打开保存数据库中的文件

注意

本文中展示的代码均为关键代码，复制粘贴到您的项目中，按照实际的情况，例如文档路径，用户名等做适当修改即可使用。

在某些项目中，数据库的文档表中使用了二进制流字段（blob）来保存Office文档，PageOffice也是可以支持在线打开此类二进制流文件的。

首先，编写一个下载文件的后台方法，比如：openStream；

然后，把此openStream方法的url地址传递给PageOfficeCtrl对象的webOpen的第一个参数即可打开；

最后，保存文件时，调用FileSaver对象的getFileBytes()或getFileStream()获取到文件二进制流并保存到数据库中。

后端代码

1. 编写下载文件的后台方法：openStream；

@RequestMapping(value = "openStream", method = RequestMethod.GET)
public void openStream(HttpServletRequest request, HttpServletResponse response) 
                          throws SQLException, ClassNotFoundException, IOException {

    String id = request.getParameter("id");

    Class.forName("org.sqlite.JDBC");

    String strUrl = "jdbc:sqlite:" + ResourceUtils.getURL("classpath:").getPath() 
                      + "static/demodata/DataBase.db";
    Connection conn = DriverManager.getConnection(strUrl);
    Statement stmt = conn.createStatement();
    ResultSet rs = stmt.executeQuery("select * from stream where id = " + id);

    if (rs.next()) {
        //******读取数据库中文件流 开始*******************************
        byte[] imageBytes = rs.getBytes("Word");
        int fileSize = imageBytes.length;

        response.reset();
        // application/msword, application/x-excel, application/ms-powerpoint, application/pdf
        response.setContentType("application/msword"); 
        response.setHeader("Content-Disposition",
                "attachment; filename=down.doc"); //fileN应该是编码后的(utf-8)
        response.setContentLength(fileSize);

        OutputStream outputStream = response.getOutputStream();
        outputStream.write(imageBytes);

        outputStream.flush();
        outputStream.close();
        outputStream = null;
        //******读取数据库中文件流 结束*******************************
    }
    rs.close();
    conn.close();
}

public void openStream()
{
    string docID = Request.Query["id"];
    string sql = "Select Word,ID  from stream where ID='" + docID + "'";
    using (SQLiteConnection conn = new SQLiteConnection(connString))
    {
        conn.Open();

        using (SQLiteCommand cmd = new SQLiteCommand(sql, conn))
        {
            cmd.ExecuteNonQuery();
            SQLiteDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                long num = dr.GetBytes(0, 0, null, 0, Int32.MaxValue);
                Byte[] b = new Byte[num];
                dr.GetBytes(0, 0, b, 0, b.Length);
                //其他文件格式换成相应类型即可 application/x-excel, application/ms-powerpoint, application/pdf 
                Response.ContentType = "Application/msword"; 
                //其他文件格式换成相应类型的filename
                Response.Headers.Add("Content-Disposition", "attachment; filename=down.doc");
                Response.Headers.Add("Content-Length", num.ToString());
                Response.Body.WriteAsync(b);
            }
        }
    }

    Response.Body.Close();
}

// Make sure to add code blocks to your code group

2. 在后端编写代码调用webOpen方法打开文件之前给SaveFilePage属性赋值（设置好保存时由哪个地址接口负责接收处理控件上传的文件流）；

PageOfficeCtrl poCtrl = new PageOfficeCtrl(request);
poCtrl.setSaveFilePage("saveStream?id=123"); // 设置保存文件的接口地址
//webOpen的第一个参数支持能够输出下载文件的Url相对地址或者文件在服务器上的磁盘路径两种方式
//查看详细，请在本站搜索“PageOffice属性或方法中涉及到的URL路径或磁盘路径的说明”
poCtrl.webOpen("openStream?id=123", OpenModeType.docNormalEdit, "张佚名"); // 打开文件

PageOfficeNetCore.PageOfficeCtrl poCtrl = new PageOfficeNetCore.PageOfficeCtrl(Request);
poCtrl.SaveFilePage = "saveStream?id=1";//设置保存文件的接口地址
poCtrl.WebOpen("openStream?id=1", PageOfficeNetCore.OpenModeType.docNormalEdit, "tom");

// Make sure to add code blocks to your code group

注意

对PageOfficeCtrl对象的所有属性赋值或函数调用都必须在WebOpen方法调用之前执行，否则会不生效。

3. 在SaveFilePage属性指向的地址接口saveStream中，创建FileSaver对象处理文件的保存工作。

@RequestMapping("saveStream")
public void saveStream(HttpServletRequest request, HttpServletResponse response) 
                      throws ClassNotFoundException, FileNotFoundException, SQLException {
    FileSaver fs = new FileSaver(request, response);

    String id = request.getParameter("id").trim();
    Class.forName("org.sqlite.JDBC");
    String strUrl = "jdbc:sqlite:" 
                 + ResourceUtils.getURL("classpath:").getPath() + "static/demodata/DataBase.db";

    Connection conn = DriverManager.getConnection(strUrl);
    String sql = "UPDATE  Stream SET Word=?  where ID=" + id;
    PreparedStatement pstmt = null;
    pstmt = conn.prepareStatement(sql);
    pstmt.setBytes(1, fs.getFileBytes());
    //pstmt.setBinaryStream(1, fs.getFileStream(),fs.getFileSize());
    pstmt.executeUpdate();
    pstmt.close();
    conn.close();

    fs.close();
}

public async Task<ActionResult> saveStream()
{
    PageOfficeNetCore.FileSaver fs = new PageOfficeNetCore.FileSaver(Request, Response);
    await fs.LoadAsync();

    string sID = Request.Query["id"];
    string sql = "UPDATE  Stream SET Word=@file WHERE ID=" + sID;

    using (SQLiteConnection conn = new SQLiteConnection(connString))
    {
        conn.Open();
        byte[] aa = fs.FileBytes;

        using (SQLiteCommand cmd = new SQLiteCommand(sql, conn))
        {
            SQLiteParameter parameter = new SQLiteParameter("@file", System.Data.DbType.Binary);
            parameter.Value = aa;
            cmd.Parameters.Add(parameter);
            cmd.ExecuteNonQuery();
        }
    }
    return fs.Close();
}

// Make sure to add code blocks to your code group

前端代码

本示例无前端关键代码。