操作IO流工具类

package org.apache.cxf.helpers;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.nio.charset.Charset;

public final class IOUtils {
    public static final Charset UTF8_CHARSET = Charset.forName("utf-8");
    private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

    private IOUtils() {

    }
    
    /**
     * Use this function instead of new String(byte[], String) to avoid surprises from 
     * non-standard default encodings.
     * @param bytes
     * @param charsetName
     * @return
     */
    public static String newStringFromBytes(byte[] bytes, String charsetName) {
        try {
            return new String(bytes, charsetName);
        } catch (UnsupportedEncodingException e) {
            throw 
                new RuntimeException("Impossible failure: Charset.forName(\""
                                     + charsetName + "\") returns invalid name.");

        }
    }
    
    
    /**
     * Use this function instead of new String(byte[]) to avoid surprises from non-standard default encodings.
     * @param bytes
     * @return
     */
    public static String newStringFromBytes(byte[] bytes) {
        return newStringFromBytes(bytes, UTF8_CHARSET.name());        
    }
    
    /**
     * Use this function instead of new String(byte[], int, int, String) 
     * to avoid surprises from non-standard default encodings.
     * @param bytes
     * @param charsetName
     * @param start
     * @param length
     * @return
     */
    public static String newStringFromBytes(byte[] bytes, String charsetName, int start, int length) {
        try {
            return new String(bytes, start, length, charsetName);
        } catch (UnsupportedEncodingException e) {
            throw 
                new RuntimeException("Impossible failure: Charset.forName(\""
                                     + charsetName + "\") returns invalid name.");

        }
    }

    /**
     * Use this function instead of new String(byte[], int, int) 
     * to avoid surprises from non-standard default encodings.
     * @param bytes
     * @param start
     * @param length
     * @return
     */
    public static String newStringFromBytes(byte[] bytes, int start, int length) {
        return newStringFromBytes(bytes, UTF8_CHARSET.name(), start, length);
    }

    public static int copy(final InputStream input, final OutputStream output)
        throws IOException {
        return copy(input, output, DEFAULT_BUFFER_SIZE);
    }

    public static int copyAndCloseInput(final InputStream input,
            final OutputStream output) throws IOException {
        try {
            return copy(input, output, DEFAULT_BUFFER_SIZE);
        } finally {
            input.close();
        }
    }

    public static int copyAndCloseInput(final InputStream input,
            final OutputStream output, int bufferSize) throws IOException {
        try {
            return copy(input, output, bufferSize);
        } finally {
            input.close();
        }
    }

    public static int copy(final InputStream input, final OutputStream output,
            int bufferSize) throws IOException {
        int avail = input.available();
        if (avail > 262144) {
            avail = 262144;
        }
        if (avail > bufferSize) {
            bufferSize = avail;
        }
        final byte[] buffer = new byte[bufferSize];
        int n = 0;
        n = input.read(buffer);
        int total = 0;
        while (-1 != n) {
            if (n == 0) {
                throw new IOException("0 bytes read in violation of InputStream.read(byte[])");
            }
            output.write(buffer, 0, n);
            total += n;
            n = input.read(buffer);
        }
        return total;
    }

    public static void copy(final Reader input, final Writer output,
            final int bufferSize) throws IOException {
        final char[] buffer = new char[bufferSize];
        int n = 0;
        n = input.read(buffer);
        while (-1 != n) {
            if (n == 0) {
                throw new IOException("0 bytes read in violation of InputStream.read(byte[])");
            }
            output.write(buffer, 0, n);
            n = input.read(buffer);
        }
    }

    public static String toString(final InputStream input) throws IOException {
        return toString(input, DEFAULT_BUFFER_SIZE);
    }
    public static String toString(final InputStream input, String charset) throws IOException {
        return toString(input, DEFAULT_BUFFER_SIZE, charset);
    }
    public static String toString(final InputStream input, int bufferSize)
        throws IOException {
        return toString(input, bufferSize, null);
    }
    public static String toString(final InputStream input, int bufferSize, String charset)
        throws IOException {

        
        int avail = input.available();
        if (avail > bufferSize) {
            bufferSize = avail;
        }
        Reader reader = charset == null ? new InputStreamReader(input, UTF8_CHARSET) 
            : new InputStreamReader(input, charset);
        return toString(reader, bufferSize);
    }

    public static String toString(final Reader input) throws IOException {
        return toString(input, DEFAULT_BUFFER_SIZE);
    }
    public static String toString(final Reader input, int bufSize) throws IOException {

        StringBuilder buf = new StringBuilder();
        final char[] buffer = new char[bufSize];
        int n = 0;
        n = input.read(buffer);
        while (-1 != n) {
            if (n == 0) {
                throw new IOException("0 bytes read in violation of InputStream.read(byte[])");
            }
            buf.append(new String(buffer, 0, n));
            n = input.read(buffer);
        }
        input.close();
        return buf.toString();
    }

    public static String readStringFromStream(InputStream in)
        throws IOException {

        StringBuilder sb = new StringBuilder(1024);

        for (int i = in.read(); i != -1; i = in.read()) {
            sb.append((char) i);
        }

        in.close();

        return sb.toString();
    }

    /**
     * Load the InputStream into memory and return a ByteArrayInputStream that
     * represents it. Closes the in stream.
     * 
     * @param in
     * @return
     * @throws IOException
     */
    public static ByteArrayInputStream loadIntoBAIS(InputStream in)
        throws IOException {
        int i = in.available();
        if (i < DEFAULT_BUFFER_SIZE) {
            i = DEFAULT_BUFFER_SIZE;
        }
        LoadingByteArrayOutputStream bout = new LoadingByteArrayOutputStream(i);
        copy(in, bout);
        in.close();
        return bout.createInputStream();
    }
    
    public static void consume(InputStream in) throws IOException {
        int i = in.available();
        if (i == 0) {
            //if i is 0, then we MAY have already hit the end of the stream
            //so try a read and return rather than allocate a buffer and such 
            int i2 = in.read();
            if (i2 == -1) {
                return;
            }
            //reading the byte may have caused a buffer to fill
            i = in.available();
        }
        if (i < DEFAULT_BUFFER_SIZE) {
            i = DEFAULT_BUFFER_SIZE;
        }
        if (i > 65536) {
            i = 65536;
        }
        byte bytes[] = new byte[i];
        while (in.read(bytes) != -1) {
            //nothing - just discarding
        }
    }

    public static byte[] readBytesFromStream(InputStream in) throws IOException {
        int i = in.available();
        if (i < DEFAULT_BUFFER_SIZE) {
            i = DEFAULT_BUFFER_SIZE;
        }
        ByteArrayOutputStream bos = new ByteArrayOutputStream(i);
        copy(in, bos);
        in.close();
        return bos.toByteArray();
    }
}