Package org.apache.commons.fileupload2.core

Class MultipartInput

  • public final class MultipartInput
extends java.lang.Object
    Low-level API for processing file uploads.

    This class can be used to process data streams conforming to MIME 'multipart' format as defined in RFC 1867. Arbitrarily large amounts of data in the stream can be processed under constant memory usage.

    The format of the stream is defined in the following way: 

       multipart-body := preamble 1*encapsulation close-delimiter epilogue
    
   encapsulation := delimiter body CRLF
    
   delimiter := "--" boundary CRLF
    
   close-delimiter := "--" boundary "--"
    
   preamble := <ignore>
    
   epilogue := <ignore>
    
   body := header-part CRLF body-part
    
   header-part := 1*header CRLF
    
   header := header-name ":" header-value
    
   header-name := <printable ASCII characters except ":">
    
   header-value := <any ASCII characters except CR & LF>
    
   body-data := <arbitrary data>

    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 required to have a boundary token of the same length as the parent stream (see setBoundary(byte[])).

    Here is an example of usage of this class: 

     try {
     MultipartInput multipartStream = MultipartInput.builder()
             .setBoundary(boundary)
             .setInputStream(input)
             .get();
     boolean nextPart = multipartStream.skipPreamble();
     OutputStream output;
     while (nextPart) {
         String header = multipartStream.readHeaders();
         // process headers
         // create some output stream
         multipartStream.readBodyData(output);
         nextPart = multipartStream.readBoundary();
     }
 } catch (MultipartInput.MalformedStreamException e) {
     // the stream failed to follow required syntax
 } catch (IOException e) {
     // a read or write error occurred
 }

    • Method Detail

      • findByte

        protected int findByte​(byte value,
                       int pos)
        Searches for a byte of specified value in the buffer, starting at the specified position.
        Parameters:
        value - The value to find.
        pos - The starting position for searching.
        Returns:
        The position of byte found, counting from beginning of the buffer, or -1 if not found.

      • findSeparator

        protected int findSeparator()
        Searches for the boundary in the buffer region delimited by head and tail.
        Returns:
        The position of the boundary found, counting from the beginning of the buffer, or -1 if not found.

      • getHeaderCharset

        public java.nio.charset.Charset getHeaderCharset()
        Gets the character encoding used when reading the headers of an individual part. When not specified, or null, the platform default encoding is used.
        Returns:
        The encoding used to read part headers.

      • getPartHeaderSizeMax

        public int getPartHeaderSizeMax()
        Returns the per part size limit for headers.
        Returns:
        The maximum size of the headers in bytes.
        Since:
        2.0.0-M4

      • readBodyData

        public long readBodyData​(java.io.OutputStream output)
                  throws MultipartInput.MalformedStreamException,
                         java.io.IOException
        Reads body-data from the current encapsulation and writes its contents into the output Stream.

        Arbitrary large amounts of data can be processed by this method using a constant size buffer. (see builder()).

        Parameters:
        output - The Stream to write data into. May be null, in which case this method is equivalent to discardBodyData().
        Returns:
        the amount of data written.
        Throws:
        MultipartInput.MalformedStreamException - if the stream ends unexpectedly.
        java.io.IOException - if an i/o error occurs.

      • readByte

        public byte readByte()
              throws java.io.IOException
        Reads a byte from the buffer, and refills it as necessary.
        Returns:
        The next byte from the input stream.
        Throws:
        java.io.IOException - if there is no more data available.

      • setBoundary

        public void setBoundary​(byte[] boundary)
                 throws MultipartInput.FileUploadBoundaryException
        Changes the boundary token used for partitioning the stream.

        This method allows single pass processing of nested multipart streams.

        The boundary token of the nested stream is required to be of the same length as the boundary token in parent stream.

        Restoring the parent stream boundary token after processing of a nested stream is left to the application.

        Parameters:
        boundary - The boundary to be used for parsing of the nested stream.
        Throws:
        MultipartInput.FileUploadBoundaryException - if the boundary has a different length than the one being currently parsed.

      • setHeaderCharset

        public void setHeaderCharset​(java.nio.charset.Charset headerCharset)
        Sets the character encoding to be used when reading the headers of individual parts. When not specified, or null, the platform default encoding is used.
        Parameters:
        headerCharset - The encoding used to read part headers.

      • skipPreamble

        public boolean skipPreamble()
                     throws java.io.IOException
        Finds the beginning of the first encapsulation.
        Returns:
        true if an encapsulation was found in the stream.
        Throws:
        java.io.IOException - if an i/o error occurs.