Module java.base
Package java.util.zip

Class ZipInputStream

java.lang.Object
java.io.InputStream
java.io.FilterInputStream
java.util.zip.InflaterInputStream
java.util.zip.ZipInputStream
All Implemented Interfaces:
Closeable, AutoCloseable
Direct Known Subclasses:
JarInputStream
public class ZipInputStream extends InflaterInputStream
An input stream for reading compressed and uncompressed ZIP file entries from a stream of bytes in the ZIP file format.

Reading Zip File Entries

The getNextEntry() 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

    Fields
    Modifier and Type
    Field
    Description
    static final int
    CENATT
    Central directory (CEN) header internal file attributes field offset.
    static final int
    CENATX
    Central directory (CEN) header external file attributes field offset.
    static final int
    CENCOM
    Central directory (CEN) header comment length field offset.
    static final int
    CENCRC
    Central directory (CEN) header uncompressed file crc-32 value field offset.
    static final int
    CENDSK
    Central directory (CEN) header disk number start field offset.
    static final int
    CENEXT
    Central directory (CEN) header extra field length field offset.
    static final int
    CENFLG
    Central directory (CEN) header encrypt, decrypt flags field offset.
    static final int
    CENHDR
    Central directory (CEN) header size in bytes (including signature).
    static final int
    CENHOW
    Central directory (CEN) header compression method field offset.
    static final int
    CENLEN
    Central directory (CEN) header uncompressed size field offset.
    static final int
    CENNAM
    Central directory (CEN) header filename length field offset.
    static final int
    CENOFF
    Central directory (CEN) header LOC header offset field offset.
    static final long
    CENSIG
    Central directory (CEN) header signature.
    static final int
    CENSIZ
    Central directory (CEN) header compressed size field offset.
    static final int
    CENTIM
    Central directory (CEN) header modification time field offset.
    static final int
    CENVEM
    Central directory (CEN) header version made by field offset.
    static final int
    CENVER
    Central directory (CEN) header version needed to extract field offset.
    static final int
    ENDCOM
    End of central directory (END) header zip file comment length field offset.
    static final int
    ENDHDR
    End of central directory (END) header size in bytes (including signature).
    static final int
    ENDOFF
    End of central directory (END) header offset for the first CEN header field offset.
    static final long
    ENDSIG
    End of central directory (END) header signature.
    static final int
    ENDSIZ
    End of central directory (END) header central directory size in bytes field offset.
    static final int
    ENDSUB
    End of central directory (END) header number of entries on this disk field offset.
    static final int
    ENDTOT
    End of central directory (END) header total number of entries field offset.
    static final int
    EXTCRC
    Extra local (EXT) header uncompressed file crc-32 value field offset.
    static final int
    EXTHDR
    Extra local (EXT) header size in bytes (including signature).
    static final int
    EXTLEN
    Extra local (EXT) header uncompressed size field offset.
    static final long
    EXTSIG
    Extra local (EXT) header signature.
    static final int
    EXTSIZ
    Extra local (EXT) header compressed size field offset.
    static final int
    LOCCRC
    Local file (LOC) header uncompressed file crc-32 value field offset.
    static final int
    LOCEXT
    Local file (LOC) header extra field length field offset.
    static final int
    LOCFLG
    Local file (LOC) header general purpose bit flag field offset.
    static final int
    LOCHDR
    Local file (LOC) header size in bytes (including signature).
    static final int
    LOCHOW
    Local file (LOC) header compression method field offset.
    static final int
    LOCLEN
    Local file (LOC) header uncompressed size field offset.
    static final int
    LOCNAM
    Local file (LOC) header filename length field offset.
    static final long
    LOCSIG
    Local file (LOC) header signature.
    static final int
    LOCSIZ
    Local file (LOC) header compressed size field offset.
    static final int
    LOCTIM
    Local file (LOC) header modification time field offset.
    static final int
    LOCVER
    Local file (LOC) header version needed to extract field offset.

