高手帮个忙

<%@   page contentType="text/html;charset=utf8"%>
<%@   page import="java.sql.*"%>
<%@   page import="java.util.*"%>
<%@   page import="java.text.*"%>
<%@   page import="java.io.*"%>
<%@   page import="java.awt.*"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head></head>
<body>
<%   
   Class.forName("com.mysql.jdbc.Driver").newInstance();
   String url="jdbc:mysql://localhost:3306/customer" +
"?useUnicode=true&characterEncoding=utf8";
   Connection   con   =   DriverManager.getConnection(url,"root","1234");      
   String   sql   =   "select   *   from  Picture where id=1";     
   Statement stmt = con.createStatement(); 
   
   ResultSet rs = stmt.executeQuery(sql); 
   if(rs.next()) {  

    InputStream in = rs.getBinaryStream("picName"); 
    ServletOutputStream op = response.getOutputStream(); 
    int len; 
    byte[] buf=new byte[1024]; 
    while((len= in.read(buf))!=-1) { 
     op.write(buf, 0, len); 
    } 
    op.close(); 
    in.close(); 
   } 
   
   rs.close(); 
   stmt.close(); 
    con.close(); 
  %>
</body>
</html>在数据库中读取图片显示在jsp页面中，但是只显示了图片的名字，并抛出异常 Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:610)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:198)
at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125)