为啥文件中没有写入数据?
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【中文标题】为啥文件中没有写入数据?【英文标题】:Why no data is being written in the file?为什么文件中没有写入数据? 【发布时间】:2021-09-08 16:44:58 【问题描述】:我创建了一个从 url 下载图像文件的应用程序,但文件中没有任何数据
图片网址:https://instagram.fidr1-1.fna.fbcdn.net/v/t51.2885-15/e35/190664842_184685183538740_5039921250568173600_n.jpg?tp=1&_nc_ht=instagram.fidr1-1.fna.fbcdn.net&_nc_cat=108&_nc_ohc=RrEU4lTwYCwAX-vgVQ4&edm=AABBvjUBAAAA&ccb=7-4&oh=3ac34be54793fa59134380fd9e0bd617&oe=60DCB7E6&_nc_sid=83d603
代码:
@Override
protected Void doInBackground(String... strings)
try
URL url = new URL(strings[0]);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestProperty("User-Agent", "Mozilla/5.0
(Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.2)
Gecko/20100316 Firefox/3.6.2");
con.setRequestMethod("GET");
con.setDoOutput(true);
con.connect();
File file = Environment.getExternalStorageDirectory();
File f1 = new File(file, "_Url download");
if(!f1.exists())
f1.mkdir();
fileName = System.currentTimeMillis() + ".jpg";
File f2 = new File(f1, fileName);
f2.createNewFile();
InputStream er = con.getErrorStream();
Log.i("ErrorCode", con.getResponseCode()+"");
Log.i("ErrorMessage", con.getResponseMessage());
Log.i("ErrorStream", er+"");
InputStream in = con.getInputStream();
FileOutputStream out = new FileOutputStream(f2);
byte[] buffer = new byte[1024];
int len;
System.out.println(Arrays.toString(buffer));
while((len = in.read(buffer, 0, 1024)) > 0)
out.write(buffer, 0, len);
out.close();
in.close();
catch (MalformedURLException e)
e.printStackTrace();
catch (ProtocolException e)
e.printStackTrace();
catch (IOException e)
Log.i("IOException", e.toString());
return null;
结果:
Image of file path where the file is being saved
编辑
下载按钮:
downloadButton.setOnClickListener(v ->
if(ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)
ActivityCompat.requestPermissions(this, new String[]Manifest.permission.READ_EXTERNAL_STORAGE, 101);
if(ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)
ActivityCompat.requestPermissions(this, new String[]Manifest.permission.WRITE_EXTERNAL_STORAGE, 102);
else if(ContextCompat.checkSelfPermission(this, Manifest.permission.INTERNET) != PackageManager.PERMISSION_GRANTED)
ActivityCompat.requestPermissions(this, new String[]Manifest.permission.INTERNET, 103);
else
BackgroundTask task = new BackgroundTask(this);
task.execute(et.getText().toString());
);
清单权限:
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.INTERNET"/>
EDIT2
日志:
2021-06-26 09:26:25.532 26760-26890/com.example.urldownload I/ErrorCode: 400
2021-06-26 09:26:25.533 26760-26890/com.example.urldownload I/ErrorMessage: Bad Request
2021-06-26 09:26:25.533 26760-26890/com.example.urldownload I/Errorstream: buffer(com.android.okhttp.internal.http.Http1xStream$FixedLengthSource@fbb2c70).inputStream()
2021-06-26 09:26:25.534 26760-26890/com.example.urldownload I/IOException: java.io.FileNotFoundException: https://instagram.fidr1-1.fna.fbcdn.net/v/t51.2885-15/e35/190664842_184685183538740_5039921250568173600_n.jpg?tp=1&_nc_ht=instagram.fidr1-1.fna.fbcdn.net&_nc_cat=108&_nc_ohc=RrEU4lTwYCwAX-vgVQ4&edm=AABBvjUBAAAA&ccb=7-4&oh=3ac34be54793fa59134380fd9e0bd617&oe=60DCB7E6&_nc_sid=83d603
【问题讨论】:
首先,您的文件名中有一个空格。可能不是你想要的。 System.currentTimeMillis() + "看看这个SO answer。 setDoOutput(true)
似乎将请求方法更改为 POST。
【讨论】:
那是什么?请分享! 我将 setDoOutput(true) 更改为 setDoOutput(false),并且成功了。 如果有帮助,您能否将答案标记为已接受?以上是关于为啥文件中没有写入数据?的主要内容,如果未能解决你的问题,请参考以下文章
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