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如何使用php curl函數

發布時間:2021-10-20 11:06:47 來源:億速云 閱讀:216 作者:iii 欄目:編程語言
# 如何使用PHP cURL函數

## 目錄
1. [cURL簡介](#curl簡介)
2. [安裝與配置](#安裝與配置)
3. [基本使用流程](#基本使用流程)
4. [常用cURL函數詳解](#常用curl函數詳解)
5. [GET請求示例](#get請求示例)
6. [POST請求示例](#post請求示例)
7. [文件上傳](#文件上傳)
8. [HTTP認證](#http認證)
9. [處理HTTPS請求](#處理https請求)
10. [設置請求頭](#設置請求頭)
11. [處理Cookie](#處理cookie)
12. [并發請求](#并發請求)
13. [錯誤處理](#錯誤處理)
14. [性能優化](#性能優化)
15. [實際應用場景](#實際應用場景)
16. [安全注意事項](#安全注意事項)
17. [常見問題解答](#常見問題解答)

<a id="curl簡介"></a>
## 1. cURL簡介

cURL(Client URL Library)是一個強大的開源庫,支持多種協議(HTTP、HTTPS、FTP等),允許你通過URL傳輸數據。PHP中的cURL擴展提供了與libcurl庫的接口,使PHP能夠與其他服務器進行通信。

主要特點:
- 支持多種協議(HTTP/HTTPS/FTP/FTPS等)
- 支持SSL證書
- HTTP POST/PUT/DELETE等方法
- 表單提交
- 文件上傳/下載
- Cookie支持
- 代理支持

