如果你需要从不同的服务器（不同域名）上获取数据就需要使用跨域 HTTP 请求。
跨域请求在网页上非常常见。很多网页从不同服务器上载入 CSS, 图片，Js脚本等。
在现代浏览器中，为了数据的安全，所有请求被严格限制在同一域名下，如果需要调用不同站点的数据，需要通过跨域来解决。
- 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 @{ 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
