在Xpages中使用Java下载多个文件

Question

我在我的xpage中使用此代码从远程服务器下载文件.当用户从xpage单击下载按钮时,将打开一个新的download.xsp页面并运行下面的代码.

#{javascript:
var exCon = facesContext.getExternalContext();
var response = exCon.getResponse();
var out = response.getOutputStream();

var zipfile = sessionScope.thezip;
var dname = zipfile.substring(zipfile.lastIndexOf("\\")+1);

dl.download(zipfile,dname);
sessionScope.thezip = null;

response.setContentType("application/zip, application/octet-stream");
response.addHeader("Content-disposition","attachment; filename="+dname);
response.setHeader("Cache-Control", "no-cache");

facesContext.responseComplete();
out.close();

下载方法(db.download(string,string))是一种Java方法,它作为托管bean引入xpage.

public void download(String filepath, String dname){
        Connection con = null;
        PreparedStatement stm = null;
        ResultSet rs = null;
        try{
            Class.forName(jdbcClass);
            con = DriverManager.getConnection(url);

                String insSql = "INSERT INTO Cache(name,zip) SELECT '"+filepath+"',* FROM OPENROWSET(BULK N'"+filepath+"', SINGLE_BLOB) AS import;";
                stm = con.prepareStatement(insSql);
                stm.executeUpdate();

            String sql = "SELECT TOP 1 * FROM Cache where name = ?;";
            stm = con.prepareStatement(sql);
            stm.setString(1, filepath);
            rs = stm.executeQuery();

            while(rs.next()){
                InputStream zip = rs.getBinaryStream("zip");

                FacesContext facesContext = FacesContext.getCurrentInstance(); 
                ExternalContext externalContext = facesContext.getExternalContext();
                HttpServletResponse response = (HttpServletResponse) externalContext.getResponse();
                response.setContentType("application/zip, application/octet-stream");
                response.setHeader("Content-disposition","attachment; filename="+dname);
                response.setHeader("Cache-Control", "no-cache");

                byte[] buf = new byte[8192];
                int c = 0;

                while ((c = zip.read(buf, 0, buf.length)) > 0) {
                    OutputStream o = response.getOutputStream();
                    o.write(buf, 0, c);
                    o.close();
                }
                zip.close();
            }

        }catch(Exception e){
            e.printStackTrace();
        }finally{
            try{
                if(stm!=null){stm.close();}
                if(rs!=null){rs.close();}
                if(con!=null){con.close();}
            }catch(Exception ex){ex.printStackTrace();}
        }

    }

此java代码运行sql查询以获取zip文件作为字节并将其存储在表中.然后它选择此行并将字节返回给调用者java方法.这样我就可以获得远程文件,因为没有网络服务器来提供网址.

我的问题是如何使用httpResponse outputStream来下载2或3个文件？如果我复制粘贴代码我只得到第一个文件.我尝试不关闭outputStream我得到一个错误,该流已被使用.

有谁有想法吗？

PS:以上代码经过测试,如果我只想下载1个文件,可以正常工作.

Answer 1

您最好的选择可能是使用java.util.zip类动态地将多个文件合并到另一个ZIP文件中.您可以包装输出流,ZipOutputStream然后循环遍历ResultSet行,创建ZipEntry对象以区分其中的每个文件.