Commons FileUpload example source code file (LimitedInputStream.java)

This example Commons FileUpload source code file (LimitedInputStream.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons FileUpload tags/keywords

closeable, closeable, filterinputstream, filterinputstream, io, ioexception, ioexception, limitedinputstream, limitedinputstream

The Commons FileUpload LimitedInputStream.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.fileupload.util;

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


/**
 * An input stream, which limits its data size. This stream is
 * used, if the content length is unknown.
 */
public abstract class LimitedInputStream
        extends FilterInputStream implements Closeable {
    /**
     * The maximum size of an item, in bytes.
     */
    private long sizeMax;
    /**
     * The current number of bytes.
     */
    private long count;
    /**
     * Whether this stream is already closed.
     */
    private boolean closed;

    /**
     * Creates a new instance.
     * @param pIn The input stream, which shall be limited.
     * @param pSizeMax The limit; no more than this number of bytes
     *   shall be returned by the source stream.
     */
    public LimitedInputStream(InputStream pIn, long pSizeMax) {
        super(pIn);
        sizeMax = pSizeMax;
    }

    /**
     * Called to indicate, that the input streams limit has
     * been exceeded.
     * @param pSizeMax The input streams limit, in bytes.
     * @param pCount The actual number of bytes.
     * @throws IOException The called method is expected
     *   to raise an IOException.
     */
    protected abstract void raiseError(long pSizeMax, long pCount)
            throws IOException;

    /** Called to check, whether the input streams
     * limit is reached.
     * @throws IOException The given limit is exceeded.
     */
    private void checkLimit() throws IOException {
        if (count > sizeMax) {
            raiseError(sizeMax, count);
        }
    }

    /**
     * Reads the next byte of data from this input stream. The value
     * byte is returned as an <code>int in the range
     * <code>0 to 255. If no byte is available
     * because the end of the stream has been reached, the value
     * <code>-1 is returned. This method blocks until input data
     * is available, the end of the stream is detected, or an exception
     * is thrown.
     * <p>
     * This method
     * simply performs <code>in.read() and returns the result.
     *
     * @return     the next byte of data, or <code>-1 if the end of the
     *             stream is reached.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterInputStream#in
     */
    public int read() throws IOException {
        int res = super.read();
        if (res != -1) {
            count++;
            checkLimit();
        }
        return res;
    }

    /**
     * Reads up to <code>len bytes of data from this input stream
     * into an array of bytes. If <code>len is not zero, the method
     * blocks until some input is available; otherwise, no
     * bytes are read and <code>0 is returned.
     * <p>
     * This method simply performs <code>in.read(b, off, len)
     * and returns the result.
     *
     * @param      b     the buffer into which the data is read.
     * @param      off   The start offset in the destination array
     *                   <code>b.
     * @param      len   the maximum number of bytes read.
     * @return     the total number of bytes read into the buffer, or
     *             <code>-1 if there is no more data because the end of
     *             the stream has been reached.
     * @exception  NullPointerException If <code>b is null.
     * @exception  IndexOutOfBoundsException If <code>off is negative,
     * <code>len is negative, or len is greater than
     * <code>b.length - off
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterInputStream#in
     */
    public int read(byte[] b, int off, int len) throws IOException {
        int res = super.read(b, off, len);
        if (res > 0) {
            count += res;
            checkLimit();
        }
        return res;
    }

    /**
     * Returns, whether this stream is already closed.
     * @return True, if the stream is closed, otherwise false.
     * @throws IOException An I/O error occurred.
     */
    public boolean isClosed() throws IOException {
        return closed;
    }

    /**
     * Closes this input stream and releases any system resources
     * associated with the stream.
     * This
     * method simply performs <code>in.close().
     *
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterInputStream#in
     */
    public void close() throws IOException {
        closed = true;
        super.close();
    }
}