Java single-threaded file download, support for breakpoint continuation function

Objective:

program download files, sometimes because of a variety of reasons to download the interruption, small files have little impact, can be quickly re-download, but when downloading large files, it will take a long time, so the breakpoint continuation function for large files is necessary.

File download of the breakpoint continue to pass:

　1, first download temporary files, used to record the downloaded size:

2. Set the range parameter when HTTP requests

3, download the data of this request;

Directly on the code:

1  PackageCom.test.service;2 3 ImportJava.io.File;4 ImportJava.io.InputStream;5 ImportJava.io.RandomAccessFile;6 Importjava.net.HttpURLConnection;7 ImportJava.net.URL;8 ImportJava.text.NumberFormat;9 Ten ImportOrg.slf4j.Logger; One Importorg.slf4j.LoggerFactory; A ImportOrg.springframework.beans.factory.annotation.Value; - Importorg.springframework.stereotype.Component; -  the /** - * <p> - * File download, can support the continuation of the breakpoint - * Not used at this stage + * </p> -  *  @author  +  *  @version1.0 A  * */ at @Component -  Public classdownloadonly { -  -     Private Static FinalLogger Logger = Loggerfactory.getlogger (downloadonly.class); -      -@Value ("${onair.download.ddxc:true}") in     BooleanDDXC =true; -      to     intStartIndex = 0; +      -     LongDownloadsize = 0; the      *     BooleanDownloadfinish =false; $     Panax Notoginseng     intTotlesize = 0; -      the      Public BooleanDownload (String url,string File_path,intdownloadtimeout) { +  A         //start a thread to detect the download progress the         NewThread (NewRunnable () { +              - @Override $              Public voidrun () { $                 Try { -NumberFormat NT =numberformat.getpercentinstance ();  -                       //Set percent accuracy 3 to retain three decimal places theNt.setminimumfractiondigits (1);  -                      while(!downloadfinish) {WuyiThread.Sleep (30000); theLogger.debug ("Downloaded size {}, Progress {}", Getdownloadsize (), Nt.format (Getdownloadsize () * 1.0/totlesize)); -                     } Wu}Catch(interruptedexception e) { - e.printstacktrace (); About                 } $                  -             } - }). Start (); -          ALogger.info ("Download file: Source path {}, Destination path: {}", Url,file_path); +Randomaccessfile RAF =NULL; theInputStream in =NULL; -          $         Try { theURL File_url =Newurl (url); theHttpURLConnection conn =(HttpURLConnection) file_url.openconnection (); the conn.setconnecttimeout (downloadtimeout); theConn.setrequestmethod ("GET"); -File tmpfile =NewFile (file_path+ "_tmp"); in             if(DDXC) { the                 if(Tmpfile.exists () &&Tmpfile.isfile ()) { theDownloadsize =tmpfile.length (); AboutStartIndex = (int) downloadsize; the                 } theConn.setrequestproperty ("Range", "bytes=" + StartIndex + "-"); the}Else{ +                 if(Tmpfile.exists () &&tmpfile.isfile ()) - Tmpfile.delete (); the             }Bayi             intStatus =Conn.getresponsecode (); theTotlesize = (int) Downloadsize +conn.getcontentlength (); theLogger.info ("Total file size {}, download request for return status code: {}, size required to download {}", totlesize,status,totlesize-downloadsize); -             if(status== | | status = = 206 ){ -RAF =NewRandomaccessfile (Tmpfile, "RWD"); the Raf.seek (startIndex); thein =Conn.getinputstream (); the                 byte[] buffer =New byte[1024]; the                 intSize = 0; -                  while(Size=in.read (buffer))!=-1 ){ theRaf.write (buffer, 0, size); theDownloadsize + =size; the                 }94 raf.close (); the in.close (); theFile dest =NewFile (file_path); the                 returnTmpfile.renameto (dest);98             } About}Catch(Throwable e) { -Logger.error ("File download failed: {}", E.getmessage (), e);101}finally {102Downloadfinish =true;//download Complete or interrupted103         }104         return false; the     }106 107      Public Longgetdownloadsize () {108         returndownloadsize;109     } the     111      Public Static voidMain (string[] args) { theDownloadonly downloadonly =Newdownloadonly ();113     } the      the}

Java single-threaded file download, support for breakpoint continuation function