Blob、InputStream、byte[]、String互转

1、InputStream转byte[]

private byte[] InputStreamToByte(InputStream is) throws IOException {

   ByteArrayOutputStream bytestream = new ByteArrayOutputStream();

   int ch;

   while ((ch = is.read()) != -1) {

    bytestream.write(ch);

   }

   byte imgdata[] = bytestream.toByteArray();

   bytestream.close();

   return imgdata;

  }

2、Blob转byte[]

从数据库中读取Blob类型数据后，要转换成String类型，即转换成InputStream，再从InputStream转成byte[]，再到String即可。如下：

//把数据库中blob类型转换成String类型

public String convertBlobToString(Blob blob){

  

  String result = "";

  try {

   ByteArrayInputStream msgContent =(ByteArrayInputStream) blob.getBinaryStream();

   byte[] byte_data = new byte[msgContent.available()];

   msgContent.read(byte_data, 0,byte_data.length);

   result = new String(byte_data);

  } catch (SQLException e) {

   // TODO Auto-generated catch block

   e.printStackTrace();

  }

  return result;

 }

 

3、byte[]转InputStream

byte[] data;   

InputStream is = new ByteArrayInputStream(data); 

4、byte[]转String

String a = new String(byte,"utf-8");

或者

String b = new String(byte);

5、String转byte[]

String a = "abcdefg";

byte[] b = a.getBytes();