Написать на Java API соеденение по примеру PHP

Это все очень далеко от того, что делает PHP

Для того, чтобы отправить http запрос, лучше использовать что-то более высокоуровневое, к примеру, я взял okhttp, подключайте зависимость:

https://mvnrepository.com/artifact/com.squareup.okhttp3/okhttp/4.9.3

Поскольку я не знаю секретного ключа, то пртестировать это не могу, однако, примерно это будет выглядеть так (дальше разбирайтесь и дебажте):

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.stream.Collectors;
import javax.xml.bind.DatatypeConverter;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class Test {

    public static void main(String[] args) throws Exception {
        
        Map<String, String> postargs = new LinkedHashMap<>();

        postargs.put("anonymous", "1");
        postargs.put("dtmfUserAnswer", "0");
        postargs.put("firstTime", "0");
        postargs.put("from", "27.04.2022");
        postargs.put("fromNumber", "");
        postargs.put("names", "0");
        postargs.put("numbersInvolved", "0");
        postargs.put("numbersRinged", "0");
        postargs.put("outgoingLine", "1");
        postargs.put("showTreeId", "1");
        postargs.put("state", "0");
        postargs.put("to", "27.04.2022");
        postargs.put("toAnswer", "");
        postargs.put("toNumber", "");
        postargs.put("tree", "");
        postargs.put("type", "0");
        postargs.put("user", "081121");

        String secret = "secret";

        String urlAdress = "https://someurl.com/api/statistic/export";

        Map<String, String> postargsWithMd5 = addMd5(secret, postargs);

        String content = send(urlAdress, postargsWithMd5);

        System.out.println(content);

    }

    private static Map<String, String> addMd5(String secret, Map<String, String> postargs) throws NoSuchAlgorithmException {
        StringBuilder sb = new StringBuilder();
        for (Map.Entry<String, String> entry : postargs.entrySet()) sb.append(entry.getValue()).append("+");
        String hashString = sb.append(secret).toString();
        MessageDigest md = MessageDigest.getInstance("MD5");
        md.update(hashString.getBytes());
        postargs.put("hash", DatatypeConverter.printHexBinary(md.digest()));
        return postargs;
    }
    
    private static String send(String url, Map<String, String> postargs) throws IOException {
        FormBody.Builder bodyBuilder = new FormBody.Builder();
        for (Map.Entry<String, String> entry : postargs.entrySet()) bodyBuilder.add(entry.getKey(), entry.getValue());
        Request request = new Request.Builder()
                .addHeader("Content-Disposition", String.join("", "attachment; filename=stat_", postargs.get("from"), "-" + postargs.get("to"), ".csv"))
                .url(url)
                .post(bodyBuilder.build())
                .build();
        Response response = new OkHttpClient().newCall(request).execute();
        return new BufferedReader(new InputStreamReader(response.body().byteStream(), StandardCharsets.UTF_8))
                .lines().collect(Collectors.joining("\n"));
    }

}

Для отправка http запрос, вы можете использовать мою библиотеку. Итак, охраняйте это код как отдельный класс

public class HttpPutData extends Thread {
private final String url;
private final String method;
String result_data = "Empty";
final String[] data;
final String[] field;

// Initialize the spannable string builders.
final SpannableStringBuilder requestHeadersBuilder = new SpannableStringBuilder();

public HttpPutData(String url, String method, String[] field, String[] data) {
    this.url = url;
    this.method = method;
    this.data = new String[data.length];
    this.field = new String[field.length];
    System.arraycopy(field, 0, this.field, 0, field.length);
    System.arraycopy(data, 0, this.data, 0, data.length);
}

@Override
public void run() {
    try {
        String UTF8 = "UTF-8", iso = "iso-8859-1";
        URL url = new URL(this.url);
        HttpURLConnection httpUrlConnection = (HttpURLConnection) url.openConnection();
        httpUrlConnection.setRequestMethod(this.method);
        httpUrlConnection.setDoOutput(true);
        httpUrlConnection.setDoInput(true);

