我想集成一个自动检查功能，以防止用户忘记使用文本框保存所做的更改'是要否
如果是->保存 如果没有->返回
这是我的代码，没有检查
namespace WindowsFormsApp1
{
public partial class Form1 : Form
{
OleDbConnection conn;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
conn = new
OleDbConnection("Provider=Microsoft.Jet.OleDb.4.0;Data
Source=" + @Application.StartupPath + "\\Database1.mdb");
fill_lb();
}
private void fill_lb()
{
listBox1.Items.Clear();
if (conn.State != ConnectionState.Open) { conn.Close();
conn.Open(); }
OleDbCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "SELECT * FROM [table1] ORDER BY firstn";
cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
OleDbDataAdapter da = new OleDbDataAdapter(cmd);
da.Fill(dt);
foreach (DataRow dr in dt.Rows)
{
listBox1.Items.Add(dr["firstn"].ToString());
}
conn.Close();
}
private void listBox1_SelectedIndexChanged(object sender,
EventArgs e)
{
textBox_fn.Text = string.Empty;
textBox_ln.Text = string.Empty;
if (conn.State != ConnectionState.Open) { conn.Close();
conn.Open(); }
OleDbCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "SELECT * FROM [table1] WHERE firstn='" +
listBox1.SelectedItem.ToString() + "'";
cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
OleDbDataAdapter da = new OleDbDataAdapter(cmd);
da.Fill(dt);
foreach (DataRow dr in dt.Rows)
{
textBox_fn.Text = dr["firstn"].ToString();
textBox_ln.Text = dr["lastn"].ToString();
}
conn.Close();
}
private void button_savenew_Click(object sender, EventArgs e)
{
if (conn.State != ConnectionState.Open) { conn.Close();
conn.Open(); }
OleDbCommand cmd = new OleDbCommand();
cmd.Connection = conn;
cmd.CommandText = "INSERT INTO [table1] ([firstn],[lastn])
values ([@firstn],[@lastn])";
cmd.Parameters.AddWithValue("@firstn", textBox_fn.Text);
cmd.Parameters.AddWithValue("@lastn", textBox_ln.Text);
cmd.ExecuteNonQuery();
fill_lb();
conn.Close();
}
private void button_modify_Click(object sender, EventArgs e)
{
if (conn.State != ConnectionState.Open) { conn.Close();
conn.Open(); }
OleDbCommand cmd = new OleDbCommand();
cmd.Connection = conn;
cmd.CommandText = "UPDATE [Table1] SET [firstn]=[@firstn],
[lastn]=[@lastn] WHERE firstn = '" +
listBox1.SelectedItem.ToString() + "'";
cmd.Parameters.AddWithValue("@firstn", textBox_fn.Text);
cmd.Parameters.AddWithValue("@lastn", textBox_ln.Text);
cmd.ExecuteNonQuery();
fill_lb();
conn.Close();
}
private void button_new_Click(object sender, EventArgs e)
{
textBox_fn.Text = string.Empty;
textBox_ln.Text = string.Empty;
}
}
}
我所做的没有成功的事情：
Bool modified = false
private void textBox_fn_TextChanged(object sender, EventArgs e)
{
modified = true;
}
private void textBox_ln_TextChanged(object sender, EventArgs e)
{
modified = true;
}
private void listBox1_SelectedIndexChanged(object sender,
EventArgs e)
{
if (modified.Equals(true))
{
DialogResult dialogr = MessageBox.Show("Do you want to
save change ?","", MessageBoxButtons.YesNo);
switch (dialogr)
{
case DialogResult.Yes:
button_savenew.PerformClick();
modifie = false;
break;
case DialogResult.No:
return;
}
}
modified = false;
textBox_fn.Text = string.Empty;
textBox_ln.Text = string.Empty;
}
这不起作用，因为每次我单击列表框时都要求保存
我该怎么办？
答案 0 :(得分：2)
我会考虑使用MessageBox。这将大大简化您的工作。在后台执行检查，如果没有保存，请执行以下操作：
string message = "Are you sure you don't want to save?";
string caption = "Error Detected in Input";
MessageBoxButtons buttons = MessageBoxButtons.YesNo;
DialogResult result;
// Displays the MessageBox.
