public class TestDB { 
public static void main(String[] args) { 
try { 

/** Loading the driver*/ 

Class.forName("com.oracle.jdbc.Driver"); 

/** Getting Connection*/ 
Connection con = DriverManager.getConnection("jdbc:oracle://localhost:3306/test","test","test"); 

PreparedStatement pstmt = con.prepareStatement("insert into Emp(id,name,description)values(?,?,?)"); 
pstmt.setInt(1,5); 
pstmt.setString(2,"Das"); 
// Create a big CLOB value...AND inserting as a CLOB 
StringBuffer sb = new StringBuffer(400000); 

sb.append("This is the Example of CLOB .."); 
String clobValue = sb.toString(); 
pstmt.setString(3, clobValue); 
int i= pstmt.executeUpdate(); 
System.out.println("Done Inserted"); 
pstmt.close(); 
     con.close(); 

     // Retrive CLOB values 
Connection con = DriverManager.getConnection("jdbc:oracle://localhost:3306/test","test","test"); 
PreparedStatement pstmt = con.prepareStatement("select * from Emp where id=5"); 
ResultSet rs = pstmt.executeQuery(); 
Reader instream = null; 
int chunkSize; 
if(rs.next()){ 
String name = rs.getString("name"); 
java.sql.Clob clob = result.getClob("description") 
StringBuffer sb1 = new StringBuffer(); 

chunkSize = ((oracle.sql.CLOB)clob).getChunkSize(); 
instream = clob.getCharacterStream(); 
BufferedReader in = new BufferedReader(instream); 
String line = null; 
while ((line = in.readLine()) != null) { 
sb1.append(line); 
    } 
if(in != null){ 
in.close(); 
} 

String clobdata = sb1.toString(); // this is the clob data converted into string 

} 


} catch (Exception e) { 

e.printStackTrace(); 
} 
     } 
}

------解决方案--------------------
从数据库中取出的数据放入byte[]数组中.
String转换byte[]数组可以用String.getBytes() 方法。