Class ZipOutputStream

java.util.zip.ZipOutputStream

All Implemented Interfaces:: Closeable, Flushable, AutoCloseable

Direct Known Subclasses:: JarOutputStream

public class ZipOutputStream extends DeflaterOutputStream

This class implements an output stream filter for writing files in the ZIP file format. Includes support for both compressed and uncompressed entries.

Unless otherwise noted, passing a null argument to a constructor or method in this class will cause a NullPointerException to be thrown.

Since:: 1.1

Field Summary

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`	`DEFLATED`	Compression method for compressed (DEFLATED) entries.
`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.
`static final int`	`STORED`	Compression method for uncompressed (STORED) entries.

Fields declared in class DeflaterOutputStream

buf, def

Fields declared in class FilterOutputStream

out

Constructor Summary

Constructor	Description
`ZipOutputStream(OutputStream out)`	Creates a new ZIP output stream.
`ZipOutputStream(OutputStream out, Charset charset)`	Creates a new ZIP output stream.

Method Summary

Modifier and Type	Method	Description
`void`	`close()`	Closes the underlying stream and the stream being filtered after the contents of the ZIP output stream are fully written.
`void`	`closeEntry()`	Closes the current ZIP entry and positions the stream for writing the next entry.
`void`	`finish()`	Finishes writing the contents of the ZIP output stream without closing the underlying stream.
`void`	`putNextEntry(ZipEntry e)`	Begins writing a new ZIP file entry and positions the stream to the start of the entry data.
`void`	`setComment(String comment)`	Sets the ZIP file comment.
`void`	`setLevel(int level)`	Sets the compression level for subsequent entries which are DEFLATED.
`void`	`setMethod(int method)`	Sets the default compression method for subsequent entries.
`void`	`write(byte[] b, int off, int len)`	Writes an array of bytes to the current ZIP entry data.

Methods declared in class DeflaterOutputStream

deflate, flush, write

Methods declared in class FilterOutputStream

write

Methods declared in class OutputStream

nullOutputStream

Methods declared in class Object

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

Field Details

STORED

public static final int STORED

Compression method for uncompressed (STORED) entries.

See Also:

DEFLATED

public static final int DEFLATED

Compression method for compressed (DEFLATED) entries.

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LOCSIG

static final long LOCSIG

Local file (LOC) header signature.

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EXTSIG

static final long EXTSIG

Extra local (EXT) header signature.

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CENSIG

static final long CENSIG

Central directory (CEN) header signature.

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ENDSIG

static final long ENDSIG

End of central directory (END) header signature.

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LOCHDR

static final int LOCHDR

Local file (LOC) header size in bytes (including signature).

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EXTHDR

static final int EXTHDR

Extra local (EXT) header size in bytes (including signature).

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CENHDR

static final int CENHDR

Central directory (CEN) header size in bytes (including signature).

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ENDHDR

static final int ENDHDR

End of central directory (END) header size in bytes (including signature).

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LOCVER

static final int LOCVER

Local file (LOC) header version needed to extract field offset.

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LOCFLG

static final int LOCFLG

Local file (LOC) header general purpose bit flag field offset.

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LOCHOW

static final int LOCHOW

Local file (LOC) header compression method field offset.

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LOCTIM

static final int LOCTIM

Local file (LOC) header modification time field offset.

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LOCCRC

static final int LOCCRC

Local file (LOC) header uncompressed file crc-32 value field offset.

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LOCSIZ

static final int LOCSIZ

Local file (LOC) header compressed size field offset.

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LOCLEN

static final int LOCLEN

Local file (LOC) header uncompressed size field offset.

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LOCNAM

static final int LOCNAM

Local file (LOC) header filename length field offset.

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LOCEXT

static final int LOCEXT

Local file (LOC) header extra field length field offset.

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EXTCRC

static final int EXTCRC

Extra local (EXT) header uncompressed file crc-32 value field offset.

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EXTSIZ

static final int EXTSIZ

Extra local (EXT) header compressed size field offset.

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EXTLEN

static final int EXTLEN

Extra local (EXT) header uncompressed size field offset.

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CENVEM

static final int CENVEM

Central directory (CEN) header version made by field offset.

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CENVER

static final int CENVER

Central directory (CEN) header version needed to extract field offset.

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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.

