java+flex怎么上传文件

Question

java和flex通讯使用的BlazeDs组件.怎么实现flex+java的上传功能,后台使用的是hibernate+spring,没有使用servlet. 最好能写出例子,谢谢!

Answer 1

关于flex上传功能的实现依赖于FileReference类。该类实例对象的创建有两种方法：使用var myFileReference = new FileReference(); FileReferenceList.browse()。使用browse()或者FileReference.browse()方法可以打开上传窗口。
下面部分资源来自互联网，一个简单的上传组件代码，包括了监听ProgressEvent，选择的selectEvent和完成的completeEvent。为了避免硬编码，将urlRequest路径配置在一个xml里面，使用了httpservice进行请求，将结果用于UrlRequest的参数。这个HttpService采用了resultFormat="e4x"，那么要求返回来值为XML类型的

Flex上传需要两个包apache common fileupload.jar和apache common io.jar
下载地址
http://jakarta.apache.org/commons/fileupload/
http://commons.apache.org/io/download_io.cgi

upload.mxml
Xml代码

<?xml version="1.0" encoding="utf-8"?>

xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600"
creationComplete="init()">

<fx:Declarations>  
    <!-- 将非可视元素（例如服务、值对象）放在此处 -->  
    <mx:HTTPService id="httpService" resultFormat="e4x"/>     
</fx:Declarations>  

<fx:Script>  
    <![CDATA[ 
        import mx.rpc.events.FaultEvent;    
        import mx.rpc.events.ResultEvent;    
        import flash.net.FileReference;    
        import mx.controls.Alert;    
        import mx.events.CloseEvent;    
        import flash.events.*;    

        private var file:FileReference;    

        private var filePath:String="";    
        private function init():void   
        {    
            Security.allowDomain("*");    
            file=new FileReference();    
            file.addEventListener(ProgressEvent.PROGRESS, onProgress);    
            file.addEventListener(Event.SELECT, onSelect);    
            file.addEventListener(Event.COMPLETE,fileUploadCompleteHandler);    

            httpService.url="config.xml";    
            httpService.showBusyCursor=true;    
            httpService.send();    
            httpService.addEventListener(ResultEvent.RESULT,hsResultHandler);    
            httpService.addEventListener(FaultEvent.FAULT,hsFaultHandler);    
        }    

        private function hsResultHandler(e:ResultEvent):void{    
            var xml:XML=e.result as XML;    
            filePath=xml.filepath.@path;    
        }    

        private function hsFaultHandler(e:FaultEvent):void{    
            Alert.show(e.fault.toString(),'http请求错误');    
        }    

        private function fileUploadCompleteHandler(e:Event):void{    
            Alert.show("上传完成");    
            vBox.removeChild(bar);    
        }    

        private function upload():void   
        {    
            var imageTypes:FileFilter=new FileFilter("Images (*.jpg, *.jpeg, *.png)", "*.jpg;*.jpeg;*.png");    
            var docFilter:FileFilter = new FileFilter("Documents", "*.pdf;*.doc;*.txt"); 
            //var viewFilter:FileFilter = new FileFilter("Views", "*.avi;*.flv;*.rmvb"); 
            var allTypes:Array=new Array(imageTypes,docFilter);    
            //              file.browse(allTypes);    
            file.browse();    
        }    

        private function onSelect(e:Event):void   
        {    
            Alert.show("上传 " + file.name + " (共 " + Math.round(file.size) + " 字节)?", "确认上传", Alert.YES | Alert.NO, null, proceedWithUpload);    
        }    

        private function onProgress(e:ProgressEvent):void   
        {    
            lbProgress.text=" 已上传 " + e.bytesLoaded + " 字节，共 " + e.bytesTotal + " 字节";    
            var proc:uint=e.bytesLoaded / e.bytesTotal * 100;    
            bar.setProgress(proc, 100);    
            bar.label="当前进度: " + " " + proc + "%";    
        }    

        private function proceedWithUpload(e:CloseEvent):void   
        {    
            if (e.detail == Alert.YES)    
            {    
                var request:URLRequest=new URLRequest(filePath);    
                try   
                {    
                    file.upload(request);    
                }    
                catch (error:Error)    
                {    
                    trace("上传失败");    
                }    

