downloadservlet.java~16~

一个上传的例子

package com.xiaobai.bbsupload;

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

/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2004</p>
 * <p>Company: 下载的servlet</p>
 * @author 1232Maxine
 * @version 1.0
 */

public class downloadServlet extends HttpServlet {
  public downloadServlet() {
  }
  private static final String CONTENT_TYPE = "application/x-msdownload";//下载头
  //Initialize global variables
  public void init() throws ServletException {
  }

  //Process the HTTP Get request
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws
      ServletException, IOException {
    String picdir =request.getContextPath()+request.getParameter("picdir");
    if (picdir == null) {
      picdir = "";
    }
    picdir = picdir;
    String filename=request.getParameter("fileName");
    //PrintWriter out = response.getWriter();
    File file = new File("uploadtext/uploadfiles/xiaobai11185712179370bizhi.jpg");//检查文件是否存在
    if (!file.exists()) {
   this.getServletContext().getRequestDispatcher(response.encodeURL("/error.jsp?errorinfo=此文件过期，已经不存在！")).forward(request, response);
      return ;
 }

    long filelength = file.length();
    InputStream inStream=new FileInputStream(picdir);
//设置输出的格式
    response.reset();
    response.setContentType(CONTENT_TYPE);  //设置下载头
    response.setContentLength((int)filelength);
    response.addHeader("Content-Disposition","attachment; filename=\"" + toUtf8String(filename) + "\"");
//循环取出流中的数据
    byte[] b = new byte[100];
    int len;
  while((len=inStream.read(b)) >0) ///每次读出100字节
  response.getOutputStream().write(b,0,len);   //输出到响应流中
  inStream.close();
  if(file!=null){
    file=null;
  }

  }

  //Process the HTTP Post request
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws
      ServletException, IOException {
    doGet(request, response);
  }

  //Clean up resources
  public void destroy() {
  }
  private String toUtf8String(String s) {///转换成UTF-8
  StringBuffer sb = new StringBuffer();
  for (int i=0;i<s.length();i++) {
  char c = s.charAt(i);
  if (c >= 0 && c <= 255) {
  sb.append(c);
  } else {
  byte[] b;
  try {
  b = Character.toString(c).getBytes("utf-8");
  } catch (Exception ex) {
  System.out.println(ex);
  b = new byte[0];
  }
  for (int j = 0; j < b.length; j++) {
  int k = b[j];
  if (k < 0) k += 256;
  sb.append("%" + Integer.toHexString(k).
  toUpperCase());
  }
  }
  }
  return sb.toString();
  }

}