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如何用struts上传文件,并限制文件扩展名和文件大小.

2010-08-17 10:41 489 查看
在做开发时难免会碰到上传文件,近来我就来和大家分享一下心得,供大家讨论.多提宝贵意见.

在struts中上传文件当然要用struts的标签了,<html:file>.用该标签是需要注意以下几点:

<html:file> 该标签必须和,<html:form>一起使用并且必须嵌套在<html:form>中,其实struts的html标签必须要写在<html:form>中.

<html:form>中的method属性必须是post

.

<html:form>的enctype属性必须是multipart/form-data

<html:file>必须设置property

属性,并且该属性的值必须和ActionFormBean 中的 org.apache.struts.upload.FormFile类型属性对应.

upload.jsp代码如下:

<%...@ page language="java" pageEncoding="utf-8"%>
<%...@ taglib uri="http://jakarta.apache.org/struts/tags-bean"
prefix="bean"%>
<%...@ taglib uri="http://jakarta.apache.org/struts/tags-html"
prefix="html"%>
<%...@ taglib uri="http://jakarta.apache.org/struts/tags-logic"
prefix="logic"%>
<%...@ taglib uri="http://jakarta.apache.org/struts/tags-tiles"
prefix="tiles"%>
<%...@ taglib uri="http://jakarta.apache.org/struts/tags-template"
prefix="template"%>
<%...@ taglib uri="http://jakarta.apache.org/struts/tags-nested"
prefix="nested"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html:html locale="true">
<head>
<html:base />
<title>upload.jsp</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css" mce_href="styles.css">
-->
</head>
<body>
<h3>
上传文件测试
</h3>
<html:form action="upload.do" method="post" enctype="multipart/form-data">
<html:file property="file"></html:file><br>
<html:submit></html:submit>
</html:form>
</body>
</html:html>


(upload.jsp)

大家注意upload.jsp中<html:file> 的property属性.该值和actionfrom的属性相同,HtmlfileForm代码如下

/**//*
* Generated by MyEclipse Struts
* Template path: templates/java/JavaClass.vtl
*/
package com.uploadtest.struts.form;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.upload.FormFile;
/** *//**
* MyEclipse Struts Creation date: 02-29-2008
*
* XDoclet definition:
*
* @struts.form name="htmlfileForm"
*/
public class HtmlfileForm extends ActionForm ...{
/**//*
* Generated Methods
*/
private FormFile file;
public FormFile getFile() ...{
return file;
}
public void setFile(FormFile file) ...{
this.file = file;
}
/** *//**
* Method validate
*
* @param mapping
* @param request
* @return ActionErrors
*/
public ActionErrors validate(ActionMapping mapping,
HttpServletRequest request) ...{
// TODO Auto-generated method stub
return null;
}
/** *//**
* Method reset
*
* @param mapping
* @param request
*/
public void reset(ActionMapping mapping, HttpServletRequest request) ...{
// TODO Auto-generated method stub
}
}


（HtmlfileForm)

然后就是最主要的处理代码部分代码如下(UploadAction),在该Action中做了很多处理,都有注释,自己看.

/**//*
* Generated by MyEclipse Struts
* Template path: templates/java/JavaClass.vtl
*/
package com.uploadtest.struts.action;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.upload.FormFile;
import com.uploadtest.struts.form.HtmlfileForm;
/** *//**
* MyEclipse Struts Creation date: 02-29-2008
*
* XDoclet definition:
*
* @struts.action path="/upload" name="htmlfileForm" input="/upload.jsp"
*                scope="request" validate="true"
*/
public class UploadAction extends Action ...{
/**//*
* Generated Methods
*/
/** *//**
* Method execute
*
* @param mapping
* @param form
* @param request
* @param response
* @return ActionForward
*/
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) ...{
// webapps/uploadtest/upload
String dir = servlet.getServletContext().getRealPath("/upload");
List<String> list = new ArrayList<String>();//注意文件类型最好全部用小写
list.add("jpg");
list.add("jpeg");
list.add("gif");
list.add("bmp");
// 允许上传的文件类型列表可以写在配置文件中，通过xml的解析获得。
if (!dir.endsWith("/"))
dir = dir.concat("/");
HtmlfileForm htmlfileForm = (HtmlfileForm) form;// TODO Auto-generated
// method stub
FormFile file = htmlfileForm.getFile();
if (file == null) ...{
return mapping.getInputForward();
}
String fname = file.getFileName();// 获取文件名
int fsize = file.getFileSize();// 获取文件大小
String ext = fname.substring(fname.lastIndexOf(".") + 1, fname.length());
// 获取文件类型，即扩展名,通过String类的substring方法截取字符串，lastIndexOf获取某个字符串最后出现的索引。
ext = ext.toLowerCase();// 全部转换成小写。
if (!list.contains(ext)) ...{// 判断该类型是否为允许上传的文件类型
System.out.println("不支持该文件类型上传，该文件类型是：" + ext);
// 可以在此构建ActionMessage对象并返回页面显示错误
return mapping.getInputForward();
}
if (fsize > 1024 * 1024) ...{// 判断文件大小是否为允许上传的大小。
// 可以在此构建ActionMessage对象并返回页面显示错误
System.out.println("文件太大");
return mapping.getInputForward();
}
InputStream in = null;// 输入流用来读取用户上传文件
OutputStream out = null;// 用来将用户上传文件存出在服务器特定目录中。
try ...{
in = file.getInputStream();
out = new FileOutputStream(dir + fname);
int byteread = 0;
byte[] bytes = new byte[8192];
while ((byteread = in.read(bytes, 0, 8192)) != -1) ...{
out.write(bytes, 0, byteread);
}
} catch (Exception e) ...{
System.out.println(e.getMessage());
return mapping.getInputForward();
} finally ...{
try ...{
in.close();
out.close();
} catch (Exception e) ...{
System.out.println(e.getMessage());
return mapping.getInputForward();
}
}
System.out.println("chenggong");
return mapping.findForward("suc");//suc只是一个成功跳转的设置.
}
}


(UploadAction)

以下是struts的配置文件.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN" "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd">
<struts-config>
<data-sources />
<form-beans>
<form-bean name="htmlfileForm"
type="com.uploadtest.struts.form.HtmlfileForm" />

</form-beans>
<global-exceptions />
<global-forwards />
<action-mappings>
<action attribute="htmlfileForm" input="/upload.jsp"
name="htmlfileForm" path="/upload" scope="request"
type="com.uploadtest.struts.action.UploadAction">
<forward name="suc" path="/suc.jsp" />
</action>

</action-mappings>
<controller processorClass="com.uploadtest.struts.util.CharSet"></controller>
<message-resources
parameter="com.uploadtest.struts.ApplicationResources" />
</struts-config>
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