我想从服务器下载pdf并存储在sdcard上.我尝试像下面的代码,但它不会进入其他条件,因为我没有创建一个文件,仍然会给MSG文件存在.为什么呢
String pdf;
String filenameWithExtension="";
protected void onCreate(Bundle savedInstanceState) {
Intent intent=getIntent();
pdf=intent.getStringExtra("pdfurl");
String PATH2 = Environment.getExternalStorageDirectory()+"/pictures";
Log.v("log_tag initial path","PATH: " + PATH2);
File file2 = new File(PATH2);
if(file2.exists()==true)
{
}else
{
Log.v("directory is created","new dir");
file2.mkdir();
}
/**extracting the pdf filname from url**/
int slashIndex = pdf.lastIndexOf('/');
int dotIndex = pdf.lastIndexOf('.');
filenameWithExtension=pdf.substring(slashIndex + 1);
DownloadFile downloadFile = new DownloadFile(filenameWithExtension);
downloadFile.execute(pdf);
}
private class DownloadFile extends AsyncTask<String,Integer,String>{
String filename="";
public DownloadFile(String _filename) {
this.filename=_filename;
}
String PATH = Environment.getExternalStorageDirectory()+"/pictures/"+filename;
File filecheck=new File(PATH);
@Override
protected String doInBackground(String... str) {
Log.v("name of file",this.filename);
if(filecheck.exists()){
Log.v("in if condition","file is alredy exist");
}else{
Log.v("in else condition","file not present....");
try {
URL url = new URL(str[0]);
HttpURLConnection c = (HttpURLConnection)url.openConnection();
c.setRequestMethod("GET");
c.setDoOutput(true);
c.connect();
// this will be useful so that you can show a typical 0-100% progress bar
int lenghtOfFile = c.getContentLength();
// downlod the file
// InputStream input = new BufferedInputStream(url.openStream());
//OutputStream output = new FileOutputStream("/sdcard/somewhere/nameofthefile.ext");
String PATH = Environment.getExternalStorageDirectory()+ "/pictures/";
Log.v("log_tag","PATH: " + PATH);
File file = new File(PATH);
Boolean check=filecheck.createNewFile();
Log.v("check file creation..::",check.toString());
if(file.mkdirs()==false)
{
Log.v("file is alredy exist in sdcard","exist file");
}else
{
Log.v("file is created in card","new dir");
file.mkdirs();
}
File outputFile = new File(file,filenameWithExtension);
FileOutputStream fos = new FileOutputStream(outputFile);
InputStream is = c.getInputStream();
long total = 0;
byte[] buffer = new byte[1024];
int len1 = 0;
while ((len1 = is.read(buffer)) != -1) {
total +=len1;
publishProgress((int)(total*100/lenghtOfFile));
fos.write(buffer,len1);
}
fos.close();
is.close();
} catch (IOException e) {
Log.d("log_tag of background","Error: " + e);
}
}
Log.v("In aync task filename extension",filenameWithExtension);
return filenameWithExtension;
}
解决方法
您可以使用
File.exists()检查文件是否存在
File f = new File(filePathString);
if(f.exists())
{
/* do something */
}
else
{
file.mkdirs();
//And your other stuffs goes here
}
注意：exists()将为目录返回true
如果你想检查一个特定的文件是否存在,你必须使用File.isFile()
boolean fileExists = new File("path/to/file.txt").isFile();
新文件(“C：/”).exists()将返回true,但不允许您作为文件打开和读取.
你的代码中的问题是你的文件名是空的.
编辑2：
尝试这个 ：
String filename="";
String PATH="";
File fileCheck=null;
public DownloadFile(String _filename) {
this.filename=_filename;
PATH = Environment.getExternalStorageDirectory()+"/pictures/"+filename;
filecheck=new File(PATH);
}
要么
或者在AsyncTask的onPreExecute()中放置这两个语句
PATH = Environment.getExternalStorageDirectory()+"/pictures/"+filename;
filecheck=new File(PATH);