Flex上传下载的实现
在flex中,和传统的JSP一样,有的时候也需要实现文件上传和下载的功能,但是在flex里文件的上传和下载的实现相对来说比较复杂,如何实现,请看下面。
由于flex是一个比较新的技术,在研究的时候,还是按着JSP的方式去尝试,在开始之初,主要有以下几种思路:
A、利用ftp的方式进行文件的上传和下载,需要利用flex的socket接口。
B、利用WebService的方式来进行文件的上传和下载
C、利用flex+sevlet+fileupload组件实现文件的上传和下载
在通过比较后,最后选择了第三种,用Flex+sevlet的方式来完成文件上传和下载的功能,理由如下(与上面的思路相对应):
A、涉及到了流的操作,实现起来比较复杂,出现错误的几率比较高
B、关于flex端的可参考的资料比较少,并且还需要启动WebService服务
C、这个技术比较成熟,从flex2.0开始,在flex端已经可以引用FileReference类了,并且在java端有成熟的组件可以使用,所以最后考虑使用该种方法来处理。
一、文件的上传
1、Flex端
A、使用到的类介绍:
FileReference类提供了在用户计算机和服务器之间上载和下载文件的方法。 操作系统对话框会提示用户选择要上载的文件或用于下载的位置。它主要能实现一个文件的上传。
FileReferenceList 类提供了让用户选择一个或多个要上载的文件的方法。 FileReferenceList 对象将用户磁盘上的一组本地文件(一个或多个文件)表示为 FileReference 对象的数组。
B、使用 FileReferenceList类 实现多文件上传:
1) 将该类实例化:var myFileRef = new FileReferenceList();
2) 调用 FileReferenceList.browse() 方法,该方法将打开一个对话框,让用户选择一个或多个要上载的文件:myFileRef.browse();
3) 在成功调用 browse() 方法之后,使用 FileReference对象数组来填充 FileReferenceList 对象的fileList属性。 对 fileList数组中的每个元素调用 FileReference.upload()
代码如下:
/** *//** * 执行上传操作 * */ private function upLoadFiles():void { try { selectFileList.browse(new Array(imageFilter, textFilter)); selectFileList.addEventListener(Event.SELECT, selectHandler1); } catch (error:Error) { Alert.show("文件选择出现错误,请选择正确的文件"); } } /** *//** * 如果文件被选中,则执行该方法 * */ function selectHandler1(event:Event):void { var request:URLRequest = new URLRequest("FileUploadServlet"); var upLoadFile:FileReference; var upLoadFileList:FileReferenceList = FileReferenceList(event.target); var selectedFileArray:Array = upLoadFileList.fileList; login =(testPress)(PopUpManager.createPopUp( this, testPress , true)); for (var i:uint = 0; i < selectedFileArray.length; i++) { upLoadFile = FileReference(selectedFileArray[i]); upLoadFile.addEventListener(Event.COMPLETE, UpLoadcompleteHandler); upLoadFile.addEventListener(ProgressEvent.PROGRESS, progressHandler); try { upLoadFile.upload(request); } catch (error:Error) { Alert.show(error.message.toString()); } } }function UpLoadcompleteHandler(event:Event):void{ var upLoadFiles:FileReference = FileReference(event.target); var fileNames = upLoadFiles.name; //Alert.show(‘文件’+fileNames+’上传成功’) login.myLabels.text = ‘文件’+fileNames+’上传成功’;}private function progressHandler(e:ProgressEvent):void{ var proc: uint = e.bytesLoaded / e.bytesTotal * 100; login.bar.setProgress(proc, 100); login.bar.label= "当前进度: " + " " + proc + "%"; } testPress.mxml<?xml version="1.0" encoding="utf-8"?><mx:TitleWindow xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" width="528" height="236"><mx:Script> <![CDATA[ import mx.managers.PopUpManager; public function clickMe():void { PopUpManager.removePopUp(this); } ]]></mx:Script> <mx:ProgressBar id="bar" labelPlacement="bottom" themeColor="#F20D7A" minimum="0" visible="true" maximum="100" label="当前进度: 0%" direction="right" mode="manual" width="200" x="154" y="84"/> <mx:Button x="221" y="135" label="关闭" click = "clickMe();"/> <mx:Label x="173" y="27" id="myLabels" width="157"/></mx:TitleWindow>
