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SSM file upload and download

2022-06-11 08:20:00 【WldKid_ zxy】

1. Add jar package (mysl Connected by different versions Jar The bag is different )

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2. Upload files html page

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h2> Administrator file upload </h2>
<form method="post" action="fileUploads" enctype="multipart/form-data">
  <p> file name :<input type="file" name="file1"></p>
  <p> file name :<input type="file" name="file2"></p>
  <p> file name :<input type="file" name="file3"></p>
  <p> file name :<input type="submit" value=" Submit "></p>
</form>
</body>
</html>

3 ssm.ml File configuration （aplication.xmx Self configuring ）

    <!-- File upload configuration -->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- Set the size of the file (1048576=1M)-->
        <property name="maxUploadSize" value="4194304"/>
        <!-- Buffer size -->
        <property name="maxInMemorySize" value="4096"/>
        <property name="defaultEncoding" value="utf-8"/>
    </bean>

4. The code of each layer

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5. Upload files Controer（ Code ）

    @RequestMapping("fileUploads")
    public String upload(HttpServletRequest request) throws IOException {
    
        //  Initialize the current context to  CommonsMutipartResolver （ Multipart parser ）
        CommonsMultipartResolver multipartResolver =
                new CommonsMultipartResolver(request.getSession().getServletContext());

        //  Check form If there  enctype="multipart/form-data"
        if (multipartResolver.isMultipart(request)) {
    
            //  take request Become part of request
            MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request;
            //  obtain multiRequest  All the filenames in 
            Iterator iter = multiRequest.getFileNames();
            while (iter.hasNext()) {
    
                //  Traverse all files at once 
                MultipartFile file = multiRequest.getFile(iter.next().toString());
                if (file != null && file.getOriginalFilename() != "") {
    
                    // Judgment of file format   File name processing is omitted 
                    String fileName = file.getOriginalFilename();
                    /*UUID Name the file to avoid duplicate file names */
                    String uuid = UUID.randomUUID().toString();
                    String path = request.getSession().getServletContext()
                            .getRealPath("/userFile/") + uuid + "_" + fileName;
                    // Need to be in web Next create a userFile Folder （ There must be a sub file under this folder ）
                    file.transferTo(new File(path));
                    //  Upload to the database 
                    filesService.addFile(uuid + "_" + fileName);
                }
            }
        }
        return "index";
    }

6. Upload files （javaWeb Chapter 246 ）

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7. File download （Controller Code ）

7.1html file

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title> File download </title>
</head>
<script src="js/jquery-1.12.4.min.js"></script>
<script>
    $(function () {
    
        $.getJSON("filesList", function (data) {
    
            console.log(data);
            loadData(data);
        });
    });

    function loadData(data) {
    
        $("#t tr:gt(0)").remove();
        for (var i = 0; i < data.length; i++) {
    
            var str = "<tr><td>";
            str += "<input type='checkbox' class='choose' value='" + data[i].fileId + "'/></td><td>";
            str += data[i].fileId + "</td><td>";
            str += data[i].fileName.substr(data[i].fileName).slice(37) + "</td><td>";
            str += "<a href='fileDowns?filename=" + data[i].fileName + "'> download </a></td></tr>";
            $("#t").append(str);
        }
    }

</script>
<body>

<a href="fileDowns?filename=5a54247f-2127-4f4f-b3bf-d2025077c7fc_c3p0.zip"> File download </a>
<div>
    <h3 style="color: red"> File download </h3>
    <button><a href="index.html"> home page </a></button>
    <table id="t" border="1" cellpadding="3" cellspacing="3">
        <tr>
            <th><input type="checkbox" onclick="" id="all"></th>
            <th> Serial number </th>
            <th> file name </th>
            <th> operation </th>
        </tr>
    </table>
</div>
</body>
</html>

7.2 Front end output file name （ Download according to the file name of the database ）

    @RequestMapping(value = "filesList")
    @ResponseBody
    public String getFilesList() {
    
        System.out.println(" Get into filesList_>");

        // Call the underlying method to get the file name from the data 
        List<Files> list = filesService.getFiles();
        String string = JSON.toJSONString(list);
        System.out.println(string);
        return string;
    }

7.3 File download


    @RequestMapping(value = "fileDowns")
    public void download(HttpServletRequest request, HttpServletResponse response, String filename) throws IOException {
    
        //checkPay.apk For files that need to be downloaded 
        //String filename = "checkPay.apk"; // What I use here is a fixed file , Methods can be written without filename Parameters 
        // Get the absolute path name of the file ,apk Is a folder under the root directory , This can only get the absolute path of the root folder 
        String path = request.getSession().getServletContext().getRealPath("userFile") + "\\" + filename;
        System.out.println(path);

        // Get the file to download 
        File file = new File(path);
        if (!file.exists()) {
    
            response.setContentType("text/html; charset=UTF-8");// Be careful text/html, and application/html
            response.getWriter().print("<html><body><script type='text/javascript'>alert(' The resource you are downloading has been deleted ！');</script></body></html>");
            response.getWriter().close();
            System.out.println(" The resource you are downloading has been deleted ！！");
            return;
        }
        // transcoding , In order to avoid Chinese garbled file names 
        filename = URLEncoder.encode(filename, "UTF-8");
        // Set file download header 
        response.addHeader("Content-Disposition", "attachment;filename=" + filename.substring(37));
        //1. Settings file ContentType type , Set this way , It will automatically determine the type of downloaded files 
        response.setContentType("multipart/form-data");
        //  Read the file to download , Save to file input stream 
        FileInputStream in = new FileInputStream(path);
        //  Create output stream 
        OutputStream out = response.getOutputStream();
        //  Create buffer 
        byte buffer[] = new byte[1024]; //  The buffer size setting is a mystery   I don't get it either 
        int len = 0;
        // Loop reads the contents of the input stream into the buffer 
        while ((len = in.read(buffer)) > 0) {
    
            out.write(buffer, 0, len);
        }
        // Close file input stream 
        in.close();
        //  Close output stream 
        out.close();
    }