JSON PHP
A common use of JSON is to read data from a web server, and display the data in a web page.
This chapter will teach you how to exchange JSON data between the client and a PHP server.
The PHP File
PHP has some built-in functions to handle JSON.
Objects in PHP can be converted into JSON by using the PHP function json_encode():
PHP 文件
<?php
$myObj->name = "John";
$myObj->age = 30;
$myObj->city = "New York";
$myJSON = json_encode($myObj);
echo $myJSON;
?>
显示 PHP 文件 »
The Client JavaScript
Here is a JavaScript on the client, using an AJAX call to request the PHP file from the example above:
例子
Use JSON.parse() to convert the result into a JavaScript object:
const xmlhttp = new XMLHttpRequest();
xmlhttp.onload = 函数（）{
const myObj = JSON.解析（this.responseText）;
document.getElementById("demo").innerHTML = myObj.name;
}
xmlhttp.open("GET", "demo_file.html");
xmlhttp.send();
亲自尝试 »
PHP Array
Arrays in PHP will also be converted into JSON when using the PHP function json_encode():
PHP 文件
<?php
$myArr = array("John", "Mary", "Peter", "Sally");
$myJSON = json_encode($myArr);
echo $myJSON;
?>
显示 PHP 文件 »
The Client JavaScript
Here is a JavaScript on the client, using an AJAX call to request the PHP file from the array example above:
例子
Use JSON.parse() to convert the result into a JavaScript array:
var xmlhttp = new XMLHttpRequest();
xmlhttp.onload = 函数（）{
const myObj = JSON.解析（this.responseText）;
document.getElementById("demo").innerHTML = myObj[2];
}
xmlhttp.open("GET", "demo_file_array.html", true);
xmlhttp.send();
亲自尝试 »
PHP Database
PHP is a server side programming language, and can be used to access a database.
Imagine you have a database on your server, and you want to send a request to it from the client where you ask for the 10 first rows in a table called "customers".
On the client, make a JSON object that describes the numbers of rows you want to return.
Before you send the request to the server, convert the JSON object into a string and send it as a parameter to the url of the PHP page:
例子
Use JSON.stringify() to convert the JavaScript object into JSON:
const limit = {"limit":10};
const dbParam = JSON.stringify(limit);
xmlhttp = new XMLHttpRequest();
xmlhttp.onload = 函数（）{
document.getElementById("demo").innerHTML = this.responseText;
}
xmlhttp.open("GET","json_demo_db.html?x=" + dbParam);
xmlhttp.send();
亲自尝试 »
Example explained:
- Define an object containing a "limit" property and value.
- Convert the object into a JSON string.
- Send a request to the PHP file, with the JSON string as a parameter.
- Wait until the request returns with the result (as JSON)
- Display the result received from the PHP file.
Take a look at the PHP file:
PHP 文件
<?php
标头（“内容类型：application/json；字符集=UTF-8”）；
$obj = json_decode($_GET["x"], false);
$conn = new mysqli("我的服务器", "我的用户", "我的密码", "Northwind");
$stmt = $conn->prepare("SELECT name FROM customers LIMIT ?");
$stmt->bind_param("s", $obj->limit);
$stmt->execute();
$result = $stmt->get_result();
$输出=$结果->fetch_all(MYSQLI_ASSOC);
echo json_encode($outp);
?>
PHP文件解释：
- 使用 PHP 函数将请求转换为对象 json_decode().
- 访问数据库，并使用请求的数据填充数组。
- Add the array to an object, and return the object as JSON using the json_encode() 功能。
Use the Data
例子
xmlhttp.onload = function() {
const myObj = JSON.解析（this.responseText）;
let text = "";
对于（让 x 在 myObj 中）{
text += myObj[x].name + "<br>";
}
document.getElementById("demo").innerHTML = text;
}
亲自尝试 »
PHP Method = POST
When sending data to the server, it is often best to use the HTTP POST method.
To send AJAX requests using the POST method, specify the method, and the correct header.
The data sent to the server must now be an argument to the send() method:
例子
const dbParam = JSON.stringify({"limit":10});
const xmlhttp = 新的 XMLHttpRequest();
xmlhttp.onload = 函数（）{
const myObj = JSON.解析（this.responseText）;
let text ="";
对于（让 x 在 myObj 中）{
text += myObj[x].name + "<br>";
}
document.getElementById("demo").innerHTML = text;
}
xmlhttp.open("POST", "json_demo_db_post.html");
xmlhttp.setRequestHeader（“内容类型”，“application/x-www-form-urlencoded”）；
xmlhttp.send("x=" + dbParam);
亲自尝试 »
The only difference in the PHP file is the method for getting the transferred data.
PHP 文件
Use $_POST instead of $_GET:
<?php
标头（“内容类型：application/json；字符集=UTF-8”）；
$obj = json_decode($_POST["x"], false);
$conn = new mysqli("我的服务器", "我的用户", "我的密码", "Northwind");
$stmt = $conn->prepare("SELECT name FROM customers LIMIT ?");
$stmt->bind_param("s", $obj->limit);
$stmt->execute();
$result = $stmt->get_result();
$输出=$结果->fetch_all(MYSQLI_ASSOC);
echo json_encode($outp);
?>
