Large fields in Java/jsp Oracle store binary/large text

The database provides two field types: blob and clob, which are used to store large strings or binary data (slices ).

Blob is stored in a single byte and is suitable for storing binary data and files.
Clob uses multi-byte storage and is suitable for storing large text data.

The processing of Blob/clob fields in Oracle is quite special, so pay special attention to the following two points:

1. Use the Stream Mechanism in Oracle JDBC to read and write blob/clob. Therefore, be sure not to read and write blob/clob fields in batch processing; otherwise
Stream type cannot be used in batching exception.

2. the Blob/clob field in Oracle has a cursor. JDBC uses a cursor to operate the Blob/clob field. Before the Blob/clob field is created, the cursor handle cannot be obtained.
Connection reset by peer: Socket write error exception.

The correct method is: first create an empty blob/clob field, and then obtain the cursor from this empty blob/clob field. For example, the following code:

Preparedstatement PS = conn. preparestatement ("insert into picture (image, resume) values (?,?) ");
// Use oralce. SQL. Blob/clob. empty_lob () to construct an empty blob/clob object
PS. setblob (1, Oracle. SQL. Blob. empty_lob ());
PS. setclob (2, Oracle. SQL. clob. empty_lob ());

PS. excuteupdate ();
PS. Close ();

// Read The Blob/clob handle again
PS = conn. preparestatement ("select image, resume from picture where id =? For Update ");
PS. setint (1,100 );

Resultset rs = ps.exe cutequery ();
Rs. Next ();

Oracle. SQL. Blob imgblob = (Oracle. SQL. Blob) Rs. getblob (1 );
Oracle. SQL. clob resclob = (Oracle. SQL. clob) Rs. getclob (2 );

// Write binary data into blob
Fileinputstream instream = new fileinputstream ("C: // image.jpg ");
Outputstream outstream = imgblob. getbinaryoutputstream ();

Byte [] Buf = new byte [1, 10240];
Int Len;
While (LEN = instream. Read (BUF)> 0 ){
Outstream. Write (BUF, 0, Len );
}
Instream. Close ();
Outstream. cloese ();

// Write the string to clob
Resclob. putstring (1, "This is a clob ");

// Update the Blob/clob field to the database.
PS = conn. preparestatement ("Update picture set image =? And resume =? Where id =? ");
PS. setblob (1, imgblob );
PS. setclob (2, resclob );
PS. setint (3,100 );

Ps.exe cuteupdate ();
PS. Close ();