java断点续传代码实现,断点续传 实现

用java向hdfs上传文件时，如何实现断点续传

@Component("javaLargeFileUploaderServlet")

@WebServlet(name = "javaLargeFileUploaderServlet", urlPatterns = { "/javaLargeFileUploaderServlet" })

public class UploadServlet extends HttpRequestHandlerServlet

implements HttpRequestHandler {

private static final Logger log = LoggerFactory.getLogger(UploadServlet.class);

@Autowired

UploadProcessor uploadProcessor;

@Autowired

FileUploaderHelper fileUploaderHelper;

@Autowired

ExceptionCodeMappingHelper exceptionCodeMappingHelper;

@Autowired

Authorizer authorizer;

@Autowired

StaticStateIdentifierManager staticStateIdentifierManager;

@Override

public void handleRequest(HttpServletRequest request, HttpServletResponse response)

throws IOException {

log.trace("Handling request");

Serializable jsonObject = null;

try {

// extract the action from the request

UploadServletAction actionByParameterName =

UploadServletAction.valueOf(fileUploaderHelper.getParameterValue(request, UploadServletParameter.action));

// check authorization

checkAuthorization(request, actionByParameterName);

// then process the asked action

jsonObject = processAction(actionByParameterName, request);

// if something has to be written to the response

if (jsonObject != null) {

fileUploaderHelper.writeToResponse(jsonObject, response);

}

}

// If exception, write it

catch (Exception e) {

exceptionCodeMappingHelper.processException(e, response);

}

}

private void checkAuthorization(HttpServletRequest request, UploadServletAction actionByParameterName)

throws MissingParameterException, AuthorizationException {

// check authorization

// if its not get progress (because we do not really care about authorization for get

// progress and it uses an array of file ids)

if (!actionByParameterName.equals(UploadServletAction.getProgress)) {

// extract uuid

final String fileIdFieldValue = fileUploaderHelper.getParameterValue(request, UploadServletParameter.fileId, false);

// if this is init, the identifier is the one in parameter

UUID clientOrJobId;

String parameter = fileUploaderHelper.getParameterValue(request, UploadServletParameter.clientId, false);

if (actionByParameterName.equals(UploadServletAction.getConfig) parameter != null) {

clientOrJobId = UUID.fromString(parameter);

}

// if not, get it from manager

else {

clientOrJobId = staticStateIdentifierManager.getIdentifier();

}

// call authorizer

authorizer.getAuthorization(

request,

actionByParameterName,

clientOrJobId,

fileIdFieldValue != null ? getFileIdsFromString(fileIdFieldValue).toArray(new UUID[] {}) : null);

}

}

private Serializable processAction(UploadServletAction actionByParameterName, HttpServletRequest request)

throws Exception {

log.debug("Processing action " + actionByParameterName.name());

Serializable returnObject = null;

switch (actionByParameterName) {

case getConfig:

String parameterValue = fileUploaderHelper.getParameterValue(request, UploadServletParameter.clientId, false);

returnObject =

uploadProcessor.getConfig(

parameterValue != null ? UUID.fromString(parameterValue) : null);

break;

case verifyCrcOfUncheckedPart:

returnObject = verifyCrcOfUncheckedPart(request);

break;

case prepareUpload:

returnObject = prepareUpload(request);

break;

case clearFile:

uploadProcessor.clearFile(UUID.fromString(fileUploaderHelper.getParameterValue(request, UploadServletParameter.fileId)));

break;

case clearAll:

uploadProcessor.clearAll();

break;

case pauseFile:

ListUUID uuids = getFileIdsFromString(fileUploaderHelper.getParameterValue(request, UploadServletParameter.fileId));

uploadProcessor.pauseFile(uuids);

break;

case resumeFile:

returnObject =

uploadProcessor.resumeFile(UUID.fromString(fileUploaderHelper.getParameterValue(request, UploadServletParameter.fileId)));

break;

case setRate:

uploadProcessor.setUploadRate(UUID.fromString(fileUploaderHelper.getParameterValue(request, UploadServletParameter.fileId)),

Long.valueOf(fileUploaderHelper.getParameterValue(request, UploadServletParameter.rate)));

break;

case getProgress:

returnObject = getProgress(request);

break;

}

return returnObject;

}

ListUUID getFileIdsFromString(String fileIds) {

String[] splittedFileIds = fileIds.split(",");

ListUUID uuids = Lists.newArrayList();

for (int i = 0; i splittedFileIds.length; i++) {

uuids.add(UUID.fromString(splittedFileIds[i]));

}

return uuids;

