java.sql.SQLRecoverableException while fetching CLOB data using Hibernate + oracle 11g

Question

I am getting "java.sql.SQLRecoverableException: Closed Connection", exception while fetching CLOB data from Oracle 11g using Hibernate in java web application. For DB connectivity I have implemented Tomcat 7 dataource.

Below is my source where I am getting an Exception :

java.sql.Clob reqClob= userBean.getRequestData();
Reader clbReader = reqClob.getCharacterStream();

In above Code while executing "clob.getCharacterStream()", I am getting below Exception :

java.sql.SQLRecoverableException: Closed Connection
at oracle.sql.CLOB.getDBAccess(CLOB.java:1389)
at oracle.sql.CLOB.getCharacterStream(CLOB.java:309)
at org.hibernate.lob.SerializableClob.getCharacterStream(SerializableClob.java:41)

Please note that, I am able to get the data from userBean for other values.

Below is the app version I have used in application:

jdk1.6.0_33 (64bit version)  
hibernate3.jar 
ojdbc6.jar 
Oracle 11g 11.2.0.1.0 - (64bit version)

One strange behavior is I am getting this issue once I have started using TOMCAT 7 Datasource.

Below is Datasource code from Context.xml :

<Resource auth="Container" driverClassName="oracle.jdbc.driver.OracleDriver" 
factory="oracle.jdbc.pool.OracleDataSourceFactory" name="jdbc/XXXX" password="XXXXX" 
type="oracle.jdbc.pool.OracleDataSource" 
url="jdbc:oracle:thin:@xx.xx.xx.xxxx:xxxx:xxxxxx" user="username"
connectionProperties="SetBigStringTryClob=true;" maxActive="20"
maxIdle="10" maxWait="-1" validationQuery="select 1 from dual" />

I have tried all possible parameters for in above code, but it didn't work.

Thanks in advance for all your help, guys...

Answer 1

I had similar problem, I changed Clob to String as below:

String clobAsString = clob.getSubString(1, (int)clob.length());

Make sure you perform this when the connection is alive. Like in DAO. This has to be performed within the transaction which retrieves Clob element from DB.