任务：
uos.docfile的content字段是longblob类型，通过Web点击链接能下载到存储在这个字段里的文件。Web点击链接类似如下形式：
http://localhost:8080/dld/downloadDocument.html?id=81&&filename=jfreechart-1.0.19.zip
1.控制器代码：
@RequestMapping("/downloadDocument")
public ModelAndView downloadDocument(HttpServletRequest request,HttpServletResponse response){
try {
// 取参数
String id=request.getParameter("id");
String filename=request.getParameter("filename");
// 设置Resposne
response.reset();
response.setHeader("Content-disposition", "attachment; filename="+filename);
response.setContentType("text/x-plain");
// 获得输出流
ServletOutputStream out = response.getOutputStream();
// 从数据库拷贝输出流
ByteArrayOutputStream byteOutputStream = new ByteArrayOutputStream(4096);
service.copyDocumentOutputStream(id, byteOutputStream);
logger.info(" call PosService.copyDocumentOutputStream successfully.");
// 转化
byte[] bt = null;
bt = byteOutputStream.toByteArray();
// 向客户端写输出
out.write(bt);
out.flush();
out.close();
return null;
} catch (Exception e) {
e.printStackTrace();
logger.error(e);
request.setAttribute("error", e.getClass());
request.setAttribute("reason", e.getMessage());
StackTraceElement[] arr=e.getStackTrace();
request.setAttribute("stackTraceElements", arr);
return new ModelAndView("pages/error/index.jsp");
}
}
2.Service中代码，同样这里也只是中转
public void copyDocumentOutputStream(final String id, final OutputStream os) throws Exception{ getPosDao().copyDocumentOutputStream(id, os); }
3.DAO中代码，这里是实质代码
public void copyDocumentOutputStream(final String id, final OutputStream os) throws Exception{ final LobHandler lobHandler=new DefaultLobHandler(); this.getJdbcTemplate().query("select content from uos.docfile where id=?",new String[] {id},new AbstractLobStreamingResultSetExtractor(){ protected void streamData(ResultSet rs) throws SQLException,IOException,DataAccessException{ FileCopyUtils.copy(lobHandler.getBlobAsBinaryStream(rs,1),os); } }); }
本文转自张昺华-sky博客园博客，原文链接：http://www.cnblogs.com/xiandedanteng/p/4168891.html，如需转载请自行联系原作者
