在Android中上传文件到服务器，通常需要以下步骤：
（图片来源网络，侵删） 1、获取文件路径
2、创建HttpURLConnection对象
3、设置请求属性
4、写入数据
5、读取响应
6、关闭连接
以下是详细的代码示例：
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); // Dont 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); } } }在这个例子中，我们首先创建一个HttpURLConnection对象，然后设置请求属性，包括请求方法、连接类型、内容类型等，我们打开一个文件输入流，读取文件内容并写入HttpURLConnection的输出流，我们读取服务器的响应并关闭连接。
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