Android：下载XML并存储到SD卡

Question

我有一个在MainActivity的onCreate方法中调用的方法。 当我调用该方法时，我希望XML文件存储在SD卡上，但是它似乎不存在，控制台似乎也没有太大帮助。 下面列出了该方法的代码。

package com.example.inftimetable;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

import android.app.Activity;
import android.os.Environment;



public class DownloadXML {

    public static void downloadXML(){
        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("http://www.w3schools.com/xml/note.xml");

            //create the new connection
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

            //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,"data.xml");

            //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;

            }
            //close the output stream when done
            fileOutput.close();
            //catch some possible errors...
    } catch (MalformedURLException e) {
            e.printStackTrace();
    } catch (IOException e) {
            e.printStackTrace();
    }

    }

}

和调用上述方法的类

package com.example.inftimetable;



import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuInflater;


public class MainActivity extends ActionBarActivity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            DownloadXML.downloadXML();


        }

        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            // Inflate the menu items for use in the action bar
            MenuInflater inflater = getMenuInflater();
            getSupportActionBar().setIcon(R.drawable.ic_action_search);
            getSupportActionBar().setDisplayShowHomeEnabled(false);
            getSupportActionBar().setDisplayShowTitleEnabled(false);
            inflater.inflate(R.menu.main_activity_actions, menu);
            return super.onCreateOptionsMenu(menu);

        }


}

Answer 1

代码正确运行，我在DDMS中的错误目录中查找