如何用Java模拟登录网页系统 Java表单登录请求示例

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.CookieStore;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.impl.client.BasicCookieStore;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

import java.util.ArrayList;
import java.util.List;

public class WebLoginSimulator {

    public static void main(String[] args) throws Exception {
        // 1. 创建Cookie存储，用于管理会话Cookie
        CookieStore cookieStore = new BasicCookieStore();
        // 2. 创建HttpClient上下文，将Cookie存储关联进去
        HttpClientContext context = HttpClientContext.create();
        context.setCookieStore(cookieStore);

        // 3. 创建HttpClient实例，配置重定向策略（可选，但推荐）
        CloseableHttpClient httpClient = HttpClients.custom()
                .setDefaultCookieStore(cookieStore) // 也可以直接设置到HttpClient中
                .build();

        try {
            // --- 步骤一：访问登录页面，获取可能的CSRF token或初始化Cookie ---
            // 有些网站会在登录页面的HTML中嵌入一个CSRF token，或者在访问时设置一个session cookie
            String loginPageUrl = "http://your-target-website.com/login"; // 替换为实际的登录页面URL
            HttpGet getLoginPage = new HttpGet(loginPageUrl);
            getLoginPage.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124124 Safari/537.36");

            System.out.println("访问登录页面: " + loginPageUrl);
            HttpResponse loginPageResponse = httpClient.execute(getLoginPage, context);
            HttpEntity loginPageEntity = loginPageResponse.getEntity();
            String loginPageContent = EntityUtils.toString(loginPageEntity, "UTF-8");
            EntityUtils.consume(loginPageEntity); // 确保关闭输入流

            // 这里可以解析 loginPageContent 来提取CSRF token等隐藏字段
            // 例如：String csrfToken = extractCsrfToken(loginPageContent);
            // 简单示例，我们假设不需要CSRF token或者直接知道其值

            // --- 步骤二：构建并发送登录POST请求 ---
            String loginPostUrl = "http://your-target-website.com/doLogin"; // 替换为实际的登录处理URL
            HttpPost httpPost = new HttpPost(loginPostUrl);

            // 设置请求头，模拟浏览器行为
            httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124124 Safari/537.36");
            httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded");
            // 某些网站会检查Referer，可以加上
            httpPost.setHeader("Referer", loginPageUrl);

            // 准备表单参数
            List<NameValuePair> params = new ArrayList<>();
            params.add(new BasicNameValuePair("username", "your_username")); // 替换为你的用户名
            params.add(new BasicNameValuePair("password", "your_password")); // 替换为你的密码
            // 如果有CSRF token，也在这里添加：
            // params.add(new BasicNameValuePair("csrf_token", csrfToken));

            httpPost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));

            System.out.println("\n发送登录请求到: " + loginPostUrl);
            HttpResponse response = httpClient.execute(httpPost, context); // 执行POST请求，上下文会自动处理Cookie
            HttpEntity entity = response.getEntity();

            System.out.println("登录响应状态码: " + response.getStatusLine().getStatusCode());
            String responseBody = EntityUtils.toString(entity, "UTF-8");
            System.out.println("登录响应体: \n" + responseBody);
            EntityUtils.consume(entity); // 确保关闭输入流

            // 检查登录是否成功 (通常通过状态码、重定向或响应内容判断)
            if (response.getStatusLine().getStatusCode() == 200 || response.getStatusLine().getStatusCode() == 302) {
                System.out.println("\n登录请求似乎已发送成功。");
                // 此时，CookieStore中应该已经包含了服务器返回的会话Cookie

                // --- 步骤三：访问登录后的页面，验证是否成功登录 ---
                String loggedInPageUrl = "http://your-target-website.com/dashboard"; // 替换为登录后的目标页面URL
                HttpGet getLoggedInPage = new HttpGet(loggedInPageUrl);
                getLoggedInPage.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124124 Safari/537.36");

                System.out.println("\n尝试访问登录后的页面: " + loggedInPageUrl);
                HttpResponse loggedInResponse = httpClient.execute(getLoggedInPage, context); // 再次使用相同的上下文，携带Cookie
                HttpEntity loggedInEntity = loggedInResponse.getEntity();
                String loggedInContent = EntityUtils.toString(loggedInEntity, "UTF-8");
                System.out.println("登录后页面响应状态码: " + loggedInResponse.getStatusLine().getStatusCode());
                System.out.println("登录后页面内容摘要 (前500字): \n" + loggedInContent.substring(0, Math.min(loggedInContent.length(), 500)) + "...");
                EntityUtils.consume(loggedInEntity);

                // 根据页面内容判断是否真的登录成功，比如检查是否有“欢迎，[用户名]”字样或特定元素
                if (loggedInContent.contains("欢迎") || loggedInContent.contains("Dashboard")) { // 替换为实际的成功标识
                    System.out.println("\n成功模拟登录并访问了登录后页面！");
                } else {
                    System.out.println("\n登录后页面内容未显示成功标识，可能登录失败或页面内容不同。");
                }

            } else {
                System.err.println("登录请求失败，状态码: " + response.getStatusLine().getStatusCode());
            }

        } finally {
            httpClient.close(); // 确保关闭HttpClient连接
        }
    }

    // 辅助方法，用于从HTML内容中提取CSRF token (这里只是一个占位符，实际需要更健壮的HTML解析)
    // private static String extractCsrfToken(String htmlContent) {
    //     // 使用Jsoup或其他HTML解析库来查找 <input type="hidden" name="csrf_token" value="...">
    //     // 例如：Document doc = Jsoup.parse(htmlContent);
    //     //       Element csrfInput = doc.select("input[name=csrf_token]").first();
    //     //       return csrfInput != null ? csrfInput.attr("value") : null;
    //     return "dummy_csrf_token"; // 实际项目中需要实现
    // }
}