Java read/Update Oracle database BLOB fields

In the process of writing a Java program, how to read a field of type BLOB for an Oracle database table?

Here's a workaround when I write a program. The core statement. (Transfer up to make a change, format do not learn, develop good habits)

For details, please refer to:

Read Sequence id:http://blog.csdn.net/yzsind/article/details/6918506

Blob Related: http://jslfl.iteye.com/blog/1771949

Http://www.linuxidc.com/Linux/2011-08/40218.htm

http://xwwccsucn.blog.163.com/blog/static/979145792011925234392/

1. Read the Blob field

Import Oracle.sql.BLOB;

ResultSet rs = ps.executequery (SQL);

Blob blob = (BLOB) Rs.getblob ("content");

String s = blobtostring (BLOB);

2. Blobtostring () method

Private String blobtostring (Blob blob) throws SQLException, Unsupportedencodingexception {

Long bloblength; Blob field length

int i = 1; Loop variable

byte[] bytes; Blob temporary storage byte array

String newstr = ""; return string

byte[] msgcontent = Blob.getbytes (); Blob conversion to byte array

Bloblength = Blob.length (); Get blob length

if (msgcontent = = NULL | | Bloblength = = 0)//If empty, return null value

{

Return "";

} else {

while (i <= bloblength)//loop processing string conversion, each 1024;oracle string limit 4k max

{

bytes = Blob.getbytes (i, 1024);

i = i + 1024;

NEWSTR = newstr + new String (bytes);

}

}

return newstr;

}

3. Update BLOB field

public void InsertData (string task_name, String tast_target) {

int num = 0;

String hql = "INSERT into table values (Sequence_id.nextval,?,empty_blob ()) returning IDs into?";

try {

Connection conn = Globaldata.getconnection ();

Oraclepreparedstatement Ops = (oraclepreparedstatement) conn.preparestatement (HQL);

Ops.setstring (1, task_name);

Ops.registerreturnparameter (2, oracletypes.number);

num = Ops.executeupdate ();

ResultSet RSet = Ops.getreturnresultset ();//Rest is not null

Long id = 0;

while (Rset.next ()) {

id = rset.getlong (1);

System.out.println ("Insert returnning:" + ID);

}

Update BLOB fields

Statement BST = Conn.createstatement ();

ResultSet bset = Bst.executequery ("Select tast_target from table where id=" + ID + "for UPDATE");

Blob blob = null;

while (Bset.next ()) {

blob = ((Oracleresultset) bset). GetBLOB (1);

}

Final Java.io.BufferedOutputStream out = new Java.io.BufferedOutputStream (Blob.getbinaryoutputstream ());//output stream

Bytearrayinputstream streamtemp = null;//input stream

try {

Streamtemp = new Bytearrayinputstream (tast_target.getbytes ("iso-8859-1"));

} catch (Unsupportedencodingexception ex) {

Logger.getlogger (Oraclegeneldaoimpl.class

. GetName ()). log (Level.severe, NULL, ex);

}

byte[] buffer = new byte[1024];//buffers

int length =-1;

try {

while (length = streamtemp.read (buffer))! =-1) {

Out.write (buffer, 0, length);

}

Streamtemp.close ();

Out.close ();

} catch (IOException ex) {

Logger.getlogger (Oraclegeneldaoimpl.class

. GetName ()). log (Level.severe, NULL, ex);

}

Conn.commit ();

Ops.close ();

Bst.close ();

} catch (SQLException ex) {

Logger.getlogger (Oraclegeneldaoimpl.class

. GetName ()). log (Level.severe, NULL, ex);

}

}

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Java read/Update Oracle database BLOB fields