1 此类核心续传servlet
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3
4
5 import java.io.BufferedOutputStream;
6 import java.io.File;
7 import java.io.IOException;
8 import java.io.OutputStream;
9 import java.io.RandomAccessFile;
10 import java.util.concurrent.ConcurrentSkipListMap;
11 import javax.servlet.ServletException;
12 import javax.servlet.http.HttpServlet;
13 import javax.servlet.http.HttpServletRequest;
14 import javax.servlet.http.HttpServletResponse;
15 import org.apache.commons.logging.Log;
16 import org.apache.commons.logging.LogFactory;
17 import org.springframework.util.Assert;
18
19 //HTTP 断点续传 demo（客户端测试工具：快车、迅雷）
20 public class MyHttpDownloadServlet extends HttpServlet {
21 private static final long serialVersionUID = 1L;
22 final static Log log = LogFactory.getLog(ArcSyncHttpDownloadServlet. class);
23
24 @Override
25 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
26 this.doPost(req, resp);
27 }
28
29 @Override
30 protected void doPost(HttpServletRequest request, HttpServletResponse response) {
31 String name = request. getParameter("filename");
32
33 try {
34 log.info( "请求下载的连接地址为：" + request.getRequestURL() + "?" + request.getQueryString());
35 Assert. hasText(name);
36 } catch (IllegalArgumentException e) {
37 log.error( "请求下载的文件名参数为空！" );
38 return;
39 }
40 String path = "D:/Install/" + name;
41 log.info( "文件拼装路径：" + path);
42 File downloadFile = new File(path);
43 if (downloadFile.exists()) {
44 if (downloadFile.isFile()) {
45 if (downloadFile.length() > 0) {
46 } else {
47 log.info( "请求下载的文件是一个空文件" );
48 return;
49 }
50 if (!downloadFile.canRead()) {
51 log.info( "请求下载的文件不是一个可读的文件" );
52 return;
53 } else {
54 }
55 } else {
56 log.info( "请求下载的文件是一个文件夹" );
57 return;
58 }
59 } else {
60 log.info( "请求下载的文件不存在！" );
61 return;
62 }
63
64 long fileLength = downloadFile.length(); // 记录文件大小
65 long pastLength = 0; // 记录已下载文件大小
66 int rangeSwitch = 0; // 0：从头开始的全文下载；1：从某字节开始的下载（bytes=27000-）；2：从某字节开始到某字节结束的下载（bytes=27000-39000）
67 long toLength = 0; // 记录客户端需要下载的字节段的最后一个字节偏移量（比如bytes=27000-39000，则这个值是为39000）
68 long contentLength = 0; // 客户端请求的字节总量
69 String rangeBytes = ""; // 记录客户端传来的形如“bytes=27000-”或者“bytes=27000-39000”的内容
70 RandomAccessFile raf = null; // 负责读取数据
71 OutputStream os = null; // 写出数据
72 OutputStream out = null; // 缓冲
73 byte b[] = new byte[1024]; // 暂存容器
74
75 if (request.getHeader( "Range") != null) { // 客户端请求的下载的文件块的开始字节
76 response.setStatus(javax.servlet.http.HttpServletResponse. SC_PARTIAL_CONTENT);
77 log.info( "request.getHeader(\"Range\")=" + request.getHeader("Range" ));
78 rangeBytes = request.getHeader("Range" ).replaceAll("bytes=" , "" );
79 if (rangeBytes.indexOf( '-') == rangeBytes.length() - 1) {// bytes=969998336-
80 rangeSwitch = 1;
81 rangeBytes = rangeBytes.substring(0, rangeBytes.indexOf('-'));
82 pastLength = Long.parseLong(rangeBytes.trim());
83 contentLength = fileLength - pastLength; // 客户端请求的是 969998336 之后的字节
84 } else { // bytes=1275856879-1275877358
85 rangeSwitch = 2;
86 String temp0 = rangeBytes.substring(0, rangeBytes.indexOf('-'));
87 String temp2 = rangeBytes.substring(rangeBytes.indexOf('-' ) + 1, rangeBytes.length());
