Class ZipInputStream
- All Implemented Interfaces:
Closeable
,AutoCloseable
- Direct Known Subclasses:
JarInputStream
Unless otherwise noted, passing a null
argument to a constructor
or method in this class will cause a NullPointerException
to be
thrown.
Reading Zip File Entries
ThegetNextEntry()
method is used to read the next ZIP file entry
(Local file (LOC) header record in the ZIP format) and position the stream at
the entry's file data. The file data may read using one of the
ZipInputStream
read methods such
as read
or readAllBytes()
.
For example:
Path jar = Path.of("foo.jar");
try (InputStream is = Files.newInputStream(jar);
ZipInputStream zis = new ZipInputStream(is)) {
ZipEntry ze;
while ((ze = zis.getNextEntry()) != null) {
var bytes = zis.readAllBytes();
System.out.printf("Entry: %s, bytes read: %s%n", ze.getName(),
bytes.length);
}
}
- API Note:
- The LOC header contains metadata about the ZIP file entry.
ZipInputStream
does not read the Central directory (CEN) header for the entry and therefore will not have access to its metadata such as the external file attributes. ZipFile may be used when the information stored within the CEN header is required. - Since:
- 1.1
-
Field Summary
Modifier and TypeFieldDescriptionstatic final int
Central directory (CEN) header internal file attributes field offset.static final int
Central directory (CEN) header external file attributes field offset.static final int
Central directory (CEN) header comment length field offset.static final int
Central directory (CEN) header uncompressed file crc-32 value field offset.static final int
Central directory (CEN) header disk number start field offset.static final int
Central directory (CEN) header extra field length field offset.static final int
Central directory (CEN) header encrypt, decrypt flags field offset.static final int
Central directory (CEN) header size in bytes (including signature).static final int
Central directory (CEN) header compression method field offset.static final int
Central directory (CEN) header uncompressed size field offset.static final int
Central directory (CEN) header filename length field offset.static final int
Central directory (CEN) header LOC header offset field offset.static final long
Central directory (CEN) header signature.static final int
Central directory (CEN) header compressed size field offset.static final int
Central directory (CEN) header modification time field offset.static final int
Central directory (CEN) header version made by field offset.static final int
Central directory (CEN) header version needed to extract field offset.static final int
End of central directory (END) header ZIP file comment length field offset.static final int
End of central directory (END) header size in bytes (including signature).static final int
End of central directory (END) header offset for the first CEN header field offset.static final long
End of central directory (END) header signature.static final int
End of central directory (END) header central directory size in bytes field offset.static final int
End of central directory (END) header number of entries on this disk field offset.static final int
End of central directory (END) header total number of entries field offset.static final int
Extra local (EXT) header uncompressed file crc-32 value field offset.static final int
Extra local (EXT) header size in bytes (including signature).static final int
Extra local (EXT) header uncompressed size field offset.static final long
Extra local (EXT) header signature.static final int
Extra local (EXT) header compressed size field offset.static final int
Local file (LOC) header uncompressed file crc-32 value field offset.static final int
Local file (LOC) header extra field length field offset.static final int
Local file (LOC) header general purpose bit flag field offset.static final int
Local file (LOC) header size in bytes (including signature).static final int
Local file (LOC) header compression method field offset.static final int
Local file (LOC) header uncompressed size field offset.static final int
Local file (LOC) header filename length field offset.static final long
Local file (LOC) header signature.static final int
Local file (LOC) header compressed size field offset.static final int
Local file (LOC) header modification time field offset.static final int
Local file (LOC) header version needed to extract field offset.Fields inherited from class java.util.zip.InflaterInputStream
buf, inf, len
Fields inherited from class java.io.FilterInputStream
in
-
Constructor Summary
ConstructorDescriptionCreates a new ZIP input stream.ZipInputStream
(InputStream in, Charset charset) Creates a new ZIP input stream. -
Method Summary
