W3.JS 数据服务器
动态数据
上一章中使用的数据是从服务器获取的静态数据。
从数据库获取动态数据的服务器代码可以用多种语言编写。
以下是一些示例
运行 PHP 和 MySQL 的服务器
<?php
header("Access-Control-Allow-Origin: *");
header("Content-Type: application/json; charset=UTF-8");
$conn = new mysqli("myServer", "user", "pass", "myDB");
$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"] . '"}';
}
$outp ='{"customers":['.$outp.']}';
$conn->close();
echo($outp);
?>
跨站点 HTTP 请求
从不同服务器（非请求页面所在的服务器）请求数据的请求称为**跨站点** HTTP 请求。
跨站点请求在网络中很常见。许多页面从不同的服务器加载 CSS、图像或脚本。
但是，出于安全原因，在现代浏览器中，来自**脚本**的 HTTP 请求被限制在**同一站点**。
以下代码行（在上面的 PHP 示例中）允许从跨站点访问页面
header("Access-Control-Allow-Origin: *");
运行 Node.js 和 MySQL 的服务器
var express = require('express');
var app = express();
app.get('/', function (req, res) {
var sql = require("mssql");
var config = {user:'user', password:'pass', server:'myServer', database:'myDB'};
sql.connect(config, function (err) {
if (err) console.log(err);
var request = new sql.Request();
request.query('SELECT CompanyName, City, Country FROM Customers', function (err, recordset) {
if (err) console.log(err)
res.send(recordset);
});
});
});
var server = app.listen(5000, function () {
console.log('Server is running..');
});
运行 ASP.NET、Razor 和 SQL Lite 的服务器
@{
Response.AppendHeader("Access-Control-Allow-Origin", "*")
Response.AppendHeader("Content-type", "application/json")
var db = Database.Open("myDB");
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 + "customers" + c + ":[" + outp + "]}"
@outp
运行 PHP 和 MS Access 的服务器
<?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=myDB.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();
}
$outp ='{"customers":['.$outp.']}';
$conn->close();
echo ($outp);
?>
运行 ASP.NET、VB 和 MS Access 的服务器
<%@ 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=myDB.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 & "customers" & c & ":[" & outp & "]}"
conn.close
response.write(outp)
%>