}

private Serializable getProgress(HttpServletRequest request)

throws MissingParameterException {

Serializable returnObject;

String[] ids =

new Gson()

.fromJson(fileUploaderHelper.getParameterValue(request, UploadServletParameter.fileId), String[].class);

CollectionUUID uuids = Collections2.transform(Arrays.asList(ids), new FunctionString, UUID() {

@Override

public UUID apply(String input) {

return UUID.fromString(input);

}

});

returnObject = Maps.newHashMap();

for (UUID fileId : uuids) {

try {

ProgressJson progress = uploadProcessor.getProgress(fileId);

((HashMapString, ProgressJson) returnObject).put(fileId.toString(), progress);

}

catch (FileNotFoundException e) {

log.debug("No progress will be retrieved for " + fileId + " because " + e.getMessage());

}

}

return returnObject;

}

private Serializable prepareUpload(HttpServletRequest request)

throws MissingParameterException, IOException {

// extract file information

PrepareUploadJson[] fromJson =

new Gson()

.fromJson(fileUploaderHelper.getParameterValue(request, UploadServletParameter.newFiles), PrepareUploadJson[].class);

// prepare them

final HashMapString, UUID prepareUpload = uploadProcessor.prepareUpload(fromJson);

// return them

return Maps.newHashMap(Maps.transformValues(prepareUpload, new FunctionUUID, String() {

public String apply(UUID input) {

return input.toString();

};

}));

}

private Boolean verifyCrcOfUncheckedPart(HttpServletRequest request)

throws IOException, MissingParameterException, FileCorruptedException, FileStillProcessingException {

UUID fileId = UUID.fromString(fileUploaderHelper.getParameterValue(request, UploadServletParameter.fileId));

try {

uploadProcessor.verifyCrcOfUncheckedPart(fileId,

fileUploaderHelper.getParameterValue(request, UploadServletParameter.crc));

}

catch (InvalidCrcException e) {

// no need to log this exception, a fallback behaviour is defined in the

// throwing method.

// but we need to return something!

return Boolean.FALSE;

}

return Boolean.TRUE;

}

}

java web断点续传,我用的是fileupload来做的上传。

使用Struts2上传文件：

Struts文件上传需要使用File Upload Filter。Filter Upload Filter使用一些默认的规则：

Form中的s:file name="image"/s:file标签对应着Action类中的三个属性分别是：上传文件（java.io.File类型），文件名（java.lang.String类型），文件类型（java.lang.String类型，例如：image/jpeg）。命名规约为：

文件：名字与s:file标签中的name属性一致，这里为：image

文件名：文件 + FileName，这里为：imageFileName

文件类型：文件 + ContentType，这里为：imageContentType

所以针对上述s:file name="image"/s:file表示啊的上传文件的JSP和Action类被别为：

imageUpload.jsp：

[html] view plain copy

%@ page contentType="text/html;charset=UTF-8" language="java" %

%@taglib prefix="s" uri="/struts-tags" %

html

headtitleImage Upload/title/head

body

h1 Image Upload Page /h1

s:form action="imageUpload" method="post" enctype="multipart/form-data"

s:file name="image"/s:file

s:submit/s:submit

/s:form

/body

/html

ImageUploadAction.java：

[html] view plain copy

package com.jpleasure;

import com.opensymphony.xwork2.ActionSupport;

import java.io.File;

import java.io.InputStream;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

public class ImageUploadAction extends ActionSupport {

private File image;

private String imageFileName;

private String imageContentType;

public File getImage() {

return image;

}

public void setImage(File image) {

this.image = image;

}

public String getImageFileName() {

return imageFileName;

}

public void setImageFileName(String imageFileName) {

this.imageFileName = imageFileName;

}

public String getImageContentType() {

return imageContentType;

}

public void setImageContentType(String imageContentType) {

this.imageContentType = imageContentType;

}

public String execute() {

if (image != null) {

System.out.println("file name is:" + this.imageFileName);

System.out.println("file content type is:" + this.imageContentType);

System.out.println("file length is:" + this.image.length());

}

return SUCCESS;

}

}

Struts.xml配置文件：

[html] view plain copy

action name="imageUpload" class="com.jpleasure.ImageUploadAction"

result/success.jsp/result

/action

这样当我们选中上传文件，提交的时候：文件内容会以File类型的方式放在image声明的变量中。文件的名字将会被放在imageFileName命名的变量中，文件的类型被放在imageContentType命名的变量中。

