[原]Struts2-文件上传与下载

[标题]:[原]Struts2-文件上传与下载
[时间]:2009-8-7
[摘要]:Struts FileUpload & Download
[关键字]:浪曦视频，Struts2应用开发系列，WebWork，Apache，上传，下载，upload，download，commons
[环境]:struts-2.1.6、JDK6、MyEclipse7、Tomcat6
[作者]:Winty (wintys@gmail.com) http://www.blogjava.net/wintys

[正文]:
1、Apache Commons
Struts文件上传下载使用commons-fileupload与commons-io，struts-2.1.6中已有commons-fileupload-1.2.1.jar与commons-io-1.3.2.jar。其源代码下载地址分别为:
http://commons.apache.org/fileupload/
http://commons.apache.org/io/

2、文件上传
a.Servlet文件上传原理
此时，应将web.xml中的Struts filter注释掉，不然会导致错误。

/StrutsHelloWorld/WebRoot/upload/upload.jsp主要内容:

......
<form name="upload"
       action="uploadServlet"
       method="post"
       enctype="multipart/form-data">

       用户名:<input type="text" name="user" /><br/>
       附件:<input type="file" name="attachment"/><br/>
       <input type="submit" name="submit" value="提交"/>
</form>
......

文件上传，需要设置method="post"，enctype="multipart/form-data"。enctype默认值为:application/x-www-form-urlencoded。

服务器端接收，并将原始信息输出。
/StrutsHelloWorld/src/wintys/struts2/upload/UploadServlet.java:

package wintys.struts2.upload;

import java.io.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
* Servlet文件上传原理示例
*
* @author Winty (wintys@gmail.com)
* @version 2009-8-1
* @see http://wintys.blogjava.net
*/
public class UploadServlet extends HttpServlet {
   private static final long serialVersionUID = -8676112500347837364L;

   public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       System.out.println("UploadServlet...");

       InputStream input = request.getInputStream();
       BufferedInputStream bis = new BufferedInputStream(input);

       String upfile = "c:/UploadedFile.txt";
       OutputStream os = new FileOutputStream(upfile);
       BufferedOutputStream bos = new BufferedOutputStream(os);

       final int bytesReaded = 128;
       byte[] buf = new byte[bytesReaded];
       int len = -1;
       while( (len = bis.read(buf, 0, bytesReaded)) != -1){
           bos.write(buf, 0, len);
       }
       bis.close();
       bos.close();

       response.setContentType("text/html;charset=GBK");
       PrintWriter out = response.getWriter();
       out.println("上传完成!存放于:" + upfile);
       out.close();
   }

   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp)
           throws ServletException, IOException {
       doPost(req , resp);
   }
}

在web.xml中的配置:
<servlet>
<servlet-name>UploadServlet</servlet-name>
<servlet-class>wintys.struts2.upload.UploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UploadServlet</servlet-name>
<url-pattern>/upload/uploadServlet</url-pattern>
</servlet-mapping>

b.使用apache commons上传文件
/StrutsHelloWorld/WebRoot/upload/commonsUpload.jsp:

......
<form name="upload"
       action="commonsUploadServlet"
       method="post"
       enctype="multipart/form-data">

       用户名:<input type="text" name="user" /><br/>
       附件:<input type="file" name="attachment"/><br/>
       <input type="submit" name="submit" value="提交"/>
</form>
......

/StrutsHelloWorld/src/wintys/struts2/upload/CommonsUploadServlet.java:

package wintys.struts2.upload;

import java.io.*;
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.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
* 使用Apache Commons FileUpload 上传单个文件
*
* @author Winty (wintys@gmail.com)
* @version 2009-8-5
* @see http://wintys.blogjava.net
*/
@SuppressWarnings("serial")
public class CommonsUploadServlet extends HttpServlet {

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

   @SuppressWarnings("unchecked")
   public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       //构造FileItemFactory工厂
       int sizeThreshold = 1024;
       File repository = new File("c:/upload/temp");
       repository.mkdirs();
       FileItemFactory factory = new DiskFileItemFactory(sizeThreshold,repository);

       //解析上传表单
       ServletFileUpload upload = new ServletFileUpload(factory);
       List<FileItem> items = null;
       try {
           items = upload.parseRequest(request);
       } catch (FileUploadException e) {
           System.err.println(e.getMessage());
           e.printStackTrace();
       }