    Fields declared in class java.util.zip.InflaterInputStream

    buf, inf, len

    Fields declared in class java.io.FilterInputStream

    in

  • Constructor Summary

    Constructors
    Constructor
    Description
    ZipInputStream(InputStream in)
    Creates a new ZIP input stream.
    ZipInputStream(InputStream in, Charset charset)
    Creates a new ZIP input stream.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    available()
    Returns 0 when end of stream is detected for the current ZIP entry or closeEntry() 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
    closeEntry()
    Closes the current ZIP entry and positions the stream for reading the next entry.
    protected ZipEntry
    createZipEntry(String name)
    Creates a new ZipEntry object for the specified entry name.
    ZipEntry
    getNextEntry()
    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[]
    readAllBytes()
    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 discards n bytes of data from this input stream for the current ZIP entry.
    void
    skipNBytes(long n)
    Skips over and discards exactly n 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 declared in class java.util.zip.InflaterInputStream

    fill, mark, markSupported, reset

    Methods declared in class java.io.FilterInputStream

    read

    Methods declared in class java.io.InputStream

    nullInputStream

    Methods declared in class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • LOCSIG

      static final long LOCSIG
      Local file (LOC) header signature.
      See Also:

    • EXTSIG

      static final long EXTSIG
      Extra local (EXT) header signature.
      See Also:

    • CENSIG

      static final long CENSIG
      Central directory (CEN) header signature.
      See Also:

    • ENDSIG

      static final long ENDSIG
      End of central directory (END) header signature.
      See Also:

    • LOCHDR

      static final int LOCHDR
      Local file (LOC) header size in bytes (including signature).
      See Also:

    • EXTHDR

      static final int EXTHDR
      Extra local (EXT) header size in bytes (including signature).
      See Also:

    • CENHDR

      static final int CENHDR
      Central directory (CEN) header size in bytes (including signature).
      See Also:

    • ENDHDR

      static final int ENDHDR
      End of central directory (END) header size in bytes (including signature).
      See Also:

    • LOCVER

      static final int LOCVER
      Local file (LOC) header version needed to extract field offset.
      See Also:

    • LOCFLG

      static final int LOCFLG
      Local file (LOC) header general purpose bit flag field offset.
      See Also:

    • LOCHOW

      static final int LOCHOW
      Local file (LOC) header compression method field offset.
      See Also:

    • LOCTIM

      static final int LOCTIM
      Local file (LOC) header modification time field offset.
      See Also:

    • LOCCRC

      static final int LOCCRC
      Local file (LOC) header uncompressed file crc-32 value field offset.
      See Also:

    • LOCSIZ

      static final int LOCSIZ
      Local file (LOC) header compressed size field offset.
      See Also:

    • LOCLEN

      static final int LOCLEN
      Local file (LOC) header uncompressed size field offset.
      See Also:

    • LOCNAM

      static final int LOCNAM
      Local file (LOC) header filename length field offset.
      See Also:

    • LOCEXT

      static final int LOCEXT
      Local file (LOC) header extra field length field offset.
      See Also:

    • EXTCRC

      static final int EXTCRC
      Extra local (EXT) header uncompressed file crc-32 value field offset.
      See Also:

    • EXTSIZ

      static final int EXTSIZ
      Extra local (EXT) header compressed size field offset.
      See Also:

    • EXTLEN

      static final int EXTLEN
      Extra local (EXT) header uncompressed size field offset.
      See Also:

    • CENVEM

      static final int CENVEM
      Central directory (CEN) header version made by field offset.
      See Also:

    • CENVER

      static final int CENVER
      Central directory (CEN) header version needed to extract field offset.
      See Also:

    • CENFLG

      static final int CENFLG
      Central directory (CEN) header encrypt, decrypt flags field offset.
      See Also:

    • CENHOW

      static final int CENHOW
      Central directory (CEN) header compression method field offset.
      See Also:

    • CENTIM

      static final int CENTIM
      Central directory (CEN) header modification time field offset.
      See Also:

    • CENCRC

      static final int CENCRC
      Central directory (CEN) header uncompressed file crc-32 value field offset.
      See Also:

    • CENSIZ

      static final int CENSIZ
      Central directory (CEN) header compressed size field offset.
      See Also:

    • CENLEN

      static final int CENLEN
      Central directory (CEN) header uncompressed size field offset.
      See Also:

    • CENNAM

      static final int CENNAM
      Central directory (CEN) header filename length field offset.
      See Also:

    • CENEXT

      static final int CENEXT
      Central directory (CEN) header extra field length field offset.
      See Also:

    • CENCOM

      static final int CENCOM
      Central directory (CEN) header comment length field offset.
      See Also:

    • CENDSK

      static final int CENDSK
      Central directory (CEN) header disk number start field offset.
      See Also:

    • CENATT

      static final int CENATT
      Central directory (CEN) header internal file attributes field offset.
      See Also:

    • CENATX

      static final int CENATX
      Central directory (CEN) header external file attributes field offset.
      See Also:

    • CENOFF

      static final int CENOFF
      Central directory (CEN) header LOC header offset field offset.
      See Also:

