c#将文件写入mysql中和从mysql中读数据

主代码

这样需要自定义mysql的连接参数;主要代码如下

MySqlCommand cmd = new MySqlCommand();
cmd.CommandText = sql;//这句需传参数;
cmd.CommandType = CommandType.Text;

cmd.Parameters.Add("@id", MySql.Data.MySqlClient.MySqlDbType.Int16);
cmd.Parameters.Add("@fileName", MySql.Data.MySqlClient.MySqlDbType.VarChar);
cmd.Parameters.Add("@filecontent", MySql.Data.MySqlClient.MySqlDbType.Blob);//文件在mysql中存为Blob

cmd.Parameters[0].Value = curIndex;//这句需传参数
cmd.Parameters[1].Value = fileName;
cmd.Parameters[2].Value = bytes;//文件传入的参数应该是字节数组;
cmd.Connection = conn;

cmd.ExecuteNonQuery();

mysql封装

我们把mysql的操作抽象成如下的代码;其中MySql.Data这个命名空间其实是一个外在的mysqldata.dll的引用;
这里提供下载

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using MySql.Data.MySqlClient;
    using System.Data;
    public class MySQLDataHelper : IDisposable
    {

        string host = "127.0.0.1";
        int port = 3306;
        string uid = "root";
        string password = "";
        string dbname = "testforfileopert";

        MySqlConnection conn = null;


        // 构造函数 私有化
        private MySQLDataHelper()
        {
            string connStr = "server=" + host
                            + ";port=" + port
                            + ";uid=" + uid
                            + ";password=" + password
                            + ";database=" + dbname;
            conn = new MySqlConnection(connStr); //数据库连接 
        }
        // 单例模式
        public static readonly MySQLDataHelper Instance = new MySQLDataHelper();

        // 连接数据库
        public Boolean ConnectToDB()
        {
            if (conn == null)
                return false;
            if (conn.State == System.Data.ConnectionState.Open)
                return true;
            try
            {
                conn.Open();
            }
            catch (Exception e)
            {
                return false;
            }
            return true;
        }
        //轻易不要这样用
        public void Dispose()
        {
            if (conn != null)
            {
                conn.Dispose();
                conn = null;
            }
        }

        public DataTable GetDataTable(string sql)
        {
            if (conn != null)
            {
                if (conn.State == System.Data.ConnectionState.Open || ConnectToDB())
                {
                    MySqlDataAdapter da = new MySqlDataAdapter(sql, conn);
                    DataSet MyDataSet = new DataSet();
                    da.Fill(MyDataSet);
                    return MyDataSet.Tables[0];
                }
            }
            return null;
        }

        //运行sql代码，只用于insert、update和delete，返回影响的行数
        public int runSql(String sql)
        {
            if (conn != null)
            {
                if (conn.State == System.Data.ConnectionState.Open || ConnectToDB())
                {
                    MySqlCommand cmd = new MySqlCommand(sql, conn);
                    return cmd.ExecuteNonQuery();
                }
            }
            return 0;
        }


        /// 

        /// 运行SQL代码,这句话供Dragon来上传文件到表中；
        /// 
        /// 
        /// 
        public int upFile(String sql, Byte[] bytes,int curIndex,string fileName)
        {
            if (conn != null)
            {
                if (conn.State == System.Data.ConnectionState.Open || ConnectToDB())
                {
                    MySqlCommand cmd = new MySqlCommand();
                    cmd.CommandText = sql;//这句需传参数;
                    cmd.CommandType = CommandType.Text;

                    cmd.Parameters.Add("@id", MySql.Data.MySqlClient.MySqlDbType.Int16);
                    cmd.Parameters.Add("@fileName", MySql.Data.MySqlClient.MySqlDbType.VarChar);
                    cmd.Parameters.Add("@filecontent", MySql.Data.MySqlClient.MySqlDbType.Blob);//这句需传参数;
                    cmd.Parameters[0].Value = curIndex;
                    cmd.Parameters[1].Value = fileName;
                    cmd.Parameters[2].Value = bytes;
                    cmd.Connection = conn;


                    return cmd.ExecuteNonQuery();


                }
            }
            return 0;
        }
        /// 

        /// 用来从数据库下载文件
        /// 
        /// 查询语句
        /// 输出的字节数组，内含文件
        /// 
        public long downFile(String sql, out byte[] buffer)
        {
            if (conn != null)
            {
                if (conn.State == System.Data.ConnectionState.Open || ConnectToDB())
                {
                    MySql.Data.MySqlClient.MySqlCommand cmd = new MySql.Data.MySqlClient.MySqlCommand();
                    cmd.CommandType = CommandType.Text;
                    cmd.CommandText = sql;
                    cmd.Connection = conn;
                    System.Data.Common.DbDataReader reader = cmd.ExecuteReader();
                    buffer = null;
                    if (reader.HasRows)
                    {
                        reader.Read();
                        long len = reader.GetBytes(0, 0, null, 0, 0);//1是picture
                        buffer = new byte[len];
                        len = reader.GetBytes(0, 0, buffer, 0, (int)len);
                        //System.IO.MemoryStream ms = new System.IO.MemoryStream(buffer);
                        //System.Drawing.Image iamge = System.Drawing.Image.FromStream(ms);
                        //pictureBox1.Image = iamge;
                        return len;
                    }
                }
            }
            buffer = null;
            return 0;

        }

    }

测试代码

下面是一个小程序用来保存word文件到数据库和从数据库中下载word文件

        static void saveWord()
        {
            //MySQLDataHelper mdh = MySQLDataHelper.Instance;
            //打开word文件并保存为字节数组;
            string filePath = @"E:\资料\onedrive\文档\2015E8013261145_邓力.docx";
            string fileName = filePath.Split('\\')[4];
            FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
            byte[] buffByte = new byte[fs.Length];
            fs.Read(buffByte, 0, (int)fs.Length);
            fs.Close();
            fs = null;
            int curIndex = 1;
            string sql = "insert into testforfileopert.t_filesave values(?id,?fileName,?filecontent)";
            MySQLDataHelper msdl = MySQLDataHelper.Instance;
            int num = msdl.upFile(sql, buffByte, curIndex, fileName);
            Console.WriteLine("num="+num);

        }
        /// 

        /// 下载word文件到本地;
        /// 
        static void downLoadWord()
        {
            //先从服务器下载数据;
            string sql = "select fileContent from testforfileopert.t_filesave where id = 1";
            byte[] bytes = null;
            MySQLDataHelper mdhl = MySQLDataHelper.Instance;
            long num=mdhl.downFile(sql, out bytes);
            FileStream fs = new FileStream(@"D:\test.docx", FileMode.OpenOrCreate, FileAccess.Write);
            fs.Write(bytes, 0,(int)num);
            Console.WriteLine("下载上传num=" + num);
            fs.Close();
        }
        static void Main(string[] args)
        {
            saveWord();

            downLoadWord();
        }

这样程序也可以读取其它文件格式。