该代码部署在LINUX环境上的JBOSS服务器上。以下是使用JDBC API从oracle访问CLOB数据的代码。

使用的JDBC jar是ojdbc6.jar。 JAVA版本：jdk1.8.0_221-amd64 Oracle Java版本：1.8.0_121

import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;

public class GetGenericpdFData {

     public String GetPDFData(String SolutionID) throws IOException {

           String PDFData = null;

           try {

                Class.forName("oracle.jdbc.driver.OracleDriver");
                Connection con = DriverManager.getconnection("jdbc:oracle:thin:@ServerIP:1521:SID","username","password");

                String Query = "select pdf_data from stage1.pdf_queue where system_id in (select system_id from (select * from pdf_queue where solution_id = ? 
and status = 'Completed' order by time_stamp desc) where rownum=1)";

                PreparedStatement preparedStatement = con.prepareStatement(Query);
                preparedStatement.setString(1,SolutionID);

                ResultSet rs = preparedStatement.executeQuery(); 

                while(rs.next()){

                     PDFData = rs.getString("pdf_data");

                }

                //Below data is coming out as null
                System.out.println(PDFData);

                con.close();

           } catch (ClassnotFoundException | SQLException e) {
                // TODO Auto-generated catch block               
                System.out.println("GetGenericpdFData.GetPDFData 7");               
                e.printStackTrace();            
                PDFData = "false";              
           }

           return PDFData;
     }

}