        String userAgent = "Mozilla/5.0 (Linux; Android;") AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Mobile Safari/537.36";
        // Set the `User-Agent` header property.
        httpUrlConnection.setRequestProperty("User-Agent", userAgent);

        // Add the `User-Agent` header to the string builder and format the text.
        requestHeadersBuilder.append(System.getProperty("line.separator"));
        requestHeadersBuilder.append("User-Agent", new StyleSpan(Typeface.BOLD), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        requestHeadersBuilder.append(":  ");
        requestHeadersBuilder.append(userAgent);

        // send Accept-Language
        String localeString = Locale.getDefault().toString();
        // Set the `Accept-Language` header property.
        httpUrlConnection.setRequestProperty("Accept-Language", localeString);

        // Add the `Accept-Language` header to the string builder and format the text.
        requestHeadersBuilder.append(System.getProperty("line.separator"));
        requestHeadersBuilder.append("Accept-Language", new StyleSpan(Typeface.BOLD), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        requestHeadersBuilder.append(":  ");
        requestHeadersBuilder.append(localeString);

        // Get the cookies for the current domain.
        String cookiesString = CookieManager.getInstance().getCookie(url.toString());
        // Only process the cookies if they are not null.
        if (cookiesString != null) {
            // Add the cookies to the header property.
            httpUrlConnection.setRequestProperty("Cookie", cookiesString);

            // Add the cookie header to the string builder and format the text.
            requestHeadersBuilder.append(System.getProperty("line.separator"));
            requestHeadersBuilder.append("Cookie", new StyleSpan(Typeface.BOLD), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
            requestHeadersBuilder.append(":  ");
            requestHeadersBuilder.append(cookiesString);
        }

        OutputStream outputStream = httpUrlConnection.getOutputStream();
        BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, UTF8));
        StringBuilder post_data = new StringBuilder();
        for (int i = 0; i < this.field.length; i++) {
            post_data.append(URLEncoder.encode(this.field[i], "UTF-8")).append("=").append(URLEncoder.encode(this.data[i], UTF8)).append("&");
        }
        bufferedWriter.write(post_data.toString());
        bufferedWriter.flush();
        bufferedWriter.close();
        outputStream.close();
        InputStream inputStream = httpUrlConnection.getInputStream();
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, iso));
        StringBuilder result = new StringBuilder();
        String result_line;
        while ((result_line = bufferedReader.readLine()) != null) {
            result.append(result_line);
        }
        bufferedReader.close();
        inputStream.close();
        httpUrlConnection.disconnect();
        setData(result.toString());
    } catch (IOException e) {
        setData(e.toString());
    }
}

public boolean startPut() {
    HttpPutData.this.start();
    return true;
}

public boolean onComplete() {
    while (true) {
        if (!this.isAlive()) {
            return true;
        }
    }
}

public String getResult() {
    return this.getData();
}

public void setData(String result_data) {
    this.result_data = result_data;
}

public String getData() {
    return result_data;
}

}

затем на ваш Activity или Fragment вызовите это код

    Handler handler = new Handler();
        handler.post(() -> {

        // count and key
        String[] field = new String[2]; // list with key
        field[0] = "key1"; //index and key
        field[1] = "key2"; //index and key

        //Creating array for data
        String[] data = new String[2]; // list with data
        data[0] = "value1"; // index and value
        data[1] = "value2"; // index and value

        HttpPutData httpPutData = new HttpPutData("http://url.com/main.php", "POST", field, data); // link, method, arrayKey, arrayValue;

        if (httpPutData.startPut()) {
            if (httpPutData.onComplete()) {
                String result = httpPutData.getResult();
                if(result != null){
                  Log.i("HttpPutData", result);
                }
            }
        }
    }); // end handler

не забудьте добавить разрешения на использование интернета в manifest!

весь данные будет отправлено в виде массива, на страница main.php где вы можете легко обрабатывать с помощью php.