About cross-domain HTTP requests

If you need to get data from different servers (different domain names), you need to use cross-domain HTTP requests.

Cross-domain requests are very common on web pages. Many web pages load CSS, images, Js scripts, etc. from different servers.

In modern browsers, for data security, all requests are strictly limited to the same domain name. If you need to call data from different sites, you need to resolve it across domains.

1. PHP 和 MySql 代码实例
   <?php
   header("Access-Control-Allow-Origin: *");
   header("Content-Type: application/json; charset=UTF-8");

$conn = new mysqli("myServer", "myUser", "myPassword", "Northwind");

$result = $conn->query("SELECT CompanyName, City, Country FROM Customers");

$outp = "";
while($rs = $result->fetch_array(MYSQLI_ASSOC)) {
if ($outp != "") {$outp .= ",";}
$outp .= '{"Name":"' . $rs["CompanyName"] . '",';
$outp .= '"City":"' . $rs["City"] . '",';
$outp .= '"Country":"'. $rs["Country"] . '"}';
}
$outp ='{"records":['.$outp.']}';
$conn->close();

echo($outp);

www.djznrobot.com

?>

2. PHP 和 MS Access 代码实例
   <?php
   header("Access-Control-Allow-Origin: *");
   header("Content-Type: application/json; charset=ISO-8859-1");

$conn = new COM("ADODB.Connection");
$conn->open("PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=Northwind.mdb");

$rs = $conn->execute("SELECT CompanyName, City, Country FROM Customers");

$outp = "";
while (!$rs->EOF) {
if ($outp != "") {$outp .= ",";}
$outp .= '{"Name":"' . $rs["CompanyName"] . '",';
$outp .= '"City":"' . $rs["City"] . '",';
$outp .= '"Country":"'. $rs["Country"] . '"}';
$rs->MoveNext();
}
$outp ='{"records":['.$outp.']}';

$conn->close();

echo ($outp);
?>

3. ASP.NET, VB 和 MS Access 代码实例
   <%@ Import Namespace="System.IO"%>
   <%@ Import Namespace="System.Data"%>
   <%@ Import Namespace="System.Data.OleDb"%>
   <%
   Response.AppendHeader("Access-Control-Allow-Origin", "*")
   Response.AppendHeader("Content-type", "application/json")
   Dim conn As OleDbConnection
   Dim objAdapter As OleDbDataAdapter
   Dim objTable As DataTable
   Dim objRow As DataRow
   Dim objDataSet As New DataSet()
   Dim outp
   Dim c
   conn = New OledbConnection("Provider=Microsoft.Jet.OLEDB.4.0;data source=Northwind.mdb")
   objAdapter = New OledbDataAdapter("SELECT CompanyName, City, Country FROM Customers", conn)
   objAdapter.Fill(objDataSet, "myTable")
   objTable=objDataSet.Tables("myTable")

outp = ""
c = chr(34)
for each x in objTable.Rows
if outp <> "" then outp = outp & ","
outp = outp & "{" & c & "Name" & c & ":" & c & x("CompanyName") & c & ","
outp = outp & c & "City" & c & ":" & c & x("City") & c & ","
outp = outp & c & "Country" & c & ":" & c & x("Country") & c & "}"
next

outp ="{" & c & "records" & c & ":[" & outp & "]}"
response.write(outp)
conn.close
%>

4. ASP.NET, VB Razor 和 SQL Lite 代码实例br/>@{
   Response.AppendHeader("Access-Control-Allow-Origin", "*")
   Response.AppendHeader("Content-type", "application/json")
   var db = Database.Open("Northwind");
   var query = db.Query("SELECT CompanyName, City, Country FROM Customers");
   var outp =""
   var c = chr(34)
   }
   @foreach(var row in query)
   {
   if outp <> "" then outp = outp + ","
   outp = outp + "{" + c + "Name" + c + ":" + c + @row.CompanyName + c + ","
   outp = outp + c + "City" + c + ":" + c + @row.City + c + ","
   outp = outp + c + "Country" + c + ":" + c + @row.Country + c + "}"
   }
   outp ="{" + c + "records" + c + ":[" + outp + "]}"
   @outp