[Java] java文件上传下载代码实例

@requestmapping(value="/uploadfile",method=requestmethod.post)
 public resultobject uploadfiles(@requestparam("file")multipartfile file,httpservletrequest request){
  resultobject rs = null;//返回上传完成信息
  string uploaddir = "files";//上传目录,文件保存在webapp下的files文件中
   if(!file.isempty()) {
   //可以对user做一些操作如存入数据库
   //以下的代码是将文件file重新命名并存入tomcat的webapp目录下项目的下级目录
   string filerealname = file.getoriginalfilename();      //获得原始文件名;
   /*int pointindex = filerealname.indexof(".");      //点号的位置
   string filesuffix = filerealname.substring(pointindex);     //截取文件后缀
   uuid fileid = uuid.randomuuid();      //生成文件的前缀包含连字符
   string savedfilename = fileid.tostring().replace("-", "").concat(filesuffix);  //文件存取名
   */
   
   string saveddir = request.getsession().getservletcontext().getrealpath(uploaddir); //获取服务器指定文件存取路径
   file savedfile = new file(saveddir, filerealname);
   boolean iscreatesuccess;
   try {
     iscreatesuccess = savedfile.createnewfile();
     if (iscreatesuccess) {
 
     file.transferto(savedfile); //转存文件
     rs = resultobject.getsuccessresult("上传文件成功");
     long size = file.getsize();//获取文件大小
 
 
     rs.setdata(uploaddir+filerealname);
     }else{
     rs = resultobject.getfailresult("请修改文件名,重新上传");
     }
   } catch (ioexception e) {
     e.printstacktrace();
   }
   }else{
   rs = resultobject.getfailresult("文件不能为空");
   }
   return rs;
 }

@requestmapping(value = "/filterpermission/appdownload", method = requestmethod.get)
  public void appdownload(httpservletrequest request, httpservletresponse response) {
  //url是上面文件上传的url
  download(url,request,response);
  }

public string download(string filepath, httpservletrequest request, httpservletresponse response) {
  bufferedinputstream bis = null;
  bufferedoutputstream bos = null;
  try {
    //获取文件名
    string filename = filepath.substring(filepath.lastindexof("/")+1);
    response.setcharacterencoding("utf-8");
    response.setcontenttype("application/octet-stream");
    //response.setcontenttype("application/force-download");
    //处理下载弹出框名字的编码问题
    response.setheader("content-disposition", "attachment;filename="
      + new string( filename.getbytes("gb2312"), "iso8859-1" ));
    //获取文件的下载路径
    string path = request.getsession().getservletcontext().getrealpath(filepath);
    //利用输入输出流对文件进行下载
    inputstream inputstream = new fileinputstream(new file(path));
    //设置文件大小
    response.setheader("content-length", string.valueof(inputstream.available()));
 
    bis = new bufferedinputstream(inputstream);//构造读取流
    bos = new bufferedoutputstream(response.getoutputstream());//构造输出流
    byte[] buff = new byte[1024];
    int bytesread;
    //每次读取缓存大小的流，写到输出流
    while (-1 != (bytesread = bis.read(buff, 0, buff.length))) {
    bos.write(buff, 0, bytesread);
    }
    response.flushbuffer();//将所有的读取的流返回给客户端
 
  } catch (filenotfoundexception e) {
    e.printstacktrace();
  } catch (ioexception e) {
    e.printstacktrace();
  }finally{
    try{
    if(null != bis){
      bis.close();
    }
    if(null != bos){
      bos.close();
    }
    }catch(ioexception e){
    system.out.println("下载文件失败,"+"文件路径:"+filepath+e);
    logger.error("文件下载失败!", e);
    }
  }
  // 返回值要注意，要不然就出现下面这句错误！
  //java+getoutputstream() has already been called for this response
  return null;
  }