jsp页面显示数据库中的二进制保存的图片及下载

上传一张图片，以Blob的形式保存进数据库。保存进之后如何在页面显示这张图片呢？

废话少说，直接上代码。

jsp页面代码：

<img src="/webusermng/userh/showuserhbusinesslicense.do?hbusinesslicenseId=<%=userHBusinessLicense[0][1]%>" width="77" height="93" style="cursor: pointer;" onmouseover="javascript:document.getElementById('divimglicense').style.display='';" onmouseout="javascript:setTimeout(function(){document.getElementById('divimglicense').style.display='none'}, 1000);"/>

 

对了，你猜对了。其实就是一个image的src请求：

<img src="/webusermng/userh/showuserhbusinesslicense.do?hbusinesslicenseId=<%=userHBusinessLicense[0][1]%>" />

 

后台如何处理呢？

private ActionForward showUserHBusinessLicense(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws BizException
{
        String hbusinesslicenseId = request.getParameter("hbusinesslicenseId");
        
        if(hbusinesslicenseId == null || "".equals(hbusinesslicenseId))
        {
            throw new BizException("营业执照编号不正确！");
        }
        try
        {
            Web_file web_file = serviceLocator.getUserHService().queryHBusinessLicenseImage(Integer.valueOf(hbusinesslicenseId));
            if(web_file != null)
            {
                byte[] buf = web_file.getUpf_context();// 获取Blob字节数组
                response.setContentType(web_file.getUpf_contexttype());
                OutputStream hblicense = response.getOutputStream();// 获取输出流
                for(int i = 0; i < buf.length; i++)
                {
                    hblicense.write(buf[i]);// 输出到页面
                }
                hblicense.close();// 关闭输出流
            }
            return null;
        }
        catch(Exception e)
        {
            e.printStackTrace();
            return null;
        }
}

 

这儿最主要的就是流的读出：

OutputStream hblicense = response.getOutputStream();// 获取输出流
for(int i = 0; i < buf.length; i++)
{
     hblicense.write(buf[i]);// 输出到页面
}
hblicense.close();// 关闭输出流

看一看serivce的queryHBusinessLicenseImage实现层如何处理的

public Web_file queryHBusinessLicenseImage(Integer upf_id) throws BizException
{
        SQLHelper sqlExec = new SQLHelper(false);
        Web_file web_file = null;
        try
        {
            sqlExec_lietou.beginTrans();
            web_file = new Web_file();
            web_file.setUpf_id(upf_id);
            web_file = (Web_file) ORMHelper.getObjectByPK(sqlExec, web_file);
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            sqlExec_lietou.close();
        }
        return web_file;
}

 

呵呵，很简单吧！

 

另外一种上传附件，下载另存为附件的方法。

@RequestMapping(value = "/downloadcandidateannex/", method = RequestMethod.GET)
    public void downLoadCandidateAnnex(HttpServletRequest request, HttpServletResponse response) throws Exception
    {
        Integer userh_id = this.getCurrentUserId(request);
        if(userh_id == null || userh_id <= 0)
        {
            throw new BizException("用户编号不正确！");
        }
        String webfileId = request.getParameter("webfileId");
        WebFileForm webFileForm = serviceFactory.getPcdetailService().getCandidateAnnex(userh_id, webfileId);
        response.setContentType("application/x-msdownload");
        try
        {
            String fileName = new String(webFileForm.getWeb_file().getUpf_filename().getBytes("gbk"), "ISO-8859-1");
            response.setHeader("Content-Disposition", "attachment;" + " filename=" + fileName);
            InputStream ips = serviceFactory.getMongoDBService().getFileInputStream(IMongoDBService.TABLE_WEB_FILE, Integer.valueOf(webfileId));
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            int b = 0;
            while((b = ips.read()) != -1)
                baos.write(b);
            
            response.getOutputStream().write(baos.toByteArray());
        }
        catch(Exception e)
        {
            throw new BizException("文件下载出错！", e);
        }
    }

  一：设置下载头信息response.setContentType("application/x-msdownload");

 二：获取文件流，读出

InputStream ips = serviceFactory.getMongoDBService().getFileInputStream(IMongoDBService.TABLE_WEB_FILE, Integer.valueOf(webfileId));
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            int b = 0;
            while((b = ips.read()) != -1)
                baos.write(b);
            
            response.getOutputStream().write(baos.toByteArray());

评论

3 楼 xurichusheng 2014-11-05  

Z_408 写道

这个可以的，你不妨试试。
Action中代码：
public String displayImage(){
String sql = "SELECT empHeadImg,empHeadImgName FROM t_personal WHERE id= " + employeeId;
PreparedStatement ps = null;
ResultSet rs = null;
InputStream is = null;
OutputStream os = null;
try {
Class.forName(driverClassName);
Connection conn = DriverManager.getConnection(url, username,password);
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
if (rs.next()) {
Blob blob = rs.getBlob("empHeadImg");
is = blob.getBinaryStream();
HttpServletResponse response = this.getResponse();
response.setContentType("image/jpeg");
os = response.getOutputStream();
int num = (int) blob.length();
byte buf[] = new byte[num];
while ((num = is.read(buf)) != -1) {
os.write(buf);
}
}
}catch(Exception e){
e.printStackTrace();
}
return null;
}
jsp中代码：
<img width="130" height="172" src="displayImage.action?employeeId=${employeeDetails.employeeId }"/>

使用2楼Z_408 的方法可以显示图像

2 楼 Z_408 2012-12-25  

这个可以的，你不妨试试。
Action中代码：
public String displayImage(){
String sql = "SELECT empHeadImg,empHeadImgName FROM t_personal WHERE id= " + employeeId;
PreparedStatement ps = null;
ResultSet rs = null;
InputStream is = null;
OutputStream os = null;
try {
Class.forName(driverClassName);
Connection conn = DriverManager.getConnection(url, username,password);
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
if (rs.next()) {
Blob blob = rs.getBlob("empHeadImg");
is = blob.getBinaryStream();
HttpServletResponse response = this.getResponse();
response.setContentType("image/jpeg");
os = response.getOutputStream();
int num = (int) blob.length();
byte buf[] = new byte[num];
while ((num = is.read(buf)) != -1) {
os.write(buf);
}
}
}catch(Exception e){
e.printStackTrace();
}
return null;
}
jsp中代码：
<img width="130" height="172" src="displayImage.action?employeeId=${employeeDetails.employeeId }"/>

1 楼 hesai_vip 2012-07-25  

请问有上传图片到BLOB的例子么