == tail) { head = 0; // Refill. tail = input.read(buffer, head, bufSize); if (tail == -1) { // No more data available. throw new IOException("No more data is available"); } } return buffer[head++]; } /** * Skips a <code>boundary token, and checks whether more * <code>encapsulations are contained in the stream. * * @return <code>true if there are more encapsulations in * this stream; <code>false otherwise. * * @exception MalformedStreamException if the stream ends unexpecetedly or * fails to follow required syntax. */ public boolean readBoundary() throws MalformedStreamException { byte[] marker = new byte[2]; boolean nextChunk = false; head += boundaryLength; try { marker[0] = readByte(); marker[1] = readByte(); if (arrayequals(marker, STREAM_TERMINATOR, 2)) { nextChunk = false; } else if (arrayequals(marker, FIELD_SEPARATOR, 2)) { nextChunk = true; } else { throw new MalformedStreamException( "Unexpected characters follow a boundary"); } } catch (IOException e) { throw new MalformedStreamException("Stream ended unexpectedly"); } return nextChunk; } /** * <p>Changes the boundary token used for partitioning the stream. * * <p>This method allows single pass processing of nested multipart * streams. * * <p>The boundary token of the nested stream is required * to be of the same length as the boundary token in parent stream. * * <p>Restoring the parent stream boundary token after processing of a * nested stream is left to the application. * * @param boundary The boundary to be used for parsing of the nested * stream. * * @exception IllegalBoundaryException if the <code>boundary * has a different length than the one * being currently parsed. */ public void setBoundary(byte[] boundary) throws IllegalBoundaryException { if (boundary.length != boundaryLength - 4) { throw new IllegalBoundaryException( "The length of a boundary token can not be changed"); } System.arraycopy(boundary, 0, this.boundary, 4, boundary.length); } /** * <p>Reads the header-part of the current * <code>encapsulation. * * <p>Headers are returned verbatim to the input stream, including the * trailing <code>CRLF marker. Parsing is left to the * application. * * <p>TODO allow limiting maximum header size to * protect against abuse. * * @return The <code>header-part of the current encapsulation. * * @exception MalformedStreamException if the stream ends unexpecetedly. */ public String readHeaders() throws MalformedStreamException { int i = 0; byte b[] = new byte[1]; // to support multi-byte characters ByteArrayOutputStream baos = new ByteArrayOutputStream(); int sizeMax = HEADER_PART_SIZE_MAX; int size = 0; while (i < 4) { try { b[0] = readByte(); } catch (IOException e) { throw new MalformedStreamException("Stream ended unexpectedly"); } size++; if (b[0] == HEADER_SEPARATOR[i]) { i++; } else { i = 0; } if (size <= sizeMax) { baos.write(b[0]); } } String headers = null; if (headerEncoding != null) { try { headers = baos.toString(headerEncoding); } catch (UnsupportedEncodingException e) { // Fall back to platform default if specified encoding is not // supported. headers = baos.toString(); } } else { headers = baos.toString(); } return headers; } /** * <p>Reads body-data from the current * <code>encapsulation and writes its contents into the * output <code>Stream. * * <p>Arbitrary large amounts of data can be processed by this * method using a constant size buffer. (see {@link * #MultipartStream(InputStream,byte[],int) constructor}). * * @param output The <code>Stream to write data into. * * @return the amount of data written. * * @exception MalformedStreamException if the stream ends unexpectedly. * @exception IOException if an i/o error occurs. */ public int readBodyData(OutputStream output) throws MalformedStreamException, IOException { boolean done = false; int pad; int pos; int bytesRead; int total = 0; while (!done) { // Is boundary token present somewere in the buffer? pos = findSeparator(); if (pos != -1) { // Write the rest of the data before the boundary. output.write(buffer, head, pos - head); total += pos - head; head = pos; done = true; } else { // Determine how much data should be kept in the // buffer. if (tail - head > keepRegion) { pad = keepRegion; } else { pad = tail - head; } // Write out the data belonging to the body-data. output.write(buffer, head, tail - head - pad); // Move the data to the beging of the buffer. total += tail - head - pad; System.arraycopy(buffer, tail - pad, buffer, 0, pad); // Refill buffer with new data. head = 0; bytesRead = input.read(buffer, pad, bufSize - pad); // [pprrrrrrr] if (bytesRead != -1) { tail = pad + bytesRead; } else { // The last pad amount is left in the buffer. // Boundary can't be in there so write out the // data you have and signal an error condition. output.write(buffer, 0, pad); output.flush(); total += pad; throw new MalformedStreamException( "Stream ended unexpectedly"); } } } output.flush(); return total; } /** * <p> Reads body-data from the current * <code>encapsulation and discards it. * * <p>Use this method to skip encapsulations you don't need or don't * understand. * * @return The amount of data discarded. * * @exception MalformedStreamException if the stream ends unexpectedly. * @exception IOException if an i/o error occurs. */ public int discardBodyData() throws MalformedStreamException, IOException { boolean done = false; int pad; int pos; int bytesRead; int total = 0; while (!done) { // Is boundary token present somewere in the buffer? pos = findSeparator(); if (pos != -1) { // Write the rest of the data before the boundary. total += pos - head; head = pos; done = true; } else { // Determine how much data should be kept in the // buffer. if (tail - head > keepRegion) { pad = keepRegion; } else { pad = tail - head; } total += tail - head - pad; // Move the data to the beging of the buffer. System.arraycopy(buffer, tail - pad, buffer, 0, pad); // Refill buffer with new data. head = 0; bytesRead = input.read(buffer, pad, bufSize - pad); // [pprrrrrrr] if (bytesRead != -1) { tail = pad + bytesRead; } else { // The last pad amount is left in the buffer. // Boundary can't be in there so signal an error // condition. total += pad; throw new MalformedStreamException( "Stream ended unexpectedly"); } } } return total; } /** * Finds the beginning of the first <code>encapsulation. * * @return <code>true if an encapsulation was found in * the stream. * * @exception IOException if an i/o error occurs. */ public boolean skipPreamble() throws IOException { // First delimiter may be not preceeded with a CRLF. System.arraycopy(boundary, 2, boundary, 0, boundary.length - 2); boundaryLength = boundary.length - 2; try { // Discard all data up to the delimiter. discardBodyData(); // Read boundary - if succeded, the stream contains an // encapsulation. return readBoundary(); } catch (MalformedStreamException e) { return false; } finally { // Restore delimiter. System.arraycopy(boundary, 0, boundary, 2, boundary.length - 2); boundaryLength = boundary.length; boundary[0] = 0x0D; boundary[1] = 0x0A; } } /** * Compares <code>count first bytes in the arrays * <code>a and b. * * @param a The first array to compare. * @param b The second array to compare. * @param count How many bytes should be compared. * * @return <code>true if count first bytes in arrays * <code>a and b are equal. */ public static boolean arrayequals(byte[] a, byte[] b, int count) { for (int i = 0; i < count; i++) { if (a[i] != b[i]) { return false; } } return true; } /** * Searches for a byte of specified value in the <code>buffer, * starting at the specified <code>position. * * @param value The value to find. * @param pos The starting position for searching. * * @return The position of byte found, counting from beginning of the * <code>buffer, or -1 if not found. */ protected int findByte(byte value, int pos) { for (int i = pos; i < tail; i++) { if (buffer[i] == value) { return i; } } return -1; } /** * Searches for the <code>boundary in the buffer * region delimited by <code>head and tail. * * @return The position of the boundary found, counting from the * beginning of the <code>buffer, or -1 if * not found. */ protected int findSeparator() { int first; int match = 0; int maxpos = tail - boundaryLength; for (first = head; (first <= maxpos) && (match != boundaryLength); first++) { first = findByte(boundary[0], first); if (first == -1 || (first > maxpos)) { return -1; } for (match = 1; match < boundaryLength; match++) { if (buffer[first + match] != boundary[match]) { break; } } } if (match == boundaryLength) { return first - 1; } return -1; } /** * Returns a string representation of this object. * * @return The string representation of this object. */ public String toString() { StringBuffer sbTemp = new StringBuffer(); sbTemp.append("boundary='"); sbTemp.append(String.valueOf(boundary)); sbTemp.append("'\nbufSize="); sbTemp.append(bufSize); return sbTemp.toString(); } /** * Thrown to indicate that the input stream fails to follow the * required syntax. */ public class MalformedStreamException extends IOException { /** * Constructs a <code>MalformedStreamException with no * detail message. */ public MalformedStreamException() { super(); } /** * Constructs an <code>MalformedStreamException with * the specified detail message. * * @param message The detail message. */ public MalformedStreamException(String message) { super(message); } } /** * Thrown upon attempt of setting an invalid boundary token. */ public class IllegalBoundaryException extends IOException { /** * Constructs an <code>IllegalBoundaryException with no * detail message. */ public IllegalBoundaryException() { super(); } /** * Constructs an <code>IllegalBoundaryException with * the specified detail message. * * @param message The detail message. */ public IllegalBoundaryException(String message) { super(message); } } // ------------------------------------------------------ Debugging methods // These are the methods that were used to debug this stuff. /* // Dump data. protected void dump() { System.out.println("01234567890"); byte[] temp = new byte[buffer.length]; for(int i=0; i<buffer.length; i++) { if (buffer[i] == 0x0D || buffer[i] == 0x0A) { temp[i] = 0x21; } else { temp[i] = buffer[i]; } } System.out.println(new String(temp)); int i; for (i=0; i<head; i++) System.out.print(" "); System.out.println("h"); for (i=0; i<tail; i++) System.out.print(" "); System.out.println("t"); System.out.flush(); } // Main routine, for testing purposes only. // // @param args A String[] with the command line arguments. // @exception Exception, a generic exception. public static void main( String[] args ) throws Exception { File boundaryFile = new File("boundary.dat"); int boundarySize = (int)boundaryFile.length(); byte[] boundary = new byte[boundarySize]; FileInputStream input = new FileInputStream(boundaryFile); input.read(boundary,0,boundarySize); input = new FileInputStream("multipart.dat"); MultipartStream chunks = new MultipartStream(input, boundary); int i = 0; String header; OutputStream output; boolean nextChunk = chunks.skipPreamble(); while (nextChunk) { header = chunks.readHeaders(); System.out.println("!"+header+"!"); System.out.println("wrote part"+i+".dat"); output = new FileOutputStream("part"+(i++)+".dat"); chunks.readBodyData(output); nextChunk = chunks.readBoundary(); } } */ }

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