我正在开发一个Android应用程序，我需要在其中下载托管在的文本文件： - https://www.dropbox.com/s/2smsdqknrjg5zda/try1.txt/?dl=0
从我的应用内部获取/加载其文本视图中的内容。 我正在使用 AsyncTask的doInBackground（）方法进行下载。
这是我到目前为止提出的MainActivity.java中的代码。 该文件已在 /storage/sdcard/file_try7.ext 中下载，但由于某种原因，我在DDMS中看到它的大小为0.
在LogCat部分，我收到消息＆＃34; java.io.FileNotFoundException ＆＃34;。
有人可以看看，看看问题可能是什么.. ??
package com.example.xxxxx;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.text.InputFilter.LengthFilter;
import android.database.Cursor;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.Toast;
import android.os.Build;
import android.provider.MediaStore;
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
private class MyAsyncTask extends AsyncTask<Void, Void, Void>{
//execute on background (out of the UI thread)
@Override
protected Void doInBackground(Void... params) {
try {
//set the download URL, a url that points to a file on the internet
//this is the file to be downloaded
URL url = new URL("https://www.dropbox.com/s/2smsdqknrjg5zda/try1.txt/?dl=0");
//create the new connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
//set up some things on the connection
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
//and connect!
urlConnection.connect();
//set the path where we want to save the file
//in this case, going to save it on the root directory of the
//sd card.
File SDCardRoot = Environment.getExternalStorageDirectory();
//create a new file, specifying the path, and the filename
//which we want to save the file as.
File file = new File(SDCardRoot,"menu7.ext");
// if (!file.exists()) {
// file.createNewFile();
// }
//this will be used to write the downloaded data into the file we created
FileOutputStream fileOutput = new FileOutputStream(file);
//this will be used in reading the data from the internet
InputStream inputStream = urlConnection.getInputStream();
//this is the total size of the file
int totalSize = urlConnection.getContentLength();
//variable to store total downloaded bytes
int downloadedSize = 0;
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0; //used to store a temporary size of the buffer
//now, read through the input buffer and write the contents to the file
while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
//add the data in the buffer to the file in the file output stream (the file on the sd card
fileOutput.write(buffer, 0, bufferLength);
//add up the size so we know how much is downloaded
downloadedSize += bufferLength;
//this is where you would do something to report the prgress, like this maybe
//updateProgress(downloadedSize, totalSize);
}
//close the output stream when done
fileOutput.close();
//catch some possible errors...
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// TODO Auto-generated method stub
return null;
}
}
public void get_menu(View v)
{
MyAsyncTask async = new MyAsyncTask();
async.execute();
//Toast.makeText(this.getApplicationContext(),"Inside get_menu",Toast.LENGTH_SHORT).show();
}
//Method to get the FileInputStream object as a string.
public static String convertStreamToString(InputStream is) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line).append("\n");
}
reader.close();
return sb.toString();
}
/*Method to get text of the file with path as filePath as string by calling
convertStreamToString.*/
public static String getStringFromFile (String filePath) throws Exception {
File fl = new File(filePath);
FileInputStream fin = new FileInputStream(fl);
String ret = convertStreamToString(fin);
fin.close();
return ret;
}
public void load_menu(View v)
{
//Method which actually loads the text by calling the getStringFromFile method.
String baseDir = Environment.getExternalStorageDirectory().getAbsolutePath();
EditText editText2=(EditText)findViewById(R.id.editText2);
//String fileName=editText2.getText().toString();
String path = baseDir + "/" + "menu7" + ".ext";
try {
String inp_string=getStringFromFile(path);
//EditText editText1=(EditText)findViewById(R.id.editText1);
editText2.setText(inp_string);
} catch (Exception e) {
Toast.makeText(this.getApplicationContext(),"File not found.",Toast.LENGTH_SHORT).show();
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
答案 0 :(得分：0)
您正在通过get方法打开网址，这就是为什么它没有在缓冲区中提供输出文件，而是下载文件的链接。检查下面的屏幕截图。确保下载文件，然后将文件放入缓冲区。但我想知道如果你已经下载了文件，为什么还要这样做呢。
