利用Struts2 实现文件下载

 

需求如下：

进来项目中需要添加文件下载Excel功能;决定使用Struts2自带的文件下载功能

1. 减轻工作量，提高工作效率，不需要再写常常的Header头了
2. 要求不需要生成中间文件

Java Code

/*
* $Id: FileDownloadAction.java 496318 2007-01-15 13:58:24Z husted $
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.    See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.    The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License.    You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied.    See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.struts2.showcase.filedownload;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;

import org.apache.commons.lang.StringUtils;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.Action;

/**
* Demonstrates file resource download.
* Set filePath to the local file resource to download,
* relative to the application root ("/images/struts.gif").
*
*/
public class FileDownloadAction implements Action {
         private String inputPath;
         private String fileName;
         private String contentType;
         /**
         * 输入流
         */
         private InputStream inputStream;
        
         public void setInputStream(InputStream inputStream) {
     this.inputStream = inputStream;
  }

   public String getFileName() {
     return fileName;
  }

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

   public String getContentType() {
     return contentType;
  }

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

   public void setInputPath(String value) {
                inputPath = value;
        }

         /**
         * 如果设置了inputStream 则将inputStream输出到浏览器
         * 如果通过inputPath获取文件，并将文件输出至浏览器;
         * @return
         * @throws Exception
         */
         public InputStream getInputStream() throws Exception {
           if(inputStream != null){
             return inputStream;
          }
                 return ServletActionContext.getServletContext().getResourceAsStream(inputPath);
        }

         public String execute() throws Exception {
           this.setContentType( "application/vnd.ms-excel");
           this.setFileName( "wk.xls");
           /**
            * 生成Excls文件
            */
           if(StringUtils.isBlank(inputPath)){
             ByteArrayOutputStream output = new ByteArrayOutputStream();        
             HSSFWorkbook wb = new HSSFWorkbook();
             HSSFSheet sheet = wb.createSheet( "new sheet 2");
                     // Create a row and put some cells in it. Rows are 0 based.
                    HSSFRow row = sheet.createRow(0);
                     // Create a cell and put a value in it.
                    HSSFCell cell = row.createCell(0);
                    cell.setCellValue(1);
                     // Or do it on one line.
                    row.createCell(1).setCellValue(1.2);
                    row.createCell(2).setCellValue( "This is a string");
                    row.createCell(3).setCellValue( true);            
             wb.write(output);
             InputStream is = new ByteArrayInputStream(output.toByteArray());
             this.setInputStream(is);
          }
//            return is;
                 return SUCCESS;
        }

}

 

Struts.xml

                 < action name ="download2" class ="org.apache.struts2.showcase.filedownload.FileDownloadAction" >
                         < result name ="success" type ="stream" >
                                 < param name ="contentType" >${contentType} </ param >
                                 < param name ="inputName" >inputStream </ param >
                                 < param name ="contentDisposition" >filename=${fileName} </ param >
                                 < param name ="bufferSize" >4096 </ param >
                         </ result >
                 </ action >

 

遗留问题：中文名称; Struts 如果是图片等等 会默认打开。稍后完善