java 读取本地文件并转换为byte数组

　　　　　private byte[] InputStream2ByteArray(String filePath) throws IOException {

                InputStream in = new FileInputStream(filePath);
                byte[] data = toByteArray(in);
                in.close();

                return data;
        }

        private byte[] toByteArray(InputStream in) throws IOException {

                ByteArrayOutputStream out = new ByteArrayOutputStream();
                byte[] buffer = new byte[1024 * 4];
                int n = 0;
                while ((n = in.read(buffer)) != -1) {
                        out.write(buffer, 0, n);
                }
                return out.toByteArray();
        }