response实现文件下载

package cn.itcast.response;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
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 ResponseDemo extends HttpServlet {

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

        String path = this.getServletContext().getRealPath("/download/日本妞.jpg");
        String filename = path.substring(path.lastIndexOf("\\") + 1);
        
        //如果下载文件是中文文件，则文件名需要经过URL编码
        response.setHeader("content-disposition", "attachment;filename="
                + URLEncoder.encode(filename,"UTF-8"));

        InputStream in = null;
        OutputStream out = null;

        in = new FileInputStream(path);
        int len = 0;
        byte buffer[] = new byte[1024];

        out = response.getOutputStream();
        while ((len = in.read(buffer)) > 0) {
            out.write(buffer, 0, len);
        }

        in.close();
        out.close();

    }

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

    }

}