文件下载与上传

jsp

<style type="text/css">
        form{
            margin:0px auto; 
            border:1px solid red;
            500px;
            padding:20px;
        }
    </style>
  </head>
  
  <body>
   <form action="${pageContext.request.contextPath }/frist.do" method="post" enctype="multipart/form-data">
       <h1>文件上传</h1>
       文件：<input type="file" name="uploadFile"/><br/>
       文件：<input type="file" name="uploadFile"/><br/>
       文件：<input type="file" name="uploadFile"/><br/>
       <input type="submit" value="上传">
   </form>
  </body>

单文件上传

通过对文件的大小来判断是否有文件

通过文件的类型来判断是否是允许

@Controller

public class MyController {

    @RequestMapping(value="/frist.do", method=RequestMethod.POST)

    public String doFirst(HttpSession session,MultipartFile uploadFile)throws Exception{

        if(uploadFile.getSize()>0){

            //02.获取前半部分路径，jiangWebRoot下一个名称为images文件夹  转换成绝对路径

            String path = session.getServletContext().getRealPath("/upload");

            //01.获取文件名作为保存到服务器的文件名称

            String fileName=uploadFile.getOriginalFilename();

            if(fileName.endsWith(".jpg")||fileName.endsWith(".JPG")){

                //03.路径拼接

                File file = new File(path,fileName);

                uploadFile.transferTo(file);

            }

            return "welcome.jsp";

        }

        return "error.jsp";

    }

applicationContext.xml配置

<?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:context="http://www.springframework.org/schema/context"

    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"

    xmlns:mvc="http://www.springframework.org/schema/mvc"

    xsi:schemaLocation="

        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd

        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd

        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd

        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd

        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd

        ">
 
    <!-- 配置包扫描器 -->

    <context:component-scan base-package="cn.controller"></context:component-scan>
 
    <bean id="multipartResolver"

        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">

        <property name="defaultEncoding" value="utf-8"></property><!-- 客户端发送数据的编码 -->

        <property name="maxUploadSize" value="5242880"></property><!-- 上传文件的大小 -->

        <!-- <property name="uploadTempDir" value="/upload"></property> -->

    </bean>

    <!-- mvc注解驱动 -->

    <mvc:annotation-driven />
 
</beans>

web.xml

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

<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://java.sun.com/xml/ns/javaee

    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

  <display-name></display-name>

  <!-- ================spring mvc 适配器================ -->  

  <servlet>

    <servlet-name>springmvc</servlet-name>

    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

    <init-param>

      <param-name>contextConfigLocation</param-name>

      <param-value>classpath:applicationContext.xml</param-value>

    </init-param>

    <load-on-startup>1</load-on-startup>

  </servlet>

  <servlet-mapping>

    <servlet-name>springmvc</servlet-name>

    <url-pattern>*.do</url-pattern>

  </servlet-mapping>

 <!-- ================================================== --> 

  <welcome-file-list>

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

  </welcome-file-list>
</web-app>

多文件上传(多文件上传与单文件上传配置相同下面介绍一下不同的地方)

标记为红色的字段为多文件上传与单文件上传的区别

　@RequestMapping(value="/firstdown.do")

public String doFirst(@RequestParam MultipartFile[] uploadFile,HttpSession session)throws Exception{

    for (MultipartFile item : uploadFile) {

        if(item.getSize()>0){

            //02.获取前半部分路径，jiangWebRoot下一个名称为images文件夹  转换成绝对路径

            String path = session.getServletContext().getRealPath("/upload");

            //01.获取文件名作为保存到服务器的文件名称

            String fileName=item.getOriginalFilename();

            if(fileName.endsWith(".jpg")||fileName.endsWith(".JPG")){

                //03.路径拼接

                File file = new File(path,fileName);

                item.transferTo(file);

            }

            return "welcome.jsp";

        }

    }

    return "error.jsp";
}

文件下载

1	`@RequestMapping(value="/first.do")`

<br> public static void download(HttpServletRequest request, 

            HttpServletResponse response, String storeName, String contentType

           ) throws Exception { 

        request.setCharacterEncoding("UTF-8"); 

        BufferedInputStream bis = null; 

        BufferedOutputStream bos = null; 

        //获取项目根目录

        String ctxPath = request.getSession().getServletContext() 

                .getRealPath(""); 

        //获取下载文件露肩

        String downLoadPath = ctxPath+"/uploadFile/"+ storeName; 

        //获取文件的长度

        long fileLength = new File(downLoadPath).length(); 
 
        //设置文件输出类型

        response.setContentType("application/octet-stream"); 

        response.setHeader("Content-disposition", "attachment; filename=" 

                + new String(storeName.getBytes("utf-8"), "ISO8859-1"));

        //设置输出长度

        response.setHeader("Content-Length", String.valueOf(fileLength)); 

        //获取输入流

        bis = new BufferedInputStream(new FileInputStream(downLoadPath)); 

        //输出流

        bos = new BufferedOutputStream(response.getOutputStream()); 

        byte[] buff = new byte[2048]; 

        int bytesRead; 

        while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) { 

            bos.write(buff, 0, bytesRead); 

        } 

        //关闭流

        bis.close(); 

        bos.close(); 

    }

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