SizedFileInputStream

SizedFileInputStream

// Your package here

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import com.dropbox.sync.android.DbxException;
import com.dropbox.sync.android.DbxFile;

/**
 * Wraps an InputStream obtained from a standard File or DbxFile.
 * Allows the total file size to be known before reading any data.
 */
public class SizedFileInputStream extends InputStream {

    private final FileInputStream mStream;
    private long mFileSize;

    public SizedFileInputStream(File file) throws FileNotFoundException {
        mStream = new FileInputStream(file);
        mFileSize = file.length();
    }

    public SizedFileInputStream(DbxFile file) throws DbxException, IOException {
        mStream = file.getReadStream();
        mFileSize = file.getInfo().size;
    }

    @Override
    public int read() throws IOException {
        int read = mStream.read();
        return read;
    }

    @Override
    public int read(byte[] buffer) throws IOException {
        int read = mStream.read(buffer);
        return read;
    }

    @Override
    public int read(byte[] buffer, int byteOffset, int byteCount) throws IOException {
        int read = mStream.read(buffer, byteOffset, byteCount);
        return read;
    }

    @Override
    public int available() throws IOException {
        return mStream.available();
    }

    @Override
    public void close() throws IOException {
        this.mStream.close();
    }

    @Override
    public boolean markSupported() {
        return mStream.markSupported();
    }

    @Override
    public void mark(int readLimit) {
        mStream.mark(readLimit);
    }

    @Override
    public long skip(long byteCount) throws IOException {
        return mStream.skip(byteCount);
    }

    public long getFileSize() {
        return mFileSize;
    }
}

This is from a project where I needed to pass an InputStream around based on a File, but classes reading from that InputStream want to know the total size of the file so that an accurate progress indicator can be displayed. The Dropbox stuff may not be relevant to you.