Android上傳檔案到Web伺服器，PHP接收檔案（二）

接上一篇文章《Android上傳檔案到Web伺服器，PHP接收檔案（一）》，這次在之前的基礎上添加進度顯示，Java代碼如下所示：

package com.lenovo.uptest;import java.io.DataInputStream;import java.io.DataOutputStream;import java.io.File;import java.io.FileInputStream;import java.net.HttpURLConnection;import java.net.URL;import android.app.Activity;import android.app.AlertDialog;import android.app.ProgressDialog;import android.content.DialogInterface;import android.os.AsyncTask;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.TextView;public class UploadtestActivity extends Activity {/** Called when the activity is first created. *//** * Upload file to web server with progress status, client: android; * server:php * **/private TextView mtv1 = null;private TextView mtv2 = null;private Button bupload = null;private String uploadFile = "/sdcard/testimg.jpg";private String actionUrl = "http://10.100.1.208/receive_file.php";@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);mtv1 = (TextView) findViewById(R.id.mtv1);mtv1.setText("檔案路徑：\n" + uploadFile);mtv2 = (TextView) findViewById(R.id.mtv2);mtv2.setText("上傳地址：\n" + actionUrl);bupload = (Button) findViewById(R.id.bupload);bupload.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubFileUploadTask fileuploadtask = new FileUploadTask();fileuploadtask.execute();}});}// show Dialog methodprivate void showDialog(String mess) {new AlertDialog.Builder(UploadtestActivity.this).setTitle("Message").setMessage(mess).setNegativeButton("確定", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {}}).show();}class FileUploadTask extends AsyncTask<Object, Integer, Void> {private ProgressDialog dialog = null;HttpURLConnection connection = null;DataOutputStream outputStream = null;DataInputStream inputStream = null;//the file path to uploadString pathToOurFile = "/sdcard/testimg.jpg";//the server address to process uploaded fileString urlServer = "http://10.100.1.208/receive_file.php";String lineEnd = "\r\n";String twoHyphens = "--";String boundary = "*****";File uploadFile = new File(pathToOurFile);long totalSize = uploadFile.length(); // Get size of file, bytes@Overrideprotected void onPreExecute() {dialog = new ProgressDialog(UploadtestActivity.this);dialog.setMessage("正在上傳...");dialog.setIndeterminate(false);dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);dialog.setProgress(0);dialog.show();}@Overrideprotected Void doInBackground(Object... arg0) {long length = 0;int progress;int bytesRead, bytesAvailable, bufferSize;byte[] buffer;int maxBufferSize = 256 * 1024;// 256KBtry {FileInputStream fileInputStream = new FileInputStream(new File(pathToOurFile));URL url = new URL(urlServer);connection = (HttpURLConnection) url.openConnection();// Set size of every block for postconnection.setChunkedStreamingMode(256 * 1024);// 256KB// Allow Inputs & Outputsconnection.setDoInput(true);connection.setDoOutput(true);connection.setUseCaches(false);// Enable POST methodconnection.setRequestMethod("POST");connection.setRequestProperty("Connection", "Keep-Alive");connection.setRequestProperty("Charset", "UTF-8");connection.setRequestProperty("Content-Type","multipart/form-data;boundary=" + boundary);outputStream = new DataOutputStream(connection.getOutputStream());outputStream.writeBytes(twoHyphens + boundary + lineEnd);outputStream.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\""+ pathToOurFile + "\"" + lineEnd);outputStream.writeBytes(lineEnd);bytesAvailable = fileInputStream.available();bufferSize = Math.min(bytesAvailable, maxBufferSize);buffer = new byte[bufferSize];// Read filebytesRead = fileInputStream.read(buffer, 0, bufferSize);while (bytesRead > 0) {outputStream.write(buffer, 0, bufferSize);length += bufferSize;progress = (int) ((length * 100) / totalSize);publishProgress(progress);bytesAvailable = fileInputStream.available();bufferSize = Math.min(bytesAvailable, maxBufferSize);bytesRead = fileInputStream.read(buffer, 0, bufferSize);}outputStream.writeBytes(lineEnd);outputStream.writeBytes(twoHyphens + boundary + twoHyphens+ lineEnd);publishProgress(100);// Responses from the server (code and message)int serverResponseCode = connection.getResponseCode();String serverResponseMessage = connection.getResponseMessage();/* 將Response顯示於Dialog */// Toast toast = Toast.makeText(UploadtestActivity.this, ""// + serverResponseMessage.toString().trim(),// Toast.LENGTH_LONG);// showDialog(serverResponseMessage.toString().trim());/* 取得Response內容 */// InputStream is = connection.getInputStream();// int ch;// StringBuffer sbf = new StringBuffer();// while ((ch = is.read()) != -1) {// sbf.append((char) ch);// }//// showDialog(sbf.toString().trim());fileInputStream.close();outputStream.flush();outputStream.close();} catch (Exception ex) {// Exception handling// showDialog("" + ex);// Toast toast = Toast.makeText(UploadtestActivity.this, "" +// ex,// Toast.LENGTH_LONG);}return null;}@Overrideprotected void onProgressUpdate(Integer... progress) {dialog.setProgress(progress[0]);}@Overrideprotected void onPostExecute(Void result) {try {dialog.dismiss();// TODO Auto-generated method stub} catch (Exception e) {}}}}

       伺服器端仍然和之前的一樣。

        這裡使用了AsyncTask，它使建立需要與使用者介面互動的長時間啟動並執行任務變得更簡單，適用於簡單的非同步處理，不需要藉助線程和Handler即可實現。
        AsyncTask是抽象類別.AsyncTask定義了三種泛型型別 Params，Progress和Result。
　　Params 啟動任務執行的輸入參數，比如HTTP請求的URL。
　　Progress 背景工作執行的百分比。
　　Result 後台執行任務最終返回的結果，比如String。

        AsyncTask的執行分為四個步驟，每一步都對應一個回調方法，這些方法不應該由應用程式調用，開發人員需要做的就是實現這些方法。
　　1) 子類化AsyncTask
　　2) 實現AsyncTask中定義的下面一個或幾個方法
　　onPreExecute(), 該方法將在執行實際的後台操作前被UI thread調用。可以在該方法中做一些準備工作，如在介面上顯示一個進度條。
　　doInBackground(Params...), 將在onPreExecute 方法執行後馬上執行，該方法運行在後台線程中。這裡將主要負責執行那些很耗時的後台計算工作。可以調用 publishProgress方法來更新即時的任務進度。該方法是抽象方法，子類必須實現。
　　onProgressUpdate(Progress...),在publishProgress方法被調用後，UI thread將調用這個方法從而在介面上展示任務的進展情況，例如通過一個進度條進行展示。
　　onPostExecute(Result), 在doInBackground 執行完成後，onPostExecute 方法將被UI thread調用，背景計算結果將通過該方法傳遞到UI thread.

        為了正確的使用AsyncTask類，以下是幾條必須遵守的準則：
　　1) Task的執行個體必須在UI thread中建立
　　2) execute方法必須在UI thread中調用
　　3) 不要手動的調用onPreExecute(), onPostExecute(Result)，doInBackground(Params...), onProgressUpdate(Progress...)這幾個方法
　　4) 該task只能被執行一次，否則多次調用時將會出現異常
        doInBackground方法和onPostExecute的參數必須對應，這兩個參數在AsyncTask聲明的泛型參數列表中指定，第一個為doInBackground接受的參數，第二個為顯示進度的參數，第三個為doInBackground返回和onPostExecute傳入的參數。

運行結果如下：