Reading from a ZipInputStream into a ByteArrayOutputStream

Question

I am trying to read a single file from a java.util.zip.ZipInputStream, and copy it into a java.io.ByteArrayOutputStream (so that I can then create a

Answer 1

You probably tried reading from a FileInputStream like this:

ZipInputStream in = new ZipInputStream(new FileInputStream(...));

This won’t work since a zip archive can contain multiple files and you need to specify which file to read.

You could use java.util.zip.ZipFile and a library such as IOUtils from Apache Commons IO or ByteStreams from Guava that assist you in copying the stream.

Example:

ByteArrayOutputStream out = new ByteArrayOutputStream();
try (ZipFile zipFile = new ZipFile("foo.zip")) {
    ZipEntry zipEntry = zipFile.getEntry("fileInTheZip.txt");

    try (InputStream in = zipFile.getInputStream(zipEntry)) {
        IOUtils.copy(in, out);
    }
}