package com.learn.util;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

import com.learn.db.ConnectionFactory; // 自己实现一个连接工厂类

public class LoadImage {
/* 
     if exists (select * from sysobjects where id = object_id('ImageContainer') and
     OBJECTPROPERTY(id, 'IsUserTable') = 1) drop table obj

     CREATE TABLE [ImageContainer] (
                [rid] [int] IDENTITY (1, 1) NOT NULL ,
                [rname] [varchar] (100) COLLATE Chinese_PRC_CI_AS NULL ,
                [rpath] [varchar] (500) COLLATE Chinese_PRC_CI_AS NULL ,
                [rfilesize] [int] NULL ,
                [rbinary] [image] NULL 
            ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
*/
    
    public void getFileFromDatabaseByRid(int rid,
            HttpServletResponse response) {
        String strSQL = null;
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rst = null;
        ServletOutputStream sos = null;
        BufferedInputStream bis = null;
        try {
            strSQL = "SELECT * FROM ImageContainer WHERE rid = ?";
            conn = ConnectionFactory.getConnection(); // 取得Connection，代码略
            pstmt = conn.prepareStatement(strSQL);
            pstmt.setInt(1, rid);
            rst = pstmt.executeQuery();
            if (rst.next()) {
                bis = new BufferedInputStream(rst.getBinaryStream("rbinary"));
                sos = response.getOutputStream();
                byte[] b = new byte[10 * 1024];
                int len = 0;
                while ((len = bis.read(b)) != -1) {
                    sos.write(b, 0, len);
                }
                bis.close();
                sos.flush();
                sos.close();
            } else {
                System.out.println("picture dose not exist!");
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (SQLException sqle) {
            sqle.printStackTrace();
        } finally{
            ConnectionFactory.close(rst);
            ConnectionFactory.close(pstmt);
            ConnectionFactory.close(conn);
        }
    }
}