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From "Ken Weiner (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IO-339) MaxBytesInputStream to limit size of bytes read
Date Tue, 24 Jul 2012 17:13:37 GMT
Ken Weiner created IO-339:
-----------------------------

             Summary: MaxBytesInputStream to limit size of bytes read
                 Key: IO-339
                 URL: https://issues.apache.org/jira/browse/IO-339
             Project: Commons IO
          Issue Type: Improvement
          Components: Streams/Writers
    Affects Versions: 2.4
            Reporter: Ken Weiner
            Priority: Minor


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.

{code}

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;
    }
}
{code}

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