java http怎樣處理Cookie

在Java中，處理HTTP Cookie通常涉及到兩個方面：接收和發送Cookie。這里，我們將使用Java的java.net.HttpURLConnection類來演示如何處理Cookie。

1. 發送Cookie：

當你需要向服務器發送Cookie時，可以將它們添加到HTTP請求頭中。以下是一個示例：

import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class SendCookie {
    public static void main(String[] args) {
        try {
            URL url = new URL("https://example.com/login");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);

            // 創建一個Cookie對象
            String cookieName = "username";
            String cookieValue = "JohnDoe";
            String cookieHeader = cookieName + "=" + cookieValue;

            // 將Cookie添加到請求頭中
            connection.setRequestProperty("Cookie", cookieHeader);

            // 發送請求
            OutputStream outputStream = connection.getOutputStream();
            outputStream.write("username=JohnDoe&password=123456".getBytes());
            outputStream.flush();
            outputStream.close();

            // 獲取響應狀態碼
            int responseCode = connection.getResponseCode();
            System.out.println("Response Code: " + responseCode);

            // 讀取響應內容（可選）
            // ...

            // 關閉連接
            connection.disconnect();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

2. 接收Cookie：

當服務器返回Cookie時，你需要從HTTP響應頭中提取它們。以下是一個示例：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class ReceiveCookie {
    public static void main(String[] args) {
        try {
            URL url = new URL("https://example.com/login");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);

            // 發送請求
            OutputStream outputStream = connection.getOutputStream();
            outputStream.write("username=JohnDoe&password=123456".getBytes());
            outputStream.flush();
            outputStream.close();

            // 獲取響應狀態碼
            int responseCode = connection.getResponseCode();
            System.out.println("Response Code: " + responseCode);

            // 讀取響應內容
            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line;
            StringBuilder response = new StringBuilder();
            while ((line = reader.readLine()) != null) {
                response.append(line);
            }
            reader.close();

            // 提取Cookie
            String setCookieHeader = connection.getHeaderField("Set-Cookie");
            System.out.println("Set-Cookie: " + setCookieHeader);

            // 關閉連接
            connection.disconnect();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

注意：在實際應用中，你可能需要使用更高級的庫（如Apache HttpClient或OkHttp）來處理HTTP請求和響應，因為它們提供了更簡潔的API和更強大的功能。但是，了解如何使用HttpURLConnection處理Cookie仍然是非常重要的。