       //分别处理简单表单和文件
       for(FileItem item : items){
           String name = item.getFieldName();
           String value = null;

           if(item.isFormField()){
               //获取简单表单项的内容
               value = item.getString("GBK");
           }
           else{
               //获取上传文件的原始名
               value = item.getName();

               //如果有包含路径，则去掉
               int slashIndex = -1;
               if((slashIndex = value.lastIndexOf('/')) != -1
                       || (slashIndex = value.lastIndexOf('""')) != -1){
                   value = value.substring(slashIndex + 1);
               }

               //写文件
               File parent = new File("c:/upload");
               parent.mkdirs();
               File fileStore = new File(parent , value);
               try {
                   item.write(fileStore);
               } catch (Exception e) {
                   e.printStackTrace();
               }
           }

           request.setAttribute(name, value);
       }

       request.getRequestDispatcher("/upload/result.jsp")
                  .forward(request, response);
   }
}

FileItem.isFormField()表示是否为file或简单表单项。

在web.xml中的配置:

<servlet>
   <servlet-name>CommonsUploadServlet</servlet-name>
   <servlet-class>wintys.struts2.upload.CommonsUploadServlet</servlet-class>
</servlet>
<servlet-mapping>
   <servlet-name>CommonsUploadServlet</servlet-name>
   <url-pattern>/upload/commonsUploadServlet</url-pattern>
</servlet-mapping>

c.Struts文件上传

/StrutsHelloWorld/WebRoot/upload/strutsUpload.jsp :

......
       <s:fielderror></s:fielderror>
       <form name="upload"
               action="strutsUpload"
               method="post"
               enctype="multipart/form-data">

               用户名:<input type="text" name="user" /><br/>
               附件:<input type="file" name="attachment"/><br/>
               <input type="submit" name="submit" value="提交"/>
       </form>
......

/StrutsHelloWorld/src/wintys/struts2/upload/UploadAction.java:
package wintys.struts2.upload;

import java.io.*;
import com.opensymphony.xwork2.ActionSupport;

/**
* 使用Struts上传单个文件
*
* @author Winty (wintys@gmail.com)
* @version 2009-8-5
* @see http://wintys.blogjava.net
*/
@SuppressWarnings("serial")
public class UploadAction extends ActionSupport {
   String user;
   File attachment;
   String attachmentFileName;
   String attachmentFileContentType;

   //此处省略了getter and setter...

   @Override
   public String execute() throws Exception {
       InputStream input = new FileInputStream(attachment);

       File parent = new File("c:/upload");
       parent.mkdirs();
       OutputStream output
           = new FileOutputStream(new File(parent , attachmentFileName));

       byte[] buf = new byte[1024*10];
       int len = -1;
       while((len = input.read(buf)) > 0){
           output.write(buf, 0, len);
       }

       input.close();
       output.close();

       return SUCCESS;
   }

   @Override
   public void validate() {
       if(attachment == null){
           addFieldError("attachment", "请选择上传的文件");
       }
   }
}

其中，"File attachment;"与form中的name相同<input type="file" name="attachment"/>。而"attachment"，又决定了attachmentFileName、attachmentFileContentType的名称。

/StrutsHelloWorld/WebRoot/upload/strutsResult.jsp:

Result:<br/>
user: ${ requestScope.user } <br/>
attachment: <br/>
${ requestScope.attachmentFileName }<BR/>

在struts.xml中的配置:

<action name="strutsUpload" class="wintys.struts2.upload.UploadAction">
<result name="success">/upload/strutsResult.jsp</result>
<result name="input">/upload/strutsUpload.jsp</result>
</action>

d.上传固定数量的文件

/StrutsHelloWorld/WebRoot/upload/strutsMultiFileUpload.jsp:

......
<s:fielderror></s:fielderror>
<form name="upload"
       action="strutsMultiFileUpload"
       method="post"
       enctype="multipart/form-data">

       用户名:<input type="text" name="user" /><br/>
       附件1:<input type="file" name="attachment"/><br/>
       附件2:<input type="file" name="attachment"/><br/>
       附件3:<input type="file" name="attachment"/><br/>
       <input type="submit" name="submit" value="提交"/>
</form>
......

/StrutsHelloWorld/src/wintys/struts2/upload/MultiFileUploadAction.java:

package wintys.struts2.upload;

import java.io.*;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.opensymphony.xwork2.ActionSupport;

/**
*
* @author Winty (wintys@gmail.com)
* @version 2009-8-6
* @see http://wintys.blogjava.net
*/
@SuppressWarnings("serial")
public class MultiFileUploadAction extends ActionSupport {
   String user;
   List<File> attachment;
   List<String> attachmentFileName;
   List<String> attachmentFileContentType;

   //此处省略了getter and setter...