文件下载：

文件下载需要使用一个特殊的Result，stream类型的Result。Stream类型的Result主要用来处理文件下载操作。

处理原理为：所有的下载文件都是将一个二进制的流写入到HttpResponse中去。在Action类中定义一个InputSream类型的二进制流，在Result返回给用户的时候返回给用户。

扩展上述的代码，将上传来的文件直接下载给用户：

ImageUploadAction中需要追加一个InputSream类型的对象，并且指向上传的文件，代码如下，红色部分表示变化：

[html] view plain copy

package com.jpleasure;

import com.opensymphony.xwork2.ActionSupport;

import java.io.File;

import java.io.InputStream;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

public class ImageUploadAction extends ActionSupport {

private File image;

private String imageFileName;

private String imageContentType;

private InputStream imageInputStream = null;

public InputStream getImageInputStream() {

return imageInputStream;

}

public void setImageInputStream(InputStream imageInputStream) {

this.imageInputStream = imageInputStream;

}

public File getImage() {

return image;

}

public void setImage(File image) {

this.image = image;

}

public String getImageFileName() {

return imageFileName;

}

public void setImageFileName(String imageFileName) {

this.imageFileName = imageFileName;

}

public String getImageContentType() {

return imageContentType;

}

public void setImageContentType(String imageContentType) {

this.imageContentType = imageContentType;

}

public String execute() {

if (image != null) {

System.out.println("file name is:" + this.imageFileName);

System.out.println("file content type is:" + this.imageContentType);

System.out.println("file length is:" + this.image.length());

try {

this.imageInputStream = new FileInputStream (image);

} catch (FileNotFoundException e) {

e.printStackTrace();

}

}

return SUCCESS;

}

}

配置文件为，红色为变化部分：

[html] view plain copy

action name="imageUpload" class="com.jpleasure.ImageUploadAction"

result name="success" type="stream"

param name="contentType"image/pjpeg/param

param name="inputName"imageInputStream/param

param name="contentDisposition"attachment;filename="image.jpg"/param

param name="bufferSize"1024/param

/result

/action

ContentType表示下载文件的类型。

InputName表示Action类中用来下载文件的字段的名字。

ContentDisposition用来控制文件下载的一些信息，包括是否打开另存对话框，下载文件名等。

BufferSize表示文件下载时使用的缓冲区的大小。

实际项目开发的考虑：

控制上传文件的类型和最大允许上传文件的size

使用File Upload Intercepter的参数可盈控制上传文件的类型和最大允许上传文件的size。例如：

[html] view plain copy

struts

package name="myPackage" extends="struts-default"

interceptor-ref name="fileUpload"

param name="maximumSize"2MB/param

param name="allowedTypes"text/html,image/jpeg/param

/interceptor-ref

interceptor-ref name="basicStack"/

action name="imageUpload" class="com.jpleasure.ImageUploadAction"

result name="success" type="stream"

param name="contentType"image/pjpeg/param

param name="inputName"imageInputStream/param

param name="contentDisposition"

attachment;filename="image.jpg"

/param

param name="bufferSize"1024/param

/result

/action

/package

/struts

上述表示允许上传jpeg和html类型的文件，且最大文件上传size为2MB

显示错误信息：

可以使用如下key表示的message来显示文件上传出错的提示信息：

消息Key    说明  

struts.messages.error.uploading    文件无法正常上传时的公共错误  

struts.messages.error.file.too.large    文件大小超过最大允许size时的错误提示  

struts.messages.error.content.type.not.allowed    文件类型不在上传文件允许类型中的错误提示  

java实现ftp断点续传问题

//尝试移动文件内读取指针,实现断点续传

result

=

uploadFile(remoteFileName,

f,

ftpClient,

remoteSize);

//如果断点续传没有成功，则删除服务器上文件，重新上传

if(result

==

UploadStatus.Upload_From_Break_Failed){

if(!ftpClient.deleteFile(remoteFileName)){

return

UploadStatus.Delete_Remote_Faild;

}

result

=

uploadFile(remoteFileName,

f,

ftpClient,

0);

}

关于JAVA断点续传

024字节）。第一次B接收了512字节，那么第二次连接A就应该从513字节开始传输。

也就是说，在第二次传输时，B要提供“我要从513字节开始传送文件F”的信息，然后A使用FileInputStream构建输入流读取本地文件，使用skip(512)方法跳过文件F的前512字节再传送文件，之后B将数据追加（append）到先前接收的文件末尾即可。

进一步考虑，如果要实现多线程传送，即分块传输，也同样的道理。假如B要求分作两块同时传输，那么A启动两个线程，一个从513字节读到768字节（工256字节），第二个线程从769字节到1024字节即可。

