用Struts2实现文件上传

　　文件的上传和下载是网页开发中经常要遇到的问题，本文将结合MyEclipse+Struts2开发一个文件上传系统。

　　本文利用的Java组件是Commons fileUpload（commons-fileupload-1.2.1.jar）

1 文件上传：

　　这是实现后的页面效果图：

1.1 准备

　　打开MyEclipse，建立web project名为DDDemo1，右击MyEclipse→Project facets，选择struts2.x，添加Struts2组件。

　　注意：在选择URL pattern时必须选择【/*】，否则将无法读取struts标签，当然如果你不用struts标签就无所谓了╮(╯_╰)╭

1.2 JSP

　　首先是输入页面fileUploadInput.jsp，如上图所示，代码为：

 1 <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
 2 <%
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 %>
 6 <%@ taglib prefix = "s" uri = "/struts-tags" %>
 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 8 <html>
 9   <head>
10     <title>Upload File</title>
11       <s:head/>
12   </head>
13   
14   <body>
15     <s:form action = "fileUpload" enctype = "multipart/form-data" method = "post">
16         <s:file name = "file" label = "File"/>
17         <s:submit/>
18     </s:form>
19   </body>
20 </html>

　　如果经过Action返回SUCCESS，跳转页面为fileUploadSuccess.jsp,同时显示文件名称及扩展名。

 1 <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
 2 <%
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 %>
 6 <%@ taglib prefix = "s" uri = "/struts-tags" %>
 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 8 <html>
 9   <head>
10     <title>Upload File</title>
11       <s:head/>
12   </head>
13   
14   <body>
15     <h1>File Upload Success</h1>
16     File Name:<s:property value = "fileFileName"/><br/>
17     File Content Type:<s:property value = "fileContentType"/>
18     <s:submit value = "返回" align="left" onclick="javascript:history.go(-1);" />
19   </body>
20 </html>

　　如果失败，则跳转到fileUploadError.jsp，按键"返回"返回到之前页面

 1 <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
 2 <%
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 %>
 6 <%@ taglib prefix = "s" uri = "/struts-tags" %>
 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 8 <html>
 9   <head>
10     <title>Upload File</title>
11       <s:head/>
12   </head>
13   
14   <body>
15     <h1>File Upload Error</h1>
16     <s:submit value = "返回" align="left" onclick="javascript:history.go(-1);" />
17   </body>
18 </html>

1.3 文件上传Action页面FileUploadAction

 1 package action;
 2 
 3 import java.io.File;
 4 import java.io.FileInputStream;
 5 import java.io.FileOutputStream;
 6 import java.io.InputStream;
 7 import java.io.OutputStream;
 8 
 9 import com.opensymphony.xwork2.ActionSupport;
10 
11 public class FileUploadAction extends ActionSupport {
12 
13     /**
14      * 
15      */
16     private static final long serialVersionUID = -4311773232805645652L;
17     private File file;
18     private String fileContentType;
19     private String fileFileName;
20 
21     public String execute() throws Exception {
22         byte[] buffer = new byte[1024];
23         InputStream in = new FileInputStream(file);
24         OutputStream out = new FileOutputStream(new File("f:///Test//"
25                 + fileFileName));
26         int length = in.read(buffer);
27         while (length > 0) {
28             out.write(buffer);
29             length = in.read(buffer);
30         }
31         in.close();
32         out.flush();
33         out.close();
34 
35         return SUCCESS;
36     }
37 
38     public File getFile() {
39         return file;
40     }
41 
42     public void setFile(File file) {
43         this.file = file;
44     }
45     
46     public String getFileFileName() {
47         return fileFileName;
48     }
49 
50     public void setFileFileName(String fileFileName) {
51         this.fileFileName = fileFileName;
52     }
53 
54     public String getFileContentType() {
55         return fileContentType;
56     }
57 
58     public void setFileContentType(String fileContentType) {
59         this.fileContentType = fileContentType;
60     }
61 
62 }

1.4 struts.xml

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
 3 <struts>
 4     <package name="qian" extends="struts-default">
 5         <action name="fileUpload" class="action.FileUploadAction">
 6             <result name = "input">fileUploadError.jsp</result>
 7             <result name = "success">fileUploadSuccess.jsp</result>
 8         </action>
 9     </package>
10 </struts>

1.5 文件类型过滤

这里以图片格式为例，将struts.xml修改为：

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
 3 <struts>
 4     <package name="qian" extends="struts-default">
 5         <action name="fileUpload" class="action.FileUploadAction">
 6             <interceptor-ref name="defaultStack">
 7                 <!-- 设置文件类型 -->
 8                 <param name="fileUpload.allowedTypes">
 9                     image/bmp,image/png,image/gif,image/jpeg,image/jpg 
10                 </param>
11                 <!-- 限制文件大小，这里设置10MB -->
12                 <param name="fileUpload.maximumSize">10485760</param>
13             </interceptor-ref>         
14             <result name = "input">fileUploadError.jsp</result>
15             <result name = "success">fileUploadSuccess.jsp</result>
16         </action>
17     </package>
18 </struts>

1.6 小结

　　对上传系统进行测试，首先输入地址，选择上传的文件：

　　成功界面，并在相应磁盘中找到上传的文件：

　　失败界面：