Java : ZipInputStream with Examples
July 15, 2023 
February 7, 2023
ZipInputStream (Java SE 19 & JDK 19) API Examples.
You will find code examples on most ZipInputStream methods.
Summary
This class implements an input stream filter for reading files in the ZIP file format. Includes support for both compressed and uncompressed entries.
final var path = Path.of("R:", "java-work", "aaa.zip");
System.out.println(path); // R:\java-work\aaa.zip
// --------
// Compression
try (final var zos = new ZipOutputStream(Files.newOutputStream(path))) {
zos.putNextEntry(new ZipEntry("bbb.txt"));
zos.write("YYYYY".getBytes());
zos.putNextEntry(new ZipEntry("ccc.txt"));
zos.write("ZZZZZ".getBytes());
}
// --- PowerShell ---
//PS R:\java-work> ls -name
//aaa.zip
//
//PS R:\java-work> Expand-Archive .\aaa.zip .
//PS R:\java-work> ls -name
//aaa.zip
//bbb.txt
//ccc.txt
//
//PS R:\java-work> cat .\bbb.txt
//YYYYY
//PS R:\java-work> cat .\ccc.txt
//ZZZZZ
// --------
// Decompression
try (final var zis = new ZipInputStream(Files.newInputStream(path))) {
final var entry1 = zis.getNextEntry();
if (entry1 != null) {
System.out.println(entry1.getName()); // bbb.txt
final var uncompressed = zis.readAllBytes();
System.out.println(Arrays.toString(uncompressed)); // [89, 89, 89, 89, 89]
System.out.println(new String(uncompressed)); // YYYYY
}
final var entry2 = zis.getNextEntry();
if (entry2 != null) {
System.out.println(entry2.getName()); // ccc.txt
final var uncompressed = zis.readAllBytes();
System.out.println(Arrays.toString(uncompressed)); // [90, 90, 90, 90, 90]
System.out.println(new String(uncompressed)); // ZZZZZ
}
System.out.println(zis.getNextEntry()); // null
}
Helper method for code examples
Code examples on this page use the helper method below.
// Compress a string.
public byte[] deflate(String name, String str) throws IOException {
final var out = new ByteArrayOutputStream();
try (final var zos = new ZipOutputStream(out)) {
zos.putNextEntry(new ZipEntry(name));
zos.write(str.getBytes());
}
return out.toByteArray();
}
Fields
static final int CENATT
Central directory (CEN) header internal file attributes field offset.
System.out.println(ZipInputStream.CENATT); // 36
static final int CENATX
Central directory (CEN) header external file attributes field offset.
System.out.println(ZipInputStream.CENATX); // 38
static final int CENCOM
Central directory (CEN) header comment length field offset.
System.out.println(ZipInputStream.CENCOM); // 32
static final int CENCRC
Central directory (CEN) header uncompressed file crc-32 value field offset.
System.out.println(ZipInputStream.CENCRC); // 16
static final int CENDSK
Central directory (CEN) header disk number start field offset.
System.out.println(ZipInputStream.CENDSK); // 34
static final int CENEXT
Central directory (CEN) header extra field length field offset.
System.out.println(ZipInputStream.CENEXT); // 30
static final int CENFLG
Central directory (CEN) header encrypt, decrypt flags field offset.
System.out.println(ZipInputStream.CENFLG); // 8
static final int CENHDR
Central directory (CEN) header size in bytes (including signature).
System.out.println(ZipInputStream.CENHDR); // 46
static final int CENHOW
Central directory (CEN) header compression method field offset.
System.out.println(ZipInputStream.CENHOW); // 10
static final int CENLEN
Central directory (CEN) header uncompressed size field offset.
System.out.println(ZipInputStream.CENLEN); // 24
static final int CENNAM
Central directory (CEN) header filename length field offset.
System.out.println(ZipInputStream.CENNAM); // 28
static final int CENOFF
Central directory (CEN) header LOC header offset field offset.
System.out.println(ZipInputStream.CENOFF); // 42
static final long CENSIG
Central directory (CEN) header signature.