    • ENDSUB

      static final int ENDSUB
      End of central directory (END) header number of entries on this disk field offset.
      See Also:

    • ENDTOT

      static final int ENDTOT
      End of central directory (END) header total number of entries field offset.
      See Also:

    • ENDSIZ

      static final int ENDSIZ
      End of central directory (END) header central directory size in bytes field offset.
      See Also:

    • ENDOFF

      static final int ENDOFF
      End of central directory (END) header offset for the first CEN header field offset.
      See Also:

    • ENDCOM

      static final int ENDCOM
      End of central directory (END) header zip file comment length field offset.
      See Also:

  • Constructor Details

    • ZipInputStream

      public ZipInputStream(InputStream in)
      Creates a new ZIP input stream.

      The UTF-8 charset is used to decode the entry names.

      Parameters:
      in - the actual input stream

    • ZipInputStream

      public ZipInputStream(InputStream in, Charset charset)
      Creates a new ZIP input stream.
      Parameters:
      in - the actual input stream
      charset - 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

      public ZipEntry getNextEntry() throws IOException
      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 occurred
      IOException - if an I/O error has occurred

    • closeEntry

      public void closeEntry() throws IOException
      Closes the current ZIP entry and positions the stream for reading the next entry.
      Throws:
      ZipException - if a ZIP file error has occurred
      IOException - if an I/O error has occurred

    • available

      public int available() throws IOException
      Returns 0 when end of stream is detected for the current ZIP entry or closeEntry() 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 class InflaterInputStream
      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

      public int read() throws IOException
      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 class InflaterInputStream
      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

      public byte[] readAllBytes() throws IOException
      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 class InputStream
      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

      public byte[] readNBytes(int len) throws IOException
      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 to len bytes are read from the stream. Fewer than len 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 of len 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 class InputStream
      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

      public int readNBytes(byte[] b, int off, int len) throws IOException
      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 until len 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 and 0 is returned; otherwise, there is an attempt to read up to len bytes.

      The first byte read is stored into element b[off], the next one in to b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k ] through b[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 and b 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 class InputStream
      Parameters:
      b - the byte array into which the data is read
      off - the start offset in b at which the data is written
      len - the maximum number of bytes to read
      Returns:
      the actual number of bytes read into the buffer
      Throws:
      NullPointerException - if b is null
      IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
      IOException - if an I/O error occurs
      Since:
      9

    • skipNBytes

      public void skipNBytes(long n) throws IOException
      Skips over and discards exactly n bytes of data from this input stream for the current ZIP entry. If n is zero, then no bytes are skipped. If n 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 class InputStream
      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

      public long transferTo(OutputStream out) throws IOException
      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 class InputStream
      Parameters:
      out - the output stream, non-null
      Returns:
      the number of bytes transferred
      Throws:
      NullPointerException - if out is null
      IOException - if an I/O error occurs when reading or writing
      Since:
      9

    • read

      public int read(byte[] b, int off, int len) throws IOException
      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. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned.

      If the current entry is compressed and this method returns a nonzero integer n then buf[off] through buf[off+n-1] contain the uncompressed data. The content of elements buf[off+n] through buf[off+len-1] is undefined, contrary to the specification of the InputStream 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 of buf[off] through buf[off+len -1] is undefined.

      Overrides:
      read in class InflaterInputStream
      Parameters:
      b - the buffer into which the data is read
      off - the start offset in the destination array b
      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:
      NullPointerException - if b is null.
      IndexOutOfBoundsException - if off is negative, len is negative, or len is greater than b.length - off
      ZipException - if a ZIP file error has occurred
      IOException - if an I/O error has occurred
      See Also:

    • skip

      public long skip(long n) throws IOException
      Skips over and discards n bytes of data from this input stream for the current ZIP entry.
      Overrides:
      skip in class InflaterInputStream
      Parameters:
      n - the number of bytes to skip
      Returns:
      the actual number of bytes skipped
      Throws:
      ZipException - if a ZIP file error has occurred
      IOException - if an I/O error has occurred
      IllegalArgumentException - if n < 0
      See Also:

    • close

      public void close() throws IOException
      Closes this input stream and releases any system resources associated with the stream.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class InflaterInputStream
      Throws:
      IOException - if an I/O error has occurred
      See Also:

    • createZipEntry

      protected ZipEntry createZipEntry(String name)
      Creates a new ZipEntry object for the specified entry name.
      Parameters:
      name - the ZIP file entry name
      Returns:
      the ZipEntry just created