在Android中上傳文件到服務(wù)器，通常需要以下步驟：

1、獲取文件路徑

2、創(chuàng)建HttpURLConnection對象

3、設(shè)置請求屬性

4、寫入數(shù)據(jù)

5、讀取響應(yīng)

6、關(guān)閉連接

以下是詳細的代碼示例：

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
public class UploadToServer {
    // server url where the file will be posted
    private static final String UPLOAD_URL = "http://yourserverurl.com/upload";
    public void uploadFile(String sourceFileUri) {
        String fileName = sourceFileUri;
        HttpURLConnection conn = null;
        DataOutputStream dos = null;
        String lineEnd = "r
";
        String twoHyphens = "";
        String boundary = "*****";
        int bytesRead, bytesAvailable, bufferSize;
        byte[] buffer;
        int maxBufferSize = 1 * 1024 * 1024;
        File sourceFile = new File(sourceFileUri);
        if (!sourceFile.isFile()) {
            Log.e("Huzzaman", "Source File not exist :" + sourceFileUri);
            return;
        }
        try {
            // open a URL connection to the Servlet
            FileInputStream fileInputStream = new FileInputStream(sourceFile);
            URL url = new URL(UPLOAD_URL);
            conn = (HttpURLConnection) url.openConnection(); // Open a HTTP  connection to  the URL
            conn.setDoInput(true); // Allow Inputs
            conn.setDoOutput(true); // Allow Outputs
            conn.setUseCaches(false); // Don't use a Cached Copy
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Connection", "KeepAlive");
            conn.setRequestProperty("ENCTYPE", "multipart/formdata");
            conn.setRequestProperty("ContentType", "multipart/formdata;boundary=" + boundary);
            conn.setRequestProperty("file", fileName);
            dos = new DataOutputStream(conn.getOutputStream());
            dos.writeBytes(twoHyphens + boundary + lineEnd);
            dos.writeBytes("ContentDisposition: formdata; name="file";filename="" + fileName + """ + lineEnd);
            dos.writeBytes(lineEnd);
            bytesAvailable = fileInputStream.available(); // create a buffer of  maximum size
            bufferSize = Math.min(bytesAvailable, maxBufferSize);
            buffer = new byte[bufferSize];
            // read file and write it into form...
            bytesRead = fileInputStream.read(buffer, 0, bufferSize);
            while (bytesRead > 0) {
                dos.write(buffer, 0, bufferSize);
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);
            }
            // send multipart form data necesssary after file data...
            dos.writeBytes(lineEnd);
            dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
            // Responses from the server (code and message)
            serverResponseCode = conn.getResponseCode();
            String serverResponseMessage = conn.getResponseMessage();
            Log.i("Upload file to server", "HTTP Response is : " + serverResponseMessage + ": " + serverResponseCode);
            if (serverResponseCode == 200) {
                // Toast message
                Runnable completeMsg = () > Toast.makeText(getActivity(), "File Upload Complete.", Toast.LENGTH_SHORT).show();
                getActivity().runOnUiThread(completeMsg);
            }
            //close the streams //
            fileInputStream.close();
            dos.flush();
            dos.close();
        } catch (MalformedURLException ex) {
            ex.printStackTrace();
            Log.e("Upload file to server", "error: " + ex.getMessage(), ex);
        } catch (Exception e) {
            e.printStackTrace();
            Log.e("Upload file to server", "Could not upload file: " + e.getMessage(), e);
        }
    }
}

在這個例子中，我們首先創(chuàng)建一個HttpURLConnection對象，然后設(shè)置請求屬性，包括請求方法、連接類型、內(nèi)容類型等，我們打開一個文件輸入流，讀取文件內(nèi)容并寫入HttpURLConnection的輸出流，我們讀取服務(wù)器的響應(yīng)并關(guān)閉連接。