我目前正在开发一个小型数据库项目，我尝试在其中实现图像浏览器，以便相应地为每个玩家保存。
我特别挣扎着将图像的路径拧成字符串，并将该字符串存储到arraylist中，然后使用存储在该arraylist中的路径来加载文件。正如您在代码中看到的那样，我尝试将OpenFd.FileName分配给名为pathToImage的字符串，但它不起作用，使用MessageBox.Show(pathToImage)进行快速调试检查后字符串仍然为空
任何人都可以帮助我吗？
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;
using System.Collections;
using System.Text.RegularExpressions;
using System.Runtime.Serialization.Formatters.Binary;
namespace Assignment1_Template2
{
public partial class Form1 : Form
{
// =======================The data Structure ===========================
// ========Uses [SERIALIZABLE] to allow simple loading/saving ==========
[Serializable]
private struct myStruct
{ // The "constructor". Fills data structure with default values
public myStruct(int playerId)
{
uniquePlayerId = new int[playerId];
playerIgName = "";
contactStreet = "";
contactTown = "";
contactPostcode = "";
contactEmail = "";
contactTelephone = "";
imagePath = "";
for (int i = 0; i < playerId; ++i) uniquePlayerId[i] = 0;
}
// The data types of the struct
public int[] uniquePlayerId;
public string playerIgName;
public string contactStreet;
public string contactTown;
public string contactPostcode;
public string contactEmail;
public string contactTelephone;
public string imagePath;
}
// ================== End of data Structure definition ===================
// =======================================================================
// ================ Global Variables used in the Program =================
private ArrayList dataList; // This is the main data collection
private int currentEntryShown = 0; // current myStruct on display
private int numberOfEntries = 0; // total number of myStructs
private string filename = "C:\\test.dat"; // path of the file being read in
public string pathToImage = "";
public string pathToImagePlaceholder = "";
// =======================================================================
// ================== STARTING POINT FOR THE PROGRAM =====================
public Form1()
{
// Brings up the window.
InitializeComponent();
// Create the ArrayList
dataList = new ArrayList();
// Call methods implemented below
LoadData();
ShowData();
UpdatePrevNextBtnStatus();
}
// =========================================================================
// =================== END OF STARTING POINT FOR PROGRAM ===================
// ========= All further events are now triggered by user actions ==========
// =========================================================================
// =========================================================================
// ========================= BUTTON ACTION HANDLERS ========================
// =========================================================================
private void showPreviousBtn_Click(object sender, EventArgs e)
{
--currentEntryShown;
ShowData();
UpdatePrevNextBtnStatus();
}
private void showNextBtn_Click(object sender, EventArgs e)
{
++currentEntryShown;
if (currentEntryShown != dataList.Count)
{
ShowData();
}
UpdatePrevNextBtnStatus();
}
private void addNewPlayerBtn_Click(object sender, EventArgs e)
{
++numberOfEntries; // "Add" clicked: we need to create one more entry
currentEntryShown = numberOfEntries - 1; // scroll to an empty record at the end
// Create a new data structure, its constructor will fill it with default values
myStruct aNewStruct = new myStruct(5);
dataList.Add(aNewStruct); // add the frshly created struct to the ArrayList
ShowData(); // display
addNewPlayerBtn.Enabled = true; // can't do this again before saving
UpdatePrevNextBtnStatus();
}
private void SaveBtn_Click(object sender, EventArgs e)
{
SaveData(); // Call the Save() method implemented below
addNewPlayerBtn.Enabled = true; // After saving we can add another new record
UpdatePrevNextBtnStatus(); // Set 'Next' and 'Previous' button appearance
}
// =========================================================================
