ssm 前端上传文件，java后台接收文件并存储到mysql数据库（绝对路径）和下载

准备

首先导入两个jar包，下方是maven依赖，版本可自己选

		<dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>1.4</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.2</version>
        </dependency>

html

<form name="form" action="" enctype="multipart/form-data"
				method="post">
	<input type="file" name="uploadFile" id="upload">
	<button type="submit" onclick="formSave()">保存</button>
</form>

<script>
function formSave() {
	document.form.action="${pageContext.request.contextPath}/test/save.do";
}
</script>

java后端

@RequestMapping("/save.do")
public void save(Contract contract, @RequestParam("uploadFile") MultipartFile file, HttpServletRequest	request) throws Exception {
        String trueName = file.getOriginalFilename();
        String path = "d:/";  //自己设置一个路径

        File file1 = new File(path + trueName);
        String uploadURL = path + trueName;
//        判断当前文件父级文件夹是否存在，如果不存在，就创建文件夹
        if (!file1.getParentFile().exists()) {
            file1.mkdirs();
        }
        try {
//            上传文件，核心功能
            file.transferTo(file1);
        } catch (IOException e) {
            e.printStackTrace();
        }
		
}

几个注意点

接下来就是写service层和dao层，很简单，普通的增删改查（略）

下载

<a href="${pageContext.request.contextPath}/contract/downLoadAppendices.do?id=${contract.ID}">下载</a>

    @RequestMapping("/downLoadAppendices.do")
    public void downLoadAppendices(HttpServletRequest request,HttpServletResponse response) throws IOException {
    //前端传id值，根据id值查出数据库字段中的地址字符串
        String id = request.getParameter("id");
        String path = contractService.downLoadAppendices(id);
        // 修改文件名的编码格式
        String fName = path.trim();
        String fileName = fName.substring(fName.lastIndexOf("/")+1);
        ServletContext servletContext = request.getServletContext();
        FileInputStream fis = new FileInputStream(path);
        //MIME类型:在互联网通信过程中定义的一种文件数据类型
        String mimeType = servletContext.getMimeType(fileName);
        response.setHeader("content-type",mimeType);
        response.setHeader("content-disposition","attachment;filename="+fileName);
        ServletOutputStream sos = response.getOutputStream();
        byte[] buff = new byte[1024];
        int len = 0;
        while((len=fis.read(buff))!=-1){
            sos.write(buff,0,len);
        }
        fis.close();
    }

本文地址：https://blog.csdn.net/qq_29468977/article/details/109629682