servlet下载文件

package myjava.cn;

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.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class DownLoadServlet
 */
@WebServlet("/DownLoadServlet")
public class DownLoadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public DownLoadServlet() {
		super();
		// TODO Auto-generated constructor stub
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String path = this.getServletContext().getRealPath("/download/日本.png");
		String fileName = path.substring(path.lastIndexOf('\\')+1);
		response.setHeader("Content-Disposition", "attachment;filename=" +URLEncoder.encode(fileName,"utf-8")); 

		InputStream in = null;
		OutputStream out = null;
		try {
			in = new FileInputStream(path);
			out = response.getOutputStream();
			int len = 0;
			byte[] b = new byte[1024];
			while ((len = in.read(b)) > 0) {
				out.write(b, 0, len);
			}
		} catch (Exception ex) {
			throw ex;
		} finally {
			if (out != null) {
				out.flush();
				out.close();
			}
			if (in != null) {
				in.close();
			}
		}

		// in.read(b)

	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}