W3.JS 数据服务器
动态数据
上一章中使用的都是从服务器获取的静态数据。
用于从数据库获取动态数据的服务器代码可以用多种不同的语言编写。
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
从与请求页面不同的服务器请求数据，称为跨站点 HTTP 请求。
跨站点请求在 Web 上很常见。许多页面从不同服务器加载 CSS、图片或脚本。
但是，在现代浏览器中，出于安全原因，来自脚本的 HTTP 请求被限制在同一站点。
以下行（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)
%>
