简单的把文件转成流保存的上传下载方法：

常量定义：

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1 2	private static final String filePath = "D:/a_photo/";//本地测试 //  private static final String filePath = "/var/";//服务器测试

　注意：对应的 controller 类，注解不能用：@RestController ，而是使用 @Controller

 上传方法：

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/**      * 上传文件      * @author Mongo      * @param file      * @param request      * @param response      */     @RequestMapping(value = "/fileUpload", method = RequestMethod.POST, produces = "text/html; charset=UTF-8")     public void fileUpload(MultipartFile file, HttpServletRequest request,HttpServletResponse response) {                   Map<String, Object> data = new HashMap<String, Object>();         data.put("msg", "fail");         data.put("data", null);         try {             if (file.isEmpty()) {                 logger.info("==== 上传的文件为空 ====");                 data.put("msg", "上传的文件为空");                 response.setContentType("text/html; charset=UTF-8");                 JsonUtils.writeValue(response.getWriter(), data);                 return;             }             String fileName = file.getOriginalFilename(); // 文件名             String suffixName = fileName.substring(fileName.lastIndexOf(".")); // 后缀名             String uuid = UUID.randomUUID().toString().replace("-", "");             fileName = uuid + suffixName; // 新文件名             File nameAndPath = new File(filePath + fileName);<br>　　　　　　　　　　　　　　dest.setWritable(true,false);//linux下需要赋予权限才能上传成功             if (!nameAndPath.getParentFile().exists()) {                 nameAndPath.getParentFile().mkdirs();             }             file.transferTo(nameAndPath);             logger.info("==== 上传成功 ====");             data.put("msg", "success");             data.put("data", fileName);             //往浏览器输出成功与否结果             response.setContentType("text/html; charset=UTF-8");             JsonUtils.writeValue(response.getWriter(), data);         } catch (IOException e) {             e.printStackTrace();             logger.error("==== 上传失败异常 ====",e);         }         return;     }

　　下载方法：

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/**      * 下载文件url      * @author Mongo      * @param request      * @param response      * @param filename      */     @RequestMapping(value = "/fileDownland", method = RequestMethod.GET, produces = "text/html; charset=UTF-8")     public void fileDownland(HttpServletRequest request, HttpServletResponse response) {                   String fileName = request.getParameter("fileName");         String path = filePath + fileName;         logger.info("== 下载链接为： == "+path);         File file = new File(path);                   OutputStream out = null;         FileInputStream in = null;         try {             // 文件存在才下载             if (file.exists()) {                 // 1.读取要下载的内容                 in = new FileInputStream(file);                 // 2. 告诉浏览器下载的方式以及一些设置                 // 解决文件名乱码问题，获取浏览器类型，转换对应文件名编码格式，IE要求文件名必须是utf-8, firefo要求是iso-8859-1编码                 String agent = request.getHeader("user-agent");                 if (agent.contains("FireFox")) {                     fileName = new String(fileName.getBytes("UTF-8"), "iso-8859-1");                 } else {                     fileName = URLEncoder.encode(fileName, "UTF-8");                 }                 // 设置下载文件的mineType，告诉浏览器下载文件类型（下面这两句可以不要）                 //String mineType = request.getServletContext().getMimeType(fileName);                 //response.setContentType(mineType);                 // 设置一个响应头，无论是否被浏览器解析，都下载                 response.setHeader("Content-disposition", "attachment; filename=" + fileName);                 // 将要下载的文件内容通过输出流写到浏览器                 out = response.getOutputStream();                 int len = 0;                 byte[] buffer = new byte[1024];                 while ((len = in.read(buffer)) > 0) {                     out.write(buffer, 0, len);                 }             }         } catch (Exception e) {             e.printStackTrace();         } finally {             try {                 if (out != null) {                     out.close();                 }                 if (in != null) {                     in.close();                 }             } catch (Exception e2) {                 // TODO: handle exception             }         }     }

　　对应的工具类：

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private static ObjectMapper mapper = new ObjectMapper();<br>/**  * 将对象转换为JSON流  *  * @param writer  *            writer  * @param value  *            对象  */ public static void writeValue(Writer writer, Object value) {     try {         mapper.writeValue(writer, value);     } catch (JsonGenerationException e) {         e.printStackTrace();     } catch (JsonMappingException e) {         e.printStackTrace();     } catch (IOException e) {         e.printStackTrace();     } }

　　相应的 jar 包引入：

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import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.OutputStream; import java.net.URLEncoder; import java.util.HashMap; import java.util.Map; import java.util.UUID; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.slf4j.Logger; import org.slf4j.LoggerFactory; 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;