[置顶] Android上传文件到Web服务器，PHP接收文件（二）

接上一篇文章《Android上传文件到Web服务器，PHP接收文件（一）》，这次在之前的基础上添加进度显示，Java代码如下所示：

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("文件路径：\n" + uploadFile);mtv2 = (TextView) findViewById(R.id.mtv2);mtv2.setText("上传地址：\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("确定", 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("正在上传...");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();/* 将Response显示于Dialog */// Toast toast = Toast.makeText(UploadtestActivity.this, ""// + serverResponseMessage.toString().trim(),// Toast.LENGTH_LONG);// showDialog(serverResponseMessage.toString().trim());/* 取得Response内容 */// 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) {}}}}

服务器端仍然和之前的一样。

这里使用了AsyncTask，它使创建需要与用户界面交互的长时间运行的任务变得更简单，适用于简单的异步处理，不需要借助线程和Handler即可实现。
AsyncTask是抽象类.AsyncTask定义了三种泛型类型 Params，Progress和Result。
　　Params 启动任务执行的输入参数，比如HTTP请求的URL。
　　Progress 后台任务执行的百分比。
　　Result 后台执行任务最终返回的结果，比如String。

AsyncTask的执行分为四个步骤，每一步都对应一个回调方法，这些方法不应该由应用程序调用，开发者需要做的就是实现这些方法。
　　1) 子类化AsyncTask
　　2) 实现AsyncTask中定义的下面一个或几个方法
　　onPreExecute(), 该方法将在执行实际的后台操作前被UI thread调用。可以在该方法中做一些准备工作，如在界面上显示一个进度条。
　　doInBackground(Params...), 将在onPreExecute 方法执行后马上执行，该方法运行在后台线程中。这里将主要负责执行那些很耗时的后台计算工作。可以调用 publishProgress方法来更新实时的任务进度。该方法是抽象方法，子类必须实现。
　　onProgressUpdate(Progress...),在publishProgress方法被调用后，UI thread将调用这个方法从而在界面上展示任务的进展情况，例如通过一个进度条进行展示。
　　onPostExecute(Result), 在doInBackground 执行完成后，onPostExecute 方法将被UI thread调用，后台的计算结果将通过该方法传递到UI thread.

为了正确的使用AsyncTask类，以下是几条必须遵守的准则：
　　1) Task的实例必须在UI thread中创建
　　2) execute方法必须在UI thread中调用
　　3) 不要手动的调用onPreExecute(), onPostExecute(Result)，doInBackground(Params...), onProgressUpdate(Progress...)这几个方法
　　4) 该task只能被执行一次，否则多次调用时将会出现异常
doInBackground方法和onPostExecute的参数必须对应，这两个参数在AsyncTask声明的泛型参数列表中指定，第一个为doInBackground接受的参数，第二个为显示进度的参数，第三个为doInBackground返回和onPostExecute传入的参数。

运行结果如下：

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