jsp 如何从数据库中读取二进制文件（图片）并显示

提供的jsp页面代码：
<%@ page contentType="text/html;charset=gb2312"%>
<%@ taglib uri="struts/html" prefix="html" %>
<%@ taglib uri="struts/bean" prefix="bean" %>
<%@ taglib uri="struts/logic" prefix="logic" %>




<%
String type=String.valueOf(request.getParameter("type"));
int i;
if("old".equals(type)){
i=0;
}else{
i=1;
}
%>

上传照片

师大首页--> <% if("old".equals(type)) out.print("校园老照片-->上传老照片"); else out.print("校园新貌-->上传新照片"); %> 照 片： 注释内容： 上传 重填

主要的java类：
package com.toowell.schoolPhoto.action;

import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.Action;
import org.apache.struts.upload.FormFile;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.sql.ResultSet;
import java.util.Vector;
import java.io.*;

import com.toowell.common.DbBean;
import com.toowell.common.Util;
import com.toowell.common.Upload;
import com.toowell.common.UserUtil;
import com.toowell.common.page.PageBean;
import com.toowell.schoolPhoto.form.PhotosForm;
import com.toowell.schoolPhoto.model.PhotosBean;
import com.toowell.schoolPhoto.model.PhotosVo;

/**
* Created by IntelliJ IDEA.
* User: Administrator
* Date: 2005-10-27
* Time: 9:11:05
* To change this template use Options | File Templates.
*/
public class PhotoShowAction extends Action {
public ActionForward execute(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) throws Exception{

String parameter= mapping.getParameter();

boolean isAdmin=UserUtil.isAdmin(request);
boolean isAudit=UserUtil.isAudit(request);
//查询老照片
if("old".equalsIgnoreCase(parameter)) {
String sql="select * from schoolPhoto where state=0 and audit=1 order by id desc";
if(isAdmin){
sql=null;
sql="select * from schoolPhoto where state=0 order by id desc";
}
System.out.println(sql);
PageBean pageBean =new PageBean();
pageBean.pageshow(request,sql,"com.toowell.schoolPhoto.model.PhotosList",16);

request.setAttribute("type","old");
return mapping.findForward("success");
}
//查询新照片
if("new".equalsIgnoreCase(parameter)) {
String sql="select * from schoolPhoto where state=1 and audit=1 order by id desc";
if(isAdmin){
sql=null;
sql="select * from schoolPhoto where state=1 order by id desc";
}
System.out.println(sql);
PageBean pageBean =new PageBean();
pageBean.pageshow(request,sql,"com.toowell.schoolPhoto.model.PhotosList",16);
request.setAttribute("type","new");
return mapping.findForward("success");
}
//
if("add".equalsIgnoreCase(parameter)) {
String servletDir = servlet.getServletContext().getRealPath("/schoolPhoto/images");
PhotosForm photos=(PhotosForm)form;
String explain=Util.changeCode(photos.getExplain());

String state=photos.getState();
int type=Integer.parseInt(state);
int id=0;
try{
id = PhotosBean.getNowID()+1;
} catch(Exception e){
return mapping.findForward("imageError");
}
//获取上传的图片文件
FormFile formFile = photos.getSchoolPhoto();
//上传位置加上文件名，不含扩展名。回为扩展名可以自动判断
String dir = servletDir + "/" +id;

Upload up = new Upload(formFile,dir);
up.upload();
String imageType =up.getFileType();
PhotosVo photosVo=new PhotosVo();
photosVo.setId(id);
photosVo.setImageType(imageType);
photosVo.setExplain(explain);
try{
PhotosBean.add(photosVo,state);
}catch(Exception e){
return mapping.findForward("imageError");
}
if(type==0){

request.setAttribute("type","old");
return mapping.findForward("oldSuccess");
} else{
request.setAttribute("type","new");
return mapping.findForward("newSuccess");
}
}

if("delete".equalsIgnoreCase(parameter)) {
String servletDir = servlet.getServletContext().getRealPath("/schoolPhoto/images");
String id=request.getParameter("id");
ResultSet rs=null;
int state=0;
//删除照片
String sqlImageType="select imageType,state from schoolPhoto where id="+id;
try{
rs= DbBean.getRs(sqlImageType);
rs.next();
String imageType=rs.getString(1);
state=rs.getInt(2);
String imageName = id+imageType;

File file = new File(servletDir,imageName);
file.delete();
DbBean.close();
}catch(Exception e){
return mapping.findForward("imageError");
}
//删除照片数据库记录
String sql="delete from schoolPhoto where id="+id;
try{
DbBean.execute(sql);
DbBean.close();
}catch(Exception e){
return mapping.findForward("imageError");
}
if(state==0){

request.setAttribute("type","old");
return mapping.findForward("oldSuccess");
} else{
request.setAttribute("type","new");
return mapping.findForward("newSuccess");
}

}

if("modify".equalsIgnoreCase(parameter)) {
ResultSet rs=null;
Vector list=new Vector();
String id=request.getParameter("id");
String sql="select * from schoolPhoto where id="+id;
String servletDir = servlet.getServletContext().getRealPath("/schoolPhoto/images");
String state=request.getParameter("type");
try{
rs=DbBean.getRs(sql);

while(rs.next()){
PhotosVo photosVo=new PhotosVo();
photosVo.setId(rs.getInt(1));
photosVo.setImageType(rs.getString(2));
photosVo.setExplain(rs.getString(3));
photosVo.setState(rs.getInt(6));
list.add(photosVo);
}
}catch(Exception e){
return mapping.findForward("imageError");
}

request.setAttribute("listPhoto",list);
if(state.equals("old")){

request.setAttribute("type","old");

} else{
request.setAttribute("type","new");

}
return mapping.findForward("success");
}
if("modifyOne".equalsIgnoreCase(parameter)) {
String id=request.getParameter("id");

PhotosForm photo=(PhotosForm)form;
String explain=Util.changeCode(photo.getExplain());
int state=Integer.parseInt(photo.getState());
System.out.println("----=-=-=-=-=--"+state);
String sql="update schoolPhoto set explain='"+explain+"',audit=0 where id="+id;
System.out.println(sql);
try{
DbBean.execute(sql);
DbBean.close();
}catch(Exception e){
return mapping.findForward("imageError");
}
if(state==0){

request.setAttribute("type","old");
return mapping.findForward("oldSuccess");
} else{
request.setAttribute("type","new");
return mapping.findForward("newSuccess");
}
}
if("audit".equalsIgnoreCase(parameter)) {
String id=request.getParameter("id");
String state=request.getParameter("type");
String sql="update schoolPhoto set audit=1 where id="+id;
// System.out.println(sql);
try{
DbBean.execute(sql);
DbBean.close();
}catch(Exception e){
return mapping.findForward("imageError");
}
if(state.equals("old")){

request.setAttribute("type","old");
return mapping.findForward("oldSuccess");
} else{
request.setAttribute("type","new");
return mapping.findForward("newSuccess");
}
}
return null;
}
}

以上代码仅供参考，恕不能提供更多的代码；
祝好运