StreamZip

A zip explorer library with functionalities similar to the standard java ZipFile class, but unlike ZipFile class, it uses an input stream as its data source instead of a File object.

Import

Maven

Add JitPack repository to your pom.xml file

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

Finally, add this dependency.

<dependency>
    <groupId>com.github.buggysofts-com</groupId>
    <artifactId>StreamZip</artifactId>
    <version>v1.0.6</version>
</dependency>

And you are done importing the library in your maven project.

Gradle

Add JitPack repository to your project-level build.gradle file

...

allprojects {
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}

Or, in newer gradle projects, specially in android, if you need to the add repository in settings.gradle file...

...

dependencyResolutionManagement {
    ...
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}

Finally, add this dependency to your app/module level build.gradle file

...

dependencies {
    ...
    implementation 'com.github.buggysofts-com:StreamZip:v1.0.6'
}

And you are done importing the library in your gradle project.

Sample codes

To create an instance from a FileInputStream do something like...

StreamZip zip = new StreamZip(
    new FileInputStream(
        new File("/home/ragib/workspace/zips/a.zip")
    )
);

Then you can use different methods that are similar to the standard java ZipFile class. For example here are the publicly available methods.

• getEntry(String name) Returns the entry mapped with the specified name, or null if there is no entry mapped with that name.
• entries() Returns all the available entries as a list of ZipEntry.
• getInputStream(...) Opens(and returns) a bounded input stream currently positioning at the start of the requested entry's data block.
• size() Returns the total number of available entries.
• getComment() Returns the principal comment of the zip file.
• close() Closes the zip file, and any subsequent call to getInputStream(...) will throw an exception. However, other methods of the class that are saved in memory will still be available after call to close().

Please Note

• The ZipEntry we mentioned above is a part of this library and has similar methods as the standard ZipEntry class in java jdk.
• If you do not have a ZipEntry instance, and only have the name of the entry, you can use the minimal constructor ( i.e. ZipEntry(String name)) to obtain an input stream. Of course, you would get an exception if the entry does not exist.

Usage

If you are wondering why the hell we would need a zip explorer that takes FileInputStream as its source, after all, if you can get a file input stream, you can get a File object as well, so why use this library?

Well... there can be a lots of usage. Perhaps the biggest, and in my opinion, the best usage is on Android. As you may know, Android is very restrictive these days, and will not give you read access through classic File objects if you want to read a file residing outside an app's private storage area, specially on external storage devices. Instead, the current way to access a file (in Android) these days is to use something called DocumentFile. We can get an input stream with the code InputStream in = getContentResolver().openInputStream(documentFile.getUri()). Then we use our StreamZip constructor to obtain the zip explorer with something like

StreamZip zip = new StreamZip((FileInputStream)in);

Performance

The performance is similar to the Standard ZipFile class. Before this, the only way to read a zip file in this kind of situation was to use the ZipInputStream class which basically reads every byte in its way to get to the next entry. That is, to list, or to get data of all the entries of a zip file, it is equivalent of reading the whole file. Imagine you have to read some metadata within some big zip files, may be 100 zip files, think how much time it would take! Of course, you can use some caching technique, which I was doing for a long time, in fact there is still a library in the git repo, which does exactly that. But in any way, that is not enough, it takes a lot of memory, and the performance is limited to many constraints.

Please share & rate the library if you find it useful.

Happy coding!