简历HTTP文件下载在java中 [英] Resume http file download in java

问题描述

 网​​址URL =新的URL（http://download.thinkbroadband.com/20MB.zip）;

URLConnection的连接= url.openConnection（）;
文件fil​​eThatExists =新的文件（路径）;
的OutputStream输出=新的FileOutputStream（路径，真实）;
connection.setRequestProperty（范围，字节=+ fileThatExists.length（）+ - ）;

connection.connect（）;

INT lenghtOfFile = connection.getContentLength（）;

的InputStream输入=新的BufferedInputStream（url.openStream（））;
字节的数据[] =新的字节[1024];

总长= 0;

而（（计数= input.read（数据））！=  -  1）{
    共有+ =计数;

    output.write（数据，0，计数）;
}
 

在此code我尝试恢复下载。目标文件是20MB。但是，当我停止下载的10MB，那么contunue，我得到的文件，文件大小为30MB。它似乎继续写入文件，但不能部分来自服务器下载。 wget的-c与此文件的伟大工程。我怎样才能恢复文件下载？

解决方案

  HttpURLConnection的连接=（HttpURLConnection类）url.openConnection（）;
    如果（ISSUE_DOWNLOAD_STATUS.intValue（）== ECMConstant.ECM_DOWNLOADING）{
        档案文件=新的文件（destination_path可）;
        如果（file.exists（））{
             下载=（int）的file.length（）;
             connection.setRequestProperty（范围，字节=+（file.length（））+ - ）;
        }
    }其他{
        connection.setRequestProperty（范围，字节=+下载+ - ）;
    }
    connection.setDoInput（真正的）;
    connection.setDoOutput（真正的）;
    progressBar.setMax（connection.getContentLength（））;
     在=新的BufferedInputStream（connection.getInputStream（））;
     FOS =（下载== 0）？新的FileOutputStream（destination_path可）：新的FileOutputStream（destination_path可，真正的）;
     布特=新的BufferedOutputStream（FOS，1024）;
    byte []的数据=新的字节[1024];
    INT X = 0;
    而（（X = in.read（数据，0，1024））＆GT; = 0）{
        bout.write（数据，0，x）的;
         下载+ = X;
         progressBar.setProgress（下载）;
    }
 

这是不是我的code，但它的工作原理。

URL url = new URL("http://download.thinkbroadband.com/20MB.zip");

URLConnection connection = url.openConnection();
File fileThatExists = new File(path); 
OutputStream output = new FileOutputStream(path, true);
connection.setRequestProperty("Range", "bytes=" + fileThatExists.length() + "-");

connection.connect();

int lenghtOfFile = connection.getContentLength();

InputStream input = new BufferedInputStream(url.openStream());
byte data[] = new byte[1024];

long total = 0;

while ((count = input.read(data)) != -1) {
    total += count;

    output.write(data, 0 , count);
}

in this code I try to resume download. Target file is 20MB. But when I stop download on 10mb, then contunue, I get file with filesize 30MB. It seems that it continue writing to file, but cant partly download from server. Wget -c works great with this file. How can I resume file download?

解决方案

 HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    if(ISSUE_DOWNLOAD_STATUS.intValue()==ECMConstant.ECM_DOWNLOADING){
        File file=new File(DESTINATION_PATH);
        if(file.exists()){
             downloaded = (int) file.length();
             connection.setRequestProperty("Range", "bytes="+(file.length())+"-");
        }
    }else{
        connection.setRequestProperty("Range", "bytes=" + downloaded + "-");
    }
    connection.setDoInput(true);
    connection.setDoOutput(true);
    progressBar.setMax(connection.getContentLength());
     in = new BufferedInputStream(connection.getInputStream());
     fos=(downloaded==0)? new FileOutputStream(DESTINATION_PATH): new FileOutputStream(DESTINATION_PATH,true);
     bout = new BufferedOutputStream(fos, 1024);
    byte[] data = new byte[1024];
    int x = 0;
    while ((x = in.read(data, 0, 1024)) >= 0) {
        bout.write(data, 0, x);
         downloaded += x;
         progressBar.setProgress(downloaded);
    }

This is not my code, but it works.

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