Servlet实现文件下载

package com.aib.soft;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class download extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse res)
			throws ServletException, IOException {

		//获取资源的绝对路径
		String path = this.getServletContext().getRealPath("/image/gr.jpg");
		//获取资源名
		String filename = path.substring(path.lastIndexOf("\") + 1);
		// 以下载方式打开的响应头content-disposition，并用URLEncoder.encode方法转码
		res.setHeader("content-disposition", 
				"attachment;filename="+URLEncoder.encode(filename,"UTF-8"));

		//获取字节流（非文本资源必须用字节流）
		OutputStream out = res.getOutputStream();
		//文件输入流
		InputStream in=new FileInputStream(path);
		
		//向代表客户端的response输出资源
		byte[] buf=new byte[1024];
		int len=0;
		while((len=in.read(buf))>0){
			out.write(buf, 0, len);
		}
		//out.flush();  response由Servlet管理，可不关闭流
		//out.close();
		in.close(); // 由程序员自己管理 
		System.out.println("-------s");
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

	}

}