在Struts 2中实现文件上传（2）

来源：互联网发布：儿童舞蹈包淘宝编辑：程序博客网时间：2024/06/07 08:21

在Struts 2中实现文件上传（2）

来源：chinaitlab [2007-04-18] 作者：admin 编辑：admin

下面我们就来看看上传成功的页面：
<% @ page language = " java " contentType = " text/html; charset=utf-8 " pageEncoding = " utf-8 " %>
<% @ taglib prefix = " s " uri = " /struts-tags " %>
<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >
< html xmlns ="http://www.w3.org/1999/xhtml" >
< head >
    < title > Struts 2 File Upload </ title >
</ head >
< body >
    < div style ="padding: 3px; border: solid 1px #cccccc; text-align: center" >
        < img src ='UploadImages/<s:property value ="imageFileName" /> ' />
        < br />
        < s:property value ="caption" />
    </ div >
</ body >
</ html > 清单4 ShowUpload.jsp
ShowUpload.jsp获得imageFileName，将其UploadImages组成URL，从而将上传的图像显示出来。
然后是Action的配置文件：
<? xml version="1.0" encoding="UTF-8" ?>
<! DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd" >
< struts >
    < package name ="fileUploadDemo" extends ="struts-default" >
        < action name ="fileUpload" class ="tutorial.FileUploadAction" >
            < interceptor-ref name ="fileUploadStack" />
            < result name ="success" > /ShowUpload.jsp </ result >
        </ action >
    </ package >
</ struts >
fileUpload Action显式地应用fileUploadStack的拦截器。
最后是web.xml配置文件：
<? xml version="1.0" encoding="UTF-8" ?>
< web-app id ="WebApp_9" version ="2.4"
    xmlns ="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation ="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" >
    < display-name > Struts 2 Fileupload </ display-name >
    < filter >
        < filter-name > struts-cleanup </ filter-name >
        < filter-class >
            org.apache.struts2.dispatcher.ActionContextCleanUp
        </ filter-class >
    </ filter >

    < filter >
        < filter-name > struts2 </ filter-name >
        < filter-class >
            org.apache.struts2.dispatcher.FilterDispatcher
        </ filter-class >
    </ filter >

    < filter-mapping >
        < filter-name > struts-cleanup </ filter-name >
        < url-pattern > /* </ url-pattern >
    </ filter-mapping >
    < filter-mapping >
        < filter-name > struts2 </ filter-name >
        < url-pattern > /* </ url-pattern >
    </ filter-mapping >
    < welcome-file-list >
        < welcome-file > index.html </ welcome-file >
    </ welcome-file-list >
</ web-app >
更多配置
在运行上述例子，如果您留心一点的话，应该会发现服务器控制台有如下输出：
Mar 20 , 2007 4 : 08 : 43 PM org.apache.struts2.dispatcher.Dispatcher getSaveDir
INFO: Unable to find 'struts.multipart.saveDir' property setting. Defaulting to javax.servlet.context.tempdir
Mar 20 , 2007 4 : 08 : 43 PM org.apache.struts2.interceptor.FileUploadInterceptor intercept
INFO: Removing file myFile C:/Program Files/Tomcat 5.5 /work/Catalina/localhost/Struts2_Fileupload/upload_251447c2_1116e355841__7ff7_00000006.tmp 清单9 服务器控制台输出
上述信息告诉我们，struts.multipart.saveDir没有配置。struts.multipart.saveDir用于指定存放临时文件的文件夹，该配置写在struts.properties文件中。例如，如果在struts.properties文件加入如下代码：
struts.multipart.saveDir = /tmp 清单10 struts配置
这样上传的文件就会临时保存到你根目录下的tmp文件夹中（一般为c:/tmp），如果此文件夹不存在，Struts 2会自动创建一个。

百事通

错误处理
上述例子实现的图片上传的功能，所以应该阻止用户上传非图片类型的文件。在Struts 2中如何实现这点呢？其实这也很简单，对上述例子作如下修改即可。
首先修改FileUpload.jsp，在<body>与<s:form>之间加入“<s:fielderror />”，用于在页面上输出错误信息。
然后修改struts.xml文件，将Action fileUpload的定义改为如下所示：
        < action name ="fileUpload" class ="tutorial.FileUploadAction" >
            < interceptor-ref name ="fileUpload" >
                < param name ="allowedTypes" >
                    image/bmp,image/png,image/gif,image/jpeg
                </ param >
            </ interceptor-ref >
            < interceptor-ref name ="defaultStack" />
            < result name ="input" > /FileUpload.jsp </ result >
            < result name ="success" > /ShowUpload.jsp </ result >
        </ action > 清单11 修改后的配置文件
显而易见，起作用就是fileUpload拦截器的allowTypes参数。另外，配置还引入defaultStack它会帮我们添加验证等功能，所以在出错之后会跳转到名称为“input”的结果，也即是FileUpload.jsp。
多文件上传
与单文件上传相似，Struts 2实现多文件上传也很简单。你可以将多个<s:file />绑定Action的数组或列表。如下例所示。
< s:form action ="doMultipleUploadUsingList" method ="POST" enctype ="multipart/form-data" >
    < s:file label ="File (1)" name ="upload" />
    < s:file label ="File (2)" name ="upload" />
    < s:file label ="FIle (3)" name ="upload" />
    < s:submit />
</ s:form > 清单14 多文件上传JSP代码片段
如果你希望绑定到数组，Action的代码应类似：
     private File[] uploads;
     private String[] uploadFileNames;
     private String[] uploadContentTypes;
     public File[] getUpload()  { return this .uploads; }
      public void setUpload(File[] upload)  { this .uploads = upload; }

      public String[] getUploadFileName()  { return this .uploadFileNames; }
      public void setUploadFileName(String[] uploadFileName)  { this .uploadFileNames = uploadFileName; }

      public String[] getUploadContentType()  { return this .uploadContentTypes; }
      public void setUploadContentType(String[] uploadContentType)  { this .uploadContentTypes = uploadContentType; } 清单15 多文件上传数组绑定Action代码片段
如果你想绑定到列表，则应类似：
     private List < File > uploads = new ArrayList < File > ();
     private List < String > uploadFileNames = new ArrayList < String > ();
     private List < String > uploadContentTypes = new ArrayList < String > ();
     public List < File > getUpload()  {
         return this .uploads;
    }
      public void setUpload(List < File > uploads)  {
         this .uploads = uploads;
    }

      public List < String > getUploadFileName()  {
         return this .uploadFileNames;
    }
      public void setUploadFileName(List < String > uploadFileNames)  {
         this .uploadFileNames = uploadFileNames;
    }

      public List < String > getUploadContentType()  {
         return this .uploadContentTypes;
    }
      public void setUploadContentType(List < String > contentTypes)  {
         this .uploadContentTypes = contentTypes;
    }