System.out.printf("%#x", ZipInputStream.CENSIG); // 0x2014b50
static final int CENSIZ
Central directory (CEN) header compressed size field offset.
System.out.println(ZipInputStream.CENSIZ); // 20
static final int CENTIM
Central directory (CEN) header modification time field offset.
System.out.println(ZipInputStream.CENTIM); // 12
static final int CENVEM
Central directory (CEN) header version made by field offset.
System.out.println(ZipInputStream.CENVEM); // 4
static final int CENVER
Central directory (CEN) header version needed to extract field offset.
System.out.println(ZipInputStream.CENVER); // 6
static final int ENDCOM
End of central directory (END) header zip file comment length field offset.
System.out.println(ZipInputStream.ENDCOM); // 20
static final int ENDHDR
End of central directory (END) header size in bytes (including signature).
System.out.println(ZipInputStream.ENDHDR); // 22
static final int ENDOFF
End of central directory (END) header offset for the first CEN header field offset.
System.out.println(ZipInputStream.ENDOFF); // 16
static final long ENDSIG
End of central directory (END) header signature.
System.out.printf("%#x", ZipInputStream.ENDSIG); // 0x6054b50
static final int ENDSIZ
End of central directory (END) header central directory size in bytes field offset.
System.out.println(ZipInputStream.ENDSIZ); // 12
static final int ENDSUB
End of central directory (END) header number of entries on this disk field offset.
System.out.println(ZipInputStream.ENDSUB); // 8
static final int ENDTOT
End of central directory (END) header total number of entries field offset.
System.out.println(ZipInputStream.ENDTOT); // 10
static final int EXTCRC
Extra local (EXT) header uncompressed file crc-32 value field offset.
System.out.println(ZipInputStream.EXTCRC); // 4
static final int EXTHDR
Extra local (EXT) header size in bytes (including signature).
System.out.println(ZipInputStream.EXTHDR); // 16
static final int EXTLEN
Extra local (EXT) header uncompressed size field offset.
System.out.println(ZipInputStream.EXTLEN); // 12
static final long EXTSIG
Extra local (EXT) header signature.
System.out.printf("%#x", ZipInputStream.EXTSIG); // 0x8074b50
static final int EXTSIZ
Extra local (EXT) header compressed size field offset.
System.out.println(ZipInputStream.EXTSIZ); // 8
static final int LOCCRC
Local file (LOC) header uncompressed file crc-32 value field offset.
System.out.println(ZipInputStream.LOCCRC); // 14
static final int LOCEXT
Local file (LOC) header extra field length field offset.
System.out.println(ZipInputStream.LOCEXT); // 28
static final int LOCFLG
Local file (LOC) header general purpose bit flag field offset.
System.out.println(ZipInputStream.LOCFLG); // 6
static final int LOCHDR
Local file (LOC) header size in bytes (including signature).
System.out.println(ZipInputStream.LOCHDR); // 30
static final int LOCHOW
Local file (LOC) header compression method field offset.
System.out.println(ZipInputStream.LOCHOW); // 8
static final int LOCLEN
Local file (LOC) header uncompressed size field offset.
System.out.println(ZipInputStream.LOCLEN); // 22
static final int LOCNAM
Local file (LOC) header filename length field offset.
System.out.println(ZipInputStream.LOCNAM); // 26
static final long LOCSIG
Local file (LOC) header signature.
System.out.printf("%#x", ZipInputStream.LOCSIG); // 0x4034b50
static final int LOCSIZ
Local file (LOC) header compressed size field offset.
System.out.println(ZipInputStream.LOCSIZ); // 18
static final int LOCTIM
Local file (LOC) header modification time field offset.
System.out.println(ZipInputStream.LOCTIM); // 10
static final int LOCVER
Local file (LOC) header version needed to extract field offset.
