如果位置錯誤，如何爲google api請求設置錯誤消息

Question

{ 
    string url = "http://maps.google.com/maps/api/geocode/xml?address=" + Location.Text + "&sensor=false"; 

    WebRequest request = WebRequest.Create(url); 
    using (WebResponse response = (HttpWebResponse)request.GetResponse()) 
    { 
     using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8)) 
     { 
      DataSet dsResult = new DataSet(); 
      dsResult.ReadXml(reader); 

      DataTable dtCoordinates = new DataTable(); 

      dtCoordinates.Columns.AddRange(new DataColumn[4] 
      { 
       new DataColumn("Id", typeof(int)), 
        new DataColumn("Address", typeof(string)), 
        new DataColumn("Latitude",typeof(string)), 
        new DataColumn("Longitude",typeof(string)) 
      }); 

      // if (response["status"] == OK) 
      // { 

      foreach (DataRow row in dsResult.Tables["result"].Rows) 
      { 
       string geometry_id = dsResult.Tables["geometry"].Select("result_id = " + row["result_id"].ToString())[0]["geometry_id"].ToString(); 
       DataRow location = dsResult.Tables["location"].Select("geometry_id = " + geometry_id)[0]; 

       // TextBox1.Text = location["lat"]; 

       dtCoordinates.Rows.Add(row["result_id"], row["formatted_address"], location["lat"], location["lng"]); 
       // TextBox1.Text = dsResult.Tables["lat"].ToString; 
       // TextBox2.Text = location["lng"]; 
      } 
      GridView1.DataSource = dtCoordinates; 
      GridView1.DataBind(); 
} 

在此代碼中，如果我向Google API提供了錯誤的位置，則會發生錯誤，因爲未設置實例。在這裏，我需要一條消息作爲標籤或其他位置錯誤的東西。

Answer 1

請試試這個代碼：

{ 
string url = "http://maps.google.com/maps/api/geocode/xml?address=" + Location.Text + "&sensor=false"; 
try{ 
WebRequest request = WebRequest.Create(url); 
using (WebResponse response = (HttpWebResponse)request.GetResponse()) 
{ 
    using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8)) 
    { 
     DataSet dsResult = new DataSet(); 
     dsResult.ReadXml(reader); 

     DataTable dtCoordinates = new DataTable(); 

     dtCoordinates.Columns.AddRange(new DataColumn[4] 
     { 
      new DataColumn("Id", typeof(int)), 
       new DataColumn("Address", typeof(string)), 
       new DataColumn("Latitude",typeof(string)), 
       new DataColumn("Longitude",typeof(string)) 
     }); 

     // if (response["status"] == OK) 
     // { 

     foreach (DataRow row in dsResult.Tables["result"].Rows) 
     { 
      string geometry_id = dsResult.Tables["geometry"].Select("result_id = " + row["result_id"].ToString())[0]["geometry_id"].ToString(); 
      DataRow location = dsResult.Tables["location"].Select("geometry_id = " + geometry_id)[0]; 

      // TextBox1.Text = location["lat"]; 

      dtCoordinates.Rows.Add(row["result_id"], row["formatted_address"], location["lat"], location["lng"]); 
      // TextBox1.Text = dsResult.Tables["lat"].ToString; 
      // TextBox2.Text = location["lng"]; 
     } 
     GridView1.DataSource = dtCoordinates; 
     GridView1.DataBind(); 
} 
catch(Exception err) 
{ 
    if(err.Message.Contains("instance is not set"))//Check if you get error code then match error code 
    { 
     Console.Write("Custom message"); 
     MessageBox.Show("Custom message"); 
    } 
    else 
    { 
     Console.Write("Normal message"); 
     MessageBox.Show("Normal message"); 
    } 
} 
} 

如果您有任何疑問或問題，請隨時問我。