downloadaction.java

来自「spring+struts+hibernate做的银行系统」· Java 代码 · 共 122 行

package cn.com.tym.admin; 
import java.io.*;
import javax.servlet.ServletContext;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.*;

public abstract class DownloadAction extends Action
{
 public static class ResourceStreamInfo
     implements StreamInfo
 {

     private String contentType;
     private ServletContext context;
     private String path;

     public String getContentType()
     {
         return contentType;
     }

     public InputStream getInputStream()
         throws IOException
     {
         return context.getResourceAsStream(path);
     }

     public ResourceStreamInfo(String contentType, ServletContext context, String path)
     {
         this.contentType = contentType;
         this.context = context;
         this.path = path;
     }
 }

 public static class FileStreamInfo
     implements StreamInfo
 {

     private String contentType;
     private File file;

     public String getContentType()
     {
         return contentType;
     }

     public InputStream getInputStream()
         throws IOException
     {
         FileInputStream fis = new FileInputStream(file);
         BufferedInputStream bis = new BufferedInputStream(fis);
         return bis;
     }

     public FileStreamInfo(String contentType, File file)
     {
         this.contentType = contentType;
         this.file = file;
     }
 }

 public static interface StreamInfo
 {

     public abstract String getContentType();

     public abstract InputStream getInputStream()
         throws IOException;
 }


 protected static final int DEFAULT_BUFFER_SIZE = 4096;

 public DownloadAction()
 {
 }

 protected abstract StreamInfo getStreamInfo(ActionMapping actionmapping, ActionForm actionform, HttpServletRequest httpservletrequest, HttpServletResponse httpservletresponse)
     throws Exception;

 protected int getBufferSize()
 {
     return 4096;
 }

 public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
     throws Exception
 {
     StreamInfo info = getStreamInfo(mapping, form, request, response);
     String contentType = info.getContentType();
     InputStream stream = info.getInputStream();
     try
     {
         response.setContentType(contentType);
         copy(stream, response.getOutputStream());
     }
     finally
     {
         if(stream != null)
             stream.close();
     }
     return null;
 }

 public int copy(InputStream input, OutputStream output)
     throws IOException
 {
     byte buffer[] = new byte[getBufferSize()];
     int count = 0;
     for(int n = 0; -1 != (n = input.read(buffer));)
     {
         output.write(buffer, 0, n);
         count += n;
     }

     return count;
 }
}