struts2文件上传和下载

1. struts系统中的拦截器介绍

过滤器：javaweb中的服务器组件，主要针对的请求和响应进行拦截。

拦截器：主要针对方法的调用，进行拦截器，当使用代理对象调用某个方法时候

对方法的调用进行拦截，对拦截到的方法可以进行扩展，增强

Struts2中的拦截器主要针对Action中方法的调用进行拦截

 <interceptors>
  <!—声明n个拦截器-->
     <interceptor name="fileUpload"
         class="org.apache.struts2.interceptor.FileUploadInterceptor" />
     <interceptor name="i18n"
         class="com.opensymphony.xwork2.interceptor.I18nInterceptor" />
     <interceptor name="logger"
         class="com.opensymphony.xwork2.interceptor.LoggingInterceptor" />
     <interceptor name="modelDriven"
         class="com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor" />
     <interceptor name="params"
         class="com.opensymphony.xwork2.interceptor.ParametersInterceptor" />
     <interceptor name="staticParams"
         class="com.opensymphony.xwork2.interceptor.StaticParametersInterceptor" />
     <interceptor name="token"
         class="org.apache.struts2.interceptor.TokenInterceptor" />
     <interceptor name="tokenSession"
         class="org.apache.struts2.interceptor.TokenSessionStoreInterceptor" />
  <!—由已经声明的n个拦截器，组成拦截器栈-->
     <interceptor-stack name="defaultStack">
         <interceptor-ref name="exception" />
         <interceptor-ref name="alias" />
         <interceptor-ref name="servletConfig" />
         <interceptor-ref name="i18n" />
         <interceptor-ref name="prepare" />
         <interceptor-ref name="chain" />
         <interceptor-ref name="scopedModelDriven" />
         <interceptor-ref name="modelDriven" />
         <interceptor-ref name="fileUpload" />
         <interceptor-ref name="checkbox" />
         <interceptor-ref name="multiselect" />
         <interceptor-ref name="staticParams" />
         <interceptor-ref name="actionMappingParams" />
         <interceptor-ref name="params">
             <param name="excludeParams">^class\..*,^dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,^parameters\..*,^action:.*,^method:.*
             </param>
         </interceptor-ref>
         <interceptor-ref name="conversionError" />
         <interceptor-ref name="validation">
             <param name="excludeMethods">input,back,cancel,browse</param>
         </interceptor-ref>
         <interceptor-ref name="workflow">
             <param name="excludeMethods">input,back,cancel,browse</param>
         </interceptor-ref>
         <interceptor-ref name="debugging" />
         <interceptor-ref name="deprecation" />
     </interceptor-stack>
 </interceptors>
 <default-interceptor-ref name="defaultStack" />
 </package>
  

拦截器栈：

a --> b --> c --> execute() --> c --> b --> a

2.文件上传

2.1 Action

 /*** 处理文件上传的请求 **/
 public class FileAction
 {
     // org.apache.struts2.interceptor.FileUploadInterceptor
     // 1 定义文件上传需要的特定属性
     private File img; // 上传的文件对象
     private String imgContentType;// 上传的文件的内容的类型
     private String imgFileName;// 上传的文件名称
     private String path; // 文件保存到服务器上的目录

     public String getPath()
     {
         return path;
     }

     public void setPath(String path)
     {
         this.path = path;
     }

     public File getImg()
     {
         return img;
     }

     public void setImg(File img)
     {
         this.img = img;
     }

     public String getImgContentType()
     {
         return imgContentType;
     }

     public void setImgContentType(String imgContentType)
     {
         this.imgContentType = imgContentType;
     }

     public String getImgFileName()
     {
         return imgFileName;
     }

     public void setImgFileName(String imgFileName)
     {
         this.imgFileName = imgFileName;
     }

     /*** 处理文件上传的请求 ****/
     public String uploadFile()
     {
         System.out.println(img);
         System.out.println(imgContentType);
         System.out.println(imgFileName);
         // 修改文件名
         String fname = UUID.randomUUID()
                 + imgFileName.substring(imgFileName.lastIndexOf("."));
         // 将上传的文件对象img保存到服务器的指定目录
         // 1获得path的绝对路径
         String pth = ServletActionContext.getServletContext().getRealPath(path);
         // 2在pth下创建文件
         File file = new File(pth, fname);
         // 3将img内容拷贝file中
         try
         {
             FileUtils.copyFile(img, file);
         }
         catch (IOException e)
         {
             e.printStackTrace();
         }
         return Action.SUCCESS;
     }
 }

2.2 struts.xml 配置 1 <?xml version="1.0" encoding="UTF-8"?>

  <!DOCTYPE struts PUBLIC
     "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
     "http://struts.apache.org/dtds/struts-2.3.dtd">
 <struts>
     <package name="file" namespace="/" extends="struts-default">
         <interceptors>
             <!-- 自定义拦截器栈 -->
             <interceptor-stack name="mystack">
                 <!-- 引用系统文件上传的拦截器 -->
                 <interceptor-ref name="fileUpload">
                     <param name="allowedExtensions">txt,jpg,doc</param>
                     <!-- 其他属性的赋值同理 -->
                 </interceptor-ref>
　　　　　　<interceptor-ref name="staticParams"></interceptor-ref>
                 <!-- 引用系统基本拦截器栈 -->
                 <interceptor-ref name="basicStack" />
             </interceptor-stack>
         </interceptors>
         <action name="fileAction_*" class="com.guangsoft.action.FileAction"
             method="{1}">
             <!-- 引用自定义的拦截器栈 -->
             <interceptor-ref name="mystack"></interceptor-ref>
             <!-- 给path属性赋值 -->
             <param name="path">filedir</param>
             <result>/index.jsp</result>
         </action>
     </package>
 </struts>

2.3实现UI页面

 <form action="fileAction_uploadFile.action" method="post"
     enctype="multipart/form-data">
     <input type="file" name="img" />
     <input type="submit" />
 </form>

3.文件下载

3.1 Action

 //org.apache.struts2.dispatcher.StreamResult
 public class DownloadAction
 {
     private InputStream inputStream;
     private String fname;// 需要下载的文件的名字

     public InputStream getInputStream()
     {
         System.out.println("----------getInputStream");
         return inputStream;
     }

     public String getFname()
     {
         return fname;
     }

     public void setFname(String fname)
     {
         this.fname = fname;
     }

     /*** 实现文件下载 ***/
     public String download()
     {
         System.out.println("----------download");
         // 获得附件的保存目录
         String path = ServletActionContext.getServletContext().getRealPath(
                 "filedir");
         // 将下载的文件封装为InputStream的对象
         try
         {
             inputStream = new FileInputStream(path + "/" + fname);
         }
         catch (FileNotFoundException e)
         {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         return Action.SUCCESS;
     }
 }

3.2 struts.xml 配置：

 <package name="down" namespace="/down" extends="struts-default">
     <action name="downloadAction_*" class="com.guangsoft.action.DownloadAction"
         method="{1}">
         <result type="stream">
             <param name="inputName">inputStream</param>
             <!-- 指定下载的附件的类型 -->
             <param name="contentType">application/octet-stream</param>
             <!-- 指定下载的附件的名称 -->
             <param name="contentDisposition">attachment;filename=${fname}</param>
         </result>
     </action>
 </package>