Modifier and TypeMethodDescriptionint
Returns 0 when end of stream is detected for the current ZIP entry orcloseEntry()
has been called on the current ZIP entry, otherwise returns 1.void
close()
Closes this input stream and releases any system resources associated with the stream.void
Closes the current ZIP entry and positions the stream for reading the next entry.protected ZipEntry
createZipEntry
(String name) Creates a newZipEntry
object for the specified entry name.Reads the next ZIP file entry and positions the stream at the beginning of the entry data.int
read()
Reads the next byte of data from the input stream for the current ZIP entry.int
read
(byte[] b, int off, int len) Reads the requested number of bytes from the input stream into the given byte array for the current ZIP entry returning the number of inflated bytes.byte[]
Reads all remaining bytes from the input stream for the current ZIP entry.int
readNBytes
(byte[] b, int off, int len) Reads the requested number of bytes from the input stream into the given byte array for the current ZIP entry returning the number of inflated bytes.byte[]
readNBytes
(int len) Reads up to a specified number of bytes from the input stream for the current ZIP entry.long
skip
(long n) Skips over and discardsn
bytes of data from this input stream for the current ZIP entry.void
skipNBytes
(long n) Skips over and discards exactlyn
bytes of data from this input stream for the current ZIP entry.long
transferTo
(OutputStream out) Reads all bytes from this input stream for the current ZIP entry and writes the bytes to the given output stream in the order that they are read.Methods inherited from class java.util.zip.InflaterInputStream
fill, mark, markSupported, reset
Methods inherited from class java.io.FilterInputStream
read
Methods inherited from class java.io.InputStream
nullInputStream
-
Field Details
-
LOCSIG
static final long LOCSIGLocal file (LOC) header signature.- See Also:
-
EXTSIG
static final long EXTSIGExtra local (EXT) header signature.- See Also:
-
CENSIG
static final long CENSIGCentral directory (CEN) header signature.- See Also:
-
ENDSIG
static final long ENDSIGEnd of central directory (END) header signature.- See Also:
-
LOCHDR
static final int LOCHDRLocal file (LOC) header size in bytes (including signature).- See Also:
-
EXTHDR
static final int EXTHDRExtra local (EXT) header size in bytes (including signature).- See Also:
-
CENHDR
static final int CENHDRCentral directory (CEN) header size in bytes (including signature).- See Also:
-
ENDHDR
static final int ENDHDREnd of central directory (END) header size in bytes (including signature).- See Also:
-
LOCVER
static final int LOCVERLocal file (LOC) header version needed to extract field offset.- See Also:
-
LOCFLG
static final int LOCFLGLocal file (LOC) header general purpose bit flag field offset.- See Also:
-
LOCHOW
static final int LOCHOWLocal file (LOC) header compression method field offset.- See Also:
-
LOCTIM
static final int LOCTIMLocal file (LOC) header modification time field offset.- See Also:
-
LOCCRC
static final int LOCCRCLocal file (LOC) header uncompressed file crc-32 value field offset.- See Also:
-
LOCSIZ
static final int LOCSIZLocal file (LOC) header compressed size field offset.- See Also:
-
LOCLEN
static final int LOCLENLocal file (LOC) header uncompressed size field offset.- See Also:
-
LOCNAM
static final int LOCNAMLocal file (LOC) header filename length field offset.- See Also:
-
LOCEXT
static final int LOCEXTLocal file (LOC) header extra field length field offset.- See Also:
-
EXTCRC
static final int EXTCRCExtra local (EXT) header uncompressed file crc-32 value field offset.- See Also:
-
EXTSIZ
static final int EXTSIZExtra local (EXT) header compressed size field offset.- See Also:
-
EXTLEN
static final int EXTLENExtra local (EXT) header uncompressed size field offset.- See Also:
-
CENVEM
static final int CENVEMCentral directory (CEN) header version made by field offset.- See Also:
-
CENVER
static final int CENVERCentral directory (CEN) header version needed to extract field offset.- See Also:
-
CENFLG
static final int CENFLGCentral directory (CEN) header encrypt, decrypt flags field offset.- See Also:
-
CENHOW
static final int CENHOWCentral directory (CEN) header compression method field offset.- See Also:
-
CENTIM
static final int CENTIMCentral directory (CEN) header modification time field offset.- See Also:
-
CENCRC
static final int CENCRCCentral directory (CEN) header uncompressed file crc-32 value field offset.- See Also:
-
CENSIZ
static final int CENSIZCentral directory (CEN) header compressed size field offset.- See Also:
-
CENLEN
static final int CENLENCentral directory (CEN) header uncompressed size field offset.- See Also:
