使用 Flex 和Java servlets 将文件上传到 RED5 服务器的步骤
本文使用一个 demo 来演示如何使用 Flex 和 Java servlets 上传一个任意类型的本地文件到 RED5 服务器。使用的是 Flex 的 FileReference 接口，该接口可以对远程服务器上的文件进行上传、下载。FileReference 类提供了一个对话框接口和一个 upload 方法，通过该对话框，选择本地文件，而 upload 方法将会调用远程服务器端的 PHP，ASP 或者 Java 代码来进行上传。 首先创建一个 Flex3 应用程序，该程序获得本地文件，并调用 RED5 服务器 "http://localhost:5080/Red5FileUploadProj/fileupload" 的 servlet。
UploadToRed5Proj.mxml 源代码如下：
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns:net="flash.net.*" layout="absolute" creationComplete="doInit()">
<mx:Panel horizontalCenter="0" verticalCenter="0" verticalAlign="middle" horizontalAlign="center" borderColor="#FFFFFF" width="100%" height="100%" backgroundColor="#307CB7">
<mx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
import mx.controls.Alert;
[Bindable]private var fileReference:FileReference;
[Bindable]private var fileSelected:Boolean = false;
[Bindable]private var serverUrl:String = "http://localhost:5080/Red5FileUploadProj/fileupload";
private var statusArray:Array = new Array();
[Bindable]private var statusArrayCollection:ArrayCollection = new ArrayCollection();
private function doInit():void
{
fileReference = new FileReference();
fileReference.addEventListener(Event.SELECT, onFileSelect);
fileReference.addEventListener(Event.COMPLETE, onUploadComplete);
fileReference.addEventListener(ProgressEvent.PROGRESS,onUploadProgress);
fileReference.addEventListener(IOErrorEvent.IO_ERROR, onUploadError);
fileReference.addEventListener(SecurityErrorEvent.SECURITY_ERROR, onUploadError);
}
private function browseFile(event:MouseEvent):void
{
fileReference.browse();
}
private function onFileSelect(event:Event):void
{
fileSelected = true;
fileTxt.text = fileReference.name;
statusArray.push({status:"Ready to upload "+fileTxt.text});
statusArrayCollection = new ArrayCollection(statusArray);
}
private function uploadFile(event:MouseEvent):void
{
if (!fileSelected || (urlTxt.text.length == 0))
{
Alert.show("Select a file and Enter a URL");
return;
}
var urlRequest:URLRequest = new URLRequest(urlTxt.text);
fileReference.upload(urlRequest);
}
private function onUploadProgress(event:ProgressEvent):void
{
statusArray.push({status:"In progress.."+((event.bytesLoaded * 100) / event.bytesTotal).toString()+"%"});
statusArrayCollection = new ArrayCollection(statusArray);
}
private function onUploadComplete(event:Event):void
{
statusArray.push({status:"Uploaded successfully!"});
statusArrayCollection = new ArrayCollection(statusArray);
}
private function onUploadError(event:Event):void
{
if (event is IOErrorEvent)
{
statusArray.push({status:"IO Error: "+(event as IOErrorEvent).text.toString()});
statusArrayCollection = new ArrayCollection(statusArray);
}
else if (event is SecurityErrorEvent)
{
statusArray.push({status:"Security Error: "+(event as IOErrorEvent).text.toString()});
statusArrayCollection = new ArrayCollection(statusArray);
}
}
]]>
</mx:Script>
<mx:VBox height="40%" width="30%" horizontalGap="0" horizontalAlign="left">
<mx:HBox height="10%" width="100%" horizontalAlign="left">
<mx:VBox height="100%" width="30%" horizontalAlign="left">
<mx:Label text="File name"></mx:Label>
</mx:VBox>
<mx:VBox height="100%" width="40%" horizontalAlign="left">
<mx:TextInput id="fileTxt" width="200" editable="false" toolTip="Select File to upload"/>
</mx:VBox>
<mx:VBox height="100%" width="30%" horizontalAlign="left">
<mx:Button id="browseBut" label="Browse" click="browseFile(event)" />
</mx:VBox>
</mx:HBox>
<mx:HBox height="10%" width="100%" horizontalAlign="left">
<mx:VBox height="100%" width="30%" horizontalAlign="left">
<mx:Label text="Server URL"></mx:Label>
</mx:VBox>