   @Override
   public String execute() throws Exception {
       for(int i = 0 ; i < attachment.size(); i++){
           File attach = attachment.get(i);
           InputStream input = new FileInputStream(attach);

           File parent = new File("c:/upload");
           parent.mkdirs();
           File out = new File(parent , attachmentFileName.get(i));
           OutputStream output = new FileOutputStream(out);

           byte[] buf = new byte[1024];
           int len = -1;
           while((len = input.read(buf)) > 0){
               output.write(buf, 0, len);
           }

           input.close();
           output.close();
       }

       return SUCCESS;
   }

   @Override
   public void validate() {
       if(attachment == null){
           addFieldError("attachment", "请选择文件");
       }
   }

   /**
   * 当上传文件大小大于struts.multipart.maxSize提示时,
   * 客户端会出现如下错误:
   * "the request was rejected because its size (4501994)
   * exceeds the configured maximum (2097152)"。
   * 此信息在commons-fileupload.jar，
   * org.apache.commons.fileupload.FileUploadBase源代码中第904行。
   *
   * 重写addActionError()以替换默认信息。
   */
   @Override
   public void addActionError(String anErrorMessage) {
        //这里要先判断一下，是我们要替换的错误，才处理
       if (anErrorMessage.startsWith("the request was rejected because its size")) {
            //这些只是将原信息中的文件大小提取出来。
           Matcher m = Pattern.compile("""d+").matcher(anErrorMessage);
           String s1 = "";
           if (m.find())   s1 = m.group();
           String s2 = "";
           if (m.find())   s2 = m.group();
            //偷梁换柱，将信息替换掉
           super.addActionError("你上传的文件（" + s1 + "）超过允许的大小（" + s2 + "）");
       } else {//不是则不管它
           super.addActionError(anErrorMessage);
       }
   }
}

在web.xml中的配置:

<action name="strutsMultiFileUpload" class="wintys.struts2.upload.MultiFileUploadAction">
<result name="success">/upload/strutsResult.jsp</result>
<result name="input">/upload/strutsMultiFileUpload.jsp</result>
</action>

e.上传任意个数文件

wintys.struts2.upload.MultiFileUploadAction不需要改变，只需要修改strutsMultiFileUpload.jsp为
/StrutsHelloWorld/WebRoot/upload/strutsMultiUpload.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ taglib uri="/struts-tags" prefix="s"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <title>upload</title>
</head>
<style type="text/css">
   .attachLine{
       border: 1px solid #00C0EE;
       margin-bottom:10px;
   }
   .desc{
       display:inline;
       color:blue;
   }
   .attach{
       display:inline;
       border:1px solid #8800AA;
       margin-left:30px;
   }
   .remove{
       display: inline;
       margin-left:30px;
   }
</style>
<script type="text/javascript">
   var attachmentCounts = 1;

   function addMore(){
       if(attachmentCounts >= 5){
            window.alert("附件数不能大于" + 5);
            return;
        }
       attachmentCounts++;

       var attachment = document.getElementById("attachment");

       var line = document.createElement("div");
       line.setAttribute("class" , "attachLine");
       line.setAttribute("className" , "attachLine");//for IE

       //标签
       var descDiv = document.createElement("div");
       descDiv.setAttribute("class" , "desc");
       descDiv.setAttribute("className" , "desc");//for IE

       var desc = document.createTextNode("附件:");
       descDiv.appendChild(desc);
       line.appendChild(descDiv);

       //文件上传
       var attachDiv = document.createElement("div");
       attachDiv.setAttribute("class" , "attach");
       attachDiv.setAttribute("className" , "attach");//for IE

       var attach = document.createElement("input");
       attach.setAttribute("type" , "file");
       attach.setAttribute("name" , "attachment");
       attachDiv.appendChild(attach);
       line.appendChild(attachDiv);

       //移除
       var removeDiv = document.createElement("div");
       removeDiv.setAttribute("class" , "remove");
       removeDiv.setAttribute("className" , "remove");//for IE

       var remove = document.createElement("input");
       remove.setAttribute("type" , "button");
       remove.setAttribute("value" , "移除");
       remove.onclick = function removeLine(){
           attachmentCounts--;
           attachment.removeChild(line);
       }
       removeDiv.appendChild(remove);
       line.appendChild(removeDiv);


       attachment.appendChild(line);
   }
</script>
<body>
       <s:actionerror/>
       <s:fielderror></s:fielderror>
       <form name="upload"
               action="strutsMultiUpload"
               method="post"
               enctype="multipart/form-data">

