SpringMVC实现文件上传与下载

单文件上传：

pom.xml:

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>1.3.2</version>
</dependency>
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.2.1</version>
</dependency>
<dependency>
    <groupId>jstl</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
</dependency>
<dependency>
    <groupId>taglibs</groupId>
    <artifactId>standard</artifactId>
    <version>1.1.2</version>
</dependency>

upload.jsp：

1.input的type设置为file。

2.form表单的method设置为post。（get请求只会将文件名传给后台）

3.form表单的enctype设置为multipart/form-data，以二进制的形式传输数据。

<%
    String path = request.getContextPath();
    String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";
%>
<form action="<c:url value="/upload"/>" method="post" enctype="multipart/form-data">
    <input type="file" name="img">
    <input type="submit" name="提交">
</form>
<br/>
<c:if test="${filePath!=null }">
    <h1>上传的图片</h1><br/>
    <img width="300px" src="<%=basePath %>${filePath}"/>
</c:if>

FileController.java:

@RequestMapping(value="upload", method = RequestMethod.POST)
    public String upload(@RequestParam(value="img")MultipartFile img, HttpServletRequest request)
            throws Exception {
        //getSize()方法获取文件的大小来判断是否有上传文件
        if (img.getSize() > 0) {
            //获取保存上传文件的file文件夹绝对路径
            String path = request.getSession().getServletContext().getRealPath("file");
            //获取上传文件名
            String fileName = img.getOriginalFilename();
            File file = new File(path, fileName);
            img.transferTo(file);
            //保存上传之后的文件路径
            request.setAttribute("filePath", "file/"+fileName);
            System.out.println("file/"+fileName);
            return "upload";
        }
        return "error";
    }

springMVC.xml:

<!-- 配置CommonsMultipartResolver bean，id必须是multipartResolver -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
   <!-- 处理文件名中文乱码 -->
   <property name="defaultEncoding" value="utf-8"/>
   <!-- 设置多文件上传，总大小上限，不设置默认没有限制，单位为字节，1M=1*1024*1024 -->
   <property name="maxUploadSize" value="1048576"/>
   <!-- 设置每个上传文件的大小上限 -->
   <property name="maxUploadSizePerFile" value="1048576"/>
</bean>
<!-- 设置异常解析器 -->
<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
    <property name="defaultErrorView" value="/error.jsp"/>
</bean>

注意：这里需要在webapp文件下手动创建一个file文件夹。

多文件上传：

uploads.jsp:

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

<form action="uploads" method="post" enctype="multipart/form-data">
    file1:<input type="file" name="imgs"><br />
    file2:<input type="file" name="imgs"><br />
    file3:<input type="file" name="imgs"><br />
    <input type="submit" name="提交">
</form>
<c:if test="${filePaths!=null }">
    <h1>上传的图片</h1><br />
    <c:forEach items="${filePaths }" var="filePath">
        <img width="300px" src="<%=basePath %>${filePath}"/>
    </c:forEach>
</c:if>

FileController.java:

@RequestMapping(value="/uploads", method = RequestMethod.POST)
    public String uploads(@RequestParam MultipartFile[] imgs, HttpServletRequest request)throws Exception {
        //创建集合，保存上传后的文件路径
        List<String> filePaths = new ArrayList<String>();
        for (MultipartFile img : imgs) {
            if (img.getSize() > 0) {
                String path = request.getSession().getServletContext().getRealPath("file");
                String fileName = img.getOriginalFilename();
                File file = new File(path, fileName);
                filePaths.add("file/"+fileName);
                img.transferTo(file);
            }
        }
        request.setAttribute("filePaths", filePaths);
        return "uploads";
}

文件下载：

download.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
</head>
<body>
<a href="download?fileName=logo.jpg">下载图片</a>
</body>
</html>

FileController.java:

@RequestMapping("/download")
    public void downloadFile(String fileName,HttpServletRequest request,
                             HttpServletResponse response){
        if(fileName!=null){
            //获取file绝对路径
            String realPath = request.getServletContext().getRealPath("file/");
            File file = new File(realPath,fileName);
            OutputStream out = null;
            if(file.exists()){
                //设置下载完毕不打开文件
                response.setContentType("application/force-download");
                //设置文件名
                response.setHeader("Content-Disposition", "attachment;filename="+fileName);
                try {
                    out = response.getOutputStream();
                    out.write(FileUtils.readFileToByteArray(file));
                    out.flush();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }finally{
                    if(out != null){
                        try {
                            out.close();
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
    }