如何在 JSP 中使用标签显示图像

Here is the code to retrieve image in action class. I have tried it, but not able to display it I don't know about the image processing. How should I use tags in JSP to display the image?

public String displayImage()
  {
    Connection con = null;
    PreparedStatement preparedStatement = null;
    ResultSet resultSet = null;
    String sql,result="";
    con=JdbcHelper.getConnection();
    if(con!=null)
    {
      try
      {
        sql = "SELECT INPUT_FILE_BLOB FROM message_details where message_id=?";
        preparedStatement = con.prepareStatement(sql);
        preparedStatement.setString(1, messageid);
        resultSet = preparedStatement.executeQuery();
        if(resultSet.next())
        {
          Blob image = resultSet.getBlob("INPUT_FILE_BLOB");
          System.out.println("=============Image2
" +image);
          int len1 = (int) image.length();
          System.out.println("=============len1
" +len1);
          byte [] rb1 = new byte[len1];
          InputStream readImg1 = resultSet.getBinaryStream(1);
          try {
            int index1=readImg1.read(rb1, 0, len1);
            System.out.println("index1"+index1);
            response.reset();
            response.setContentType("image/jpg");
            response.getOutputStream().write(rb1,0,len1);
            response.getOutputStream().flush();
          } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
          }
        }
      }
      catch(SQLException e)
      {
        try
        {
          con.rollback();
        }
        catch (SQLException e1)
        {
          result = e1.getMessage();
          e.printStackTrace();
        }
        result = e.getMessage();
        e.printStackTrace();
      }
      finally
      {
        JdbcHelper.close(resultSet);
        JdbcHelper.close(preparedStatement);
        JdbcHelper.close(con);
      }
    }
    else
      result = Constants.SUCCESS;

  }

推荐答案

从数据库中检索图像作为 Blob 或字节数组后，您将直接写入响应.在这种情况下，您不应该返回 SUCCESS 结果，您需要返回 NONE 结果.然后在 JSP 中，您可以使用 img 标记将图像作为单独的线程访问，该标记将调用您返回图像的操作.