若是你需要从差别的服务器(差别域名)上获取数据就需要使用跨域 HTTP 请求。

跨域请求在网页上异常常见。许多网页从差别服务器上载入 CSS, 图片,Js剧本等。

在现代浏览器中,为了数据的平安,所有请求被严酷限制在统一域名下,若是需要挪用差别站点的数据,需要通过跨域来解决。

  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

?>

,

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  1. 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);
?>

  1. 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
%>

  1. 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