88 pastLength = Long. parseLong(temp0.trim()); // bytes=1275856879-1275877358，从第 1275856879 个字节开始下载
89 toLength = Long. parseLong(temp2); // bytes=1275856879-1275877358，到第 1275877358 个字节结束
90 contentLength = toLength - pastLength; // 客户端请求的是 1275856879-1275877358 之间的字节
91 }
92 } else { // 从开始进行下载
93 contentLength = fileLength; // 客户端要求全文下载
94 }
95
96 /**
97 * 如果设设置了Content -Length，则客户端会自动进行多线程下载。如果不希望支持多线程，则不要设置这个参数。 响应的格式是: Content - Length: [文件的总大小] - [客户端请求的下载的文件块的开始字节] ServletActionContext.getResponse().setHeader("Content- Length", new Long(file.length() - p).toString());
98 */
99 response.reset(); // 告诉客户端允许断点续传多线程连接下载,响应的格式是:Accept-Ranges: bytes
100 response.setHeader( "Accept-Ranges", "bytes" );// 如果是第一次下,还没有断点续传,状态是默认的 200,无需显式设置;响应的格式是:HTTP/1.1 200 OK
101 if (pastLength != 0) {
102 // 不是从最开始下载,
103 // 响应的格式是:
104 // Content-Range: bytes [文件块的开始字节]-[文件的总大小 - 1]/[文件的总大小]
105 log.info( "----------------------------不是从开始进行下载！服务器即将开始断点续传..." );
106 switch (rangeSwitch) {
107 case 1: { // 针对 bytes=27000- 的请求
108 String contentRange = new StringBuffer("bytes ").append(new Long(pastLength).toString()).append("-" ).append(new Long(fileLength - 1).toString()).append("/" ).append(new Long(fileLength).toString()).toString();
109 response.setHeader( "Content-Range", contentRange);
110 break;
111 }
112 case 2: { // 针对 bytes=27000-39000 的请求
113 String contentRange = rangeBytes + "/" + new Long(fileLength).toString();
114 response.setHeader( "Content-Range", contentRange);
115 break;
116 }
117 default: {
118 break;
119 }
120 }
121 } else {
122 // 是从开始下载
123 log.info( "----------------------------是从开始进行下载！" );
124 }
125
126 try {
127 response.addHeader( "Content-Disposition", "attachment; filename=\"" + downloadFile.getName() + "\"");
128 response.setContentType(CommonUtil. setContentType(downloadFile.getName())); // set the MIME type.
129 response.addHeader( "Content-Length", String.valueOf(contentLength));
130 os = response.getOutputStream();
131 out = new BufferedOutputStream(os);
132 raf = new RandomAccessFile(downloadFile, "r");
133 try {
134 switch (rangeSwitch) {
135 case 0: { // 普通下载，或者从头开始的下载
136 // 同1
137 }
138 case 1: { // 针对 bytes=27000- 的请求
139 raf.seek(pastLength); // 形如 bytes=969998336- 的客户端请求，跳过 969998336 个字节
140 int n = 0;
141 while ((n = raf.read(b, 0, 1024)) != -1) {
142 out.write(b, 0, n);
143 }
144 break;
145 }
146 case 2: { // 针对 bytes=27000-39000 的请求
147 raf.seek(pastLength); // 形如 bytes=1275856879-1275877358 的客户端请求，找到第 1275856879 个字节
148 int n = 0;
149 long readLength = 0; // 记录已读字节数
150 while (readLength <= contentLength - 1024) {// 大部分字节在这里读取
151 n = raf.read(b, 0, 1024);
152 readLength += 1024;
153 out.write(b, 0, n);
154 }
155 if (readLength <= contentLength) { // 余下的不足 1024 个字节在这里读取
156 n = raf.read(b, 0, ( int) (contentLength - readLength));
157 out.write(b, 0, n);
158 }
159 break;
160 }
161 default: {
162 break;
163 }
164 }
165 out.flush();
166 log.info( "------------------------------下载结束" );
167 } catch (IOException ie) {
168 /**