如果你要从网络上下载文件，就是说A方不是你实现的，那么你要先确认A方支不支持断电续传功能（HTTP1.1），然后你查阅下HTTP1.1协议，在HTTP1.1版本里，可以通过设置请求包头某个字段的信息（使用URLConnection创建连接并使用setRequestProperty(String key, String value) 方法设置）从而精确读取文件的某一段数据的。注意，基于HTTP断点续传的关键是1.1版本，1.0版本是不支持的。

补充：

嗯，查到了，是设置range属性，即setRequestProperty("range", "bytes=513-1024").你可以使用迅雷下载某个文件，然后从”线程信息“中就可以看到这个http1.1断点续传的所有行为信息了。

Java Socket如何实现文件的断点续传，有代码更好

1package com.tangshun.;

2

3import java.io.File;

4import java.io.IOException;

5import java.io.InputStream;

6import java.io.RandomAccessFile;

7import java.net.HttpURLConnection;

8import java.net.MalformedURLException;

9import java.net.URL;

10

11//断点续传

12public class DownLoad {

13

14 public static void down(String URL, long nPos, String savePathAndFile) {

15 try {

16 URL url = new URL(URL);

17 HttpURLConnection httpConnection = (HttpURLConnection) url

18 .openConnection();

19 // 设置User-Agent

20 httpConnection.setRequestProperty("User-Agent", "NetFox");

21 // 设置断点续传的开始位置

22 httpConnection.setRequestProperty("RANGE", "bytes=" + nPos);

23 // 获得输入流

24 InputStream input = httpConnection.getInputStream();

25 RandomAccessFile oSavedFile = new RandomAccessFile(savePathAndFile,

26 "rw");

27 // 定位文件指针到nPos位置

28 oSavedFile.seek(nPos);

29 byte[] b = new byte[1024];

30 int nRead;

31 // 从输入流中读入字节流，然后写到文件中

32 while ((nRead = input.read(b, 0, 1024)) 0) {

33 (oSavedFile).write(b, 0, nRead);

34 }

35 httpConnection.disconnect();

36 } catch (MalformedURLException e) {

37 e.printStackTrace();

38 } catch (IOException e) {

39 e.printStackTrace();

40 }

41 }

42

43 public static long getRemoteFileSize(String url) {

44 long size = 0;

45 try {

46 HttpURLConnection conn = (HttpURLConnection) (new URL(url))

47 .openConnection();

48 size = conn.getContentLength();

49 conn.disconnect();

50 } catch (Exception e) {

51 e.printStackTrace();

52 }

53 return size;

54 }

55

56public static void main(String[] args) {

57 String url = " ";

58 String savePath = "F:\\";

59 String fileName = url.substring(url.lastIndexOf("/"));

60 String fileNam=fileName;

61 HttpURLConnection conn = null;

62 try {

63 conn = (HttpURLConnection) (new URL(url)).openConnection();

64 } catch (Exception e) {

65 e.printStackTrace();

66 }

67 File file = new File(savePath + fileName);

68 // 获得远程文件大小

69 long remoteFileSize = getRemoteFileSize(url);

70 System.out.println("远程文件大小="+remoteFileSize);

71 int i = 0;

72 if (file.exists()) {

73 // 先看看是否是完整的，完整，换名字，跳出循环，不完整，继续下载

74 long localFileSize = file.length();

75 System.out.println("已有文件大小为:"+localFileSize);

76

77 if (localFileSize remoteFileSize) {

78 System.out.println("文件续传");

79 down(url, localFileSize, savePath + fileName);

80 }else{

81 System.out.println("文件存在，重新下载");

82 do{

83 i++;

84 fileName = fileNam.substring(0, fileNam.indexOf(".")) + "(" + i

85 + ")" + fileNam.substring(fileNam.indexOf("."));

86

87 file = new File(savePath + fileName);

88 }while(file.exists());

89 try {

90 file.createNewFile();

91 } catch (IOException e) {

92 e.printStackTrace();

93 }

94 down(url, 0, savePath + fileName);

95 }

96 // 下面表示文件存在，改名字

97

98 } else {

99 try {

100 file.createNewFile();

101 System.out.println("下载中");

102 down(url, 0, savePath + fileName);

103 } catch (IOException e) {

104 e.printStackTrace();

105 }

106 }

107 }}

108

如何用Java实现HTTP断点续传功能

断点设置方法，当有临时文件时，直接在临时文件中读取上次下载中断时的断点位置。没有临时文件，即第一次下载时，重新设置断点。 rantmpfile.seek()跳转到一个位置的目的是为了让各个断点存储的位置尽量分开。