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Java编程实现服务器端支持断点续传的方法(可支持快车、迅雷)

转载 作者：qq735679552 更新时间：2022-09-29 22:32:09 25 4
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这篇CFSDN的博客文章Java编程实现服务器端支持断点续传的方法(可支持快车、迅雷)由作者收集整理，如果你对这篇文章有兴趣，记得点赞哟.

本文实例讲述了Java编程实现服务器端支持断点续传的方法。分享给大家供大家参考，具体如下:

大家知道Tomcat之流对静态资源可以实现断点续传支持，但是如果是一个被控制的流，如有权限控制，或下载地址仅是个代理的时候，这时候需要自己实现断点续传的支持，小弟不才，这里提供基本断点续传[a-,-b,a-b]的简单实现，经验证，可支持迅雷7和火狐的多次断点续传。现贴出代码，大家共同分享:

Servlet 。

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import java.io.BufferedOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URLDecoder;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.bsteel.cloud.storage.servlet.base.BaseServlet;
import com.bsteel.cloud.storage.utils.FileUtil;
/**
  * 文件下载(支持断点续传【迅雷\快车\旋风\Firefox\Chrome】)
  * @author jdkleo
  *
  */
public class FileIoServlet extends BaseServlet {
  private static final long serialVersionUID = 1L;
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException {
   this .doPost(req, resp);
  }
  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
   download(request,response);
  }
  /**
   * 文件下载
   * @param request
   * @param response
   * @throws UnsupportedEncodingException
   */
  private void download(HttpServletRequest request,HttpServletResponse response) throws UnsupportedEncodingException {
   File downloadFile = getFile(request);
   long pos = FileUtil.headerSetting(downloadFile, request, response);
//  log.info("跳过"+pos);
   ServletOutputStream os = null ;
   BufferedOutputStream out = null ;
   RandomAccessFile raf = null ;
   byte b[] = new byte [ 1024 ]; //暂存容器
   try {
    os = response.getOutputStream();
    out = new BufferedOutputStream(os);
    raf = new RandomAccessFile(downloadFile, "r" );
    raf.seek(pos);
    try {
     int n = 0 ;
     while ((n = raf.read(b, 0 , 1024 )) != - 1 ) {
      out.write(b, 0 , n);
     }
     out.flush();
    } catch (IOException ie) {
    }
   } catch (Exception e) {
    log.error(e.getMessage(), e);
   } finally {
    if (out != null ) {
     try {
      out.close();
     } catch (IOException e) {
      log.error(e.getMessage(), e);
     }
    }
    if (raf != null ) {
     try {
      raf.close();
     } catch (IOException e) {
      log.error(e.getMessage(), e);
     }
    }
   }
  }
  private File getFile(HttpServletRequest request) throws UnsupportedEncodingException {
   String uriStr = request.getParameter( "uri" );
   if ( null != uriStr){
     uriStr = URLDecoder.decode(uriStr, "UTF-8" );
     if (uriStr.startsWith( "file://" )){
      uriStr = uriStr.substring( 7 );
      return new File(uriStr);
     } else if (uriStr.startsWith( "hbase://" )){
      try {
       return new File( new URI(uriStr));
      } catch (URISyntaxException e) {
       log.error(e.getMessage(),e);
      }
     }
   }
   throw new RuntimeException( "it's not a real uri" );
  }
}

Range支持 。

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import java.io.File;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
  * 文件处理工具
  * @author jdkleo
  *
  */
public class FileUtil {
  /**
   * 断点续传支持
   * @param file
   * @param request
   * @param response
   * @return 跳过多少字节
   */
  public static long headerSetting(File file,HttpServletRequest request, HttpServletResponse response) {
   long len = file.length(); //文件长度
   if ( null == request.getHeader( "Range" ) ){
    setResponse( new RangeSettings(len),file.getName(),response);
    return 0 ;
   }
   String range = request.getHeader( "Range" ).replaceAll( "bytes=" , "" );
   RangeSettings settings = getSettings(len,range);
   setResponse(settings,file.getName(),response);
   return settings.getStart();
  }
  private static void setResponse(RangeSettings settings,String fileName, HttpServletResponse response) {
   response.addHeader( "Content-Disposition" , "attachment; filename=\"" + IoUtil.toUtf8String(fileName) + "\"" );
   response.setContentType( IoUtil.setContentType(fileName)); // set the MIME type.
   if (!settings.isRange())
   {
    response.addHeader( "Content-Length" , String.valueOf(settings.getTotalLength()));
   }
   else
   {
    long start = settings.getStart();
    long end = settings.getEnd();
    long contentLength = settings.getContentLength();
    response.setStatus(javax.servlet.http.HttpServletResponse.SC_PARTIAL_CONTENT);
   response.addHeader( "Content-Length" , String.valueOf(contentLength));
   String contentRange = new StringBuffer( "bytes " ).append(start).append( "-" ).append(end).append( "/" ).append(settings.getTotalLength()).toString();
   response.setHeader( "Content-Range" , contentRange);
   }
  }
  private static RangeSettings getSettings( long len, String range) {
   long contentLength = 0 ;
   long start = 0 ;
   long end = 0 ;
   if (range.startsWith( "-" )) // -500，最后500个
   {
     contentLength = Long.parseLong(range.substring( 1 )); //要下载的量
     end = len- 1 ;
     start = len - contentLength;
   }
   else if (range.endsWith( "-" )) //从哪个开始
   {
    start = Long.parseLong(range.replace( "-" , "" ));
    end = len - 1 ;
    contentLength = len - start;
   }
   else //从a到b
   {
    String[] se = range.split( "-" );
    start = Long.parseLong(se[ 0 ]);
    end = Long.parseLong(se[ 1 ]);
    contentLength = end-start+ 1 ;
   }
   return new RangeSettings(start,end,contentLength,len);
  }
}