<a id="安裝與配置"></a>
## 2. 安裝與配置

### 檢查是否已安裝
```php
<?php
if (!function_exists('curl_init')) {
    die('cURL擴展未安裝');
}
?>

安裝方法

  • Linux系統

    sudo apt-get install php-curl  # Debian/Ubuntu
    sudo yum install php-curl     # CentOS/RHEL
    
  • Windows系統

    1. 打開php.ini文件
    2. 取消注釋或添加:extension=curl
    3. 重啟Web服務器

驗證安裝

<?php
phpinfo();
// 搜索"cURL support"確認是否啟用
?>

3. 基本使用流程

標準cURL請求流程: 1. 初始化cURL會話:curl_init() 2. 設置cURL選項:curl_setopt() 3. 執行請求:curl_exec() 4. 獲取錯誤信息(可選):curl_error() 5. 獲取請求信息(可選):curl_getinfo() 6. 關閉cURL會話:curl_close()

基本示例:

<?php
// 1. 初始化
$ch = curl_init();

// 2. 設置選項
curl_setopt($ch, CURLOPT_URL, "http://example.com");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

// 3. 執行并獲取結果
$output = curl_exec($ch);

// 4. 檢查錯誤
if ($output === false) {
    echo "cURL Error: " . curl_error($ch);
}

// 5. 關閉會話
curl_close($ch);

// 處理結果
echo $output;
?>

4. 常用cURL函數詳解

curl_init()

初始化一個新的cURL會話。

$ch = curl_init([string $url = null]);

curl_setopt()

設置cURL選項。

bool curl_setopt(resource $ch, int $option, mixed $value);

常用選項: - CURLOPT_URL: 請求的URL - CURLOPT_RETURNTRANSFER: 返回結果而不直接輸出 - CURLOPT_POST: 啟用POST請求 - CURLOPT_POSTFIELDS: POST數據 - CURLOPT_HEADER: 包含響應頭 - CURLOPT_HTTPHEADER: 設置請求頭 - CURLOPT_FOLLOWLOCATION: 跟隨重定向 - CURLOPT_SSL_VERIFYPEER: 驗證SSL證書 - CURLOPT_TIMEOUT: 超時時間(秒)

curl_exec()

執行cURL會話。

mixed curl_exec(resource $ch);

curl_close()

關閉cURL會話。

void curl_close(resource $ch);

curl_error()

返回最后一次錯誤的字符串。

string curl_error(resource $ch);

curl_getinfo()

獲取最后一次傳輸的信息。

mixed curl_getinfo(resource $ch [, int $opt = 0]);

常用信息: - CURLINFO_HTTP_CODE: 最后收到的HTTP代碼 - CURLINFO_TOTAL_TIME: 總傳輸時間 - CURLINFO_SIZE_DOWNLOAD: 下載字節數

5. GET請求示例

基本GET請求:

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/api?param1=value1");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

帶參數的GET請求:

<?php
$params = [
    'key1' => 'value1',
    'key2' => 'value2'
];
$url = 'http://example.com/api?' . http_build_query($params);

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

6. POST請求示例

基本POST請求:

<?php
$postData = [
    'username' => 'admin',
    'password' => 'secret'
];

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/login");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

發送JSON數據:

<?php
$data = [
    'name' => 'John Doe',
    'email' => 'john@example.com'
];
$json = json_encode($data);

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/api/users");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $json);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Content-Type: application/json',
    'Content-Length: ' . strlen($json)
]);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

7. 文件上傳

上傳單個文件:

<?php
$file = new CURLFile('path/to/file.jpg', 'image/jpeg', 'file.jpg');
$postData = [
    'userfile' => $file,
    'other_field' => 'value'
];

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/upload");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

上傳多個文件:

<?php
$files = [
    'file1' => new CURLFile('path/to/file1.jpg'),
    'file2' => new CURLFile('path/to/file2.jpg')
];

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/multi-upload");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $files);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

8. HTTP認證

基本認證:

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/protected");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_USERPWD, "username:password");
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

摘要認證:

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/protected");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_USERPWD, "username:password");
curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_DIGEST);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

9. 處理HTTPS請求

禁用SSL驗證(不推薦生產環境使用):

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://example.com");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

使用CA證書驗證:

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://example.com");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($ch, CURLOPT_CNFO, "/path/to/cacert.pem");
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

10. 設置請求頭

自定義請求頭:

<?php
$headers = [
    'Authorization: Bearer token123',
    'Content-Type: application/json',
    'X-Custom-Header: value'
];

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/api");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

獲取響應頭:

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HEADER, true);
$response = curl_exec($ch);

$header_size = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
$headers = substr($response, 0, $header_size);
$body = substr($response, $header_size);

curl_close($ch);

echo "Headers:\n$headers\n\nBody:\n$body";
?>

11. 處理Cookie

發送Cookie:

<?php
$cookie = "name=value; name2=value2";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIE, $cookie);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

保存Cookie到文件:

<?php
$cookie_file = tempnam(sys_get_temp_dir(), "cookie");

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/login");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, "username=admin&password=secret");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookie_file);
$response = curl_exec($ch);
curl_close($ch);

// 后續請求使用保存的cookie
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com/profile");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEFILE, $cookie_file);
$response = curl_exec($ch);
curl_close($ch);

echo $response;
?>

12. 并發請求

使用curlmulti*函數實現并發請求:

<?php
$urls = [
    'http://example.com/api/1',
    'http://example.com/api/2',
    'http://example.com/api/3'
];

$mh = curl_multi_init();
$handles = [];

foreach ($urls as $i => $url) {
    $handles[$i] = curl_init();
    curl_setopt($handles[$i], CURLOPT_URL, $url);
    curl_setopt($handles[$i], CURLOPT_RETURNTRANSFER, true);
    curl_multi_add_handle($mh, $handles[$i]);
}

$running = null;
do {
    curl_multi_exec($mh, $running);
    curl_multi_select($mh);
} while ($running > 0);

$results = [];
foreach ($handles as $i => $handle) {
    $results[$i] = curl_multi_getcontent($handle);
    curl_multi_remove_handle($mh, $handle);
    curl_close($handle);
}

curl_multi_close($mh);

print_r($results);
?>

13. 錯誤處理

基本錯誤處理:

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://invalid.url");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);

if ($response === false) {
    $error = curl_error($ch);
    $errno = curl_errno($ch);
    echo "cURL Error ($errno): $error";
} else {
    echo $response;
}

curl_close($ch);
?>

獲取HTTP狀態碼:

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://example.com");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);

if ($httpCode !== 200) {
    echo "請求失敗,HTTP狀態碼:$httpCode";
} else {
    echo $response;
}

curl_close($ch);
?>

14. 性能優化

  1. 復用cURL句柄: “`php <?php \(ch = curl_init(); // 第一次請求 curl_setopt(\)ch, CURLOPT_URL, “http://example.com/api1”); \(response1 = curl_exec(\)ch);

// 第二次請求(復用同一個句柄) curl_setopt(\(ch, CURLOPT_URL, "http://example.com/api2"); \)response2 = curl_exec($ch);

curl_close($ch); ?>


2. **設置合理的超時時間**:
   ```php
   curl_setopt($ch, CURLOPT_TIMEOUT, 30);        // 總超時時間
   curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10); // 連接超時時間
  1. 啟用Keep-Alive

    curl_setopt($ch, CURLOPT_TCP_KEEPALIVE, 1);
    curl_setopt($ch, CURLOPT_TCP_KEEPIDLE, 120);
    curl_setopt($ch, CURLOPT_TCP_KEEPINTVL, 60);
    
  2. 使用DNS緩存

    curl_setopt($ch, CURLOPT_DNS_CACHE_TIMEOUT, 86400); // 24小時
    

15. 實際應用場景

  1. API調用: “`php <?php \(ch = curl_init(); curl_setopt(\)ch, CURLOPT_URL, “https://api.example.com/data”); curl_setopt(\(ch, CURLOPT_RETURNTRANSFER, true); curl_setopt(\)ch, CURLOPT_HTTPHEADER, [ ‘Authorization: Bearer your_api_key’, ‘Accept: application/json’ ]); \(response = curl_exec(\)ch); curl_close($ch);

\(data = json_decode(\)response, true); ?> “`

  1. 網頁抓取: “`php <?php \(ch = curl_init(); curl_setopt(\)ch, CURLOPT_URL, “http://example.com”); curl_setopt(\(ch, CURLOPT_RETURNTRANSFER, true); curl_setopt(\)ch, CURLOPT_FOLLOWLOCATION, true); curl_setopt(\(ch, CURLOPT_USERAGENT, 'Mozilla/5.0'); \)html = curl_exec(\(ch); curl_close(\)ch);

// 使用DOM解析HTML \(dom = new DOMDocument(); @\)dom->load

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