// =========================================================================
// ================ HANDLE DATA CHANGES BY USER ============================
// =========================================================================
// If the text box string is changed by the user, update
private void playerIdBox_TextChanged(object sender, EventArgs e)
{
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.uniquePlayerId[0] = Convert.ToInt32(playerIdBox.Text);
dataList[currentEntryShown] = aNewStruct;
}
private void playerIgNameBox_TextChanged(object sender, EventArgs e)
{
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.playerIgName = playerIgNameBox.Text;
dataList[currentEntryShown] = aNewStruct;
}
private void contactStreetBox_TextChanged(object sender, EventArgs e)
{
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.contactStreet = contactStreetBox.Text;
dataList[currentEntryShown] = aNewStruct;
}
private void contactTownBox_TextChanged(object sender, EventArgs e)
{
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.contactTown = contactTownBox.Text;
dataList[currentEntryShown] = aNewStruct;
}
private void contactPostcodeBox_TextChanged(object sender, EventArgs e)
{
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.contactPostcode = contactPostcodeBox.Text;
dataList[currentEntryShown] = aNewStruct;
}
private void contactEmailBox_TextChanged(object sender, EventArgs e)
{
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.contactEmail = contactEmailBox.Text;
dataList[currentEntryShown] = aNewStruct;
}
private void contactTelephoneBox_TextChanged(object sender, EventArgs e)
{
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.contactTelephone = contactTelephoneBox.Text;
dataList[currentEntryShown] = aNewStruct;
}
// =========================================================================
// ================= HELPER METHODS FOR DISPLAYING DATA ====================
// =========================================================================
private void ShowData()
{
playerIdBox.Text = ((myStruct)dataList[currentEntryShown]).uniquePlayerId[0].ToString();
playerIgNameBox.Text = ((myStruct)dataList[currentEntryShown]).playerIgName;
contactStreetBox.Text = "" + ((myStruct)dataList[currentEntryShown]).contactStreet;
contactTownBox.Text = "" + ((myStruct)dataList[currentEntryShown]).contactTown;
contactPostcodeBox.Text = "" + ((myStruct)dataList[currentEntryShown]).contactPostcode;
contactEmailBox.Text = "" + ((myStruct)dataList[currentEntryShown]).contactEmail;
contactTelephoneBox.Text = "" + ((myStruct)dataList[currentEntryShown]).contactTelephone;
pathToImagePlaceholder = "" + ((myStruct)dataList[currentEntryShown]).imagePath;
MessageBox.Show(pathToImagePlaceholder);
try
{
playerPictureBox.Image = Image.FromFile(pathToImagePlaceholder);
}
catch
{
return;
}
}
private void UpdatePrevNextBtnStatus()
{
if (currentEntryShown > 0) showPreviousBtn.Enabled = true;
else showPreviousBtn.Enabled = false;
if (currentEntryShown < (numberOfEntries - 1)) showNextBtn.Enabled = true;
else showNextBtn.Enabled = false;
label1.Text = "Player ID";
label3.Text = (currentEntryShown + 1) + " / " + numberOfEntries;
}
// =========================================================================
// =========================================================================
// =============== HELPER METHODS FOR LOADING AND SAVING ===================
// =========================================================================
private void SaveData()
{
try
{
FileStream fs = new FileStream(filename, FileMode.Create, FileAccess.Write);
try
{
BinaryFormatter bf = new BinaryFormatter();
bf.Serialize(fs, dataList);
MessageBox.Show("Data saved to " + filename, "FILE SAVE OK", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
catch
{
MessageBox.Show("Could not serialise to " + filename,
"FILE SAVING PROBLEM", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
fs.Close();
}
catch
{