               用户名:<input type="text" name="user" /><br/>

               <div id="attachment" >
                   <div>
                       <input type="button" value="增加附件个数" onclick="addMore();"/>
                   </div>
                   <div class="attachLine">
                      <div class="desc">附件:</div>
                      <div class="attach"><input type="file" name="attachment"/></div>
                   </div>
               </div>

               <input type="submit" name="submit" value="提交" />
       </form>
</body>
</html>

在struts.xml中的配置:

<action name="strutsMultiUpload" class="wintys.struts2.upload.MultiFileUploadAction">
<result name="success">/upload/strutsResult.jsp</result>
<result name="input">/upload/strutsMultiUpload.jsp</result>
</action>

f.文件上传相关配置
给文件上传拦截器fileUpload配置参数，在struts.xml中:

......
<interceptor name="myUploadInterceptor" class="wintys.struts2.upload.MyFileUploadInterceptor" />

<interceptor-stack name="myUploadStack">
   <interceptor-ref name="fileUpload">
       <param name="maximumSize">204800</param>
       <param name="allowedTypes">
           image/jpeg,image/pjpeg,text/plain,application/vnd.ms-powerpoint
       </param>
       <param name="allowedExtensions">txt,jpg</param>
   </interceptor-ref>
   <interceptor-ref name="myUploadInterceptor" />
   <interceptor-ref name="basicStack"/>
   <interceptor-ref name="validation"/>
   <interceptor-ref name="workflow"/>
</interceptor-stack>
......
<action name="strutsMultiUpload" class="wintys.struts2.upload.MultiFileUploadAction">
   <result name="success">/upload/strutsResult.jsp</result>
   <result name="input">/upload/strutsMultiUpload.jsp</result>
   <interceptor-ref name="myUploadStack"></interceptor-ref>
</action>

说明:
   a).allowedTypes：可以从tomcat/conf/web.xml中查得minetype。
   b).myUploadInterceptor: 自定义拦截器。对Struts fileUpload进行拦截，如果上传文件中出现错误，就直接返回到Action.INPUT;如果没有错误，则继续执行。
   c).validation: 进行校验。
   d).workflow: 保证validation中添加错误后，不再执行execute()。

如果不加myUploadInterceptor，会出现上传过大文件，给客户端提示出错信息后，还继续执行validate()方法。参照FileUploadInterceptor源代码，得到以下解决方案。
myUploadInterceptor=>wintys.struts2.upload.MyFileUploadInterceptor :
/StrutsHelloWorld/src/wintys/struts2/upload/MyFileUploadInterceptor.java:

package wintys.struts2.upload;

import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.ValidationAware;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;

/**
* 用于对Struts默认文件上传拦截器(FileUploadInterceptor)进行处理，
* 如果上传文件中出现错误，就直接返回到Action.INPUT;
* 没有错误，则继续执行。
*
* 配置如下:
* <interceptor name="myUploadInterceptor" class="wintys.struts2.upload.MyFileUploadInterceptor" />
* <interceptor-stack name="myUploadStack">
*        <interceptor-ref name="fileUpload">
*            <param name="maximumSize">204800</param>
*            <param name="allowedTypes">
*                image/jpeg,image/pjpeg,text/plain,application/vnd.ms-powerpoint
*            </param>
*            <param name="allowedExtensions">txt,jpg</param>
*        </interceptor-ref>
*        <interceptor-ref name="myUploadInterceptor" />
*        <interceptor-ref name="basicStack"/>
*        <interceptor-ref name="validation"/>
*        <interceptor-ref name="workflow"/>
*   </interceptor-stack>
* @author Winty (wintys@gmail.com)
* @version 2009-8-7
* @see http://wintys.blogjava.net
*/
@SuppressWarnings("serial")
public class MyFileUploadInterceptor extends AbstractInterceptor {

   @Override
   public String intercept(ActionInvocation invocation) throws Exception {
        ValidationAware validation = null;

        Object action = invocation.getAction();

        if (action instanceof ValidationAware) {
            validation = (ValidationAware) action;
        }