Range封装 。

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public class RangeSettings{
   private long start;
   private long end;
   private long contentLength;
   private long totalLength;
   private boolean range;
   public RangeSettings(){
    super ();
   }
   public RangeSettings( long start, long end, long contentLength, long totalLength) {
    this .start = start;
    this .end = end;
    this .contentLength = contentLength;
    this .totalLength = totalLength;
    this .range = true ;
   }
   public RangeSettings( long totalLength) {
    this .totalLength = totalLength;
   }
   public long getStart() {
    return start;
   }
   public void setStart( long start) {
    this .start = start;
   }
   public long getEnd() {
    return end;
   }
   public void setEnd( long end) {
    this .end = end;
   }
   public long getContentLength() {
    return contentLength;
   }
   public void setContentLength( long contentLength) {
    this .contentLength = contentLength;
   }
   public long getTotalLength() {
    return totalLength;
   }
   public void setTotalLength( long totalLength) {
    this .totalLength = totalLength;
   }
   public boolean isRange() {
    return range;
   }
}

IO流相关处理工具类 。

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import java.io.InputStream;
public class IoUtil {
  public static String setContentType(String returnFileName){
   String contentType = "application/octet-stream" ;
   if (returnFileName.lastIndexOf( "." ) < 0 )
    return contentType;
   returnFileName = returnFileName.toLowerCase();
   returnFileName = returnFileName.substring(returnFileName.lastIndexOf( "." )+ 1 );
   if (returnFileName.equals( "html" ) || returnFileName.equals( "htm" ) || returnFileName.equals( "shtml" )){
    contentType = "text/html" ;
   } else if (returnFileName.equals( "css" )){
    contentType = "text/css" ;
   } else if (returnFileName.equals( "xml" )){
    contentType = "text/xml" ;
   } else if (returnFileName.equals( "gif" )){
    contentType = "image/gif" ;
   } else if (returnFileName.equals( "jpeg" ) || returnFileName.equals( "jpg" )){
    contentType = "image/jpeg" ;
   } else if (returnFileName.equals( "js" )){
    contentType = "application/x-javascript" ;
   } else if (returnFileName.equals( "atom" )){
    contentType = "application/atom+xml" ;
   } else if (returnFileName.equals( "rss" )){
    contentType = "application/rss+xml" ;
   } else if (returnFileName.equals( "mml" )){
    contentType = "text/mathml" ;
   } else if (returnFileName.equals( "txt" )){
    contentType = "text/plain" ;
   } else if (returnFileName.equals( "jad" )){
    contentType = "text/vnd.sun.j2me.app-descriptor" ;
   } else if (returnFileName.equals( "wml" )){
    contentType = "text/vnd.wap.wml" ;
   } else if (returnFileName.equals( "htc" )){
    contentType = "text/x-component" ;
   } else if (returnFileName.equals( "png" )){
    contentType = "image/png" ;
   } else if (returnFileName.equals( "tif" ) || returnFileName.equals( "tiff" )){
    contentType = "image/tiff" ;
   } else if (returnFileName.equals( "wbmp" )){
    contentType = "image/vnd.wap.wbmp" ;
   } else if (returnFileName.equals( "ico" )){
    contentType = "image/x-icon" ;
   } else if (returnFileName.equals( "jng" )){
    contentType = "image/x-jng" ;
   } else if (returnFileName.equals( "bmp" )){
    contentType = "image/x-ms-bmp" ;
   } else if (returnFileName.equals( "svg" )){
    contentType = "image/svg+xml" ;
   } else if (returnFileName.equals( "jar" ) || returnFileName.equals( "var" ) || returnFileName.equals( "ear" )){
    contentType = "application/java-archive" ;
   } else if (returnFileName.equals( "doc" )){
