如何用Java模拟表单提交请求 Java构造application/x-www-form格式

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

public class FormSubmitter {

    public static String submitForm(String url, Map<String, String> params) throws IOException {
        // 1. 构建请求体
        StringBuilder postData = new StringBuilder();
        for (Map.Entry<String, String> param : params.entrySet()) {
            if (postData.length() != 0) postData.append('&');
            postData.append(URLEncoder.encode(param.getKey(), StandardCharsets.UTF_8));
            postData.append('=');
            postData.append(URLEncoder.encode(param.getValue(), StandardCharsets.UTF_8));
        }
        byte[] postDataBytes = postData.toString().getBytes(StandardCharsets.UTF_8);

        // 2. 创建连接
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        // 3. 设置请求方法和头部
        con.setRequestMethod("POST");
        con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        con.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
        con.setDoOutput(true);

        // 4. 发送请求
        try (DataOutputStream wr = new DataOutputStream(con.getOutputStream())) {
            wr.write(postDataBytes);
        }

        // 5. 读取响应
        StringBuilder response = new StringBuilder();
        try (BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()))) {
            String line;
            while ((line = in.readLine()) != null) {
                response.append(line);
            }
        }

        return response.toString();
    }

    public static void main(String[] args) {
        String url = "https://httpbin.org/post"; // 一个可以接收POST请求并返回数据的测试地址
        Map<String, String> params = new HashMap<>();
        params.put("username", "testUser");
        params.put("password", "testPassword");
        params.put("message", "Hello from Java!");

        try {
            String response = submitForm(url, params);
            System.out.println("Response: " + response);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;

public class MultipartFormSubmitter {

    public static String submitFormWithFile(String url, File file, String filename) throws IOException {
        HttpClient httpClient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost(url);

        MultipartEntityBuilder builder = MultipartEntityBuilder.create();
        builder.setCharset(StandardCharsets.UTF_8);
        builder.addBinaryBody("file", file, ContentType.DEFAULT_BINARY, filename); // "file" 是服务器端接收文件的字段名
        builder.addTextBody("description", "This is a file upload.", ContentType.TEXT_PLAIN); // 添加其他文本字段

        HttpEntity multipart = builder.build();
        httpPost.setEntity(multipart);

        HttpResponse response = httpClient.execute(httpPost);
        HttpEntity responseEntity = response.getEntity();
        return EntityUtils.toString(responseEntity, StandardCharsets.UTF_8);
    }

    public static void main(String[] args) {
        String url = "https://httpbin.org/post"; // 替换为你的服务器地址
        File file = new File("example.txt"); // 替换为你的文件路径

        // 创建一个示例文件
        try {
            file.createNewFile(); // 如果文件不存在，就创建一个
        } catch (IOException e) {
            e.printStackTrace();
        }


        try {
            String response = submitFormWithFile(url, file, "example.txt");
            System.out.println("Response: " + response);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import javax.net.ssl.*;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;

// ... 之前的代码 ...

// 在创建连接之前添加以下代码：
try {
    TrustManager[] trustAllCertificates = new TrustManager[]{
            new X509TrustManager() {
                public X509Certificate[] getAcceptedIssuers() {
                    return null;
                }

                public void checkClientTrusted(X509Certificate[] certs, String authType) {
                }

                public void checkServerTrusted(X509Certificate[] certs, String authType) {
                }
            }
    };

    SSLContext sc = SSLContext.getInstance("SSL");
    sc.init(null, trustAllCertificates, new SecureRandom());
    HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());

    HostnameVerifier allHostsValid = (hostname, session) -> true;
    HttpsURLConnection.setDefaultHostnameVerifier(allHostsValid);

} catch (Exception e) {
    e.printStackTrace();
}

// ... 之后的代码，创建URL和HttpURLConnection ...

import java.net.CookieHandler;
import java.net.CookieManager;
import java.net.CookiePolicy;

// ... 之前的代码 ...

// 在main方法中，或者在类的构造函数中，初始化CookieManager：
CookieManager cookieManager = new CookieManager();
CookieHandler.setDefault(cookieManager);

// ... 之后的代码，创建URL和HttpURLConnection ...

// 发送请求后，CookieManager会自动处理Cookie。
// 如果你需要手动获取Cookie，可以使用cookieManager.getCookieStore().getCookies()。