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本篇文章為大家展示了使用struts2實(shí)現(xiàn)一個(gè)文件上傳功能并顯示進(jìn)度條,內(nèi)容簡(jiǎn)明扼要并且容易理解,絕對(duì)能使你眼前一亮,通過這篇文章的詳細(xì)介紹希望你能有所收獲。
一. struts2讀取進(jìn)度原理分析
1. 在strut2中控制文件上傳信息的類是實(shí)現(xiàn)MultiPartRequest接口的JakartaMultiPartRequest
其實(shí)第一次看到源文件時(shí)我打了個(gè)退堂鼓,因?yàn)橛X得內(nèi)容太長(zhǎng)了,不想看。冷靜下來將思路理順,將分開的各個(gè)方法還原到一個(gè)方方中中,發(fā)現(xiàn)還是很好理解的:
@Override public void parse(HttpServletRequest request, String saveDir) throws IOException { setLocale(request); //規(guī)定了File文件的格式(如文件名必須是xxFileName,文件類型xxContentType),并定義了File的保存路徑 DiskFileItemFactory factory = new DiskFileItemFactory(); ServletFileUpload upload = new ServletFileUpload(factory);//處理文件上傳的servlet upload.setProgressListener(new FileUploadProgressListener(request)); //為文件上傳添加監(jiān)聽 factory.setSizeThreshold(0); //if (saveDir != null factory.setRepository(new File(saveDir));//臨時(shí)路徑 } try { upload.setSizeMax(maxSize); List items = upload.parseRequest(createRequestContext(request)); //獲取所有請(qǐng)求 for (Object obItem : items) { FileItem item = (FileItem) obItem; //獲取每個(gè)請(qǐng)求的文件 if (LOG.isDebugEnabled()) { LOG.debug("Found item" + item.getFieldName()); } if (item.isFormField()) { //普通表單提交 LOG.debug("Item is a normal form field"); List<String> values; if (params.get(item.getFieldName()) != null) { values = params.get(item.getFieldName()); } else { values = new ArrayList<String>(); } String charset = request.getCharacterEncoding(); if (charset != null) { values.add(item.getString(charset)); } else { values.add(item.getString()); } params.put(item.getFieldName(), values); } else { //文件上傳請(qǐng)求 LOG.debug("Item is a file upload"); if (item.getName() == null || item.getName().trim().length() <= 0) { LOG.debug("No file has been uploded for the filed:" + item.getFieldName()); continue; } List<FileItem> values; if (files.get(item.getFieldName()) != null) { values = files.get(item.getFieldName()); } else { values = new ArrayList<FileItem>(); } values.add(item); files.put(item.getFieldName(), values); } } } catch (FileUploadBase.SizeLimitExceededException e) { System.out.println("錯(cuò)誤1:" + e); if (LOG.isWarnEnabled()) { LOG.warn("Request exceeded size limit!", e); } String errorMessage = buildErrorMessage(e, new Object[]{e.getPermittedSize(), e.getActualSize()}); if (!errors.contains(errorMessage)) { errors.add(errorMessage); } } catch (Exception e) { System.out.println("錯(cuò)誤1:" + e); if (LOG.isWarnEnabled()) { LOG.warn("Unable to parse request", e); } String errorMessage = buildErrorMessage(e, new Object[]{}); if (!errors.contains(errorMessage)) { errors.add(errorMessage); } } }
2. 文件上傳監(jiān)聽文件FileUploadProgressListener.java
public class FileUploadProgressListener implements ProgressListener { private final HttpSession session; private final DecimalFormat format = new DecimalFormat("#00.0"); public FileUploadProgressListener(HttpServletRequest request) { session = request.getSession(); FileUploadStatus status = new FileUploadStatus(); session.setAttribute("uploadStatus", status); } @Override public void update(long pBytesRead, long pContentLength, int pItems) { FileUploadStatus uploadStatus = (FileUploadStatus) session.getAttribute("uploadStatus"); Double uploadRate = (double) (pBytesRead * 100 / pContentLength); uploadStatus.setUploadRate(Double.valueOf(format.format(uploadRate))); uploadStatus.setReadedBytes(pBytesRead / 1024); uploadStatus.setTotalBytes(pContentLength / 1024); uploadStatus.setCurrentItems(pItems); } }
3. 添加狀態(tài)文件:FileUploadStatus.java
