jsf 之文件下载 的关键

1. package demo;
2.  
3.  
4. import java.io.BufferedInputStream;
5. import java.io.BufferedOutputStream;
6. import java.io.File;
7. import java.io.FileInputStream;
8. import java.io.IOException;
9. import java.io.InputStream;
10. import java.io.UnsupportedEncodingException;
11. import java.net.URLDecoder;
12. import java.util.logging.Logger;
13.  
14. import javax.faces.application.Application;
15. import javax.faces.context.FacesContext;
16. import javax.faces.event.ActionEvent;
17. import javax.servlet.ServletOutputStream;
18. import javax.servlet.http.HttpServletResponse;
19.  
20. import org.operamasks.faces.annotation.ManagedBean;
21. import org.operamasks.faces.annotation.ManagedBeanScope;
23. public class DownFile { 
24.   public String download() {
25.     //OaMailAttach oaMailAttach = getOaMailAttach();
26.  
27.    String path="G:\sun\";
28.    String fileName="20074111452140.doc";
29.  
30.     try {
31.     FacesContext ctx = FacesContext.getCurrentInstance();
32.     ctx.responseComplete();
33.     //String contentType = "application/octet-stream;charset=utf-8";
34.     String contentType = "application/x-download";
35.     HttpServletResponse response = (HttpServletResponse) ctx.getExternalContext().getResponse();
36.  
37.  
38.  
39.     response.setContentType(contentType);
40.  
41.     StringBuffer contentDisposition = new StringBuffer();
42.  
43.     contentDisposition.append("attachment;");
44.  
45.     contentDisposition.append("filename=\"");
46.     contentDisposition.append(fileName);
47.     contentDisposition.append("\"");
48.     //log.debug(System.getProperty("file.encoding"));
49.     response.setHeader("Content-Disposition", new String(contentDisposition.toString().getBytes(System.getProperty("file.encoding")),"iso8859_1"));
50.     // log.debug(contentDisposition.toString());
51.     ServletOutputStream out = response.getOutputStream();
52.  
53.     //log.debug(new Long(oaMailAttach.getAtFile().length()));
54.  
55.     byte[] bytes = new byte[0xffff];
56.     InputStream is = new FileInputStream(new File(path + fileName));
57.     int b = 0;
58.     while ((b = is.read(bytes, 0, 0xffff)) > 0) {
59.     out.write(bytes, 0, b);
60.     }
61.     is.close();
62.     out.flush();
63.     ctx.responseComplete();
64.     } catch (Exception e) {
65.     // TODO 自动生成 catch 块
66.     e.printStackTrace();
67.     }
68.     return null;
69.    }
70.  
71. }

关键语句：ctx.responseComplete();

不然会报错误如下：

Servlet response already use stream, Writer not possible

评论

2 楼 smudhd 2008-12-11  

厉害，找到了病根呀！

1 楼 liliugen 2008-05-18  

太牛逼，帮我解决了一个大问题，哈哈