Servlet实现文档下载功能

昨天做了一个Servlet，实现文档下载功能。
文档路径：C:\test\temp.doc

package Servlet;

import java.io. * ;
import javax.servlet. * ;
import javax.servlet.http. * ;

public class Download extends HttpServlet{
private static int DEFAULT_BUFFER_SIZE = 1024 * 4 ;
public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
  response.setContentType( " text/html " );
  response.setCharacterEncoding( " GB2312 " );
  PrintWriter out = response.getWriter();
  out.println( " <HTML> " );
  out.println( " <HEAD> " );
  out.println( " <TITLE> " );
  out.println( " 下载 " );
  out.println( " </TITLE> " );
  out.println( " </HEAD> " );
  out.println( " <BODY> " );
  out.println( " <form method=\ " post\ " action=\ " download ? file = c:\\test\\temp.doc\ " > " );
  out.println( " <h2>请单击下载按钮下载文件</h2> " );
  out.println( " <input type=\ " submit\ " value=\ " 下载\ " > " );
  out.println( " </form> " );
  out.println( " </BODY> " );
  out.println( " </HTML> " );
  out.close();
}
public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
  String fileName = (String)request.getParameter( " file " );
  ServletOutputStream output = null ;
  FileInputStream input = null ;
  File file = new File(fileName);
   if ( ! file.exists())
    throw new IOException( " 文件不存在 " );
try {
  response.setHeader( " Content-disposition " , " attachment;filename=temp.doc " );
  response.setContentType( " application/msword " );
  response.setContentLength(( int )file.length());
  output = response.getOutputStream();
  input = new FileInputStream(file);
  copy(input,output);
} catch (IOException e){e.printStackTrace();}
   finally { if (output != null )
   output.close();
   if (input != null )
   input.close();
  }

}
private static int copy(InputStream input,OutputStream output) throws IOException{
   byte [] buffer = new byte [DEFAULT_BUFFER_SIZE];
   int count = 0 ;
   int n = 0 ;
   while ( - 1 != (n = input.read(buffer))){
   output.write(buffer, 0 , n);
   count += n;
  }
return count;
}
}

Servlet配置信息如下：
<servlet>
<servlet-name>Download</servlet-name>
<display-name>download</display-name>
<description>A   Download Servlet</description>
<servlet-class>Servlet.Download</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Download</servlet-name>
<url-pattern>/download</url-pattern>
</servlet-mapping>

需要注意的问题。
1.配置路径为/download,不能是/Download.
2.response的几个方法的解读。
response.setHeader("Content-disposition", "attachment;filename=temp.doc");
//设置响应头信息，让下载的文件显示保存信息

response.setContentType("application/msword");
//设置下载文档的类型，
"application/msword"就是指word文档。还有
"application/pdf " ：pdf文档
"application/zip":   zip文档
…………

response.setContentLength((int)file.length());
//设置输出文件长度

response.getOutputStream();
//取得输出流，用于向客户发送二进制数据

Servlet实现文档下载功能

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