文件上传

    package tutorial;

     import java.io.BufferedInputStream;
     import java.io.BufferedOutputStream;
     import java.io.File;
     import java.io.FileInputStream;
     import java.io.FileOutputStream;
     import java.io.InputStream;
     import java.io.OutputStream;
     import java.util.Date;

     import org.apache.struts2.ServletActionContext;

     import com.opensymphony.xwork2.ActionSupport;

     public class FileUploadAction extends ActionSupport  {
         private static final long serialVersionUID = 572146812454l ;
         private static final int BUFFER_SIZE = 16 * 1024 ;

         private File myFile;
         private String contentType;
         private String fileName;
         private String imageFileName;
         private String caption;

         public void setMyFileContentType(String contentType)  {
             this .contentType = contentType;
        }

         public void setMyFileFileName(String fileName)  {
             this .fileName = fileName;
        }

         public void setMyFile(File myFile)  {
             this .myFile = myFile;
        }

         public String getImageFileName()  {
             return imageFileName;
        }

         public String getCaption()  {
             return caption;
        }

          public void setCaption(String caption)  {
             this .caption = caption;
        }

         private static void copy(File src, File dst)  {
             try  {
                InputStream in = null ;
                OutputStream out = null ;
                 try  {
                    in = new BufferedInputStream( new FileInputStream(src), BUFFER_SIZE);
                    out = new BufferedOutputStream( new FileOutputStream(dst), BUFFER_SIZE);
                     byte [] buffer = new byte [BUFFER_SIZE];
                     while (in.read(buffer) > 0 )  {
                        out.write(buffer);
                    }
                 } finally  {
                     if ( null != in)  {
                        in.close();
                    }
                      if ( null != out)  {
                        out.close();
                    }
                }
             } catch (Exception e)  {
                e.printStackTrace();
            }
        }

         private static String getExtention(String fileName)  {
             int pos = fileName.lastIndexOf( " . " );
             return fileName.substring(pos);
        }

        @Override
         public String execute()      {
            imageFileName = new Date().getTime() + getExtention(fileName);
            File imageFile = new File(ServletActionContext.getServletContext().getRealPath( " /UploadImages " ) + " / " + imageFileName);
            copy(myFile, imageFile);
             return SUCCESS;
        }

    }

    在FileUploadAction中我分别写了setMyFileContentType、setMyFileFileName、setMyFile和setCaption四个Setter方法，后两者很容易明白，分别对应FileUpload.jsp中的<s:file/>和<s:textfield/>标志。但是前两者并没有显式地与任何的页面标志绑定，那么它们的值又是从何而来的呢？其实，<s:file/>标志不仅仅是绑定到myFile，还有myFileContentType（上传文件的MIME类型）和myFileFileName（上传文件的文件名，该文件名不包括文件的路径）。因此，<s:file name="xxx" />对应Action类里面的xxx、xxxContentType和xxxFileName三个属性。

    FileUploadAction作用是将浏览器上传的文件拷贝到WEB应用程序的UploadImages文件夹下，新文件的名称是由系统时间与上传文件的后缀组成，该名称将被赋给imageFileName属性，以便上传成功的跳转页面使用。

    下面我们就来看看上传成功的页面：

    Java代码
    <% @ 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 >
    view plaincopy to clipboardprint?
    <% @ 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 >

-------------------------------------------------------------


    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代码
    <? 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代码
    <? 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 >


--------------------------------------------------


    <? 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 >