java.lang.IndexOutOfBoundsException at java.io.FileOutputStream.writeBytes(Native Method)

测试 DDN wos 的时候出现错误：

 available :
/usr/lk/data/linkapp/ddn_1440639847758_temp

java.lang.IndexOutOfBoundsException
    at java.io.FileOutputStream.writeBytes(Native Method)
    at java.io.FileOutputStream.write(FileOutputStream.java:)
    at com.lk.ddn.DDNRestUtil.getData(DDNRestUtil.java:)
    at com.lk.ddn.DDNRestUtil.main(DDNRestUtil.java:)

相关代码是：

    public static byte[] getData(String oid) {
        if (StringUtils.isEmpty(oid)) {
            return null;
        }
        int nFileLength = -;
        String meta = "";
        byte[] fileData = null;
        try {
            String httpurl = "http://"+host+"/cmd/get";
            httpurl = "http://localhost/disk/myFileList.action";
            httpurl = "http://localhost/register.jsp";
            URL url = new URL(httpurl);
            HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection();
            httpConnection.setRequestMethod("GET");
//            httpConnection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 " +
//                    "(KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36");
            httpConnection.setRequestProperty("content-type", "application/octet-stream");
            httpConnection.setDoOutput(true);
            httpConnection.setDoInput(true);

            int responseCode = httpConnection.getResponseCode();
            if (responseCode >= ) {
                processErrorCode(responseCode);
                return null; // -2 represent access is error
            }

            if (responseCode == HttpURLConnection.HTTP_OK) {
                if (==) {

                    InputStream inputStream = null;
                    try {
//                        inputStream = httpConnection.getInputStream();
//                        int available = inputStream.available();
//                        System.out.println(" available : " + available);
//                        fileData = new byte[available];
//                        int read = inputStream.read(fileData);
//                        System.out.println(" read : " + read);
//                        int read = 0;
//                        while ((read = inputStream.read(fileData)) != -1) {
//
//                        }

//                        String contentEncoding = httpConnection.getContentEncoding();
//                        System.out.println(" contentEncoding : " + contentEncoding);
//
//                        inputStream = httpConnection.getInputStream();
//                        int available = inputStream.available();
//                        fileData = new byte[nFileLength];
//                        int read = inputStream.read(fileData);
//                        System.out.println(" read : " + read);
//                        while ((read = inputStream.read(fileData)) != -1) {
//
//                        }

                        inputStream = httpConnection.getInputStream();
                        int available = inputStream.available();
                        System.out.println(" available : " + available);

                        int offset = ;
                        int reads;
                        int onesize = available>?:available;
//                        fileData = new byte[nFileLength];
//                        fis.reset();
//                        while ((reads = inputStream.read(fileData,offset,onesize)) != -1) {
//                            //System.out.println(new String(b));
//                            offset += reads;
//                            if (onesize >= available - offset) {
//                                onesize = available - offset;
//                                if (onesize <= 0) {
//                                    break;
//                                }
//                            }
//                        }
//                        while ((reads = inputStream.read(fileData)) != -1) {
//                            //System.out.println(new String(b));
//                            offset += reads;
//                        }

                        String downlowdPath = getTempFileDownlowdPath();
                        System.out.println(downlowdPath);
                        FileOutputStream fos = new FileOutputStream(downlowdPath);
                        int read = ;

                        int off = ;
                        available = inputStream.available();
                        byte[] b = new byte[];
                        while ((read = inputStream.read(b))!= -) {
                            System.out.println(read);
                            fos.write(b,off,read);
                            off += read;
                        }
                        if (b != null) {
//                            fos.write(b);
                        }
                        System.out.println("readed : " + read);
                        inputStream.close();
                        fos.flush();
                        fos.close();
//
                    } catch (IOException e) {
                        e.printStackTrace();
                    } finally {
                        if (inputStream != null) {
                            inputStream.close();
                        }
                    }

                }
            }

        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return fileData;

    }

为什么总是不行呢？？？

这样的简单流操作、、