out.println("Value: "+item.getString()+"<br>");        }

      }

    }

%>

4．  从数据库读取BLOB然后保存到客户端磁盘上

这段代码有点诡异，执行后将会弹出文件保存对话窗口，将BLOB数据读出保存到本地文件。全文列出如下：

<%@ page contentType="text/html; charset=GBK" import="java.io.*" import="java.sql.*" import="test.global.ConnectionFactory"%><%

      Connection con = ConnectionFactory.getConnection();

      con.setAutoCommit(false);

      Statement st = con.createStatement();

      ResultSet rs = st.executeQuery(

                     "select contents from  BLOBIMG  where  id=103 ");

      if (rs.next()) {

        Blob blob = rs.getBlob(1);

        InputStream ins = blob.getBinaryStream();

        response.setContentType("application/unknown");

        response.addHeader("Content-Disposition", "attachment; filename="+"output.txt");

        OutputStream outStream = response.getOutputStream();

        byte[] bytes = new byte[1024];

        int len = 0;

        while ((len=ins.read(bytes))!=-1) {

            outStream.write(bytes,0,len);

        }

        ins.close();

        outStream.close();

        outStream = null;

        con.commit();

        con.close();

      }

%>

注意，在<% … … %>之外，绝对不能有任何字符，空格或回车都不行，不然会导致outputStream出错，对非ASCII输出文件来说就是格式错误不可读。

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