MessageBox.Show("Could not open " + filename +
" for saving.\nNo access rights to the folder, perhaps?",
"FILE SAVING PROBLEM", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
private void LoadData()
{
try
{
FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read);
try
{
BinaryFormatter bf = new BinaryFormatter();
dataList = (ArrayList)bf.Deserialize(fs);
currentEntryShown = 0;
numberOfEntries = dataList.Count;
}
catch
{
MessageBox.Show("Could not de-serialise from " + filename +
"\nThis usually happens after you changed the data structure.\nDelete the data file and re-start program\n\nClick 'OK' to close the program",
"FILE LOADING PROBLEM", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
fs.Close(); // close file
Environment.Exit(1); // crash out
}
fs.Close();
}
catch
{
if (MessageBox.Show("Could not open " + filename + " for loading.\nFile might not exist yet.\n(This would be normal at first start)\n\nCreate a default data file?",
"FILE LOADING PROBLEM", MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation) == DialogResult.Yes)
{
// No data exist yet. Create a first entry
myStruct aNewStruct = new myStruct(5);
dataList.Add(aNewStruct);
numberOfEntries = 1;
currentEntryShown = 0;
}
}
}
// =========================================================================
// =========================================================================
// ====================== HELPER METHODS FOR SORTING =======================
// =========================================================================
// This function will sort by player name by using the PlayerNameComparer below
private void sortToolStripMenuItem_Click(object sender, EventArgs e)
{
dataList.Sort(new PlayerNameComparer());
currentEntryShown = 0;
ShowData();
UpdatePrevNextBtnStatus();
}
// Overriding (= overwriting) the default IComparer
public class PlayerNameComparer : IComparer
{
public int Compare(object x, object y)
{
return ((myStruct)x).playerIgName.CompareTo(((myStruct)y).playerIgName);
}
}
private void saveButton_Click(object sender, EventArgs e)
{
SaveData();
UpdatePrevNextBtnStatus();
}
private void deletePlayerBtn_Click(object sender, EventArgs e)
{
dataList.RemoveAt(currentEntryShown);
SaveData();
if (currentEntryShown != dataList.Count)
{
ShowData();
}
UpdatePrevNextBtnStatus();
}
private void searchToolStripMenuItem_Click(object sender, EventArgs e)
{
Form searchForm = new Form1();
searchForm.Show();
}
private void uploadButton_Click(object sender, EventArgs e)
{
try
{
OpenFileDialog OpenFd = new OpenFileDialog();
pathToImage = OpenFd.FileName;
OpenFd.Filter = "Images only. |*.jpeg; *.jpg; *.png; *.gif;";
DialogResult rd = OpenFd.ShowDialog();
if (rd == System.Windows.Forms.DialogResult.OK)
{
playerPictureBox.Image = Image.FromFile(OpenFd.FileName);
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.imagePath = pathToImage;
dataList[currentEntryShown] = aNewStruct;
// save the FileName to a string.
}
MessageBox.Show(pathToImage);
}
catch (Exception ex)
{
MessageBox.Show("Error: " + ex.Message);
}
}
}
}
答案 0 :(得分：2)
在 ShowDalog完成之后设置pathToImage ，而不是之前：
DialogResult rd = OpenFd.ShowDialog();
if (rd == System.Windows.Forms.DialogResult.OK)
{
pathToImage = OpenFd.FileName; ...
答案 1 :(得分：1)
我可能错了，因为阅读所有代码墙需要太多时间，但最后一个方法应该是
private void uploadButton_Click(object sender, EventArgs e)
{
try
{
OpenFileDialog OpenFd = new OpenFileDialog();
// REMOVED HERE .... pathToImage = OpenFd.FileName
OpenFd.Filter = "Images only. |*.jpeg; *.jpg; *.png; *.gif;";
DialogResult rd = OpenFd.ShowDialog();
if (rd == System.Windows.Forms.DialogResult.OK)
{
playerPictureBox.Image = Image.FromFile(OpenFd.FileName);
myStruct aNewStruct = new myStruct(5);
aNewStruct = (myStruct)dataList[currentEntryShown];
aNewStruct.imagePath = OpenFd.FileName; // Changed this line...
dataList[currentEntryShown] = aNewStruct;
}
// no much sense this here if the user cancel the dialogbox
// MessageBox.Show(pathToImage);
}