169 * 在写数据的时候， 对于 ClientAbortException 之类的异常， 是因为客户端取消了下载，而服务器端继续向浏览器写入数据时， 抛出这个异常，这个是正常的。 尤其是对于迅雷这种吸血的客户端软件， 明明已经有一个线程在读取 bytes=1275856879-1275877358， 如果短时间内没有读取完毕，迅雷会再启第二个、第三个。。。线程来读取相同的字节段， 直到有一个线程读取完毕，迅雷会 KILL 掉其他正在下载同一字节段的线程， 强行中止字节读出，造成服务器抛 ClientAbortException。 所以，我们忽略这种异常
170 */
171 // ignore
172 log.info( "#提醒# 向客户端传输时出现IO异常，但此异常是允许的的，有可能客户端取消了下载，导致此异常，不用关心！" );
173 }
174 } catch (Exception e) {
175 log.error(e.getMessage(), e);
176 } finally {
177 if (out != null) {
178 try {
179 out.close();
180 } catch (IOException e) {
181 log.error(e.getMessage(), e);
182 }
183 }
184 if (raf != null) {
185 try {
186 raf.close();
187 } catch (IOException e) {
188 log.error(e.getMessage(), e);
189 }
190 }
191 }
192 }
193 }
1 此类是根据扩展名返回ContentType类型
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3
4
5 public class CommonUtil {
6
7 public static String setContentType(String returnFileName) {
8 String contentType = "application/octet-stream";
9 if ( returnFileName.lastIndexOf(".") < 0)
10 return contentType;
11 returnFileName = returnFileName .toLowerCase();
12 returnFileName = returnFileName.substring(returnFileName .lastIndexOf("." ) + 1);
13
14 if ( returnFileName.equals("html") || returnFileName.equals("htm") || returnFileName .equals("shtml" )) {
15 contentType = "text/html";
16 } else if ( returnFileName.equals("apk")) {
17 contentType = "application/vnd.android.package-archive" ;
18 } else if ( returnFileName.equals("sis")) {
19 contentType = "application/vnd.symbian.install";
20 } else if ( returnFileName.equals("sisx")) {
21 contentType = "application/vnd.symbian.install";
22 } else if ( returnFileName.equals("exe")) {
23 contentType = "application/x-msdownload";
24 } else if ( returnFileName.equals("msi")) {
25 contentType = "application/x-msdownload";
26 } else if ( returnFileName.equals("css")) {
27 contentType = "text/css";
28 } else if ( returnFileName.equals("xml")) {
29 contentType = "text/xml";
30 } else if ( returnFileName.equals("gif")) {
31 contentType = "image/gif";
32 } else if ( returnFileName.equals("jpeg") || returnFileName.equals("jpg")) {
33 contentType = "image/jpeg";
34 } else if ( returnFileName.equals("js")) {
35 contentType = "application/x-javascript";
36 } else if ( returnFileName.equals("atom")) {
37 contentType = "application/atom+xml";
38 } else if ( returnFileName.equals("rss")) {
39 contentType = "application/rss+xml";
40 } else if ( returnFileName.equals("mml")) {
41 contentType = "text/mathml";
42 } else if ( returnFileName.equals("txt")) {
43 contentType = "text/plain";
44 } else if ( returnFileName.equals("jad")) {
45 contentType = "text/vnd.sun.j2me.app-descriptor" ;
46 } else if ( returnFileName.equals("wml")) {
47 contentType = "text/vnd.wap.wml";
48 } else if ( returnFileName.equals("htc")) {
49 contentType = "text/x-component";
50 } else if ( returnFileName.equals("png")) {
51 contentType = "image/png";
52 } else if ( returnFileName.equals("tif") || returnFileName.equals("tiff")) {
53 contentType = "image/tiff";
54 } else if ( returnFileName.equals("wbmp")) {
55 contentType = "image/vnd.wap.wbmp";
56 } else if ( returnFileName.equals("ico")) {
57 contentType = "image/x-icon";