System.out.println(ZipInputStream.LOCVER); // 4
Fields declared in InflaterInputStream
Fields declared in FilterInputStream
Constructors
ZipInputStream (InputStream in)
Creates a new ZIP input stream.
final var bytes = deflate("aaa.txt", "aaaaa");
System.out.println(bytes.length); // 133
try (final var zis = new ZipInputStream(new ByteArrayInputStream(bytes))) {
final var entry = zis.getNextEntry();
if (entry != null) {
System.out.println(entry.getName()); // aaa.txt
final var uncompressed = zis.readAllBytes();
System.out.println(Arrays.toString(uncompressed)); // [97, 97, 97, 97, 97]
System.out.println(new String(uncompressed)); // aaaaa
}
}
ZipInputStream (InputStream in, Charset charset)
Creates a new ZIP input stream.
Please see ZipInputStream(InputStream in) for in parameter.
final var charset = Charset.forName("Shift_JIS");
final var out = new ByteArrayOutputStream();
try (final var zos = new ZipOutputStream(out, charset)) {
zos.putNextEntry(new ZipEntry("aaa.txt"));
zos.putNextEntry(new ZipEntry("○△×.txt"));
}
final var compressed = out.toByteArray();
System.out.println(compressed.length); // 244
try (final var zis = new ZipInputStream(new ByteArrayInputStream(compressed), charset)) {
final var entry1 = zis.getNextEntry();
if (entry1 != null) {
System.out.println(entry1.getName()); // aaa.txt
}
final var entry2 = zis.getNextEntry();
if (entry2 != null) {
System.out.println(entry2.getName()); // ○△×.txt
}
}
Methods
int available ()
Returns 0 after EOF has reached for the current entry data, otherwise always return 1.
final var bytes = deflate("aaa.txt", "aaaaa");
System.out.println(bytes.length); // 133
try (final var zis = new ZipInputStream(new ByteArrayInputStream(bytes))) {
final var entry = zis.getNextEntry();
if (entry != null) {
System.out.println(entry.getName()); // aaa.txt
System.out.println(zis.available()); // 1
System.out.println(zis.read()); // 97
System.out.println(zis.available()); // 1
System.out.println(zis.read()); // 97
System.out.println(zis.available()); // 1
final var uncompressed = zis.readAllBytes();
System.out.println(Arrays.toString(uncompressed)); // [97, 97, 97]
System.out.println(new String(uncompressed)); // aaa
System.out.println(zis.available()); // 0
}
}
void close ()
Closes this input stream and releases any system resources associated with the stream.
final var file = Path.of("R:", "java-work", "aaa.zip");
System.out.println(file); // R:\java-work\aaa.zip
final var bytes = deflate("aaa.txt", "aaaaa");
System.out.println(bytes.length); // 133
Files.write(file, bytes);
try (final var zis = new ZipInputStream(Files.newInputStream(file))) {
final var entry = zis.getNextEntry();
if (entry != null) {
System.out.println(entry.getName()); // aaa.txt
final var uncompressed = zis.readAllBytes();
System.out.println(Arrays.toString(uncompressed)); // [97, 97, 97, 97, 97]
System.out.println(new String(uncompressed)); // aaaaa
}
}
An example without try-with-resources.
final var file = Path.of("R:", "java-work", "aaa.zip");
System.out.println(file); // R:\java-work\aaa.zip
final var bytes = deflate("aaa.txt", "aaaaa");
System.out.println(bytes.length); // 133
Files.write(file, bytes);
final var zis = new ZipInputStream(Files.newInputStream(file));
try {
final var entry = zis.getNextEntry();
if (entry != null) {
System.out.println(entry.getName()); // aaa.txt
final var uncompressed = zis.readAllBytes();
System.out.println(Arrays.toString(uncompressed)); // [97, 97, 97, 97, 97]
System.out.println(new String(uncompressed)); // aaaaa
}
} finally {
zis.close();
}
void closeEntry ()
Closes the current ZIP entry and positions the stream for reading the next entry.
