InputStream與String/byte[]相互轉換

public class InputStreamUtils {
 
 private static final String CHARSET_NAME = "UTF-8";
 private static final int BUFFER_SIZE = 1024;

 /**
  * 將字符串轉換成InputStream
  * @param string
  * @return
  * @throws UnsupportedEncodingException
  */
 public static InputStream string2InputStream(String string) throws UnsupportedEncodingException {
  ByteArrayInputStream inputStream = new ByteArrayInputStream(string.getBytes(CHARSET_NAME));
  return inputStream;
 }
 
 /**
  * 將InputStream轉換成指定編碼的String
  * @param is
  * @return
  * @throws Exception
  */
 public static String inputStream2String(InputStream is) throws Exception {
  ByteArrayOutputStream os = new ByteArrayOutputStream();
  byte[] data = new byte[BUFFER_SIZE];
  int len = -1;
  while (-1 != (len = is.read(data, 0, BUFFER_SIZE))) {
   os.write(data, 0, len);
  }
  return new String(os.toByteArray(), CHARSET_NAME);
 }
 
 /**
  * 將byte[]轉換成IntputStream
  * @param buf
  * @return
  */
 public static InputStream byte2InputStream(byte[] buf) {
  ByteArrayInputStream inputStream = new ByteArrayInputStream(buf);
  return inputStream;
 }
 
 /**
  * 將IntputStream轉換成byte[]
  * @param is
  * @return
  * @throws IOException
  */
 public static byte[] inputStream2Byte(InputStream is) throws IOException {
  ByteArrayOutputStream os = new ByteArrayOutputStream();
  byte[] date = new byte[BUFFER_SIZE];
  int len = -1;
  while (-1 != (len = is.read(date, 0, BUFFER_SIZE))) {
   os.write(date, 0, BUFFER_SIZE);
  }
  return os.toByteArray();
 }
 
}