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CENTIM

static final int CENTIM

Central directory (CEN) header modification time field offset.

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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.

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CENATT

static final int CENATT

Central directory (CEN) header internal file attributes field offset.

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CENATX

static final int CENATX

Central directory (CEN) header external file attributes field offset.

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CENOFF

static final int CENOFF

Central directory (CEN) header LOC header offset field offset.

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ENDSUB

static final int ENDSUB

End of central directory (END) header number of entries on this disk field offset.

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ENDTOT

static final int ENDTOT

End of central directory (END) header total number of entries field offset.

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ENDSIZ

static final int ENDSIZ

End of central directory (END) header central directory size in bytes field offset.

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ENDOFF

static final int ENDOFF

End of central directory (END) header offset for the first CEN header field offset.

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ENDCOM

static final int ENDCOM

End of central directory (END) header ZIP file comment length field offset.

See Also:

Constructor Details

ZipOutputStream

public ZipOutputStream(OutputStream out)

Creates a new ZIP output stream.

The UTF-8 charset is used to encode the entry names and comments.

Parameters:: out - the actual output stream

ZipOutputStream

public ZipOutputStream(OutputStream out, Charset charset)

Creates a new ZIP output stream.

Parameters:: out - the actual output stream; charset - the charset to be used to encode the entry names and comments
Since:: 1.7

Method Details

setComment

public void setComment(String comment)

Sets the ZIP file comment.

Parameters:: comment - the comment string
Throws:: IllegalArgumentException - if the length of the specified ZIP file comment is greater than 0xFFFF bytes

setMethod

public void setMethod(int method)

Sets the default compression method for subsequent entries. This default will be used whenever the compression method is not specified for an individual ZIP file entry, and is initially set to DEFLATED.

Parameters:: method - the default compression method
Throws:: IllegalArgumentException - if the specified compression method is invalid

setLevel

public void setLevel(int level)

Sets the compression level for subsequent entries which are DEFLATED. The default setting is DEFAULT_COMPRESSION.

Parameters:: level - the compression level (0-9)
Throws:: IllegalArgumentException - if the compression level is invalid

putNextEntry

public void putNextEntry(ZipEntry e) throws IOException

Begins writing a new ZIP file entry and positions the stream to the start of the entry data. Closes the current entry if still active.

The default compression method will be used if no compression method was specified for the entry. When writing a compressed (DEFLATED) entry, and the compressed size has not been explicitly set with the ZipEntry.setCompressedSize(long) method, then the compressed size will be set to the actual compressed size after deflation.

The current time will be used if the entry has no set modification time.

API Note:

When writing a directory entry, the STORED compression method should be used and the size and CRC-32 values should be set to 0:

     ZipEntry e = new ZipEntry(entryName);
     if (e.isDirectory()) {
         e.setMethod(ZipEntry.STORED);
         e.setSize(0);
         e.setCrc(0);
     }
     stream.putNextEntry(e);

This allows optimal performance when processing directory entries.

Parameters:

e - the ZIP entry to be written

Throws:

ZipException - if a ZIP format 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 writing the next entry.

Throws:: ZipException - if a ZIP format error has occurred; IOException - if an I/O error has occurred

write

public void write(byte[] b, int off, int len) throws IOException

Writes an array of bytes to the current ZIP entry data. This method will block until all the bytes are written.

Overrides:

write in class DeflaterOutputStream

Parameters:

b - the data to be written

off - the start offset in the data

len - the number of bytes that are written

Throws:

ZipException - if a ZIP file error has occurred

IOException - if an I/O error has occurred

See Also:

finish

public void finish() throws IOException

Finishes writing the contents of the ZIP output stream without closing the underlying stream. Use this method when applying multiple filters in succession to the same output stream.

A ZipException will be thrown if the combined length, after encoding, of the entry name, the extra field data, the entry comment and CEN Header size, exceeds 65,535 bytes.

Overrides:: finish in class DeflaterOutputStream
Throws:: ZipException - if a ZIP file error has occurred; IOException - if an I/O exception has occurred

close

public void close() throws IOException

Closes the underlying stream and the stream being filtered after the contents of the ZIP output stream are fully written.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class DeflaterOutputStream

Throws:

ZipException - if a ZIP file error has occurred

IOException - if an I/O error has occurred

See Also:

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https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/zip/ZipOutputStream.html