final var bytes = deflate("aaa.txt", "aaaaa");
System.out.println(bytes.length); // 133
try (final var zis = new ZipInputStream(new ByteArrayInputStream(bytes))) {
final var entry = zis.getNextEntry();
if (entry != null) {
System.out.println(entry.getName()); // aaa.txt
System.out.println(zis.available()); // 1
System.out.println(zis.read()); // 97
System.out.println(zis.available()); // 1
System.out.println(zis.read()); // 97
System.out.println(zis.available()); // 1
zis.closeEntry();
System.out.println(zis.available()); // 0
System.out.println(zis.read()); // -1
}
}
protected ZipEntry createZipEntry (String name)
Creates a new ZipEntry object for the specified entry name.
protected. I think it's rare to create a subclass of this class. Therefore, the code example is omitted.
ZipEntry getNextEntry ()
Reads the next ZIP file entry and positions the stream at the beginning of the entry data.
final var path = Path.of("R:", "java-work", "aaa.zip");
System.out.println(path); // R:\java-work\aaa.zip
// --------
// Compression
try (final var zos = new ZipOutputStream(Files.newOutputStream(path))) {
zos.putNextEntry(new ZipEntry("bbb.txt"));
zos.write("YYYYY".getBytes());
zos.putNextEntry(new ZipEntry("ccc.txt"));
zos.write("ZZZZZ".getBytes());
}
// --------
// Decompression
try (final var zis = new ZipInputStream(Files.newInputStream(path))) {
final var entry1 = zis.getNextEntry();
if (entry1 != null) {
System.out.println(entry1.getName()); // bbb.txt
final var uncompressed = zis.readAllBytes();
System.out.println(Arrays.toString(uncompressed)); // [89, 89, 89, 89, 89]
System.out.println(new String(uncompressed)); // YYYYY
}
final var entry2 = zis.getNextEntry();
if (entry2 != null) {
System.out.println(entry2.getName()); // ccc.txt
final var uncompressed = zis.readAllBytes();
System.out.println(Arrays.toString(uncompressed)); // [90, 90, 90, 90, 90]
System.out.println(new String(uncompressed)); // ZZZZZ
}
System.out.println(zis.getNextEntry()); // null
}
int read (byte[] b, int off, int len)
Reads from the current ZIP entry into an array of bytes.
final var str = "abcdef";
System.out.println(Arrays.toString(str.getBytes())); // [97, 98, 99, 100, 101, 102]
final var bytes = deflate("aaa.txt", str);
System.out.println(bytes.length); // 133
try (final var zis = new ZipInputStream(new ByteArrayInputStream(bytes))) {
final var entry = zis.getNextEntry();
if (entry != null) {
final var b1 = new byte[5];
System.out.println(zis.read(b1, 0, 3)); // 3
System.out.println(Arrays.toString(b1)); // [97, 98, 99, 0, 0]
final var b2 = new byte[5];
System.out.println(zis.read(b2, 1, 2)); // 2
System.out.println(Arrays.toString(b2)); // [0, 100, 101, 0, 0]
final var b3 = new byte[5];
System.out.println(zis.read(b3, 0, 5)); // 1
System.out.println(Arrays.toString(b3)); // [102, 0, 0, 0, 0]
}
}
long skip (long n)
Skips specified number of bytes in the current ZIP entry.
final var bytes = deflate("aaa.txt", "aaaaaaaaaaaaaa");
System.out.println(bytes.length); // 133
try (final var zis = new ZipInputStream(new ByteArrayInputStream(bytes))) {
final var entry = zis.getNextEntry();
if (entry != null) {
final var uncompressed = zis.readAllBytes();
System.out.println(uncompressed.length); // 14
}
}
try (final var zis = new ZipInputStream(new ByteArrayInputStream(bytes))) {
final var entry = zis.getNextEntry();
if (entry != null) {
System.out.println(zis.skip(5)); // 5
final var uncompressed = zis.readAllBytes();
System.out.println(uncompressed.length); // 9
}
}
Methods declared in InflaterInputStream
fill, mark, markSupported, read, reset
Please see the link below.
Methods declared in FilterInputStream
Methods declared in InputStream
nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo
Please see the link below.