-
CENNAM
static final int CENNAMCentral directory (CEN) header filename length field offset.- See Also:
-
CENEXT
static final int CENEXTCentral directory (CEN) header extra field length field offset.- See Also:
-
CENCOM
static final int CENCOMCentral directory (CEN) header comment length field offset.- See Also:
-
CENDSK
static final int CENDSKCentral directory (CEN) header disk number start field offset.- See Also:
-
CENATT
static final int CENATTCentral directory (CEN) header internal file attributes field offset.- See Also:
-
CENATX
static final int CENATXCentral directory (CEN) header external file attributes field offset.- See Also:
-
CENOFF
static final int CENOFFCentral directory (CEN) header LOC header offset field offset.- See Also:
-
ENDSUB
static final int ENDSUBEnd of central directory (END) header number of entries on this disk field offset.- See Also:
-
ENDTOT
static final int ENDTOTEnd of central directory (END) header total number of entries field offset.- See Also:
-
ENDSIZ
static final int ENDSIZEnd of central directory (END) header central directory size in bytes field offset.- See Also:
-
ENDOFF
static final int ENDOFFEnd of central directory (END) header offset for the first CEN header field offset.- See Also:
-
ENDCOM
static final int ENDCOMEnd of central directory (END) header ZIP file comment length field offset.- See Also:
-
-
Constructor Details
-
ZipInputStream
Creates a new ZIP input stream.The UTF-8
charset
is used to decode the entry names.- Parameters:
in
- the actual input stream
-
ZipInputStream
Creates a new ZIP input stream.- Parameters:
in
- the actual input streamcharset
- The charset to be used to decode the ZIP entry name (ignored if the language encoding bit of the ZIP entry's general purpose bit flag is set).- Since:
- 1.7
-
-
Method Details
-
getNextEntry
Reads the next ZIP file entry and positions the stream at the beginning of the entry data.- Returns:
- the next ZIP file entry, or null if there are no more entries
- Throws:
ZipException
- if a ZIP file error has occurredIOException
- if an I/O error has occurred
-
closeEntry
Closes the current ZIP entry and positions the stream for reading the next entry.- Throws:
ZipException
- if a ZIP file error has occurredIOException
- if an I/O error has occurred
-
available
Returns 0 when end of stream is detected for the current ZIP entry orcloseEntry()
has been called on the current ZIP entry, otherwise returns 1.Programs should not count on this method to return the actual number of bytes that could be read without blocking.
- Overrides:
available
in classInflaterInputStream
- Returns:
- 0 when end of stream is detected for the current ZIP entry or
closeEntry()
has been called on the current ZIP entry, otherwise 1. - Throws:
IOException
- if an I/O error occurs.
-
read
Reads the next byte of data from the input stream for the current ZIP entry. This method will block until enough input is available for decompression.- Overrides:
read
in classInflaterInputStream
- Returns:
- the byte read, or -1 if the end of the stream is reached
- Throws:
IOException
- if an I/O error has occurred- See Also:
-
readAllBytes
Reads all remaining bytes from the input stream for the current ZIP entry. This method blocks until all remaining bytes have been read and end of stream is detected, or an exception is thrown. This method does not close the input stream.When this stream reaches end of stream, further invocations of this method will return an empty byte array.
Note that this method is intended for simple cases where it is convenient to read all bytes into a byte array. It is not intended for reading input streams with large amounts of data.
If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently, the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
- Overrides:
readAllBytes
in classInputStream
- Returns:
- a byte array containing the bytes read from this input stream
- Throws:
OutOfMemoryError
- if an array of the required size cannot be allocated.IOException
- if an I/O error occurs- Since:
- 9
-
readNBytes
Reads up to a specified number of bytes from the input stream for the current ZIP entry. This method blocks until the requested number of bytes has been read, end of stream is detected, or an exception is thrown. This method does not close the input stream.The length of the returned array equals the number of bytes read from the stream. If
len
is zero, then no bytes are read and an empty byte array is returned. Otherwise, up tolen
bytes are read from the stream. Fewer thanlen
bytes may be read if end of stream is encountered.When this stream reaches end of stream, further invocations of this method will return an empty byte array.
