Dateien mit Http-Anfragen hochladen

, um Dateien auf einen HTTP-Server hochzuladen und gleichzeitig zusätzliche Parameter zu senden. Hier ist eine Aufschlüsselung des Prozesses:

multiPart/form-data codieren

MultiPart/Form-Data sind für Postanfragen ausgelegt, die beide binären (z. B. Dateien) und Charakterdaten (z. B., z. B. Parameter) kombinieren. Die Enkodierung beinhaltet die Aufteilung des Antragskörpers in mehrere Teile, die jeweils mit einem Grenzstring vorangestellt sind. importieren java.io.outputstream; Import Java.io.printwriter; importieren java.net.urlConnection; import Java.nio.charset.StandardCharets; importieren java.nio.file.files; Import Java.nio.file.Paths; öffentliche KlassendateiEUpload { public static void main (String [] args) löst Ausnahme {aus { String url = "http://example.com/upload"; String param = "value"; Datei textfile = new Datei ("/path/to/file.txt"); Datei binaryFile = new Datei ("/path/to/file.bin"); String boundary = long.tohexString (System.currentTimemillis ()); UrlConnection Connection = neue URL (URL) .OpenConnection (); connection.setDooutput (true); connection.setRequestProperty ("Content-Typ", "Multipart/Form-Data; bloße =" Grenze); try (outputStream output = connection.getOutputStream (); Printwriter writer = neuer Pressewriter (neuer Ausgangsstreamwriter (Ausgabe, Standardcharets.utf_8), True)) { // Parameter senden writer.Append ("-" Grenze) .Append ("\ r \ n"); writer.Append ("Inhaltsdisposition: Formdaten; name = \" Param \ ""). append ("\ r \ n"); writer.append ("content-type: text/plain; charset =" StandardCharets.utf_8) .Append ("\ r \ n"); writer.Append ("\ r \ n"). append (param) .Append ("\ r \ n"). Flush (); // Textdatei senden writer.Append ("-" Grenze) .Append ("\ r \ n"); writer.Append ("Inhaltsdisposition: Formdaten; name = \" textfile \ "; fileName = \" "textFile.getName ()" \ ""). append ("\ r \ n"); writer.append ("content-type: text/plain; charset =" StandardCharets.utf_8) .Append ("\ r \ n"); writer.Append ("\ r \ n"). Flush (); Dateien.Copy (textfile.topath (), output); output.flush (); writer.Append ("\ r \ n"). Flush (); // Binärdatei senden writer.Append ("-" Grenze) .Append ("\ r \ n"); writer.Append ("Inhaltsdisposition: Formdaten; name = \" BinaryFile \ "; FileName = \" "BinaryFile.getName ()" \ ""). append ("\ r \ n"); writer.Append ("Content-Typ:" urlConnection.GuessContentTypeFromName (BinaryFile.getName ())). Append ("\ r \ n"); writer.Append ("Content-transfer-kodiert: binär"). append ("\ r \ n"); writer.Append ("\ r \ n"). Flush (); Dateien.Copy (BinaryFile.topath (), Ausgabe); output.flush (); writer.Append ("\ r \ n"). Flush (); // Ende von mehrteiler/Formdaten writer.Append ("-" bloße "-"). append ("\ r \ n"). Flush (); } int responseCode = ((httpurlConnection) Verbindung) .GetResponScode (); System.out.println ("Antwortcode:" ResponseCode); } }

zusätzliche Notizen

import java.io.File;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URLConnection;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;

public class FileUpload {

    public static void main(String[] args) throws Exception {
        String url = "http://example.com/upload";
        String param = "value";
        File textFile = new File("/path/to/file.txt");
        File binaryFile = new File("/path/to/file.bin");
        String boundary = Long.toHexString(System.currentTimeMillis());

        URLConnection connection = new URL(url).openConnection();
        connection.setDoOutput(true);
        connection.setRequestProperty("Content-Type", "multipart/form-data; boundary="   boundary);

        try (OutputStream output = connection.getOutputStream();
             PrintWriter writer = new PrintWriter(new OutputStreamWriter(output, StandardCharsets.UTF_8), true)) {
            // Send parameter
            writer.append("--"   boundary).append("\r\n");
            writer.append("Content-Disposition: form-data; name=\"param\"").append("\r\n");
            writer.append("Content-Type: text/plain; charset="   StandardCharsets.UTF_8).append("\r\n");
            writer.append("\r\n").append(param).append("\r\n").flush();

            // Send text file
            writer.append("--"   boundary).append("\r\n");
            writer.append("Content-Disposition: form-data; name=\"textFile\"; filename=\""   textFile.getName()   "\"").append("\r\n");
            writer.append("Content-Type: text/plain; charset="   StandardCharsets.UTF_8).append("\r\n");
            writer.append("\r\n").flush();
            Files.copy(textFile.toPath(), output);
            output.flush();
            writer.append("\r\n").flush();

            // Send binary file
            writer.append("--"   boundary).append("\r\n");
            writer.append("Content-Disposition: form-data; name=\"binaryFile\"; filename=\""   binaryFile.getName()   "\"").append("\r\n");
            writer.append("Content-Type: "   URLConnection.guessContentTypeFromName(binaryFile.getName())).append("\r\n");
            writer.append("Content-Transfer-Encoding: binary").append("\r\n");
            writer.append("\r\n").flush();
            Files.copy(binaryFile.toPath(), output);
            output.flush();
            writer.append("\r\n").flush();

            // End of multipart/form-data
            writer.append("--"   boundary   "--").append("\r\n").flush();
        }

        int responseCode = ((HttpURLConnection) connection).getResponseCode();
        System.out.println("Response Code: "   responseCode);
    }
}