Class MultipartInput
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
 }
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Nested Class SummaryNested ClassesModifier and TypeClassDescriptionstatic classBuilds a newMultipartInputinstance.static classSignals an attempt to set an invalid boundary token.classAnInputStreamfor reading an items contents.static classSignals that the input stream fails to follow the required syntax.static classInternal class, which is used to invoke theProgressListener.
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Field SummaryFieldsModifier and TypeFieldDescriptionstatic final byteThe Carriage Return ASCII character value.static final byteThe dash (-) ASCII character value.static final intDefault per part header size limit in bytes.static final byteThe Line Feed ASCII character value.
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Method SummaryModifier and TypeMethodDescriptionstatic MultipartInput.Builderbuilder()Constructs a newMultipartInput.Builder.longReadsbody-datafrom the currentencapsulationand discards it.protected intfindByte(byte value, int pos) Searches for a byte of specified value in thebuffer, starting at the specifiedposition.protected intSearches for theboundaryin thebufferregion delimited byheadandtail.Gets the character encoding used when reading the headers of an individual part.intReturns the per part size limit for headers.Creates a newMultipartInput.ItemInputStream.longreadBodyData(OutputStream output) Readsbody-datafrom the currentencapsulationand writes its contents into the outputStream.booleanSkips aboundarytoken, and checks whether moreencapsulationsare contained in the stream.bytereadByte()Reads a byte from thebuffer, and refills it as necessary.Reads theheader-partof the currentencapsulation.voidsetBoundary(byte[] boundary) Changes the boundary token used for partitioning the stream.voidsetHeaderCharset(Charset headerCharset) Sets the character encoding to be used when reading the headers of individual parts.booleanFinds the beginning of the firstencapsulation.
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Field Details- 
CRThe Carriage Return ASCII character value.- See Also:
 
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LFThe Line Feed ASCII character value.- See Also:
 
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DASHThe dash (-) ASCII character value.- See Also:
 
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DEFAULT_PART_HEADER_SIZE_MAXDefault per part header size limit in bytes.- Since:
- 2.0.0-M4
- See Also:
 
 
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Method Details- 
builderConstructs a newMultipartInput.Builder.- Returns:
- a new MultipartInput.Builder.
 
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discardBodyDataReadsbody-datafrom the currentencapsulationand discards it.Use this method to skip encapsulations you don't need or don't understand. - Returns:
- The amount of data discarded.
- Throws:
- MultipartInput.MalformedStreamException- if the stream ends unexpectedly.
- IOException- if an i/o error occurs.
 
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findByteSearches for a byte of specified value in thebuffer, starting at the specifiedposition.- 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-1if not found.
 
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findSeparatorSearches for theboundaryin thebufferregion delimited byheadandtail.- Returns:
- The position of the boundary found, counting from the beginning of the buffer, or-1if not found.
 
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getHeaderCharsetGets the character encoding used when reading the headers of an individual part. When not specified, ornull, the platform default encoding is used.- Returns:
- The encoding used to read part headers.
 
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getPartHeaderSizeMaxReturns the per part size limit for headers.- Returns:
- The maximum size of the headers in bytes.
- Since:
- 2.0.0-M4
 
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newInputStreamCreates a newMultipartInput.ItemInputStream.- Returns:
- A new instance of MultipartInput.ItemInputStream.
 
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readBodyDatapublic long readBodyData(OutputStream output) throws MultipartInput.MalformedStreamException, IOException Readsbody-datafrom the currentencapsulationand writes its contents into the outputStream.Arbitrary large amounts of data can be processed by this method using a constant size buffer. (see builder()).- Parameters:
- output- The- Streamto 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.
- IOException- if an i/o error occurs.
 
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readBoundarypublic boolean readBoundary() throws FileUploadSizeException, MultipartInput.MalformedStreamExceptionSkips aboundarytoken, and checks whether moreencapsulationsare contained in the stream.- Returns:
- trueif there are more encapsulations in this stream;- falseotherwise.
- Throws:
- FileUploadSizeException- if the bytes read from the stream exceeded the size limits
- MultipartInput.MalformedStreamException- if the stream ends unexpectedly or fails to follow required syntax.
 
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readByteReads a byte from thebuffer, and refills it as necessary.- Returns:
- The next byte from the input stream.
- Throws:
- IOException- if there is no more data available.
 
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readHeadersReads theheader-partof the currentencapsulation.Headers are returned verbatim to the input stream, including the trailing CRLFmarker. Parsing is left to the application.TODO allow limiting maximum header size to protect against abuse. - Returns:
- The header-partof the current encapsulation.
- Throws:
- FileUploadSizeException- if the bytes read from the stream exceeded the size limits.
- MultipartInput.MalformedStreamException- if the stream ends unexpectedly.
 
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setBoundaryChanges 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 requiredto 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- boundaryhas a different length than the one being currently parsed.
 
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setHeaderCharsetSets the character encoding to be used when reading the headers of individual parts. When not specified, ornull, the platform default encoding is used.- Parameters:
- headerCharset- The encoding used to read part headers.
 
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skipPreambleFinds the beginning of the firstencapsulation.- Returns:
- trueif an- encapsulationwas found in the stream.
- Throws:
- IOException- if an i/o error occurs.
 
 
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