JavaEE上传和下载

来源：互联网发布：淘宝冷光美白仪有用么编辑：程序博客网时间：2024/06/05 10:46

先导jar包

上传：

import java.io.File;
import java.io.IOException;
import java.util.List;

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

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

@WebServlet(value="/upload",initParams={@WebInitParam(name="path",value="/upload")})
public class UpLoadServlet extends HttpServlet {
   private static final long serialVersionUID = 1L;
   private String path;

   @Override
   public void init() throws ServletException {
       //在web.xml中把path值传过来或者使用注解例如:
       /*
       * <init-param>
       *       <param-name>path</param-name>
       *        <param-value>/upload</param-value>
       *    </init-param>
       *
       */
       path = getServletConfig().getInitParameter("path");
   }


   @SuppressWarnings("unchecked")
   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

       String username = request.getParameter("username");
       //页面表单中设置了enctype="multipart/form-data"后
       //无法直接通过getParameter方法获取普通组件的参数值
       System.out.println("getParameter username = "+username);

       //获得上传目录的绝对路径
       String realpath = getServletContext().getRealPath(path);

       try {
           //构造一个文件上传处理对象
           DiskFileItemFactory factory = new DiskFileItemFactory();
           ServletFileUpload upLoad = new ServletFileUpload(factory);

           //获得表单中提交内容
           List<FileItem> list = upLoad.parseRequest(request);

           for (FileItem fileItem : list) {
               //fileItem.isFormField()返回true表示是普通的表单组件
               //fileItem.isFormField()返回false表示是上传输入框
               if (fileItem.isFormField()) {
                   //getFieldName()方法获得普通表单组件的参数名
                   String FieldName = fileItem.getFieldName();
                   //获得该参数所对应的值并指定编码
                   String Content = fileItem.getString("UTF-8");
                   //为了后面可以把普通参数从request中拿出来
                   request.setAttribute(FieldName, Content);
               } else {
                   //getName()取得上传文件的名字
                   String fileName = fileItem.getName();
                   //避免文件名字重复
                   fileName = System.currentTimeMillis()+fileName;
                   File file = new File(realpath, fileName);
                   //把上传文件进行指定目录
                   fileItem.write(file);
               }
           }

           //因为上面解析request中是数据后,把普通表单组件中的key和value放到了request中,所以这里可以拿出来
           System.out.println("request.getAttribute(\"username\") = "+request.getAttribute("username"));


       } catch (Exception e) {
           e.printStackTrace();
       }

   }

   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       doGet(request, response);
   }

}

下载：

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(value="/download",initParams={@WebInitParam(name="path",value="/download")})
public class DownLoadServlet extends HttpServlet {
   private static final long serialVersionUID = 1L;
   private String path;

   @Override
   public void init() throws ServletException {
       //在web.xml中把path值传过来或者使用注解例如:
       /*
       * <init-param>
       *       <param-name>path</param-name>
       *        <param-value>/download</param-value>
       *    </init-param>
       *
       */
       path = getServletConfig().getInitParameter("path");
   }

   @Override
   protected void doGet(HttpServletRequest request,
           HttpServletResponse response) throws ServletException, IOException {

       // 获得用户需要下载文件的名字
       String fileName = request.getParameter("fileName");

       // 下载文件所在目录的绝对路径
       String realPath = getServletContext().getRealPath(path);

       // 响应类型设置为下载:application/x-download
       response.setContentType("application/x-download");

       // 下载文件时显示文件的保存名称
       String fileDisplay = "briup_"+fileName;
       // 下载文件名的中文编码转换因为写回去的时候是字节流
       fileDisplay = new String(fileName.getBytes("utf-8"),"ISO-8859-1");

       // 设置响应头部信息(http协议中的固定设置方式)
       response.addHeader("Content-Disposition", "attachment;filename="+fileDisplay);
       try {
           ServletOutputStream out = response.getOutputStream();
           File file = new File(realPath,fileName);
           FileInputStream in = new FileInputStream(file);
           byte[] b = new byte[1024];
           int len = -1;
           while ((len = in.read(b)) != -1) {
               out.write(b, 0, len);
           }
           out.flush();
           in.close();
       } catch (Exception e) {
           e.printStackTrace();
       }

       //注意下载之后就不能使用request跳转了,因为response已经返回了
   }

   @Override
   protected void doPost(HttpServletRequest req, HttpServletResponse resp)
           throws ServletException, IOException {
       doGet(req, resp);
   }

}

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