我正在开发一个Android应用程序，我试图从此URL http://data.gov.in/sites/default/files/Date-Wise-Prices-all-Commodity.xml下载XML文件并尝试将此文件保存到我的SD卡中。
我想在点击按钮时下载文件。所以，我在我的Button Click上使用以下代码..
try
{
URL url = new URL("http://data.gov.in/sites/default/files/Date-Wise-Prices-all-Commodity.xml");
//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 = new File("/sdcard/"+"XML_folder/");
//create a new file, specifying the path, and the filename
//which we want to save the file as.
File file = new File(SDCardRoot,"webservice.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;
int progress=(int)(downloadedSize*100/totalSize);
//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(Exception e)
{
Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
}
由于我使用了try and catch来捕捉异常并向我显示此消息data.gov.in (java.net.UnknownHostException: data.gov.in)
那么，现在该怎么办？
答案 0 :(得分：1)
检查清单文件，是否给出权限，并使用AsyncTask或线程概念进行网址连接（后台工作）。
ibut.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
new Thread(new Runnable()
{
public void run()
{
try
{
//http connection code.
}
catch(Exception e)
{
Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
}
}).start();
}});
答案 1 :(得分：1)
时会出现此错误
<uses-permission android:name="android.permission.INTERNET"/>如果你忘记写这个答案 2 :(得分：0)
将权限放入清单文件
<uses-permission android:name="android.permission.INTERNET"/>
尝试使用此代码找不到文件
//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 = new File("/sdcard/"+"XML_folder/");
if(SDCardRoot.exists() == false){
SDCardRoot.mkdirs();
}
//create a new file, specifying the path, and the filename
//which we want to save the file as.
File file = new File(SDCardRoot,"webservice.xml");
答案 3 :(得分：0)
试试这个..
URL url = new URL(Your URL);
//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 = new File("/sdcard/");
//create a new file, specifying the path, and the filename
//which we want to save the file as.
File file = new File(SDCardRoot,"hello.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;
int progress=(int)(downloadedSize*100/totalSize);
//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();