58 } else if ( returnFileName.equals("jng")) {
59 contentType = "image/x-jng";
60 } else if ( returnFileName.equals("bmp")) {
61 contentType = "image/x-ms-bmp";
62 } else if ( returnFileName.equals("svg")) {
63 contentType = "image/svg+xml";
64 } else if ( returnFileName.equals("jar") || returnFileName.equals("var") || returnFileName .equals("ear" )) {
65 contentType = "application/java-archive";
66 } else if ( returnFileName.equals("doc")) {
67 contentType = "application/msword";
68 } else if ( returnFileName.equals("pdf")) {
69 contentType = "application/pdf";
70 } else if ( returnFileName.equals("rtf")) {
71 contentType = "application/rtf";
72 } else if ( returnFileName.equals("xls")) {
73 contentType = "application/vnd.ms-excel";
74 } else if ( returnFileName.equals("ppt")) {
75 contentType = "application/vnd.ms-powerpoint";
76 } else if ( returnFileName.equals("7z")) {
77 contentType = "application/x-7z-compressed";
78 } else if ( returnFileName.equals("rar")) {
79 contentType = "application/x-rar-compressed";
80 } else if ( returnFileName.equals("swf")) {
81 contentType = "application/x-shockwave-flash";
82 } else if ( returnFileName.equals("rpm")) {
83 contentType = "application/x-redhat-package-manager" ;
84 } else if ( returnFileName.equals("der") || returnFileName.equals("pem") || returnFileName .equals("crt" )) {
85 contentType = "application/x-x509-ca-cert";
86 } else if ( returnFileName.equals("xhtml")) {
87 contentType = "application/xhtml+xml";
88 } else if ( returnFileName.equals("zip")) {
89 contentType = "application/zip";
90 } else if ( returnFileName.equals("mid") || returnFileName.equals("midi") || returnFileName .equals("kar" )) {
91 contentType = "audio/midi";
92 } else if ( returnFileName.equals("mp3")) {
93 contentType = "audio/mpeg";
94 } else if ( returnFileName.equals("ogg")) {
95 contentType = "audio/ogg";
96 } else if ( returnFileName.equals("m4a")) {
97 contentType = "audio/x-m4a";
98 } else if ( returnFileName.equals("ra")) {
99 contentType = "audio/x-realaudio";
100 } else if ( returnFileName.equals("3gpp") || returnFileName.equals("3gp")) {
101 contentType = "video/3gpp";
102 } else if ( returnFileName.equals("mp4")) {
103 contentType = "video/mp4";
104 } else if ( returnFileName.equals("mpeg") || returnFileName.equals("mpg")) {
105 contentType = "video/mpeg";
106 } else if ( returnFileName.equals("mov")) {
107 contentType = "video/quicktime";
108 } else if ( returnFileName.equals("flv")) {
109 contentType = "video/x-flv";
110 } else if ( returnFileName.equals("m4v")) {
111 contentType = "video/x-m4v";
112 } else if ( returnFileName.equals("mng")) {
113 contentType = "video/x-mng";
114 } else if ( returnFileName.equals("asx") || returnFileName.equals("asf")) {
115 contentType = "video/x-ms-asf";
116 } else if ( returnFileName.equals("wmv")) {
117 contentType = "video/x-ms-wmv";
118 } else if ( returnFileName.equals("avi")) {
119 contentType = "video/x-msvideo";
120 }
121
122 return contentType;
123 }
124
125 }
