Android：如何更改下載文件的文件名？

Question

我想改變我是從互聯網上下載使用XML文件的幫助文件的文件名：

<?xml version="1.0" encoding="ISO-8859-1" ?> 
<Phonebook> 
    <PhonebookEntry> 
     <firstname>Michael</firstname> 
     <lastname>De Leon</lastname> 
     <Address>5, Cat Street</Address> 
     <FileURL>http://www.technobuzz.net/wp-content/uploads/2009/09/Android-Emulator.jpg</FileURL> 
    </PhonebookEntry> 
    <PhonebookEntry> 
     <firstname>John</firstname> 
     <lastname>Smith</lastname> 
     <Address>6, Dog Street</Address> 
     <FileURL>http://www.cellphonehits.net/uploads/2008/10/android_openmoko.jpg</FileURL> 
    </PhonebookEntry> 
    <PhonebookEntry> 
     <firstname>Jember</firstname> 
     <lastname>Dowry</lastname> 
     <Address>7, Monkey Street</Address> 
     <FileURL>http://www.techdigest.tv/android.jpg</FileURL> 
    </PhonebookEntry> 
</Phonebook> 

我的程序有以下代碼：

package com.example.parsingxml; 

import java.io.File; 
import java.io.FileOutputStream; 
import java.io.InputStream; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.Iterator; 
import java.util.List; 

import javax.xml.parsers.SAXParser; 
import javax.xml.parsers.SAXParserFactory; 

import org.xml.sax.InputSource; 
import org.xml.sax.XMLReader; 

import android.app.Activity; 
import android.app.Dialog; 
import android.app.ProgressDialog; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.os.Environment; 
import android.util.Log; 
import android.widget.TextView; 
public class ParsingXML extends Activity { 

    public static final int DIALOG_DOWNLOAD_PROGRESS = 0; 
    private ProgressDialog mProgressDialog; 
    public String FileName = ""; 
    public String FileURL = ""; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle icicle) { 
     super.onCreate(icicle); 

     /* Create a new TextView to display the parsingresult later. */ 
     TextView tv = new TextView(this); 
     tv.setText("This is the parsing program..."); 


     try { 
       /* Create a URL we want to load some xml-data from. */ 
       URL url = new URL("http://cloud.eacomm.com/jm/sampleXML.xml"); 
       url.openConnection(); 
       /* Get a SAXParser from the SAXPArserFactory. */ 
       SAXParserFactory spf = SAXParserFactory.newInstance(); 
       SAXParser sp = spf.newSAXParser(); 

       /* Get the XMLReader of the SAXParser we created. */ 
       XMLReader xr = sp.getXMLReader(); 
       /* Create a new ContentHandler and apply it to the XML-Reader*/ 
       ExampleHandler myExampleHandler = new ExampleHandler(); 
       xr.setContentHandler(myExampleHandler); 

       /* Parse the xml-data from our URL. */ 
       xr.parse(new InputSource(url.openStream())); 
       /* Parsing has finished. */ 

       /* Our ExampleHandler now provides the parsed data to us. */ 
       List<ParsedExampleDataSet> parsedExampleDataSet = myExampleHandler.getParsedData(); 

       /* Set the result to be displayed in our GUI. */ 
       //tv.setText(parsedExampleDataSet.toString()); 
       Iterator i; 
       i = parsedExampleDataSet.iterator(); 
       ParsedExampleDataSet dataItem; 
       while(i.hasNext()){ 

        dataItem = (ParsedExampleDataSet) i.next(); 
        tv.append("\n" + dataItem.getfirstname()); 
        tv.append("\n" + dataItem.getFileURL()); 
        tv.append("\n" + dataItem.getAddress()); 
        this.FileName = dataItem.getfirstname() + ".jpg"; 
        this.FileURL = dataItem.getFileURL(); 
        startDownload(); 

       } 

     } catch (Exception e) { 
       /* Display any Error to the GUI. */ 
       tv.setText("Error: " + e.getMessage()); 

     } 
     /* Display the TextView. */ 
     this.setContentView(tv); 
    } 

    private void startDownload(){ 
     new DownloadFileAsync().execute(FileURL); 
    } 

    @Override 
    protected Dialog onCreateDialog(int id) { 
     switch (id) { 
      case DIALOG_DOWNLOAD_PROGRESS: 
       mProgressDialog = new ProgressDialog(this); 
       mProgressDialog.setMessage("Downloading file.."); 
       mProgressDialog.setIndeterminate(false); 
       mProgressDialog.setMax(100); 
       mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); 
       mProgressDialog.setCancelable(true); 
       mProgressDialog.show(); 
       return mProgressDialog; 
      default: 
       return null; 
     } 
    } 


    class DownloadFileAsync extends AsyncTask<String, String, String>{ 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
      showDialog(DIALOG_DOWNLOAD_PROGRESS); 
     } 


     @Override 
     protected String doInBackground(String... aurl) { 

      try { 
       File root = Environment.getExternalStorageDirectory(); 
       URL u = new URL(FileURL); 
       HttpURLConnection c = (HttpURLConnection) u.openConnection(); 
       c.setRequestMethod("GET"); 
       c.setDoOutput(true); 
       c.connect(); 

       int lenghtOfFile = c.getContentLength(); 

       FileOutputStream f = new FileOutputStream(new File(root + "/download/", FileName)); 

       InputStream in = c.getInputStream(); 

       byte[] buffer = new byte[1024]; 
       int len1 = 0; 
       long total = 0; 

       while ((len1 = in.read(buffer)) > 0) { 
        total += len1; //total = total + len1 
        publishProgress("" + (int)((total*100)/lenghtOfFile)); 
        f.write(buffer, 0, len1); 
       } 
       f.close(); 
      } catch (Exception e) { 
       Log.d("Downloader", e.getMessage()); 
      } 

      return null; 

     } 


     protected void onProgressUpdate(String... progress) { 
      Log.d("ANDRO_ASYNC",progress[0]); 
      mProgressDialog.setProgress(Integer.parseInt(progress[0])); 
     } 

     @Override 
     protected void onPostExecute(String unused) { 
      dismissDialog(DIALOG_DOWNLOAD_PROGRESS); 
     } 


    } 

} 

，你可以看，下載文件的文件名被認爲是.jpg，但是當我查看我的SD卡/ download /時，唯一下載的文件是Jember.jpg。我相信它只是覆蓋其他兩個文件。我怎樣才能輸出Michael.jpg，John.jpg和Jember.jpg？

Answer 1

很簡單，因爲您使用實例變量（FileUrl，FileName）來下載/存儲文件，而不是傳遞給AsyncTask的值。

new DownloadFileAsync().execute(currentUrl, currentFile); 

然後，doInBackground內：調用的AsyncTask時做到這一點

@Override 
    protected String doInBackground(String... strings) { 
    String url = strings[0]; 
    String fileName = strings[1]; 
    ... 
    } 

Answer 2

你的問題是這樣的......

while(i.hasNext()) { 
    ... 
    this.FileName = dataItem.getfirstname() + ".jpg"; 
    ... 
    startDownload(); 
} 

基本上，startDownload()只需啓動一個的AsyncTask這意味着它立即返回。通過循環運行while意味着FileName將在任何AsyncTasks完成之前成爲最後一個（最可能）。

我幾乎將onCreate()方法的try/catch塊中的所有內容都重定位到DownloadFileAsync doInBackground()，只創建一個實例並讓它處理解析和迭代。