result = MessageBox.Show(message, "Are you Sure", buttons);
if (result == System.Windows.Forms.DialogResult.Yes)
{
// Save file
}
if (result == System.Windows.Forms.DialogResult.No){
this.Close();
}
答案 1 :(得分：0)
从listBox1_SelectedIndexChanged事件中删除关联代码，并在其中添加button_modify_Click的结尾。试试：
private void Check()
{
if (modified.Equals(true))
{
DialogResult dialogr = MessageBox.Show("Do you want to
save change ?","", MessageBoxButtons.YesNo);
switch (dialogr)
{
case DialogResult.Yes:
button_savenew.PerformClick();
modifie = false;
break;
case DialogResult.No:
return;
}
}
modified = false;
textBox_fn.Text = string.Empty;
textBox_ln.Text = string.Empty;
}
private void button_modify_Click(object sender, EventArgs e)
{
if (conn.State != ConnectionState.Open) { conn.Close();
conn.Open(); }
OleDbCommand cmd = new OleDbCommand();
cmd.Connection = conn;
cmd.CommandText = "UPDATE [Table1] SET [firstn]=[@firstn],
[lastn]=[@lastn] WHERE firstn = '" +
listBox1.SelectedItem.ToString() + "'";
cmd.Parameters.AddWithValue("@firstn", textBox_fn.Text);
cmd.Parameters.AddWithValue("@lastn", textBox_ln.Text);
cmd.ExecuteNonQuery();
fill_lb();
Check(); //<--added here
conn.Close();
}
答案 2 :(得分：0)
在数据库更新后 Bitmap bmp = BitmapFactory.decodeFile(imagePath);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] imageByteArray = stream.toByteArray();
String encodedImageString = Base64.encodeToString(imageByteArray, Base64.DEFAULT);
URL url = new URL(Config.CLOUD_VISION_URL);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setUseCaches(false);
con.setDoInput(true);
con.setDoOutput(true);
con.setRequestMethod("POST");
con.setRequestProperty("Content-Type", "application/json");
// Features JSON
JSONObject featuresJson = new JSONObject();
featuresJson.put("type", "FACE_DETECTION");
featuresJson.put("maxResults", 1);
JSONArray featuresJSONArray = new JSONArray();
featuresJSONArray.put(featuresJson);
// Image JSON
JSONObject imageJson = new JSONObject();
imageJson.put("content", encodedImageString);
// Requests JSON
JSONObject requestsJson = new JSONObject();
requestsJson.put("image", imageJson);
requestsJson.put("features", featuresJSONArray);
JSONArray requestsJSONArray = new JSONArray();
requestsJSONArray.put(requestsJson);
JSONObject wholeRequest = new JSONObject();
wholeRequest.put("requests", requestsJSONArray);
OutputStreamWriter out = new OutputStreamWriter(con.getOutputStream());
out.write(wholeRequest.toString());
out.flush();
out.close();
int response_code = con.getResponseCode();
Log.d("GCV Response Code", ""+response_code);
BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream()));
StringBuilder sb = new StringBuilder("");
String temp;
while((temp = br.readLine()) != null)
sb.append(temp);
String response = sb.toString();
JSONObject responseJSONObject = new JSONObject(response);
if (response_code == 200) {
Log.d("GCV", "Successful response");
}
JSONArray responsesArray = responseJSONObject.getJSONArray("responses");
JSONObject faceAnnotationsJson = responsesArray.getJSONObject(0);
JSONObject annotedEmotionsJson = faceAnnotationsJson.getJSONArray("faceAnnotations").getJSONObject(0);
return annotedEmotionsJson;
结束时尝试重置modified
答案 3 :(得分：0)
我认为我找到了使用tag属性完成工作的正确方法。
首先，我添加一个新的布尔值，该布尔值将检查是否离开文本框
bool left_txtbox = false; //when leaving textbox
然后将这段代码添加到文本框的Leave属性
private void textBox_fn_Leave(object sender, EventArgs e)
{
name = listBox1.SelectedItem.ToString();
textBox_fn.Tag = textBox_fn.Text;
left_txtbox = true;
}
private void textBox_ln_Leave(object sender, EventArgs e)
{
name = listBox1.SelectedItem.ToString();
textBox_ln.Tag = textBox_ln.Text;
left_txtbox = true;
}
在列表框上选择的索引更改我在离开文本框时添加了检查
private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
if (left_txtbox == true) Check(); // if txtbox has been left, do the check
textBox_fn.Text = string.Empty;
textBox_ln.Text = string.Empty;
if (conn.State != ConnectionState.Open) { conn.Close(); conn.Open(); }
OleDbCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "SELECT * FROM [table1] WHERE firstn='" + listBox1.SelectedItem.ToString() + "'";
cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
OleDbDataAdapter da = new OleDbDataAdapter(cmd);
da.Fill(dt);
foreach (DataRow dr in dt.Rows)
{
textBox_fn.Text = dr["firstn"].ToString();
textBox_ln.Text = dr["lastn"].ToString();
}
conn.Close();
}
最后检查本身，它将标记与存储在数据库中的值进行比较
private void Check()
{
if (conn.State != ConnectionState.Open) { conn.Close(); conn.Open(); }
OleDbCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "SELECT * FROM [table1] WHERE firstn='" + name + "'";
cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
OleDbDataAdapter da = new OleDbDataAdapter(cmd);
da.Fill(dt);
foreach (DataRow dr in dt.Rows)
{
try // ignore null values
{
if (textBox_fn.Tag.ToString() != dr["firstn"].ToString()) { modified = true; }
if (textBox_ln.Tag.ToString() != dr["lastn"].ToString()) { modified = true; }
}
catch { }
if (modified.Equals(true))
{
DialogResult dialogr = MessageBox.Show("Do you want to save change ? ", "", MessageBoxButtons.YesNo);
switch (dialogr)
{
case DialogResult.Yes:
button_savenew.PerformClick();
modified = false;
break;
case DialogResult.No:
modified = false;
return;
}
}
modified = false;
}
我认为代码可以优化