C#下载文件的方法包含本地下载，http下载，以及返回字节流方法

超、凢脫俗 2021-12-16 00:27 267阅读 0赞

#region 调用本地文件使用返回pdfbyte数组
    
            /// <summary>
            /// 调用本地文件使用返回pdfbyte数组
            /// </summary>
            /// <param name="srcPdfFile">‘D:\in2434341555551.pdf’</param>
            /// <returns></returns>
    
            public static Byte[] GetSignaturePDFByte(string srcPdfFile)
            {
                using (FileStream fsRead = new FileStream(srcPdfFile, FileMode.Open, FileAccess.Read, FileShare.Read))
                {
                    int fsLen = (int)fsRead.Length;
                    byte[] hebyte = new byte[fsLen];
                    fsRead.Read(hebyte, 0, hebyte.Length);
                    return hebyte;
                }
            }
    
            #endregion 调用本地文件使用返回pdfbyte数组
    
            #region 从网站上下载pdf，转化为字节流
    
    
            /// <summary>
            /// 从网站上下载pdf，转化为字节流
            /// </summary>
            /// <param name="srcPdfFile">文件地址：'https://******/group2/M00/00/04/wKj-mlpcoZ2IUbK5AACrpaV6k98AAAB6gAAAAAAAKu9562.pdf'</param>
    
            /// <returns></returns>
            public static Byte[] GetByteByRemoteURL(string srcPdfFile)
            {
                byte[] arraryByte;
                HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(srcPdfFile);
                req.Method = "GET";
                using (WebResponse wr = req.GetResponse())
                {
                    StreamReader responseStream = new StreamReader(wr.GetResponseStream(), Encoding.UTF8);
                    int length = (int)wr.ContentLength;
                    byte[] bs = new byte[length];
    
                    HttpWebResponse response = wr as HttpWebResponse;
                    Stream stream = response.GetResponseStream();
    
                    //读取到内存
                    MemoryStream stmMemory = new MemoryStream();
                    byte[] buffer1 = new byte[length];
                    int i;
                    //将字节逐个放入到Byte 中
                    while ((i = stream.Read(buffer1, 0, buffer1.Length)) > 0)
                    {
                        stmMemory.Write(buffer1, 0, i);
                    }
                    arraryByte = stmMemory.ToArray();
                    stmMemory.Close();
                }
                return arraryByte;
            }
    
            #endregion 从网站上下载pdf，转化为字节流
    
            #region 从网站上下载文件，保存到其他路径
    
            /// <summary>
            /// 从网站上下载文件，保存到其他路径
            /// </summary>
            /// <param name="pdfFile">文件地址</param>
            /// <param name="saveLoadFile">保存文件路径：D:\12221.pdf</param>
            /// <returns></returns>
            public static bool SaveRemoteFile(string pdfFile, string saveLoadFile)
            {
                bool flag = false;
    
                Uri downUri = new Uri(pdfFile);
                //建立一个ＷＥＢ请求，返回HttpWebRequest对象
                HttpWebRequest hwr = (HttpWebRequest)WebRequest.Create(downUri);
                //流对象使用完后自动关闭
                using (Stream stream = hwr.GetResponse().GetResponseStream())
                {
                    //文件流，流信息读到文件流中，读完关闭
                    using (FileStream fs = File.Create(saveLoadFile))
                    {
                        //建立字节组，并设置它的大小是多少字节
                        byte[] bytes = new byte[102400];
                        int n = 1;
                        while (n > 0)
                        {
                            //一次从流中读多少字节，并把值赋给Ｎ，当读完后，Ｎ为０,并退出循环
                            n = stream.Read(bytes, 0, 10240);
                            fs.Write(bytes, 0, n);　//将指定字节的流信息写入文件流中
                        }
                    }
                }
    
                return flag;
            }
    
            #endregion 从网站上下载文件，保存到其他路径