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/*
 * Copyright 2002-2013 the original author or authors.
 *
 * 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 com.xiongyingqi.util;

import java.io.*;
import java.nio.charset.Charset;


public abstract class StreamUtils {

    public static final int BUFFER_SIZE = 4096;


    
    public static byte[] copyToByteArray(InputStream in) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream(BUFFER_SIZE);
        copy(in, out);
        return out.toByteArray();
    }

    
    public static String copyToString(InputStream in, Charset charset) throws IOException {
        Assert.notNull(in, "No InputStream specified");
        StringBuilder out = new StringBuilder();
        InputStreamReader reader = new InputStreamReader(in, charset);
        char[] buffer = new char[BUFFER_SIZE];
        int bytesRead = -1;
        while ((bytesRead = reader.read(buffer)) != -1) {
            out.append(buffer, 0, bytesRead);
        }
        return out.toString();
    }

    
    public static void copy(byte[] in, OutputStream out) throws IOException {
        Assert.notNull(in, "No input byte array specified");
        Assert.notNull(out, "No OutputStream specified");
        out.write(in);
    }

    
    public static void copy(String in, Charset charset, OutputStream out) throws IOException {
        Assert.notNull(in, "No input String specified");
        Assert.notNull(charset, "No charset specified");
        Assert.notNull(out, "No OutputStream specified");
        Writer writer = new OutputStreamWriter(out, charset);
        writer.write(in);
        writer.flush();
    }

    
    public static int copy(InputStream in, OutputStream out) throws IOException {
        Assert.notNull(in, "No InputStream specified");
        Assert.notNull(out, "No OutputStream specified");
        int byteCount = 0;
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = -1;
        while ((bytesRead = in.read(buffer)) != -1) {
            out.write(buffer, 0, bytesRead);
            byteCount += bytesRead;
        }
        out.flush();
        return byteCount;
    }

    
    public static InputStream nonClosing(InputStream in) {
        Assert.notNull(in, "No InputStream specified");
        return new NonClosingInputStream(in);
    }

    
    public static OutputStream nonClosing(OutputStream out) {
        Assert.notNull(out, "No OutputStream specified");
        return new NonClosingOutputStream(out);
    }


    private static class NonClosingInputStream extends FilterInputStream {

        public NonClosingInputStream(InputStream in) {
            super(in);
        }

        @Override
        public void close() throws IOException {
        }
    }


    private static class NonClosingOutputStream extends FilterOutputStream {

        public NonClosingOutputStream(OutputStream out) {
            super(out);
        }

        @Override
        public void write(byte[] b, int off, int let) throws IOException {
            // It is critical that we override this method for performance
            out.write(b, off, let);
        }

        @Override
        public void close() throws IOException {
        }
    }
}