struts2 文件上传显示进度条

一. struts2读取进度原理分析(作为草稿存了好久，刚刚发布出来......)

1.　在strut2中控制文件上传信息的类是实现MultiPartRequest接口的JakartaMultiPartRequest

其实第一次看到源文件时我打了个退堂鼓，因为觉得内容太长了，不想看。冷静下来将思路理顺，将分开的各个方法还原到一个方方中中，发现还是很好理解的：
@Override
    public void parse(HttpServletRequest request, String saveDir)
            throws IOException {
        setLocale(request);
　　　 　//规定了File文件的格式（如文件名必须是xxFileName，文件类型xxContentType），并定义了File的保存路径　　　　                                                    DiskFileItemFactory factory = new DiskFileItemFactory(); 
        ServletFileUpload upload = new ServletFileUpload(factory);//处理文件上传的servlet
        upload.setProgressListener(new FileUploadProgressListener(request)); //为文件上传添加监听        factory.setSizeThreshold(0); //if (saveDir != null
            factory.setRepository(new File(saveDir));//临时路径
        }
        try {
            upload.setSizeMax(maxSize);
            List items = upload.parseRequest(createRequestContext(request)); //获取所有请求
            for (Object obItem : items) {
                FileItem item = (FileItem) obItem; //获取每个请求的文件
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Found item" + item.getFieldName());
                }
                if (item.isFormField()) { //普通表单提交
                    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 { //文件上传请求
                    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("错误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("错误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.  文件上传监听文件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. 添加状态文件：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" 错误 "0" 正常 "1" 完成
    private String error = "0";

    ...
        setter  getter方法
    ...        
}

4. Action类（如果是多文件上传，则将File   FileName   ContentType定义成数组形式即可）

/**
 * 利用io流上传文件
 */
public class FileStreamUploadAction extends ActionSupport {
    /**
     * serialVersionUID作用： ---相当于类的身份证。 序列化时为了保持版本的兼容性，即在版本升级时反序列化仍保持对象的唯一性。
     * 有两种生成方式： 一个是默认的1L，比如：private static final long serialVersionUID = 1L;
     * 一个是根据类名、接口名、成员方法及属性等来生成一个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()) { // 如果保存的路径不存在则创建
                filePath.mkdir();
            }
            if (image == null) {
                message = "上传文件为空";
                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 = "上传成功";
            System.out.println(message);
        } catch (FileNotFoundException e) {
            message = "找不到文件！";
            e.printStackTrace();
        } catch (IOException e) {
            message = "文件读取失败！";
            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()
      ...        
}

获取进度的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"/><!-- 默认值为2M,设置为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"/><!-- 临时路径 -->
    
        <!-- 加载自定义的文件读取配置文件 -->
        <bean type="org.apache.struts2.dispatcher.multipart.MultiPartRequest" name="Refactor" class="com.nova.core.RefactorMultiPartRequest" scope="default" />
        <constant name="struts.multipart.handler" value="Refactor" />
        <!-- 这里配置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.  进度条显示

　　View页面设置，利用ajaxfileupload.js来获取文件并进行异步上传，bootstrap中的进度条效果显示进度（利用setInterval间断的获取进度信息来形式一种进度的前进显示）

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<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">
<link rel="stylesheet" type="text/css"    href="bootstrap/css/bootstrap-responsive.css">
<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" ,"文件上传中...");
            uploadFile();
            setinterval = setInterval(uploadProgress,200);
        });
    });
    //文件上传
    function uploadFile(){
        $.ajaxFileUpload({
            url:'ajaxUploadFile_uploadFile.action', 
            secureuri:false, //是否采用安全协议，默认为false
            fileElementId:'image',
            dataType: 'json',
            success: function (data){
               $("#showImage").attr("src","/FileUpLoadTest/file/"+data);
            }
        });
    }
    //上传进度
    function uploadProgress(){
        $.get("uploadPercent_uploadPercent.action","",function(data){
            $("#ProgressRate").html("上传速度：" + data.uploadRate + "%");
            $("#readBytes").html("以读取：" + data.readedBytes + " KB");
            $("#totalBytes").html("总大小：" + data.totalBytes + " KB");
            $("#progress").attr("style","" + data.uploadRate + "%;");
            $("#progress").html(data.uploadRate + "%");
            if(data.uploadRate == 100){
                clearInterval(setinterval);
                $("#progress").html("上传成功");
                $("#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="#">文件异步上传+进度条</a>
        </div>
      </div>
    </div>
    <br><br><br>
    <div class="container">
        <input type="file" name="image" id="image"/><br/> //file的name属性必须设置的与后台Action中file的名称是相同的，否则ajaxFileUpload获取不到文件信息
        <input type="button" id="upload" value="上传" 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、总结

　　用这种方法获取上传进度有一个缺点：读取进度阶段是文件从指定目录开始在临时文件中存储的过程，而文件上传则是重临时路径下将文件转移到目标路径下，这样就造成了一个时间差，就是读取进度总会比上传文件快，上传的文件越大这个缺点越是明显。

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原文地址：https://www.cnblogs.com/daisyleamo/p/3094933.html