基于Struts2框架的文件下载 --- Struts2
Posted Thanlon
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一、Struts2指定类型文件的下载
1、最终功能实现的截图：（点击文件下载链接，下载文件 )
2、核心代码
index.jsp：
1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 5 %> 6 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 7 <html> 8 <head> 9 <base href="<%=basePath%>"> 10 11 <title>My JSP \'index.jsp\' starting page</title> 12 <meta http-equiv="pragma" content="no-cache"> 13 <meta http-equiv="cache-control" content="no-cache"> 14 <meta http-equiv="expires" content="0"> 15 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 16 <meta http-equiv="description" content="This is my page"> 17 </head> 18 <body> 19 <a href="<%=path%>/downloadFile?download=UploadFile/readme.doc">点击链接下载文件</a> 20 </body> 21 </html>
struts.xml：
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE struts PUBLIC 3 "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" 4 "http://struts.apache.org/dtds/struts-2.3.dtd"> 5 <struts> 6 <package name="default" namespace="/" extends="struts-default"> 7 <action name="downloadFile" class="com.thanlon.action.DownloadFileAction"> 8 <result name="success" type="stream"><!-- result类型是流(stream)类型 --> 9 <param name="inputName">inputStream</param><!-- inputName指向被下载文件的来源,对应Action中返回的InputStream --> 10 <param name="contentType">${contentType}</param><!-- 下载的内容类型，如图片类型、文档类型等…… --> 11 <param name="contentDisposition"> 12 <!-- 指定文件下载的处理方式，内联(inline)和附件(attachment)两种方式，attachment会弹出文件保存对话框 --> 13 attachment;filename=${filename} 14 </param> 15 </result> 16 </action> 17 </package> 18 </struts>
DownloadFileAction.java：
1 package com.thanlon.action; 2 3 import java.io.InputStream; 4 5 import org.apache.struts2.ServletActionContext; 6 7 import com.opensymphony.xwork2.Action; 8 9 public class DownloadFileAction implements Action { 10 11 private String downloadPath;// 下载的路径 12 private String contentType;// 下载文件的类型 13 private String fileName;// 文件类型 14 15 public String getDownloadPath() { 16 return downloadPath; 17 } 18 19 public void setDownloadPath(String downloadPath) { 20 this.downloadPath = downloadPath; 21 } 22 23 public String getContentType() { 24 return contentType; 25 } 26 27 public void setContentType(String contentType) { 28 this.contentType = contentType; 29 } 30 31 public String getFileName() { 32 return fileName; 33 } 34 35 public void setFileName(String fileName) { 36 this.fileName = fileName; 37 } 38 39 @Override 40 public String execute() throws Exception { 41 // TODO Auto-generated method stub 42 downloadPath = ServletActionContext.getRequest().getParameter( 43 "download"); 44 System.out.println(downloadPath);// downloadPath为相对路径，打印出“/UploadFile/readme.doc” 45 int position = downloadPath.lastIndexOf("/");// 借助lastIndexOf函数，从右向左查找第一个/ 46 System.out.println(position);// 打印"/"所造的坐标 47 if (position > 0) { 48 fileName = downloadPath.substring(position + 1);// 得到文件的名字(全名，带后缀) 49 System.out.println(fileName);// 輸出文件名，本例輸出readme.doc 50 } else { 51 fileName = downloadPath; 52 } 53 contentType = "application/msword";// 指定下载问文件的类型 54 return SUCCESS; 55 } 56 57 /** 58 * 返回InputStream 59 * 60 * @return 61 */ 62 public InputStream getInputStream() { 63 InputStream inputStream = ServletActionContext.getServletContext() 64 .getResourceAsStream(downloadPath); 65 // System.out.println(inputStream);输出inputStream，如果为null表示路径出错 66 return inputStream; 67 } 68 }
二、Struts2多种类型(不指定)文件的下载
1、火狐浏览器下测试对比后，很明显可以看出添加资源文件后，下载时文件的类型被设置成文件真实类型。
下面同样是有无资源文件的对比，也是很明显可以看出。使用资源文件的，下载文件时带上了正确的文件后缀。
2、核心代码
index.jsp：
