CODEWITHSUNDEEP
javajdbcblob
Suzon
Suzon

Reputation: 759

How to convert Blob to String and String to Blob in java

I'm trying to get string from BLOB datatype by using 

Blob blob = rs.getBlob(cloumnName[i]);
byte[] bdata = blob.getBytes(1, (int) blob.length());
String s = new String(bdata);

It is working fine but when I'm going to convert String to Blob and trying to insert into database then nothing inserting into database. I've used below code for converting String to Blob:

String value = (s);
byte[] buff = value.getBytes();
Blob blob = new SerialBlob(buff);

Can anyone help me about to converting of Blob to String and String to Blob in Java?

Upvotes: 25

Views: 189271

Answers (6)

Varun
Varun

Reputation: 4452

Here is my solution:

Retrieve blob column from the database and pass it to the below method.

 public static String blobToString(BLOB blob) throws Exception {

        byte[] data = new byte[(int) blob.length()];
        BufferedInputStream instream = null;
        try {
        instream = new BufferedInputStream(blob.getBinaryStream());
        instream.read(data);
        } catch (Exception ex) {
        throw new Exception(ex.getMessage());
        } finally {
        instream.close();
        }
        
        int chunk = 65536;
        ByteArrayInputStream bis = new ByteArrayInputStream(data);
        GZIPInputStream gis = new GZIPInputStream(bis);

         int length = 0;
        byte[] buffer = new byte[chunk];
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while ((length = gis.read(buffer, 0, chunk)) != -1) {
        bos.write(buffer, 0, length);
        }

        gis.close();
        bis.close();
        bos.close();
        
        String str = bos.toString();
        System.out.println(str);
        return str;

    }

Upvotes: 0

ucMax
ucMax

Reputation: 5428

And here is my solution, that always works for me

StringBuffer buf = new StringBuffer();
String temp;
BufferedReader bufReader = new BufferedReader(new InputStreamReader(myBlob.getBinaryStream()));
    while ((temp=bufReader.readLine())!=null) {
        bufappend(temp);
    }

Upvotes: 0

Maverick
Maverick

Reputation: 1599

To convert Blob to String in Java:

byte[] bytes = baos.toByteArray();//Convert into Byte array
String blobString = new String(bytes);//Convert Byte Array into String

Upvotes: -2

Evgeniy Dorofeev
Evgeniy Dorofeev

Reputation: 135992

try this (a2 is BLOB col)

PreparedStatement ps1 = conn.prepareStatement("update t1 set a2=? where id=1");
Blob blob = conn.createBlob();
blob.setBytes(1, str.getBytes());
ps1.setBlob(1, blob);
ps1.executeUpdate();

it may work even without BLOB, driver will transform types automatically:

   ps1.setBytes(1, str.getBytes);
   ps1.setString(1, str);

Besides if you work with text CLOB seems to be a more natural col type

Upvotes: 10

Ruchira Gayan Ranaweera
Ruchira Gayan Ranaweera

Reputation: 35547

Use this to convert String to Blob. Where connection is the connection to db object. 

    String strContent = s;
    byte[] byteConent = strContent.getBytes();
    Blob blob = connection.createBlob();//Where connection is the connection to db object. 
    blob.setBytes(1, byteContent);

Upvotes: 3

Optional
Optional

Reputation: 4507

How are you setting blob to DB? You should do:

 //imagine u have a a prepared statement like:
 PreparedStatement ps = conn.prepareStatement("INSERT INTO table VALUES (?)");
 String blobString= "This is the string u want to convert to Blob";
oracle.sql.BLOB myBlob = oracle.sql.BLOB.createTemporary(conn, false,oracle.sql.BLOB.DURATION_SESSION);
 byte[] buff = blobString.getBytes();
 myBlob.putBytes(1,buff);
 ps.setBlob(1, myBlob);
 ps.executeUpdate();

Upvotes: 0

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