Android文件上传到服务端实践指南

Android 上传文件到服务端并显示进度条 Android 上传文件到服务端并显示进度条是 Android 开发中的一项重要技术，以下是该技术的详细知识点： 一、Android 上传文件到服务端 Android 上传文件到服务端主要使用的是 HttpURLConnection 类，该类提供了基本的 HTTP 连接功能，可以用来实现文件上传。下面是一个简单的示例代码： ```java private class UploadTask extends AsyncTask<Object, Integer, Void> { private DataOutputStream outputStream = null; private String fileName; private String uri; private String mLineEnd = "\r\n"; private String mTwoHyphens = "--"; private String boundary = "*"; File uploadFile; long mTtotalSize; // Getsize of file, bytes public UploadTask(String fileName, String uri) { this.fileName = fileName; this.uri = uri; uploadFile = new File(fileName); mTtotalSize = uploadFile.length(); } / * 开始上传文件 * * @param objects * @return */ @Override protected Void doInBackground(Object... objects) { long length = 0; int mBytesRead, mBytesAvailable, mBufferSize; byte[] buffer; int maxBufferSize = 256 * 1024; // 256KB try { FileInputStream fileInputStream = new FileInputStream(new File(fileName)); URL url = new URL(uri); HttpURLConnection con = (HttpURLConnection) url.openConnection(); con.setDoOutput(true); con.setRequestMethod("POST"); con.setRequestProperty("Connection", "Keep-Alive"); con.setRequestProperty("Charset", "UTF-8"); con.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary); outputStream = new DataOutputStream(con.getOutputStream()); // 上传文件 outputStream.writeBytes(mTwoHyphens + boundary + mLineEnd); outputStream.writeBytes("Content-Disposition: form-data; name=\"file\"; filename=\"" + fileName + "\"" + mLineEnd); outputStream.writeBytes(mLineEnd); byte[] buffer = new byte[maxBufferSize]; int bytesRead; while ((bytesRead = fileInputStream.read(buffer, 0, maxBufferSize)) != -1) { outputStream.write(buffer, 0, bytesRead); length += bytesRead; publishProgress((int) ((length / (float) mTtotalSize) * 100)); } outputStream.writeBytes(mLineEnd); outputStream.writeBytes(mTwoHyphens + boundary + mTwoHyphens + mLineEnd); int responseCode = con.getResponseCode(); if (responseCode == 200) { Log.d("UploadTask", "上传成功"); } else { Log.d("UploadTask", "上传失败"); } } catch (Exception e) { Log.d("UploadTask", "上传失败" + e.getMessage()); } finally { try { if (outputStream != null) { outputStream.close(); } } catch (IOException e) { Log.d("UploadTask", "关闭流失败" + e.getMessage()); } } return null; } } ``` 二、显示进度条 显示进度条可以使用 Android 提供的 ProgressBar 组件，以下是一个简单的示例代码： ```java private ProgressBar mPgBar; // 在AsyncTask中更新进度条 @Override protected void onProgressUpdate(Integer... progress) { mPgBar.setProgress(progress[0]); } // 在AsyncTask中显示进度条 @Override protected void onPostExecute(Void result) { mPgBar.setVisibility(View.GONE); } ``` 三、服务端代码 服务端代码可以使用多种语言实现，以下是一个使用 Java 实现的简单示例代码： ```java import java.io.File; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class UploadServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String fileName = request.getHeader("file"); File file = new File("upload/" + fileName); if (!file.exists()) { file.mkdirs(); } try { ServletFileUpload upload = new ServletFileUpload(); FileItemIterator iterator = upload.getItemIterator(request); while (iterator.hasNext()) { FileItemStream item = iterator.next(); String name = item.getFieldName(); if (item.isFormField()) { String value = item.getString(); System.out.println("Form field " + name + " with value " + value); } else { String fieldName = item.getFieldName(); String fileName = item.getName(); String contentType = item.getContentType(); boolean isInMemory = item.isInMemory(); long sizeInBytes = item.getSize(); System.out.println("Field " + fieldName); System.out.println("FileName " + fileName); System.out.println("ContentType " + contentType); System.out.println("Size (bytes) " + sizeInBytes); System.out.println("InMemory " + isInMemory); // 保存文件 File uploadedFile = new File("upload/" + fileName); item.write(uploadedFile); } } } catch (Exception e) { e.printStackTrace(); } } } ``` Android 上传文件到服务端并显示进度条是一项复杂的技术，需要使用多种技术栈，包括 HttpURLConnection、AsyncTask、ProgressBar 等，但通过合理的设计和实现，我们可以实现该功能。