SpringMVC(上传下载)

SpringMVC的文件上传
1.创建项目，完善结构，导入依赖，配置web.xml

**<!-- 配置开发SpringMVC所以来的jar包 -->
<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-webmvc</artifactId>
  <version>5.1.5.RELEASE</version>
</dependency>
<!-- 配置ServletAPI依赖 -->
<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.0.1</version>
  <scope>provided</scope>
</dependency>
<!-- commons-fileupload组件 -->
<!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
<dependency>
  <groupId>commons-fileupload</groupId>
  <artifactId>commons-fileupload</artifactId>
  <version>1.3.1</version>
</dependency>**

2.创建SpringMVC配置文件

**<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/mvc
       http://www.springframework.org/schema/mvc/spring-mvc.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd">
    <!--开启注解-->
    <mvc:annotation-driven></mvc:annotation-driven>
    <!--配置自动扫描包-->
    <context:component-scan base-package="com.wangxing.springmvc.controller"></context:component-scan>
    <!-- 视图解析器-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!--maxUploadSize上传文件的大小  -->
        <property name="maxUploadSize" value="104857600" />
        <!--maxInMemorySize内存大小 -->
        <property name="maxInMemorySize" value="4096" />
        <!--defaultEncoding默认字符编码 -->
        <property name="defaultEncoding" value="UTF-8"></property>
    </bean>
</beans>**

3.创建文件上传页面，和成功的页面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>文件上传</title>
</head>
<body>

<!--
   1.form表单的method属性一定是post
   2.enctype属性一定要设置且取值multipart/form-data
    enctype 属性规定在发送到服务器之前应该如何对表单数据进行编码
    application/x-www-form-urlencoded----在发送前编码所有字符（默认）
    multipart/form-data----不对字符编码。在使用包含文件上传控件的表单时，必须使用该值。
    text/plain---空格转换为 "+" 加号，但不对特殊字符编码。
   3.文件上传控件---<input type="file" name="myfile">
-->

   <form action="upload.do" method="post" enctype="multipart/form-data">
        <input type="file" name="myfile"><br>
        <input type="submit" value="上传">
    </form>
</body>
</html>

4.创建处理文件上传请求的控制器

package com.wangxing.springmvc.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.util.Iterator;

//文件上传控制器
@Controller
public class UploadController {
    @RequestMapping(value = "/upload.do",method = RequestMethod.POST)
    public ModelAndView  upload(HttpServletRequest request)throws Exception{
        ModelAndView  mav=new ModelAndView();
        //处理包含有文件的http请求
        //1. 将当前类中的ServletContext对象转换成CommonsMultipartResolver
        ServletContext servletContext=request.getSession().getServletContext();
        CommonsMultipartResolver commonsMultipartResolver=new CommonsMultipartResolver(servletContext);
        //2.检验HttpServletRequest是否是一个文件上传请求
        if(commonsMultipartResolver.isMultipart(request)){
            //3.将HttpServletRequest请求转换成文件上传请求
            MultipartHttpServletRequest multipartreq=(MultipartHttpServletRequest)request;
            //4.从文件上传请求中得到得到文件名称
            Iterator<String> itname=multipartreq.getFileNames();
            while(itname.hasNext()){
                 //得到input元素的name属性值
                String nameshuxing=itname.next().toString();  //myfile
                //根据name属性值得到上传来的文件对象
                MultipartFile multipartfile=multipartreq.getFile(nameshuxing);
                String newfilename=""; //保存上传来的文件的名称
                if(multipartfile!=null){
                    //得到被上传来的文件的真实名称【test.html】
                    String  zhenFileName=multipartfile.getOriginalFilename();
                    //得到文件的后缀名[.html]
                    String houzhuiming=zhenFileName.substring(zhenFileName.lastIndexOf("."));
                    //得到系统时间的毫秒数，将来作为文件的名称
                    long haomiaoshu=System.currentTimeMillis();
                    newfilename=haomiaoshu+houzhuiming;
                    //获取项目的根目录
                    String realPath = servletContext.getRealPath("/upload");
                    //创建保存文件的目录
                    File uploadpicdir = new File(realPath);
                    if(!uploadpicdir.exists()){
                        //创建upload目录
                        uploadpicdir.mkdirs();
                    }
                    //组织一个保存文件的对象【文件保存目录+文件名称】
                    String pathfile=uploadpicdir.getAbsolutePath()+File.separator+newfilename;
                    System.out.println(pathfile);
                    File saveFile=new File(pathfile);
                    //保存文件到本地磁盘
                    multipartfile.transferTo(saveFile);
                }
                     //得到上传成功以后的文件的http访问地址
                    String reqURL=request.getRequestURL().toString();
                    reqURL=reqURL.substring(0,reqURL.lastIndexOf("/"));
                    reqURL=reqURL+"/upload/"+newfilename;
                    //http://127.0.0.1:8080/upload/xxxxxx.jpg
                    System.out.println("reqURL=="+reqURL);
            }
            mav.setViewName("success.html");
        }
        return mav;
    }
}

5.部署测试

SpringMVC的文件下载
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>文件上传</title>
</head>
<body>
    <h1><a href="dowload.do?myfile=avatar.png">下载avatar.png</h1>
    <h1><a href="dowload.do?myfile=bgcolor.html">下载bgcolor.html</h1>
</body>
</html>

package com.wangxing.springmvc.controller;
import org.apache.commons.io.FileUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.http.HttpServletRequest;
import java.io.File;

@Controller
public class DowloadController {
    @RequestMapping(value = "/dowload.do",method = RequestMethod.GET)
    public ResponseEntity<byte[]> dowloadMethod(HttpServletRequest req)throws Exception{
        //得到请求中的文件名称
        String filename=req.getParameter("myfile");
        String realPath = req.getSession().getServletContext().getRealPath("/upload");
        //创建保存文件的目录的文件对象
        File uploadpicdir = new File(realPath);
        //创建被下载的文件对象
        File file=new File(uploadpicdir,filename);
        System.out.println(file.getAbsolutePath());
        //设置http协议头
        HttpHeaders headers = new HttpHeaders();
        headers.setContentDispositionFormData("attachment",filename);
        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),headers, HttpStatus.CREATED);
    }
}

SpringMVC(上传下载)

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