javaweb文件下载

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 DownLoadServlet extends HttpServlet {

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

		  this.doPost(request, response);
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		//获取该文件的真实路径
		String realPath = this.getServletContext().getRealPath("download/流程.zip");
		//获取需要下载文件的文件名称.以及后缀
		String fileName = realPath.substring(realPath.lastIndexOf("\\")+1);
				
		//获取该文件的输出流
		InputStream in = this.getServletContext().getResourceAsStream("download/流程.zip");
		//以下代码用来进行输入到输出的拷贝
		OutputStream outputStream = response.getOutputStream();
		byte[] b = new byte[1024];
		int len = -1;
		while ((len = in.read(b)) != -1) {
			outputStream.write(b, 0, len);
		}
		in.close();
		//通过设置响应头，以文件下载的方式打开
		//Content-Disposition	attachment;filename=文件名称
        response.setHeader("Content-Disposition","attachment;filename="+URLEncoder.encode(fileName, "utf-8"));
		
	}

}