1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 5 %> 6 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 7 <html> 8 <head> 9 <base href="<%=basePath%>"> 10 11 <title>My JSP \'index.jsp\' starting page</title> 12 <meta http-equiv="pragma" content="no-cache"> 13 <meta http-equiv="cache-control" content="no-cache"> 14 <meta http-equiv="expires" content="0"> 15 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 16 <meta http-equiv="description" content="This is my page"> 17 </head> 18 <body> 19 <p>下面是举例说明：</p> 20 <a href="<%=path%>/downloadFile?download=UploadFile/readme.doc">点击链接下载文件(doc)</a><br> 21 <a href="<%=path%>/downloadFile?download=UploadFile/thanlon.pdf">点击链接下载文件(pdf)</a><br> 22 <a href="<%=path%>/downloadFile?download=UploadFile/demo.gif">点击链接下载文件(gif)</a><br> 23 <a href="<%=path%>/downloadFile?download=UploadFile/logo.png">点击链接下载文件(png)</a> 24 </body> 25 </html>
struts.xml：
与上一例（Struts2指定类型文件的下载）的struts.xml相同
DownloadFileAction.java：
1 package com.thanlon.action; 2 3 import java.io.InputStream; 4 5 import org.apache.struts2.ServletActionContext; 6 7 import com.opensymphony.xwork2.Action; 8 import com.opensymphony.xwork2.ActionSupport; 9 10 public class DownloadFileAction extends ActionSupport { 11 12 private String downloadPath;// 下载的路径 13 private String contentType;// 下载文件的类型 14 private String fileName;// 文件类型 15 16 public String getDownloadPath() { 17 return downloadPath; 18 } 19 20 public void setDownloadPath(String downloadPath) { 21 this.downloadPath = downloadPath; 22 } 23 24 public String getContentType() { 25 return contentType; 26 } 27 28 public void setContentType(String contentType) { 29 this.contentType = contentType; 30 } 31 32 public String getFileName() { 33 return fileName; 34 } 35 36 public void setFileName(String fileName) { 37 this.fileName = fileName; 38 } 39 40 @Override 41 public String execute() throws Exception { 42 // TODO Auto-generated method stub 43 downloadPath = ServletActionContext.getRequest().getParameter( 44 "download"); 45 System.out.println(downloadPath);// downloadPath为相对路径，打印出“/UploadFile/readme.doc” 46 int position = downloadPath.lastIndexOf("/");// 借助lastIndexOf函数，从右向左查找第一个/ 47 // System.out.println(position);// 打印"/"所在的坐标 48 if (position > 0) { 49 fileName = downloadPath.substring(position + 1);// 得到文件的名字(全名，带后缀) 50 System.out.println(fileName);// 輸出文件名 51 } else { 52 fileName = downloadPath; 53 } 54 int extPos = fileName.lastIndexOf("."); 55 System.out.println(extPos); 56 String contentTypeKey = null; 57 if (extPos > 0) { 58 contentTypeKey = "struts.contentType" + fileName.substring(extPos);//带.的后缀 59 System.out.println(contentTypeKey); 60 }else { 61 contentTypeKey = "struts.contentType.txt"; 62 //如果没有在属性文件中指定类型：如果是文件，则下载的文件默认后缀为txt文件类型;如果是图片则不会是txt类型，会是自身类型，或者特殊类型，比如jpg会是jfif类型。 63 } 64 contentType =getText(contentTypeKey);// 指定下载问文件的类型此类继承了ActionSupport，直接使用getText()函数 65 System.out.println(contentTypeKey); 66 return SUCCESS; 67 } 68 /** 69 * 返回InputStream 70 * 71 * @return 72 */ 73 public InputStream getInputStream() { 74 InputStream inputStream = ServletActionContext.getServletContext() 75 .getResourceAsStream(downloadPath); 76 // System.out.println(inputStream);输出inputStream，如果为null表示路径出错 77 return inputStream; 78 } 79 }
DownloadFileAction.properties：
1 struts.contentType.gif=image/gif 2 struts.contentType.jpg=image/jpg 3 struts.contentType.jpeg=image/jpeg 4 struts.contentType.bmp=image/bmp 5 struts.contentType.png=image/png 6 struts.contentType.txt=text/plain 7 struts.contentType.swf=application/x-shockwave-flash 8 struts.contentType.doc=application/msword 9 struts.contentType.xls=application/vnd.ms-excel 10 struts.contentType.pdf=application/pdf 11 struts.contentType.ppt=application/vnd.ms-powerpoint 12 struts.contentType.exe=application/octet-stream
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