从oracle数据库中取出Clob字段转换成String类型错误：必须登陆到服务器，请大家帮忙。

Question

方法：
public String clobToString(String sql) throws SQLException,ClassNotFoundException,IOException
{
String content=null;
             Connection con=this.con();
Statement smt=con.createStatement();
ResultSet rst1=smt.executeQuery(sql);
                if(rst1.next())
                {
                    oracle.sql.CLOB cb=(oracle.sql.CLOB)rst1.getClob(1);
                     BufferedReader br = new BufferedReader(cb.getCharacterStream());
                    String s = br.readLine();
                    while (s != null) 
                    {
                      content += s;
                      s = br.readLine();
                     }
                   
                }
                 con.close();
    smt.close();
                return content;

}
错误内容：
java.sql.SQLException: 必须登录到服务器
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)
at oracle.jdbc.dbaccess.DBError.check_error(DBError.java:1160)
at oracle.jdbc.ttc7.TTC7Protocol.assertLoggedIn(TTC7Protocol.java:2196)
at oracle.jdbc.ttc7.TTC7Protocol.getLobChunkSize(TTC7Protocol.java:3027)
at oracle.sql.LobDBAccessImpl.getChunkSize(LobDBAccessImpl.java:686)
at oracle.sql.CLOB.getChunkSize(CLOB.java:664)
at oracle.sql.CLOB.getBufferSize(CLOB.java:689)
at oracle.sql.CLOB.getCharacterStream(CLOB.java:317)
at hsj.data.clobToString(data.java:71)
at _jsp._jspnews._addnews__jsp._jspService(jspnews/addnews.jsp:60)
at com.caucho.jsp.JavaPage.service(JavaPage.java:60)
at com.caucho.jsp.Page.pageservice(Page.java:570)
at com.caucho.server.dispatch.PageFilterChain.doFilter(PageFilterChain.java:159)
at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:178)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:267)
at com.caucho.server.port.TcpConnection.run(TcpConnection.java:388)
at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:490)
at com.caucho.util.ThreadPool.run(ThreadPool.java:423)
at java.lang.Thread.run(Thread.java:595)

Answer 1

尽量这样写：
oracle.sql.CLOB clob=(oracle.sql.CLOB)rs.getClob(1);
(clob!=null){
   content= clob.getSubString((long) 1, (int) clob.length());
}
另外你这个错误可能是由于你未连接到ORACLE，再有smt.close();应放在con.close();的前面。

Answer 2

当然不是我自己写的了哦，是resin报错信息啊。

Answer 3

(clob!=null){
   content= clob.getSubString((long) 1, (int) clob.length());
}
前面是if吗