import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import java.util.Iterator;import java.util.List;import java.util.Properties;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.fileupload.FileItem;import org.apache.commons.fileupload.FileUploadException;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;public class FileUploadServlet extends HttpServlet{ // private String uploadPath = "D:\\upload\"; private String path = "file_path.properties"; private String skStr = ""; private String uploadPath = ""; private int maxPostSize = 1000 * 1024 * 1024; public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { String filePathaa = this.getServletConfig().getServletContext().getRealPath("/"); Properties p = loadProperties(path); uploadPath = p.getProperty("filepath"); res.setContentType("text/html;charset=UTF-8"); req.setCharacterEncoding("UTF-8"); DiskFileItemFactory factory = new DiskFileItemFactory(); factory.setSizeThreshold(1024*20); ServletFileUpload upload = new ServletFileUpload(factory); upload.setSizeMax(maxPostSize); try { List fileItems = upload.parseRequest(req); Iterator iter = fileItems.iterator(); while (iter.hasNext()) { FileItem item = (FileItem) iter.next(); if (!item.isFormField()) { String name = item.getName(); try { File skFile = new File(uploadPath + name); if (skFile.exists()) { skFile.delete(); item.write(new File(uploadPath + name)); } else { item.write(new File(uploadPath + name)); } } catch (Exception e) { e.printStackTrace(); } } } } catch (FileUploadException e) { e.printStackTrace(); } } public Properties loadProperties(String path) throws IOException { InputStream in = this.getClass().getResourceAsStream(path); // Properties p = new Properties(); p.load(in); in.close(); return p; }
<!– For file uploaded –><servlet> <servlet-name>FileUploadServlet</servlet-name> <servlet-class>FileUploadServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>FileUploadServlet</servlet-name> <url-pattern>/FileUploadServlet</url-pattern> </servlet-mapping>
import com.systex.flex.util.testPress;import flash.net.FileReferenceList;import mx.controls.Alert;import mx.managers.PopUpManager; var imageFilter:FileFilter = new FileFilter("Image Files (*.jpg, *.jpeg, *.gif, *.png)", "*.jpg; *.jpeg; *.gif; *.png"); var textFilter:FileFilter = new FileFilter("Text Files (*.txt, *.rtf, *.zip)", "*.txt; *.rtf; *.zip"); var selectFileList:FileReferenceList = new FileReferenceList(); var selectedFileArray:Array = new Array(); var login:testPress = new testPress(); var downloadURL:URLRequest; var DownLoadfile:FileReference; //这是要主要的地方 //http://XX.XX.XX.XX:8080/upload/main.zip private function downLoadFiles(urlAdd:String):void { downloadURL = new URLRequest(urlAdd); DownLoadfile = new FileReference(); configureListeners(DownLoadfile); DownLoadfile.download(downloadURL); } private function configureListeners(dispatcher:IEventDispatcher):void { dispatcher.addEventListener(Event.COMPLETE, completeHandler); } private function completeHandler(event:Event):void { mx.controls.Alert.show("文件下载成功"); }这里的是上面上传代码的上部分附上测试的MXML<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" ><mx:Script source="UpDownLoadFiles.as"/> <mx:Canvas width="100%" height="100%" x="10" y="170" fontSize="15"> <mx:VBox width="100%" horizontalAlign="center"> <mx:TextInput id="mytextInput"/> <mx:Button label="文件下载" click="downLoadFiles(‘http://’+mytextInput.text+’:8080/downLoading/2MSN.rar’);"/> <mx:Button label="上传文件" click="upLoadFiles();"/> </mx:VBox> </mx:Canvas></mx:Application>