public class FileUploadStatus { private Double uploadRate = 0.0; private Long readedBytes = 0L; private Long totalBytes = 0L; private int currentItems = 0; private Long uploadSpeed = 0L; private Long startTime = System.currentTimeMillis(); private Long readedTimes = 0L; private Long totalTimes = 0L; // "-1" 錯(cuò)誤 "0" 正常 "1" 完成 private String error = "0"; ... setter getter方法 ... }
4. Action類(如果是多文件上傳,則將File FileName ContentType定義成數(shù)組形式即可)
/** * 利用io流上傳文件 */ public class FileStreamUploadAction extends ActionSupport { /** * serialVersionUID作用: ---相當(dāng)于類的身份證。 序列化時(shí)為了保持版本的兼容性,即在版本升級(jí)時(shí)反序列化仍保持對(duì)象的唯一性。 * 有兩種生成方式: 一個(gè)是默認(rèn)的1L,比如:private static final long serialVersionUID = 1L; * 一個(gè)是根據(jù)類名、接口名、成員方法及屬性等來生成一個(gè)64位的哈希字段,比如: private static final long * serialVersionUID = xxxxL; */ private static final long serialVersionUID = 1L; private File image; private String imageFileName; private String imageContentType; private String message; public String uploadFile() { FileInputStream in = null; FileOutputStream out = null; System.out.println("文件名:" + imageFileName); try { this.setNewFileName(imageFileName); String realPath = ServletActionContext.getServletContext() .getRealPath("/file"); File filePath = new File(realPath); if (!filePath.exists()) { // 如果保存的路徑不存在則創(chuàng)建 filePath.mkdir(); } if (image == null) { message = "上傳文件為空"; System.out.println(message); } else { File saveFile = new File(filePath, this.getNewFileName()); out = new FileOutputStream(saveFile); } in = new FileInputStream(image); byte[] byt = new byte[1024]; int length = 0; while ((length = in.read(byt)) > 0) { out.write(byt, 0, length); out.flush(); } message = "上傳成功"; System.out.println(message); } catch (FileNotFoundException e) { message = "找不到文件!"; e.printStackTrace(); } catch (IOException e) { message = "文件讀取失?。?quot;; e.printStackTrace(); } finally { closeStream(in, out); } return "uploadSucc"; } public void closeStream(FileInputStream in, FileOutputStream out) { try { if (in != null) { in.close(); } if (out != null) { out.close(); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } ... setter() getter() ... }
獲取進(jìn)度的Action
public class FileProgressAction extends ActionSupport { private static final long serialVersionUID = 1L; private FileUploadStatus uploadStatus; public String uploadPercent() { HttpSession session = ServletActionContext.getRequest().getSession(); this.uploadStatus = (FileUploadStatus) session.getAttribute("uploadStatus"); if (uploadStatus == null) { System.out.println("action is null"); uploadStatus = new FileUploadStatus(); uploadStatus.setCurrentItems(0); } return "getPercent"; } public FileUploadStatus getUploadStatus() { return uploadStatus; } public void setUploadStatus(FileUploadStatus uploadStatus) { this.uploadStatus = uploadStatus; } }
5.struts.xml中
<struts> <constant name="struts.multipart.maxSize" value="2147483648"/><!-- 默認(rèn)值為2M,設(shè)置為2G --> <constant name="struts.custom.i18n.resources" value="messageResource" /> <constant name="struts.i18n.encoding" value="utf-8" /> <constant name="struts.multipart.saveDir" value="e:/fileUpload"/><!-- 臨時(shí)路徑 --> <!-- 加載自定義的文件讀取配置文件 --> <bean type="org.apache.struts2.dispatcher.multipart.MultiPartRequest" name="Refactor" class="com.nova.core.RefactorMultiPartRequest" scope="default" /> <constant name="struts.multipart.handler" value="Refactor" /> <!-- 這里配置struts.multipart.handler --> <package name="ajaxUpload" extends="json-default"> <!-- json-default需要struts2-json-plugin-2.3.3.jar --> <action name="ajaxUploadFile_*" class="com.nova.action.FileStreamUploadAction" method="{1}"> <result type="json" name="uploadSucc"> <param name="root">newFileName</param> <param name="contentType"> text/html </param> </result> </action> <action name="uploadPercent_*" class="com.nova.action.FileProgressAction" method="{1}"> <result name="getPercent" type="json"> <param name="root">uploadStatus</param> </result> </action> </package> </struts>
