文件下载--getOutputStream输出二进制字符

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文件下载--getOutputStream输出二进制字符

单一文件上传：

一、前台 uploadFile.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <base href="<%=basePath%>">

    <title>My JSP 'uploadFile.jsp' starting page</title>

    <meta http-equiv="pragma" content="no-cache">

    <meta http-equiv="cache-control" content="no-cache">

    <meta http-equiv="expires" content="0">

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

    <meta http-equiv="description" content="This is my page">

    <meta http-equiv="ContentType" content="text/html;charset=UTF-8">

    

  </head>

  <body>

      <form action="upload.action" method="post" enctype="multipart/form-data">

        <input type="file" name="myfile" />

          <input type="submit" name="upload" value="上传" />

      </form>

  </body>

</html>

二、后台 uploadFile.jsp

package com.zhaoran.controller;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.Part;

public class UploadServlet extends HttpServlet{

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        doPost(req, resp);

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        req.setCharacterEncoding("UTF-8");

        resp.setCharacterEncoding("UTF-8");

        resp.setContentType("text/html;charset=UTF-8");

        Part part=req.getPart("myfile");

        String filename=getFileName(part);

        writeTo(filename,part);

        req.setAttribute("msg", "文件上传成功");

        req.getRequestDispatcher("common/success.jsp").forward(req, resp);

    }

    private void writeTo(String filename, Part part) throws IOException {

        InputStream inputStream=part.getInputStream();

        OutputStream outputStream=new FileOutputStream("e://"+filename);

        byte[] buff=new byte[1024];

        int len=-1;

        while((len=inputStream.read(buff))!=-1){

            outputStream.write(buff, 0, len);

        }

        outputStream.close();

        inputStream.close();

    }

    private String getFileName(Part part) {

        //String header=part.getHeader("Content-Disposition");

        String header=part.getHeader("Content-Disposition");

        System.out.println(header);

        String filename=header.substring(header.indexOf("filename="")+10,header.lastIndexOf("""));

        System.out.println(filename);

        return filename;

    }

}

三、配置文件 web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">

  <display-name>login</display-name>

  <servlet>

      <servlet-name>loginServlet</servlet-name>

      <servlet-class>com.zhaoran.controller.LoginServlet</servlet-class>

  </servlet>

  <servlet-mapping>

      <servlet-name>loginServlet</servlet-name>

      <url-pattern>/login.action</url-pattern>

  </servlet-mapping>

  <servlet>

      <servlet-name>uploadServlet</servlet-name>

      <multipart-config></multipart-config>

      <servlet-class>com.zhaoran.controller.UploadServlet</servlet-class>

  </servlet>

  <servlet-mapping>

      <servlet-name>uploadServlet</servlet-name>

      <url-pattern>/upload.action</url-pattern>

  </servlet-mapping>

  <welcome-file-list>

    <welcome-file>index.html</welcome-file>

    <welcome-file>index.htm</welcome-file>

    <welcome-file>index.jsp</welcome-file>

    <welcome-file>default.html</welcome-file>

    <welcome-file>default.htm</welcome-file>

    <welcome-file>default.jsp</welcome-file>

  </welcome-file-list>

</web-app>

文件的批量上传：

一、前台页面

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <base href="<%=basePath%>">

    <title>My JSP 'uploadFile.jsp' starting page</title>

    <meta http-equiv="pragma" content="no-cache">

    <meta http-equiv="cache-control" content="no-cache">

    <meta http-equiv="expires" content="0">

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

    <meta http-equiv="description" content="This is my page">

    <meta http-equiv="ContentType" content="text/html;charset=UTF-8">

    

  </head>

  <body>



      <form action="upload.action" method="post" enctype="multipart/form-data">

        <input type="file" name="myfile" />

        <br />

          <input type="submit" name="upload" value="上传" />

      </form>

      <hr />

      <form action="upload2.action" method="post" enctype="multipart/form-data">

        <input type="file" name="myfile" />

        <br />

          <input type="submit" name="upload" value="上传" />

      </form>

      <hr />

      <form action="upload3.action" method="post" enctype="multipart/form-data">

        文件一：<input type="file" name="myfile1" />

        <br />

        文件二：<input type="file" name="myfile2" />

        <br />

        文件三：<input type="file" name="myfile3" />

        <br />

          <input type="submit" name="upload" value="上传" />

      </form>

  </body>

</html>

二、后台servlet   UploadServlet3.java

package com.zhaoran.controller;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.MultipartConfig;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.Part;

//采用注解方式配置servlet，文件上传中@MultipartConfig必不可少

@MultipartConfig(location="e://")

@WebServlet("/upload3.action")

public class UploadServlet3 extends HttpServlet {

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        req.setCharacterEncoding("UTF-8");

        for(Part part:req.getParts()){

//            System.out.println(part.getName());

            if(part.getName().startsWith("myfile")){

                String filename=getFileName(part);

//                System.out.println(filename);

                part.write(filename);

            }

        }

        req.setAttribute("msg", "文件批量上传成功");

        req.getRequestDispatcher("common/success.jsp").forward(req, resp);

        return;

    }

    private String getFileName(Part part) {

        String header=part.getHeader("Content-Disposition");//Content-Disposition

        String filename=header.substring(header.indexOf("filename="")+10, header.lastIndexOf("""));

        return filename;

    }

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        doPost(req, resp);

    }

}

三、采用注解方式，未使用配置文件web.xml

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原文地址：https://www.cnblogs.com/zhaoran8775/p/5521488.html