[IO-339] MaxBytesInputStream to limit size of bytes read

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Duplicate
• Affects Version/s: 2.4
• Component/s: Streams/Writers
• Assignee: Unassigned
• Reporter: Ken Weiner
• Created: 24/Jul/12 17:12
• Updated: 08/Nov/16 18:04
• Resolved: 16/May/13 14:38

Description

I wrote an input stream that stops when it reaches a configured size in bytes. I found it useful for applications that download web pages and images, but want to enforce a max size to avoid memory problems for extremely large pages/images.

I was thinking that this class is generic and useful enough to include in the commons-io distribution. Please consider it, and if it isn't appropriate for inclusion here, please recommend a better place to open source and share it.

package org.apache.commons.io.input;

import java.io.IOException;
import java.io.InputStream;

/**
 * An input stream that will end when the amount of bytes read reaches
 * the configured amount of maxBytes.
 * This is useful for preventing OutOfMemoryExceptions when downloading
 * very large files in cases where getting partial content is acceptable.
 * @author Ken Weiner
 */
public class MaxBytesInputStream extends CountingInputStream {
    private long maxBytes;

    public MaxBytesInputStream(InputStream is, long maxBytes) {
        super(is);
        this.maxBytes = maxBytes;
    }

    @Override
    protected void afterRead(int n) {
        super.afterRead((int) Math.min(n, this.maxBytes - getByteCount()));
    }

    @Override
    public int read() throws IOException {
        if (getByteCount() < this.maxBytes) {
            return super.read();
        }
        return -1;
    }

    @Override
    public int read(byte[] b) throws IOException {
        if (getByteCount() < this.maxBytes) {
            return super.read(b);
        }
        return -1;
    }

    @Override
    public int read(byte[] b, int off, int len) throws IOException {
        if (getByteCount() < this.maxBytes) {
            return super.read(b, off, len);
        }
        return -1;
    }
}

Issue Links

• duplicates: IO-197 BoundedInputStream