1 web.xml中servlet标签 2 |||||||||||||||||||| 3 4 5 <servlet> 6 <description></ description> 7 <display-name> ArcSyncHttpDownloadServlet</display-name > 8 <servlet-name> ArcSyncHttpDownloadServlet</servlet-name > 9 <servlet-class> com.MyHttpDownloadServlet</servlet-class > 10 </servlet> 11 <servlet-mapping> 12 <servlet-name> ArcSyncHttpDownloadServlet</servlet-name > 13 <url-pattern> /http</url-pattern > 14 </servlet-mapping>
1 此类为测试类
2 |||||||||||||
3
4
5 import java.io.BufferedInputStream;
6 import java.io.File;
7 import java.io.RandomAccessFile;
8 import java.io.UnsupportedEncodingException;
9 import java.net.HttpURLConnection;
10 import java.net.URL;
11 import java.net.URLDecoder;
12
13 public class TestDownload {
14
15 /**
16 * @param args
17 */
18 public static void main(String[] args) {
19 HttpURLConnection httpURLConnection = null;
20 URL url = null;
21 BufferedInputStream bis = null;
22 byte[] buf = new byte[10240];
23 int size = 0;
24 String fileName = "a.exe";
25 String filePath = "C:/Documents and Settings/Administrator/桌面";
26 StringremoteUrl= "http://10.10.129.99:8080/project/http?filename=a.exe" ;
27
28 // 检查本地文件
29 RandomAccessFile rndFile = null;
30 File file = new File(filePath + "\\" + fileName);
31 // long remoteFileSize = getRemoteFileSzie(remoteUrl);
32 // long nPos = 0;
33 long localFileSzie =0;
34 if (file.exists()) {
35 localFileSzie = file.length();
36 } else {
37 // 建立文件
38 try {
39 file.createNewFile();
40 } catch (Exception e) {
41 e.printStackTrace();
42 }
43 }
44
45 // 下载文件
46 try {
47 url = new URL(remoteUrl);
48 httpURLConnection = (HttpURLConnection)url.openConnection();
49 // 设置User-Agent
50 httpURLConnection.setRequestProperty( "User-Agent", "Net");
51 // 设置续传开始
52 System. out.println( "本地文件大小：" +localFileSzie);
53 httpURLConnection.setRequestProperty( "Range", "bytes=" + localFileSzie + "-" );
54 // 获取输入流
55 bis = new BufferedInputStream(httpURLConnection.getInputStream());
56
57 long remoteFileSize = httpURLConnection.getContentLength();
58 System. out.println( "返回结果码：" +httpURLConnection.getHeaderField("result"));
59 //System.out.println("文件名："+httpURLConnection.getHeaderField("Content-Disposition"));
60 if (localFileSzie < remoteFileSize) {
61 if (localFileSzie==0) {
62 System. out.println( "文件不存在，开始下载..." );
63 } else{
64 System. out.println( "文件续传..." );
65 }
66 } else {
67 System. out.println( "文件存在，重新下载..." );
68 file.delete();
69 try {
70 file.createNewFile();
71 } catch (Exception e) {
72 e.printStackTrace();
73 }
74 }
75
76 rndFile = new RandomAccessFile(filePath + "\\" + fileName, "rw");
77
78 rndFile.seek(localFileSzie);
79 int i = 0;
80 while ((size = bis.read(buf)) != -1) {
81 //if (i > 500) break;
82 rndFile.write(buf, 0, size);
83 i++;
84 }
85 System. out.println( "i=" + i);
86 httpURLConnection.disconnect();
87 } catch (Exception e) {
88 e.printStackTrace();
89 }
90 }
91
92 public static long getRemoteFileSzie(String url) {
93 long size = 0;
94 try {
95 HttpURLConnection httpUrl = (HttpURLConnection)( new URL(url)).openConnection();
96 size = httpUrl.getContentLength();
97 httpUrl.disconnect();
98 } catch (Exception e) {
99 e.printStackTrace();
100 }
101 return size;
102 }
103 }
来源：https://www.cnblogs.com/live365wang/archive/2013/03/02/2939994.html