            }    
        }    


    ]]>  
</fx:Script>  


<mx:Canvas width="100%"    
           height="100%"    
           x="10"    
           y="170"    
           fontSize="15">     
    <mx:VBox width="100%"    
             horizontalAlign="center" id="vBox">     
        <mx:Label id="lbProgress"    
                  text="上传"/>     
        <mx:ProgressBar id="bar"    
                        labelPlacement="bottom"    
                        minimum="0"    
                        visible="true"    
                        maximum="100"    
                        label="当前进度: 0%"    
                        direction="right"    
                        mode="manual"    
                        width="200"/>     

        <mx:Button label="上传文件"    
                   click="upload();"/>     
    </mx:VBox>     
</mx:Canvas>     

/s:Application

config.xml

Xml代码

<?xml version="1.0" encoding="UTF-8"?>

UploadServlet

Java代码

package com.test.upload;

import java.io.File;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.Iterator;

import java.util.List;

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 {

// 定义文件的上传路径

private String uploadPath = "c:\";

// 限制文件的上传大小

private int maxPostSize = 10000000 * 1024 * 1024;

protected void processRequest(HttpServletRequest request,  
        HttpServletResponse response) throws ServletException, IOException {  
    System.out.println("Access !");  
    System.out.println(uploadPath);  
    // 防止中文乱码  
    request.setCharacterEncoding("utf-8");  
    response.setContentType("text/html;charset=UTF-8");  
    PrintWriter out = response.getWriter();  
    // 保存文件到服务器中  
    DiskFileItemFactory factory = new DiskFileItemFactory();  
    factory.setSizeThreshold(4096);  
    ServletFileUpload upload = new ServletFileUpload(factory);  
    upload.setSizeMax(maxPostSize);  
    try {  
        List fileItems = upload.parseRequest(request);  
        Iterator iter = fileItems.iterator();  
        while (iter.hasNext()) {  
            FileItem item = (FileItem) iter.next();  
            if (!item.isFormField()) {  
                String name = item.getName();  
                System.out.println(name);  
                try {  
                    item.write(new File(uploadPath + name));  
                    // SaveFile s = new SaveFile();  

                    // s.saveFile(name);  

                } catch (Exception e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
    } catch (FileUploadException e) {  
        e.printStackTrace();  
        System.out.println(e.getMessage() + "结束");  
    }  
}  

protected void doGet(HttpServletRequest request,  
        HttpServletResponse response) throws ServletException, IOException {  
    this.doPost(request, response);  
}  

protected void doPost(HttpServletRequest request,  
        HttpServletResponse response) throws ServletException, IOException {  
    processRequest(request, response);  
}  

}

最后，说一下Flex的FileFilter 的用法
FileFilter 类用于指示在调用 FileReference.browse() 方法、FileReferenceList.browse() 方法或调用 File、FileReference 或 FileReferenceList 对象的 browse 方法时显示的文件浏览对话框中显示用户系统上的哪些文件。FileFilter 实例作为可选 typeFilter 参数的值传递给该方法。如果使用 FileFilter 实例，则会滤除 FileFilter 实例中未指定的扩展名和文件类型，即用户无法选择这些类型。如果未向方法传递任何 FileFilter 对象，则对话框中将显示所有文件。
可以采用以下两种方式之一使用 FileFilter 实例：
仅包含 文件扩展名的描述
包含 文件扩展名和 Macintosh 文件类型的描述
这两种格式不能在一个 browse 方法调用中互换。必须使用其中一种格式。
可以向 browse 方法传递一个或多个 FileFilter 实例，如下所示：
var imagesFilter:FileFilter = new FileFilter("Images", "*.jpg;*.gif;*.png");
var docFilter:FileFilter = new FileFilter("Documents", "*.pdf;*.doc;*.txt");
var myFileReference:FileReference = new FileReference();
myFileReference.browse([imagesFilter, docFilter]);
或者在 AIR 应用程序中：
var imagesFilter:FileFilter = new FileFilter("Images", "*.jpg;*.gif;*.png");
var docFilter:FileFilter = new FileFilter("Documents", "*.pdf;*.doc;*.txt");
var myFile:File = new File();
myFile.browseForOpen("Open", [imagesFilter, docFilter]);
var imagesFilter = new air.FileFilter("Images", "*.jpg;*.gif;*.png");
var docFilter = new air.FileFilter("Documents", "*.pdf;*.doc;*.txt");
var myFile = new air.File();
myFile.browseForOpen("Open", [imagesFilter, docFilter]);
FileFilter.extension 属性中的扩展名列表用于筛选文件浏览对话框中显示的文件。该列表实际并不显示在对话框中；若要对用户显示文件类型，必须在描述字符串以及扩展名列表中列出文件类型。