         //如果上传文件中出现错误，就直接返回到INPUT;没有错误，则继续执行
        String result = Action.INPUT;
        if(validation == null || !validation.hasErrors())
           result = invocation.invoke();

       return result;
   }
}

struts2-core-2.1.6.jar/org.apache.struts2/struts-message.properties定义了原始的提示信息。重定义提示信息，新建/StrutsHelloWorld/src/message.properties(与struts.xml相同目录):

#file upload 需要转换成unicode
struts.messages.error.file.too.large=文件过大:{1}
struts.messages.error.content.type.not.allowed=文件类型不允许:{1}
struts.messages.error.uploading=文件上传失败：发生内部错误

struts2-core-2.1.6.jar/org.apache.struts2/default.properties中定义了默认配置。自己改变配置默认(编码等)，在struts.xml中:

......

<constant name="struts.multipart.saveDir" value="c:/upload/temp"></constant>

<constant name="struts.i18n.encoding" value="GBK"></constant>

<constant name="struts.multipart.maxSize" value="2097152"></constant>
......

g.注意问题
文件过大的提示信息:
   当文件大小<maximumSize，正常上传。
   当maximumSize < 文件大小 < struts.multipart.maxSize提示struts.messages.error.file.too.large。
   当文件大小>struts.multipart.maxSize提示：
   "the request was rejected because its size (4501994) exceeds the configured maximum (2097152) "。

"the request was rejected..."这个信息是写死在代码中的(commons-fileupload-1.2.1.jar/org.apache.commons.fileupload.FileUploadBase 第902行)，没有做国际化，所以必须另外对待。直接修改FileUploadBase代码中的字符串，或override com.opensymphony.xwork2.ActionSupport.addActionError()。override addActionError()代码见/StrutsHelloWorld/src/wintys/struts2/upload/MultiFileUploadAction.java。

3、文件下载
/StrutsHelloWorld/WebRoot/upload/fileDownload.jsp:
......
<s:a href="strutsFileDownload.action" >点击这里下载文件</s:a>
......

/StrutsHelloWorld/src/wintys/struts2/upload/DownloadAction.java

package wintys.struts2.upload;

import java.io.*;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;

@SuppressWarnings("serial")
public class DownloadAction extends ActionSupport {

   public InputStream getDownloadFile(){
       String filepath = "/upload/fordownloadtest.ppt";
       InputStream is = ServletActionContext.getServletContext()
                                                              .getResourceAsStream(filepath);

       return is;
   }

   /**
   * struts.xml中配置如下:
   * <param name="contentDisposition">
   * attachment;filename="${fileName}"
   * </param>
   *
   * ${fileName}:表明需要在DownloadAction中提供getFileName()方法。
   *
   * @return 下载文件的文件名
   */
   public String getFileName(){
       String filename = "Test下载测试文件.ppt";

       String fn = "test.ppt";
       try {
           fn =new String(filename.getBytes() , "ISO8859-1");
       } catch (UnsupportedEncodingException e) {
           fn = "error.ppt";
           e.printStackTrace();
       }

       return fn;
   }

   @Override
   public String execute() throws Exception {
       return SUCCESS;
   }
}

在struts.xml中的配置:

<action name="strutsFileDownload" class="wintys.struts2.upload.DownloadAction">
   <result name="success" type="stream">
       <param name="contentType">application/octet-stream</param>
       <param name="inputName">downloadFile</param>
       <param name="contentDisposition">attachment;filename="${fileName}"</param>
   </result>
</action>

说明:
   a).inputName=downloadFile，指明DownloadAction中public InputStream getDownloadFile()返回文件流。
   b).type="stream"，说明使用org.apache.dispatcher.StreamResult处理这个result。
   c).contentDisposition、contentType等属性可以在<param>里配置，也可以在DownloadAction中直接提供getter。

[参考资料]:
[1] 《浪曦视频之Struts2应用开发系列》
[2] 谈谈我对Struts2文件上传的理解 : http://www.javaeye.com/topic/287800
[3] Struts2中文件上传错误提示信息the request was rejected because its size的解决办法 : http://www.blogjava.net/cmzy/archive/2009/04/15/265703.html
[4] 理解和灵活应用 Struts2 的文件下载功能 : http://www.blogjava.net/Unmi/archive/2009/06/17/282780.html

[附件]:
    源代码 : http://www.blogjava.net/Files/wintys/Struts_FileUpload_Download.zip

posted on 2009-08-08 08:48 天堂露珠阅读(2217) 评论(0) 编辑收藏所属分类: Struts

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