    contentType = "application/msword" ;
   } else if (returnFileName.equals( "pdf" )){
    contentType = "application/pdf" ;
   } else if (returnFileName.equals( "rtf" )){
    contentType = "application/rtf" ;
   } else if (returnFileName.equals( "xls" )){
    contentType = "application/vnd.ms-excel" ;
   } else if (returnFileName.equals( "ppt" )){
    contentType = "application/vnd.ms-powerpoint" ;
   } else if (returnFileName.equals( "7z" )){
    contentType = "application/x-7z-compressed" ;
   } else if (returnFileName.equals( "rar" )){
    contentType = "application/x-rar-compressed" ;
   } else if (returnFileName.equals( "swf" )){
    contentType = "application/x-shockwave-flash" ;
   } else if (returnFileName.equals( "rpm" )){
    contentType = "application/x-redhat-package-manager" ;
   } else if (returnFileName.equals( "der" ) || returnFileName.equals( "pem" ) || returnFileName.equals( "crt" )){
    contentType = "application/x-x509-ca-cert" ;
   } else if (returnFileName.equals( "xhtml" )){
    contentType = "application/xhtml+xml" ;
   } else if (returnFileName.equals( "zip" )){
    contentType = "application/zip" ;
   } else if (returnFileName.equals( "mid" ) || returnFileName.equals( "midi" ) || returnFileName.equals( "kar" )){
    contentType = "audio/midi" ;
   } else if (returnFileName.equals( "mp3" )){
    contentType = "audio/mpeg" ;
   } else if (returnFileName.equals( "ogg" )){
    contentType = "audio/ogg" ;
   } else if (returnFileName.equals( "m4a" )){
    contentType = "audio/x-m4a" ;
   } else if (returnFileName.equals( "ra" )){
    contentType = "audio/x-realaudio" ;
   } else if (returnFileName.equals( "3gpp" ) || returnFileName.equals( "3gp" )){
    contentType = "video/3gpp" ;
   } else if (returnFileName.equals( "mp4" ) ){
    contentType = "video/mp4" ;
   } else if (returnFileName.equals( "mpeg" ) || returnFileName.equals( "mpg" ) ){
    contentType = "video/mpeg" ;
   } else if (returnFileName.equals( "mov" )){
    contentType = "video/quicktime" ;
   } else if (returnFileName.equals( "flv" )){
    contentType = "video/x-flv" ;
   } else if (returnFileName.equals( "m4v" )){
    contentType = "video/x-m4v" ;
   } else if (returnFileName.equals( "mng" )){
    contentType = "video/x-mng" ;
   } else if (returnFileName.equals( "asx" ) || returnFileName.equals( "asf" )){
    contentType = "video/x-ms-asf" ;
   } else if (returnFileName.equals( "wmv" )){
    contentType = "video/x-ms-wmv" ;
   } else if (returnFileName.equals( "avi" )){
    contentType = "video/x-msvideo" ;
   }
   return contentType;
  }
  // UTF8转码
  public static String toUtf8String(String s) {
   StringBuffer sb = new StringBuffer();
   int len = s.toCharArray().length;
   for ( int i = 0 ; i < len; i++) {
    char c = s.charAt(i);
    if (c >= 0 && c <= 255 ) {
     sb.append(c);
    } else {
     byte [] b;
     try {
      b = Character.toString(c).getBytes( "utf-8" );
     } catch (Exception ex) {
      System.out.println(ex);
      b = new byte [ 0 ];
     }
     for ( int j = 0 ; j < b.length; j++) {
      int k = b[j];
      if (k < 0 )
       k += 256 ;
      sb.append( "%" + Integer.toHexString(k).toUpperCase());
     }
    }
   }
   String s_utf8 = sb.toString();
   sb.delete( 0 , sb.length());
   sb.setLength( 0 );
   sb = null ;
   return s_utf8;
  }
  public static InputStream skipFully(InputStream in, long howMany) throws Exception{
  long remainning = howMany;
  long len = 0 ;
  while (remainning> 0 ){
   len = in.skip(len);
   remainning -= len;
  }
  return in;
  }
}

注有些类比如IoUtil方法来自于CSDN的网友总结，另外此类还不支持多Range配置如[a-b,c-d,-e]等.

希望本文所述对大家Java程序设计有所帮助.

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