Question

这是我写的代码，但它不起作用。我不知道如何解决它。我希望你能帮助我。我没有想法:(你是我唯一的希望。

namespace Imgur
{
public partial class Form1 : Form
{
    bool flag = true;
    int downloadedNumber = 0;

    public Form1()
    {
        InitializeComponent();
    }

    public void buttonStart_Click(object sender, EventArgs e)
    {
        buttonStart.Enabled = false;
        buttonStop.Enabled = true;
        if (!flag)
        {
            flag = true;
        }

        for (int i=0;i<100000 && flag;i++)
        {
            WebClient webClient = new WebClient();
            string pic1 = rnd_str(5);
            string pic2 = ".jpg";
            string picture = pic1 + pic2;

            //********** GETTING SIZE OF IMAGE ***********
            Size sz = GetSize("http://i.imgur.com/" + picture);
            string imageSize = (sz.Width.ToString() + " " + sz.Height.ToString()); ;
            //********************************************

            if(imageSize != "161 81")
            {
                webClient.DownloadFile("http://i.imgur.com/" + picture, destination + picture);

                richTextBox1.Text += String.Format("Downloaded picture: {0}\r\n", picture);
                downloadedNumber++;
                textBoxDownloadedNumber.Text = string.Format("{0}", downloadedNumber);
            }
            webClient.Dispose();
            Application.DoEvents();
            if (i == 999995)
            {
                flag = false;
            }
        }
        richTextBox1.Text += "theend\n";
        buttonStart.Enabled = true;
        buttonStop.Enabled = false;
    }

    public static Size GetSize(string url)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.Method = "GET";
        request.Accept = "image/gif";
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        Stream s = response.GetResponseStream();
        Bitmap bmp = new Bitmap(s);
        Size sz = new Size(bmp.Width, bmp.Height);
        return sz;
    }

    public static string rnd_str(int liczba_liter)
    {
        Random r = new Random();
        int char_type;
        string return_string = "";
        int i =0;
        for (i = 0; i < liczba_liter; i++)
        {
            if (r.Next(1, 3) == 1)
            {
                char_type = r.Next(1, 4);
                switch (char_type)
                {
                    case 1:
                        return_string += (char)r.Next(48, 58); // convertion int -> ASCII character; 48-57 are ASCII digits
                        break;
                    case 2:
                        return_string += (char)r.Next(97, 123); // convertion int -> ASCII character; as above but small letters
                        break;
                    case 3:
                        return_string += (char)r.Next(65, 91); // as above; large letters
                        break;
                    default:
                        i -= 1;
                        break;//do not add any letter if no type is allowed
                }
            }
            else
            {
                i -= 1;
                return_string += "";
            }
        }
        return return_string;
    }

    private void buttonStop_Click(object sender, EventArgs e)
    {
        flag = false;
        buttonStart.Enabled = true;
    }

    public void buttonSaveTo_Click(object sender, EventArgs e)
    {
        FolderBrowserDialog fbd = new FolderBrowserDialog();
        fbd.ShowDialog();
        richTextBox1.Text = fbd.SelectedPath;
        string destination = fbd.SelectedPath;
    }
}
}

Answer 1

看起来您正在使用此行中名为destination的变量

webClient.DownloadFile("http://i.imgur.com/" + picture, destination + picture);

但是你没有声明该变量并在buttonStart_Click方法中为其赋值。

你有一个名为destination的变量在buttonSaveTo_Click方法中声明，如果这是你想在buttonStart_Click中使用的值，你需要把它变成一个类级别的字段，所以在'bool flag'旁边声明它

e.g：

public partial class Form1 : Form
{
    bool flag = true;
    int downloadedNumber = 0;
    string destination;
}

并从

中删除字符串声明

public void buttonSaveTo_Click(object sender, EventArgs e)
{
    FolderBrowserDialog fbd = new FolderBrowserDialog();
    fbd.ShowDialog();
    richTextBox1.Text = fbd.SelectedPath;
    destination = fbd.SelectedPath;
}

Answer 2

您在此处使用destination：

webClient.DownloadFile("http://i.imgur.com/" + picture, destination + picture);

但它在另一个范围（函数）中声明。具体来说，它在buttonSaveTo_Click()中声明。

您可以在顶部的int downloadedNumber = 0;下声明它：

int downloadedNumber = 0;
string destination;

然后将最后一行更改为：

destination = fbd.SelectedPath;

我不能保证这会完全修复您的代码，但会在您尝试使用它的两个地方提供destination。

将文件保存到文件夹

2 个答案: