使用 Flex 和Java servlets 将文件上传到 RED5 服务器的步骤

使用 Flex 和Java servlets 将文件上传到 RED5 服务器的步骤

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? ? ? ? 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();
    }
  }
}

? ? ? ? 如有问题，欢迎和作者进行在线交流，MSN：defonds#hotmail.com；email：defonds(at)163(dot)com。

博客原文地址：http://tharas.wordpress.com/2009/12/20/upload-files-to-red5-server/。