二. 進(jìn)度條顯示
View頁面設(shè)置,利用ajaxfileupload.js來獲取文件并進(jìn)行異步上傳,bootstrap中的進(jìn)度條效果顯示進(jìn)度(利用setInterval間斷的獲取進(jìn)度信息來形式一種進(jìn)度的前進(jìn)顯示)
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> <link rel="stylesheet" type="text/css" href="bootstrap/css/bootstrap.css" rel="external nofollow" > <link rel="stylesheet" type="text/css" href="bootstrap/css/bootstrap-responsive.css" rel="external nofollow" > <script type="text/javascript" src="js/jquery.js"></script> <script type="text/javascript" src="js/ajaxfileupload.js"></script> <script type="text/javascript" src="<%=request.getContextPath() %>/bootstrap/js/bootstrap.js"></script> <script type="text/javascript" src="<%=request.getContextPath() %>/bootstrap/js/jquery.showLoading.min.js"></script> <script type="text/javascript"> var setinterval; $(document).ready(function(){ $("#upload").click(function(){ $("#upload").addClass("disabled"); $("#upload").attr("disabled" ,true); $("#upload").attr("title" ,"文件上傳中..."); uploadFile(); setinterval = setInterval(uploadProgress,200); }); }); //文件上傳 function uploadFile(){ $.ajaxFileUpload({ url:'ajaxUploadFile_uploadFile.action', secureuri:false, //是否采用安全協(xié)議,默認(rèn)為false fileElementId:'image', dataType: 'json', success: function (data){ $("#showImage").attr("src","/FileUpLoadTest/file/"+data); } }); } //上傳進(jìn)度 function uploadProgress(){ $.get("uploadPercent_uploadPercent.action","",function(data){ $("#ProgressRate").html("上傳速度:" + data.uploadRate + "%"); $("#readBytes").html("以讀取:" + data.readedBytes + " KB"); $("#totalBytes").html("總大?。?quot; + data.totalBytes + " KB"); $("#progress").attr("style","width:" + data.uploadRate + "%;"); $("#progress").html(data.uploadRate + "%"); if(data.uploadRate == 100){ clearInterval(setinterval); $("#progress").html("上傳成功"); $("#upload").removeClass("disabled"); $("#upload").attr("disabled" ,false); } }); } </script> </head> <body> <div class="navbar navbar-inverse navbar-fixed-top"> <div class="navbar-inner"> <div class="container"> <button type="button" class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse"> <span class="icon-bar"></span> <span class="icon-bar"></span> <span class="icon-bar"></span> </button> <a class="brand" href="#" rel="external nofollow" >文件異步上傳+進(jìn)度條</a> </div> </div> </div> <br><br><br> <div class="container"> <input type="file" name="image" id="image"/><br/> //file的name屬性必須設(shè)置的與后臺(tái)Action中file的名稱是相同的,否則ajaxFileUpload獲取不到文件信息 <input type="button" id="upload" value="上傳" class="btn btn-info" title=""/><br/> <img alt="" src="" id="showImage"> <div id="ProgressRate"></div> <div id="readBytes"></div> <div id="totalBytes"></div> <div id="uploadTimes"></div> <div class="progress progress-striped span4"> <div id="progress" class="bar"> </div> </div> </div> </body> </html>
三、總結(jié)
用這種方法獲取上傳進(jìn)度有一個(gè)缺點(diǎn):讀取進(jìn)度階段是文件從指定目錄開始在臨時(shí)文件中存儲(chǔ)的過程,而文件上傳則是重臨時(shí)路徑下將文件轉(zhuǎn)移到目標(biāo)路徑下,這樣就造成了一個(gè)時(shí)間差,就是讀取進(jìn)度總會(huì)比上傳文件快,上傳的文件越大這個(gè)缺點(diǎn)越是明顯。
上述內(nèi)容就是使用struts2實(shí)現(xiàn)一個(gè)文件上傳功能并顯示進(jìn)度條,你們學(xué)到知識(shí)或技能了嗎?如果還想學(xué)到更多技能或者豐富自己的知識(shí)儲(chǔ)備,歡迎關(guān)注億速云行業(yè)資訊頻道。
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