Note that this method is intended for simple cases where it is convenient to read the specified number of bytes into a byte array. The total amount of memory allocated by this method is proportional to the number of bytes read from the stream which is bounded by
len
. Therefore, the method may be safely called with very large values oflen
provided sufficient memory is available.If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently, the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
- Overrides:
readNBytes
in classInputStream
- Implementation Note:
- This method calls
super.readNBytes(int len)
. - Parameters:
len
- the maximum number of bytes to read- Returns:
- a byte array containing the bytes read from this input stream
- Throws:
OutOfMemoryError
- if an array of the required size cannot be allocated.IOException
- if an I/O error occurs- Since:
- 11
-
readNBytes
Reads the requested number of bytes from the input stream into the given byte array for the current ZIP entry returning the number of inflated bytes. This method blocks untillen
bytes of input data have been read, end of stream is detected, or an exception is thrown. The number of bytes actually read, possibly zero, is returned. This method does not close the input stream.In the case where end of stream is reached before
len
bytes have been read, then the actual number of bytes read will be returned. When this stream reaches end of stream, further invocations of this method will return zero.If
len
is zero, then no bytes are read and0
is returned; otherwise, there is an attempt to read up tolen
bytes.The first byte read is stored into element
b[off]
, the next one in tob[off+1]
, and so on. The number of bytes read is, at most, equal tolen
. Let k be the number of bytes actually read; these bytes will be stored in elementsb[off]
throughb[off+
k-1]
, leaving elementsb[off+
k]
throughb[off+len-1]
unaffected.If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes of
b
have been updated with data from the input stream. Consequently, the input stream andb
may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.- Overrides:
readNBytes
in classInputStream
- Parameters:
b
- the byte array into which the data is readoff
- the start offset inb
at which the data is writtenlen
- the maximum number of bytes to read- Returns:
- the actual number of bytes read into the buffer
- Throws:
IndexOutOfBoundsException
- Ifoff
is negative,len
is negative, orlen
is greater thanb.length - off
IOException
- if an I/O error occurs- Since:
- 9
-
skipNBytes
Skips over and discards exactlyn
bytes of data from this input stream for the current ZIP entry. Ifn
is zero, then no bytes are skipped. Ifn
is negative, then no bytes are skipped. Subclasses may handle the negative value differently.This method blocks until the requested number of bytes has been skipped, end of file is reached, or an exception is thrown.
If end of stream is reached before the stream is at the desired position, then an
EOFException
is thrown.If an I/O error occurs, then the input stream may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
- Overrides:
skipNBytes
in classInputStream
- Parameters:
n
- the number of bytes to be skipped.- Throws:
IOException
- if the stream cannot be positioned properly or if an I/O error occurs.- Since:
- 12
- See Also:
-
transferTo
Reads all bytes from this input stream for the current ZIP entry and writes the bytes to the given output stream in the order that they are read. On return, this input stream will be at end of stream. This method does not close either stream.This method may block indefinitely reading from the input stream, or writing to the output stream. The behavior for the case where the input and/or output stream is asynchronously closed, or the thread interrupted during the transfer, is highly input and output stream specific, and therefore not specified.
If the total number of bytes transferred is greater than Long.MAX_VALUE, then
Long.MAX_VALUE
will be returned.If an I/O error occurs reading from the input stream or writing to the output stream, then it may do so after some bytes have been read or written. Consequently, the input stream may not be at end of stream and one, or both, streams may be in an inconsistent state. It is strongly recommended that both streams be promptly closed if an I/O error occurs.
- Overrides:
transferTo
in classInputStream
- Parameters:
out
- the output stream, non-null- Returns:
- the number of bytes transferred
- Throws:
IOException
- if an I/O error occurs when reading or writing- Since:
- 9
-
read
Reads the requested number of bytes from the input stream into the given byte array for the current ZIP entry returning the number of inflated bytes. Iflen
is not zero, the method blocks until some input is available; otherwise, no bytes are read and0
is returned.If the current entry is compressed and this method returns a nonzero integer n then
buf[off]
throughbuf[off+
n-1]
contain the uncompressed data. The content of elementsbuf[off+
n]
throughbuf[off+
len-1]
is undefined, contrary to the specification of theInputStream
superclass, so an implementation is free to modify these elements during the inflate operation. If this method returns-1
or throws an exception then the content ofbuf[off]
throughbuf[off+
len-1]
is undefined.- Overrides:
read
in classInflaterInputStream
- Parameters:
b
- the buffer into which the data is readoff
- the start offset in the destination arrayb
len
- the maximum number of bytes read- Returns:
- the actual number of bytes read, or -1 if the end of the entry is reached
- Throws:
IndexOutOfBoundsException
- ifoff
is negative,len
is negative, orlen
is greater thanb.length - off
ZipException
- if a ZIP file error has occurredIOException
- if an I/O error has occurred- See Also:
-
skip
Skips over and discardsn
bytes of data from this input stream for the current ZIP entry.- Overrides:
skip
in classInflaterInputStream
- Parameters:
n
- the number of bytes to skip- Returns:
- the actual number of bytes skipped
- Throws:
ZipException
- if a ZIP file error has occurredIOException
- if an I/O error has occurredIllegalArgumentException
- ifn < 0
- See Also:
-
close
Closes this input stream and releases any system resources associated with the stream.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classInflaterInputStream
- Throws:
IOException
- if an I/O error has occurred- See Also:
-
createZipEntry
-