countinginputstream.java

java上传文件的一个例子。使用了apache的第三方开源组件。

/*
 * Copyright 2001-2005 The Apache Software Foundation.
 * 
 * Licensed 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.io.input;

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

/**
 * A decorating input stream that counts the number of bytes that
 * have passed through so far.
 *
 * @author Henri Yandell
 * @author Marcelo Liberato
 * @version $Id: CountingInputStream.java 160202 2005-04-05 17:22:21Z roxspring $
 */
public class CountingInputStream extends ProxyInputStream {

    /** The count of bytes that have passed. */
    private int count;

    /**
     * Constructs a new CountingInputStream.
     * @param in InputStream to delegate to
     */
    public CountingInputStream(InputStream in) {
        super(in);
    }

    /**
     * Increases the count by super.read(b)'s return count
     * 
     * @see java.io.InputStream#read(byte[]) 
     */
    public int read(byte[] b) throws IOException {
        int found = super.read(b);
        this.count += (found >= 0) ? found : 0;
        return found;
    }

    /**
     * Increases the count by super.read(b, off, len)'s return count
     *
     * @see java.io.InputStream#read(byte[], int, int)
     */
    public int read(byte[] b, int off, int len) throws IOException {
        int found = super.read(b, off, len);
        this.count += (found >= 0) ? found : 0;
        return found;
    }

    /**
     * Increases the count by 1 if a byte is successfully read. 
     *
     * @see java.io.InputStream#read()
     */
    public int read() throws IOException {
        int found = super.read();
        this.count += (found >= 0) ? 1 : 0;
        return found;
    }
    
    /**
     * Increases the count by the number of skipped bytes.
     * 
     * @see java.io.InputStream#skip(long)
     */
    public long skip(final long length) throws IOException {
        final long skip = super.skip(length);
        this.count += skip;
        return skip;
    }

    /**
     * The number of bytes that have passed through this stream.
     *
     * @return the number of bytes accumulated
     */
    public int getCount() {
        return this.count;
    }

    /** 
     * Set the count back to 0. 
     *
     * @return the count previous to resetting.
     */
    public synchronized int resetCount() {
        int tmp = this.count;
        this.count = 0;
        return tmp;
    }

}