php怎么使用RESTful API？

使用RESTful API需要以下几个步骤：

1.定义接口：确定API接口地址、请求方式、参数及返回数据格式等。

2.编写代码：根据接口定义编写代码实现相应功能。

3.测试使用：使用网络调试工具Postman或者浏览器访问测试接口。

下面是使用PHP实现RESTful API的代码示例：

<?php
require_once "db_connect.php";

$link = mysqli_connect(DB_HOST,DB_USER,DB_PASSWORD,DB_NAME);
mysqli_set_charset($link,"utf8");

$request_method = $_SERVER["REQUEST_METHOD"];

switch($request_method)
{
    case "GET":
        if(!empty($_GET["id"]))
        {
            $id=intval($_GET["id"]);
            get_employee($id);
        }
        else
        {
            get_employee();
        }
        break;
    case "POST":
        insert_employee();
        break;
    case "PUT":
        $id=intval($_GET["id"]);
        update_employee($id);
        break;
    case "DELETE":
        $id=intval($_GET["id"]);
        delete_employee($id);
        break;
    default:
        header("HTTP/1.0 405 Method Not Allowed");
        break;
}

function get_employee($id=0)
{
    global $link;
    $query="SELECT * FROM employees";
    if($id!=0)
    {
        $query.=" WHERE id=".$id." LIMIT 1";
    }
    $result=mysqli_query($link,$query);
    $employee=array();
    while($row=mysqli_fetch_array($result))
    {
        $employee[]=$row;
    }
    header("Content-Type: application/json");
    echo json_encode($employee);
}

function insert_employee()
{
    global $link;

    $post_body = file_get_contents("php://input");
    $data = json_decode($post_body);

    $name = $data->name;
    $address = $data->address;
    $salary = $data->salary;

    $query="INSERT INTO employees(name, address, salary) VALUES("".$name."", "".$address."", "".$salary."")";

    if(mysqli_query($link,$query))
    {
        $response=array(
            "status" => 1,
            "status_message" =>"Employee Added Successfully."
        );
    }
    else
    {
        $response=array(
            "status" => 0,
            "status_message" =>"Employee Addition Failed."
        );
    }
    header("Content-Type: application/json");
    echo json_encode($response);
}

function update_employee($id)
{
    global $link;
    $put_body = file_get_contents("php://input");
    $data = json_decode($put_body);
    $name = $data->name;
    $address = $data->address;
    $salary = $data->salary;

    $query="UPDATE employees SET name="".$name."", address="".$address."", salary="".$salary."" WHERE id=".$id;
    if(mysqli_query($link,$query))
    {
        $response=array(
            "status" => 1,
            "status_message" =>"Employee Updated Successfully."
        );
    }
    else
    {
        $response=array(
            "status" => 0,
            "status_message" =>"Employee Updation Failed."
        );
    }
    header("Content-Type: application/json");
    echo json_encode($response);
}

function delete_employee($id)
{
    global $link;
    $query="DELETE FROM employees WHERE id=".$id;
    if(mysqli_query($link,$query))
    {
        $response=array(
            "status" => 1,
            "status_message" =>"Employee Deleted Successfully."
        );
    }
    else
    {
        $response=array(
            "status" => 0,
            "status_message" =>"Employee Deletion Failed."
        );
    }
    header("Content-Type: application/json");
    echo json_encode($response);
}

mysqli_close($link);
?>

以上代码定义了一个基本的CRUD（增删改查）API，使用GET、POST、PUT和DELETE请求方式，通过不同的请求方式调用执行相应的操作。通过向 API 发送HTTP请求，可以获取、创建、修改或删除数据，并且返回 JSON 格式的响应信息。