下载处理Servlet工具类

原文：http://javatar.iteye.com/blog/72265

项目中用到下载功能，一般都使用超链接做下载, 
但txt, html, csv等会被浏览器直接打开， 
写了一个工具类处理这个问题。 
很简单，放上来备忘。 

Java代码   

1. package com.xxx.servlet;  
2.   
3. import java.io.File;  
4. import java.io.FileInputStream;  
5. import java.io.IOException;  
6. import java.io.InputStream;  
7. import java.io.OutputStream;  
8.   
9. import javax.servlet.ServletConfig;  
10. import javax.servlet.ServletException;  
11. import javax.servlet.http.HttpServlet;  
12. import javax.servlet.http.HttpServletRequest;  
13. import javax.servlet.http.HttpServletResponse;  
14.   
15. /** 
16.  * 下载处理Servlet 
17.  * @author liangfei0201@163.com 
18.  * 
19.  */  
20. public class DownloadServlet extends HttpServlet {  
21.   
22.     private static final long serialVersionUID = 1L;  
23.       
24.     private static final String DEFAULT_ENCODING = "UTF-8";  
25.       
26.     private static final int DEFAULT_BUFFER_SIZE = 4096;  
27.       
28.     private String encoding = DEFAULT_ENCODING;  
29.       
30.     private int bufferSize = DEFAULT_BUFFER_SIZE;  
31.       
32.     public void init(ServletConfig sc) throws ServletException {  
33.         super.init(sc);  
34.   
35.         String paramEncoding = sc.getInitParameter("encoding");  
36.         if (paramEncoding != null && paramEncoding.trim().length() > 0) {  
37.             encoding = paramEncoding.trim();  
38.         }  
39.           
40.         String paramSize = sc.getInitParameter("bufferSize");  
41.         if (paramSize != null && paramSize.matches("^[0-9]+$")) {  
42.             bufferSize = Integer.parseInt(paramSize);  
43.         }  
44.     }  
45.   
46.     public void doGet(HttpServletRequest request, HttpServletResponse response)  
47.             throws ServletException, IOException {  
48.         doPost(request, response);  
49.     }  
50.   
51.     public void doPost(HttpServletRequest request, HttpServletResponse response)  
52.             throws ServletException, IOException {  
53.         // 查找文件  
54.         File file = new File(getServletContext().getRealPath("/") + request.getServletPath());  
55.         if (! file.exists()) {  
56.             response.sendError(HttpServletResponse.SC_NOT_FOUND);  
57.             return ;  
58.         }  
59.           
60.         // 设置response  
61.         response.setContentType("application/x-msdownload; charset=" + encoding);  
62.         response.addHeader("content-type", "application/x-msdownload;");  
63.         response.addHeader("content-disposition", "attachment; filename="+ response.encodeURL(file.getName()));  
64.         response.setContentLength((int)file.length());  
65.           
66.         // 输出  
67.         InputStream in = new FileInputStream(file);  
68.         OutputStream out = response.getOutputStream();  
69.         try {  
70.             int length = 0;  
71.             byte[] buffer = new byte[bufferSize];  
72.             while ((length = in.read(buffer)) != -1) {  
73.                 out.write(buffer, 0, length);  
74.             }  
75.             out.flush();  
76.         } finally {  
77.             if (in != null) {  
78.                 in.close();  
79.             }  
80.         }  
81.     }  
82.   
83. }  

Xml代码   

1. <servlet>  
2.     <servlet-name>download</servlet-name>  
3.     <servlet-class>com.xxx.servlet.DownloadServlet</servlet-class>  
4.     <init-param>  
5.         <param-name>encoding</param-name>  
6.         <param-value>GBK</param-value>  
7.     </init-param>  
8.     <init-param>  
9.         <param-name>bufferSize</param-name>  
10.         <param-value>8192</param-value>  
11.         </init-param>  
12.     <load-on-startup>4</load-on-startup>  
13. </servlet>  
14. <servlet-mapping>  
15.     <servlet-name>download</servlet-name>  
16.     <url-pattern>/download/*</url-pattern>  
17. </servlet-mapping>  
18. <servlet-mapping>  
19.     <servlet-name>download</servlet-name>  
20.     <url-pattern>*.csv</url-pattern>  
21. </servlet-mapping>  
22. <servlet-mapping>  
23.     <servlet-name>download</servlet-name>  
24.     <url-pattern>*.txt</url-pattern>  
25. </servlet-mapping>