<mx:VBox height="100%" width="70%" horizontalAlign="left">
<mx:TextInput id="urlTxt" width="290" text="{serverUrl}"/>
</mx:VBox>
</mx:HBox>
<mx:HBox height="10%" width="100%" horizontalAlign="center">
<mx:Button id="uploadBut" label="Upload file" click="uploadFile(event)" enabled="{fileSelected}" />
</mx:HBox>
<mx:HBox height="70%" width="100%" horizontalAlign="center">
<mx:DataGrid id="statusDG" width="100%" height="100%" dataProvider="{statusArrayCollection}" variableRowHeight="true" wordWrap="true">
<mx:columns>
<mx:DataGridColumn dataField="status" headerText="Upload Status" paddingLeft="0" paddingRight="0">
</mx:DataGridColumn>
</mx:columns>
</mx:DataGrid>
</mx:HBox>
</mx:VBox>
</mx:Panel>
</mx:Application>
服务器端的 Java Servlet 代码使用一个 Apache 的第三方类库 Commons FileUpload 包，它可以使我们的 servlets 或者 web 应用程序具有上传的功能。这个包可以从这里进行下载：http://commons.apache.org/fileupload/。Commons FileUpload 包内部使用了 Apache Commons IO 包，所以我们把这个包也下下来：http://commons.apache.org/io/。在本文的例子中，我使用的是 commons-fileupload-1.2.1.jar 和 commons-io-1.4.jar。将 commons-fileupload-1.2.1.jar、commons-io-1.4.jar 和 servlet-api.jar 复制到 RED5 项目的 /WEB-INF/lib 目录下。其中 servlet-api.jar 可以去 tomcat 安装目录下的 lib 文件夹下去找。
然后，在我们的 RED5 应用程序的 web.xml 文件夹下添加如下内容：
<servlet> <servlet-name>fileupload</servlet-name> <servlet-class>com.mycompany.ind.red5.FileUploadServlet</servlet-class> <init-param> <param-name>uploadFolder</param-name> <param-value>uploads</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>fileupload</servlet-name> <url-pattern>/fileupload</url-pattern> </servlet-mapping>
如果你熟悉 JEE，你会发现和 tomcat 的 web.xml 配置基本一致：servlet-mapping 元素将匹配 /fileupload 的 url 到名为 "fileupload" 的 servlet，servlet 元素则指示出该 servlet 具体实现类；上传的文件夹名作为 servlet 的初始参数也在这里进行定义，这里定义为 "uploads"，所以应该在我们的 RED5 项目根目录下创建一个同名文件夹。
最后，写具体实现上传的 FileUploadServlet 类：
package com.mycompany.ind.red5; 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.FileItemFactory; import org.apache.commons.fileupload.FileUploadException; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; import java.io.IOException; import java.util.Iterator; import java.util.List; import java.io.FileOutputStream; import java.io.FileNotFoundException; public class FileUploadServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { super.doGet(request, response); doPost(request,response); } @Override public void doPost( HttpServletRequest request, HttpServletResponse response ) { /** * Create a factory for new disk-based file items */ FileItemFactory factory = new DiskFileItemFactory(); /** * Create a new file upload handler */ ServletFileUpload upload = new ServletFileUpload(factory); try { /** * Parsing input request */ List items = upload.parseRequest(request); /** * Process the uploaded items */ Iterator iter = items.iterator(); while (iter.hasNext()) { FileItem item = (FileItem) iter.next(); /** * handling a normal form-field */ if (item.isFormField()) { System.out.println("A form field"); } else { /** * handling file uploads */ System.out.println("Not a form field"); String uploadFileName = item.getName(); byte[] data = item.get(); /** * Gets directory to which the file is to be uploaded */ String uploadFolder = getServletConfig().getInitParameter("uploadFolder"); String fileFolderName = getServletContext().getRealPath(uploadFolder + "\\"+uploadFileName); try { FileOutputStream fileOutSt = new FileOutputStream(fileFolderName); try { fileOutSt.write(data); fileOutSt.close(); } catch(IOException exception) { exception.printStackTrace(); } } catch(FileNotFoundException exception) { exception.printStackTrace(); } } } } catch(FileUploadException exception) { exception.printStackTrace(); } } }
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