Java实现服务器端动态流断点续传下载支持

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

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

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

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

 

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。

参考地址：http://blog.csdn.net/defonds/article/details/7074352

在此共同声明。

评论

3 楼 王博009 2016-03-18  

 

2 楼 juicewall 2014-10-28  

又测了一下，迅雷极速板和chrome 35.0，360极速浏览器7.5，360安全浏览器7都可以断点就是用IE11下载暂停按钮变灰无法暂停

1 楼 juicewall 2014-10-28  

用IE11下载暂停按钮变灰无法暂停，但是用极速360可以断点下载，请问IE11怎么解决啊！！