java cookie模拟登陆

以下是一个使用Java模拟登陆的示例代码：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.List;
import java.util.Map;

public class LoginDemo {

    public static void main(String[] args) throws Exception {
        String loginUrl = "http://example.com/login";
        String username = "your_username";
        String password = "your_password";

        // Create a new URL object
        URL url = new URL(loginUrl);

        // Create a new HttpURLConnection object
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        // Set the request method to POST
        connection.setRequestMethod("POST");

        // Set the request headers
        connection.setRequestProperty("User-Agent", "Mozilla/5.0");
        connection.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

        // Set the request parameters
        String params = "username=" + URLEncoder.encode(username, "UTF-8")
                + "&password=" + URLEncoder.encode(password, "UTF-8");
        connection.setDoOutput(true);
        connection.getOutputStream().write(params.getBytes("UTF-8"));

        // Send the request
        int responseCode = connection.getResponseCode();

        if (responseCode == HttpURLConnection.HTTP_OK) {
            // Read the response
            BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String inputLine;
            StringBuffer response = new StringBuffer();

            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
            in.close();

            // Print the response
            System.out.println(response.toString());

            // Get the cookies from the response headers
            Map<String, List<String>> headerFields = connection.getHeaderFields();
            List<String> cookiesHeader = headerFields.get("Set-Cookie");

            if (cookiesHeader != null) {
                // Parse the cookies and store them in a CookieManager object
                java.net.CookieManager cookieManager = new java.net.CookieManager();
                for (String cookie : cookiesHeader) {
                    cookieManager.getCookieStore().add(null, HttpCookie.parse(cookie).get(0));
                }
                // Use the CookieManager to send subsequent requests with the cookies
                URL newUrl = new URL("http://example.com/protected_page");
                HttpURLConnection newConnection = (HttpURLConnection) newUrl.openConnection();
                cookieManager.getCookieStore().getCookies().forEach(c -> newConnection.addRequestProperty("Cookie", c.toString()));
                int newResponseCode = newConnection.getResponseCode();

                if (newResponseCode == HttpURLConnection.HTTP_OK) {
                    // Read the response
                    BufferedReader newIn = new BufferedReader(new InputStreamReader(newConnection.getInputStream()));
                    String newInputLine;
                    StringBuffer newResponse = new StringBuffer();

                    while ((newInputLine = newIn.readLine()) != null) {
                        newResponse.append(newInputLine);
                    }
                    newIn.close();

                    // Print the response
                    System.out.println(newResponse.toString());
                } else {
                    System.out.println("Failed to fetch protected page");
                }
            }
        } else {
            System.out.println("Failed to login");
        }
    }
}

此代码将使用POST请求发送用户名和密码到登录页面。如果登录成功，它将获取响应标头中的cookie，并将其存储在CookieManager对象中。然后，它将使用CookieManager对象向受保护的页面发送新请求，并在请求中添加所有cookie。如果此请求成功，它将打印受保护页面的内容。