//方法一  org.apache.commons.io.IOUtils包下的实现（建议）

IOUtils.toByteArray(inputStream);

//方法二  用java代码实现（其实就是对上面方法一的解析）

public static byte[] toByteArray(InputStream input) throws IOException {

    ByteArrayOutputStream output = new ByteArrayOutputStream();

    byte[] buffer = new byte[1024];

    int n = 0;

    while (-1 != (n = input.read(buffer))) {

        output.write(buffer, 0, n);

    }

    return output.toByteArray();

}

    public static void inputstreamtofile(InputStream ins, File file) throws IOException {

        OutputStream os = new FileOutputStream(file);

        int bytesRead;

        byte[] buffer = new byte[8192];

        while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) {

            os.write(buffer, 0, bytesRead);

        }

        os.close();

        ins.close();

    }

//方法一  使用org.apache.commons.io.IOUtils包下的方法

IOUtils.toString(inputStream);

//方法二

    /**

     * 将InputStream转换成某种字符编码的String

     *

     * @param in

     * @param encoding

     * @return

     * @throws Exception

     */

    public static String inputStreamToString(InputStream in, String encoding) {

        String string = null;

        ByteArrayOutputStream outStream = new ByteArrayOutputStream();

        byte[] data = new byte[BUFFER_SIZE];

        int count = -1;

        try {

            while ((count = in.read(data, 0, BUFFER_SIZE)) != -1)

                outStream.write(data, 0, count);

        } catch (IOException e) {

            logger.error("io异常", e.fillInStackTrace());

        }

        try {

            string = new String(outStream.toByteArray(), encoding);

        } catch (UnsupportedEncodingException e) {

            logger.error("字符串编码异常", e.fillInStackTrace());

        }

        return string;

    }

InputStream sbs = new ByteArrayInputStream(byte[] buf); 

  public static void byte2File(byte[] buf, String filePath, String fileName)

    {

        BufferedOutputStream bos = null;

        FileOutputStream fos = null;

        File file = null;

        try

        {

            File dir = new File(filePath);

            if (!dir.exists() && dir.isDirectory())

            {

                dir.mkdirs();

            }

            file = new File(filePath + File.separator + fileName);

            fos = new FileOutputStream(file);

            bos = new BufferedOutputStream(fos);

            bos.write(buf);

        }

        catch (Exception e)

        {

            e.printStackTrace();

        }

        finally

        {

            if (bos != null)

            {

                try

                {

                    bos.close();

                }

                catch (IOException e)

                {

                    e.printStackTrace();

                }

            }

            if (fos != null)

            {

                try

                {

                    fos.close();

                }

                catch (IOException e)

                {

                    e.printStackTrace();

                }

            }

        }

    }

//先将byte[]转为inputStream,然后在转为String

InputStream is = new ByteArrayInputStream(byte[] byt);

//然后在根据上文提到的将inputStream转为String的方法去转换

FileInputStream fileInputStream = new FileInputStream(file);