Struts2 上传文件实例

实现原理

Struts 2是通过Commons FileUpload文件上传。Commons FileUpload通过将HTTP的数据保存到临时文件夹，然后Struts使用fileUpload拦截器将文件绑定到Action的实例中。从而我们就能够以本地文件方式的操作浏览器上传的文件。

具体实现

前段时间Apache发布了Struts 2.0.6 GA，所以本文的实现是以该版本的Struts作为框架的。以下是例子所依赖类包的列表：

 

目录结构：

 

创建文件上传页面FileUpload.jsp

<% ... @ 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 >
< s:fielderror  />
< div >
< p >< b > Single file upload </ b ></ p >
< s:form  action ="fileUpload"  method ="POST"  enctype ="multipart/form-data" >  
     < s:file  name ="myFile"  label ="Image File" />
     < s:textfield  name ="caption"  label ="Caption"   />
     < s:submit />
</ s:form >
</ div >
< div >
< p >< b > Multiple files upload </ b ></ p >
< s:form  action ="multiplefileUpload"  method ="POST"  enctype ="multipart/form-data" >
     < s:file  label  ="File(1)"  name  ="uploads" />  
     < s:file  label  ="File(2)"  name  ="uploads" />  
     < s:file  label  ="FIle(3)"  name  ="uploads" />  
     < s:file  label  ="FIle(4)"  name  ="uploads" />  
     < s:textfield  name ="caption"  label ="Caption"   />
     < s:submit />
</ s:form >
</ div >
</ body >
</ html >

创建FileUploadAction.java

package  fileupload;

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.ArrayList;
import  java.util.Date;
import  java.util.List;

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 = 64 * 1024;

    private File myFile;

    private String contentType;

    private String fileName;

    private String imageFileName;

    private String caption;

    private File[] uploads;

    private String[] uploadFileNames;

    private String[] uploadContentTypes;
    
    private List imageFileNames = new ArrayList() ;

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

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

    public void setMyFile(File myFile) ...{
        System.out.println("this is setMyFile[]");
        this.myFile = myFile;
    }

    public String getImageFileName() ...{
        return imageFileName;
    }

    public String getCaption() ...{
        return caption;
    }

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

    public File[] getUploads() ...{
        return this.uploads;
    }

    public void setUploads(File[] upload) ...{
        this.uploads = upload;
    }

    public String[] getUploadsFileName() ...{
        return this.uploadFileNames;
    }

    public void setUploadsFileName(String[] uploadFileName) ...{
        this.uploadFileNames = uploadFileName;
    }

    public String[] getUploadsContentType() ...{
        return this.uploadContentTypes;
    }

    public void setUploadsContentType(String[] uploadContentType) ...{
        this.uploadContentTypes = uploadContentType;
    }
    
    public List getImageFileNames() ...{
        return imageFileNames;
    }

    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);
    }

    public String execute() ...{
        if (this.fileName != null) ...{
            imageFileName = new Date().getTime() + getExtention(fileName);
            File imageFile = new File(ServletActionContext.getServletContext()
                    .getRealPath("/upload/UploadImages")
                    + "/" + imageFileName);
            copy(myFile, imageFile);
            return SUCCESS;
        } else ...{
            
            for (int i = 0; i < this.uploads.length; i++) ...{
                System.out.println(this.uploadFileNames[i]);                
                imageFileName = new Date().getTime() + i + getExtention(this.uploadFileNames[i]);
                imageFileNames.add(imageFileName);         
                File imageFile = new File(ServletActionContext.getServletContext().getRealPath("/upload/UploadImages")+ "/" + imageFileName);
                copy(this.uploads[i], imageFile);
            }
            return SUCCESS;
        }
    }
}

上传成功的页面：

ShowUpload.jsp

<% ... @ 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;width=100px" >
< fieldset >
     < legend > UploadImage:  < b >   < s:property  value ="caption" /></ b ></ legend >
     < img  src ='UploadImages/<s:property  value  ="imageFileName" /> '/>
</ fieldset >
</ div >
</ body >
</ html >

ShowMultipleUpload.jsp

<% ... @ 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;width=100px" >
< fieldset >
     < legend > UploadImage:  < b >   < s:property  value ="caption" /></ b ></ legend >
     < s:iterator  value ="imageFileNames" >
         < img  src ='UploadImages/<s:property  /> '/>
     </ s:iterator >
</ fieldset >
</ div >
</ body >
</ html >

Action的配置文件：

< package  name  ="fileUploadDemo"  extends  ="struts-default"  namespace ="/upload" >  
    
         < action  name  ="fileUpload"  class  ="fileupload.FileUploadAction" >  
        
             < interceptor-ref  name  ="fileUpload" >  
            
                 < param  name  ="allowedTypes" > image/bmp,image/png,image/gif,image/jpeg </ param >  
                
             </ interceptor-ref >  
            
             < interceptor-ref  name  ="fileUploadStack" />  
            
             < result  name  ="input" > FileUpload.jsp  </ result >  
            
             < result  name  ="success" > ShowUpload.jsp </ result >  
            
         </ action >  
        
         < action  name  ="multiplefileUpload"  class  ="fileupload.FileUploadAction" >  
            
             < result  name  ="input" > FileUpload.jsp  </ result >  
            
             < result  name  ="success" > ShowMultipleUpload.jsp </ result >  
            
         </ action >  
        
     </ package >  

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  >  

运行结果：

地址：http://localhost:8080/s2/upload/FileUpload.jsp

Single file upload Result