JSP之文件上传

摘要：本文介绍怎么结合servlet,jsp来完成文件的上传

1，需要引入两个jar包

commons-fileupload-1.2.1.jar，commons-io-1.4.jar

2，修改web.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app version="3.0" 
 3     xmlns="http://java.sun.com/xml/ns/javaee" 
 4     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 5     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
 6     http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
 7   <display-name></display-name>    
 8   
 9   
10   <servlet>
11       <servlet-name>upload</servlet-name>
12       <servlet-class>UploadServlet</servlet-class>
13   <init-param>
14     <param-name>filePath</param-name>
15       <param-value>store</param-value>
16   </init-param>
17   <init-param>
18     <param-name>tempFilePath</param-name>
19       <param-value>temp</param-value>
20   </init-param>
21   </servlet>
22   <servlet-mapping>
23   
24   <servlet-name>upload</servlet-name>
25   <url-pattern>/upload</url-pattern>
26   </servlet-mapping>
27   <welcome-file-list>
28     <welcome-file>index.jsp</welcome-file>
29   </welcome-file-list>
30 </web-app>

3,需要一个html界面来点击上传的文件路径等

 1 <html>
 2 <head>
 3 <title>Upload</title>
 4 </head>
 5 <body >
 6   <form name="uploadForm" method="POST"
 7     enctype="MULTIPART/FORM-DATA"
 8     action="upload">
 9     <table>
10       <tr>
11        <td><div align="right">User Name:</div></td>
12        <td><input type="text" name="username" size="30"/> </td>
13       </tr>
14       <tr>
15        <td><div align="right">Upload File1:</div></td>
16        <td><input type="file" name="file1" size="30"/> </td>
17       </tr>
18       <tr>
19         <td><div align="right">Upload File2:</div></td>
20         <td><input type="file" name="file2" size="30"/> </td>
21       </tr>
22       <tr>
23         <td><input type="submit" name="submit" value="upload"></td>
24         <td><input type="reset" name="reset" value="reset"></td>
25       </tr>
26     </table>
27   </form>
28 </body>
29 </html>

4，通过servlet来控制文件的上传

 1 import java.io.File;
 2 import java.io.IOException;
 3 import java.io.PrintWriter;
 4 import java.util.Iterator;
 5 import java.util.List;
 6 
 7 import javax.servlet.ServletConfig;
 8 import javax.servlet.ServletException;
 9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 
13 import org.apache.commons.fileupload.FileItem;
14 import org.apache.commons.fileupload.FileUploadException;
15 import org.apache.commons.fileupload.disk.DiskFileItemFactory;
16 import org.apache.commons.fileupload.servlet.ServletFileUpload;
17 
18 
19 public class UploadServlet extends HttpServlet{
20     private String filePath;//存放上传文件的目录
21     private String tempFilePath;//存放临时文件的目录
22     @Override
23     protected void doPost(HttpServletRequest req, HttpServletResponse res)
24             throws ServletException, IOException {
25         res.setContentType("text/plain");
26         //向客户端发送响应正文
27         PrintWriter outNet=res.getWriter();
28         //创建一个基于硬盘的FileItem工厂
29         DiskFileItemFactory factory=new DiskFileItemFactory();
30         //设置向硬盘写数据时所用的缓冲区的大小，此处为4k
31         factory.setSizeThreshold(4*1024);
32         //设置临时目录
33         factory.setRepository(new File(tempFilePath));
34         //设置一个文件上传处理器
35         ServletFileUpload upload=new ServletFileUpload(factory);
36         //设置允许上传的文件的最大尺寸，此为4m
37         upload.setFileSizeMax(4*1024*1024);
38         try {
39             List items=upload.parseRequest(req);
40             Iterator ite=items.iterator();
41             while (ite.hasNext()) {
42                 FileItem item=(FileItem) ite.next();
43                 if(item.isFormField()){
44                      processFormField(item,outNet); //处理普通的表单域
45                     
46                 }else{
47                     processUploadedFile(item,outNet); //处理上传文件
48                     
49                 }
50             }
51             outNet.close();
52             
53         } catch (FileUploadException e) {
54             throw new RuntimeException();
55         }
56     }
57 
58     private void processUploadedFile(FileItem item, PrintWriter outNet) {
59         String filename=item.getFieldName();
60         int index=filename.lastIndexOf("\");
61         filename=filename.substring(index+1,filename.length());
62         long filesize=item.getSize();
63         
64         if(filename.equals("")&&filesize==0)return;
65             
66         File uploadFile=new File(filePath+"/"+filename); 
67         
68         try {
69             item.write(uploadFile);
70             outNet.print(filename+"is saved.");
71             outNet.print("The size of"+filename+"is"+filesize+"
");
72         } catch (Exception e) {
73             throw new RuntimeException();
74         }
75         
76     }
77 
78     private void processFormField(FileItem item, PrintWriter outNet) {
79         String name=item.getFieldName();
80         String value=item.getString();
81         outNet.println(name+":"+value+"
");
82         
83     }
84 
85     @Override
86     public void init(ServletConfig config) throws ServletException {
87         
88         super.init(config);
89         filePath=config.getInitParameter("filePath");
90         tempFilePath=config.getInitParameter("tempFilePath");
91         filePath=getServletContext().getRealPath("/")+"store";
92         tempFilePath=getServletContext().getRealPath("/")+"temp";
93     }
94 }