Java : DeflaterInputStream (ZIP) with Examples

// --------
// Compression
final var buf = "aaaaaaaaaa".getBytes();
try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    final var compressed = dis.readAllBytes();

    // [120, -100, 75, 76, -124, 1, 0, 20, -31, 3, -53]
    System.out.println(Arrays.toString(compressed));

    // --------
    // Decompression
    try (final var iis = new InflaterInputStream(new ByteArrayInputStream(compressed))) {
        final var uncompressed = iis.readAllBytes();

        // [97, 97, 97, 97, 97, 97, 97, 97, 97, 97]
        System.out.println(Arrays.toString(uncompressed));

        // aaaaaaaaaa
        System.out.println(new String(uncompressed));
    }
}

protected final byte[] buf

Input buffer for reading compressed data.

protected. I think it's rare to create a subclass of this class. Therefore, the code example is omitted.

protected final Deflater def

Compressor for this stream.

protected. I think it's rare to create a subclass of this class. Therefore, the code example is omitted.

in

Please see the link below.

• Java API Examples : FilterInputStream

DeflaterInputStream (InputStream in)

Creates a new input stream with a default compressor and buffer size.

final var buf = "aaaaaaaaaaaaaa".getBytes();

// [97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97]
System.out.println(Arrays.toString(buf));

try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    final var compressed = dis.readAllBytes();

    // [120, -100, 75, 76, 68, 6, 0, 39, -41, 5, 79]
    System.out.println(Arrays.toString(compressed));
}

DeflaterInputStream (InputStream in, Deflater defl)

Creates a new input stream with the specified compressor and a default buffer size.

final var buf = "aaaaaaaaaaaaaa".getBytes();

// [97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97]
System.out.println(Arrays.toString(buf));

try (final var dis = new DeflaterInputStream(
        new ByteArrayInputStream(buf), new Deflater(Deflater.BEST_COMPRESSION))) {
    final var compressed = dis.readAllBytes();

    // [120, -38, 75, 76, 68, 6, 0, 39, -41, 5, 79]
    System.out.println(Arrays.toString(compressed));
}

DeflaterInputStream (InputStream in, Deflater defl, int bufLen)

Creates a new input stream with the specified compressor and buffer size.

Please see DeflaterInputStream(InputStream in, Deflater defl) for in, defl parameters.

class MyInputStream extends DeflaterInputStream {
    public MyInputStream(InputStream in) {
        super(in, new Deflater());
    }

    public MyInputStream(InputStream in, int bufLen) {
        super(in, new Deflater(), bufLen);
    }

    int getSize() {
        return buf.length;
    }
}

try (final var is = new MyInputStream(new ByteArrayInputStream(new byte[0]))) {
    System.out.println(is.getSize()); // 512
}

try (final var is = new MyInputStream(new ByteArrayInputStream(new byte[0]), 1024)) {
    System.out.println(is.getSize()); // 1024
}

int available ()

Returns 0 after EOF has been reached, otherwise always return 1.

final var buf = "aaaaaaaaaaaaaa".getBytes();

// [97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97]
System.out.println(Arrays.toString(buf));

try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    System.out.println(dis.available()); // 1

    System.out.println(dis.read()); // 120
    System.out.println(dis.available()); // 1

    System.out.println(dis.read()); // 156
    System.out.println(dis.available()); // 1

    System.out.println(dis.read()); // 75
    System.out.println(dis.available()); // 1

    // [76, 68, 6, 0, 39, -41, 5, 79]
    System.out.println(Arrays.toString(dis.readAllBytes()));

    System.out.println(dis.available()); // 0
}

void close ()

Closes this input stream and its underlying input stream, discarding any pending uncompressed data.

final var file = Path.of("R:", "java-work", "aaa.data");
System.out.println(file); // R:\java-work\aaa.data

Files.writeString(file, "aaaaaaaaaa");

try (final var dis = new DeflaterInputStream(Files.newInputStream(file))) {
    final var compressed = dis.readAllBytes();

    // [120, -100, 75, 76, 68, 6, 0, 39, -41, 5, 79]
    System.out.println(Arrays.toString(compressed));
}

An example without try-with-resources.

final var file = Path.of("R:", "java-work", "aaa.data");
System.out.println(file); // R:\java-work\aaa.data

Files.writeString(file, "aaaaaaaaaa");

final var dis = new DeflaterInputStream(Files.newInputStream(file));
try {
    final var compressed = dis.readAllBytes();

    // [120, -100, 75, 76, 68, 6, 0, 39, -41, 5, 79]
    System.out.println(Arrays.toString(compressed));
} finally {
    dis.close();
}

void mark (int limit)

This operation is not supported.

final var buf = "aaaaaaaaaaaaaa".getBytes();
try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    System.out.println("markSupported : " + dis.markSupported());

    dis.mark(0);
    dis.reset();

} catch (IOException e) {
    System.out.println("IOException! : " + e.getMessage());
}

// Result
// ↓
//markSupported : false
//IOException! : mark/reset not supported

boolean markSupported ()

Always returns false because this input stream does not support the mark() and reset() methods.

Please see mark(int limit).

int read ()

Reads a single byte of compressed data from the input stream.

final var buf = "aaaaaaaaaaaaaa".getBytes();
try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    System.out.println(dis.read()); // 120
    System.out.println(dis.read()); // 156
    System.out.println(dis.read()); // 75
    System.out.println(dis.read()); // 76
    System.out.println(dis.read()); // 68
    System.out.println(dis.read()); // 6
    System.out.println(dis.read()); // 0
    System.out.println(dis.read()); // 39
    System.out.println(dis.read()); // 215
    System.out.println(dis.read()); // 5
    System.out.println(dis.read()); // 79
    System.out.println(dis.read()); // -1
}

int read (byte[] b, int off, int len)

Reads compressed data into a byte array.

final var buf = "aaaaaaaaaaaaaa".getBytes();
try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    // [120, -100, 75, 76, 68, 6, 0, 39, -41, 5, 79]
    System.out.println(Arrays.toString(dis.readAllBytes()));
}

try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    final var b1 = new byte[5];
    System.out.println(dis.read(b1, 0, 3)); // 3
    System.out.println(Arrays.toString(b1)); // [120, -100, 75, 0, 0]

    final var b2 = new byte[5];
    System.out.println(dis.read(b2, 1, 2)); // 2
    System.out.println(Arrays.toString(b2)); // [0, 76, 68, 0, 0]

    final var b3 = new byte[8];
    System.out.println(dis.read(b3, 0, 8)); // 6
    System.out.println(Arrays.toString(b3)); // [6, 0, 39, -41, 5, 79, 0, 0]
}

void reset ()

This operation is not supported.

Please see mark(int limit).

long skip (long n)

Skips over and discards data from the input stream.

final var buf = "aaaaaaaaaaaaaa".getBytes();
try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    // [120, -100, 75, 76, 68, 6, 0, 39, -41, 5, 79]
    System.out.println(Arrays.toString(dis.readAllBytes()));
}

try (final var dis = new DeflaterInputStream(new ByteArrayInputStream(buf))) {
    System.out.println(dis.skip(5)); // 5

    // [6, 0, 39, -41, 5, 79]
    System.out.println(Arrays.toString(dis.readAllBytes()));
}

read

Please see the link below.

• Java API Examples : FilterInputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo

Please see the link below.

• Java API Examples : InputStream