一般会用在文件下载时，需要在浏览器中打开预览的场景，会有需求获取到对应文件的 mimeType

  1. package cn.mrcode;
  3. import java.io.IOException;
  4. import java.nio.file.Files;
  5. import java.nio.file.Path;
  6. import java.nio.file.Paths;
  7. import java.util.Arrays;
  8. import java.util.List;
  10. /**
  11.  * 根据文件名获取 mimeType
  12.  *
  13.  * @author mrcode
  14.  * @date 2021/9/1 20:59
  15.  */
  16. public class MimeTypeUtil {
  17.     /**
  18.      * 流类型
  19.      */
  20.     public static final String APPLICATION_OCTET_STREAM_VALUE = "application/octet-stream";
  22.     /**
  23.      * 根据文件名后缀获取 mimeType;
  24.      * <pre>
  25.      * 支持的类型如下：
  26.      * gif : image/gif
  27.      * bmp : image/bmp
  28.      * ico : image/x-icon
  29.      * jpeg : image/jpeg
  30.      * jpg : image/jpeg
  31.      * png : image/png
  32.      * zip : application/x-zip-compressed
  33.      * jsp : null
  34.      * pdf : application/pdf
  35.      * png : image/png
  36.      * jpg : image/jpeg
  37.      * mp4 : video/mp4
  38.      * flv : null
  39.      * ppt : application/vnd.ms-powerpoint
  40.      * pptx : application/vnd.openxmlformats-officedocument.presentationml.presentation
  41.      * xlsx : application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
  42.      * xls : application/vnd.ms-excel
  43.      * doc : application/msword
  44.      * docx : application/vnd.openxmlformats-officedocument.wordprocessingml.document
  45.      * txt : text/plain
  46.      * </pre>
  47.      *
  48.      * @return
  49.      */
  50.     public static String get(String fileName) {
  51.         return get(Paths.get(fileName));
  52.     }
  54.     public static String get(String fileName, String defaultMimeType) {
  55.         final String mimeType = get(fileName);
  56.         return mimeType == null ? defaultMimeType : mimeType;
  57.     }
  59.     public static String get(Path filePath) {
  60.         try {
  61.             return Files.probeContentType(filePath);
  62.         } catch (IOException e) {
  63.             e.printStackTrace();
  64.             return null;
  65.         }
  66.     }
  68.     public static String get(Path filePath, String defaultMimeType) {
  69.         final String mimeType = get(filePath);
  70.         return mimeType == null ? defaultMimeType : mimeType;
  71.     }
  73.     public static void main(String[] args) {
  74.         final List<String> suffixs = Arrays.asList(
  75.                 "gif", "bmp", "ico", "jpeg", "jpg", "png", "zip", "jsp", "pdf", "png", "jpg", "mp4", "flv", "ppt", "pptx", "xlsx", "xls", "doc", "docx", "txt"
  76.         );
  77.         for (int i = 0; i < suffixs.size(); i++) {
  78.             final String suffix = suffixs.get(i);
  79.             System.out.println(suffix + " : " + get(i + "." + suffix));
  80.         }
  81.     }
  82. }

文件下载、预览

使用上面的工具类获取 contentType，然后按前端传递的参数 type 来判定是在浏览器内部打开？还是使用浏览器下载

  1.         // 设置文件大小
  2.         response.setContentLength((int) Files.size(path));
  3.         response.setContentType(MimeTypeUtil.get(path, MimeTypeUtil.APPLICATION_OCTET_STREAM_VALUE));
  5.         // 文件名有中文，先编码
  6.         String fileNameEncod = URLEncoder.encode(fileName, StandardCharsets.UTF_8.toString());
  7.         String contentDispositionValue = StrUtil.format("{}; filename=\"{}\"; filename*=utf-8''{}",
  8.                 type == 1 ? "inline" : "attachment",  // inline 浏览器内部打开，attachment 下载
  9.                 fileNameEncod, fileNameEncod
  10.         );
  11.         response.setHeader("Content-Disposition", contentDispositionValue);
  12.         // java.nio.file.Files
  13.           Files.copy(path, response.getOutputStream());

openJdk 无法获取到任何类型

原因：

  • 服务器上使用 OpenJdk：使用上面的写法无法获取到任何类型，应该是对应的配置文件被阉割了
  • 本地使用 OracleJdk：可以正常获取

故而直接改成手动获取的返回了

  1. package com.runshopstore.crmbe.common_service;
  3. import java.nio.file.Path;
  4. import java.nio.file.Paths;
  5. import java.util.Arrays;
  6. import java.util.HashMap;
  7. import java.util.List;
  8. import java.util.Map;
  10. import cn.hutool.core.io.file.FileNameUtil;
  11. import cn.hutool.core.util.StrUtil;
  12. import lombok.SneakyThrows;
  13. import lombok.extern.slf4j.Slf4j;
  15. /**
  16.  * 根据文件名获取 mimeType
  17.  *
  18.  * @author mrcode
  19.  * @date 2021/9/1 20:59
  20.  */
  21. @Slf4j
  22. public class MimeTypeUtil {
  23.     private static Map<String, String> map = new HashMap<>();
  25.     static {
  26.         map.put("gif", "image/gif");
  27.         map.put("bmp", "image/bmp");
  28.         map.put("ico", "image/x-icon");
  29.         map.put("jpeg", "image/jpeg");
  30.         map.put("jpg", "image/jpeg");
  31.         map.put("png", "image/png");
  32.         map.put("zip", "application/x-zip-compressed");
  33.         map.put("jsp", "null");
  34.         map.put("pdf", "application/pdf");
  35.         map.put("png", "image/png");
  36.         map.put("jpg", "image/jpeg");
  37.         map.put("mp4", "video/mp4");
  38.         map.put("flv", "null");
  39.         map.put("ppt", "application/vnd.ms-powerpoint");
  40.         map.put("pptx", "application/vnd.openxmlformats-officedocument.presentationml.presentation");
  41.         map.put("xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
  42.         map.put("xls", "application/vnd.ms-excel");
  43.         map.put("doc", "application/msword");
  44.         map.put("docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document");
  45.         map.put("txt", "text/plain");
  46.     }
  48.     /**
  49.      * 流类型
  50.      */
  51.     public static final String APPLICATION_OCTET_STREAM_VALUE = "application/octet-stream";
  53.     /**
  54.      * 根据文件名后缀获取 mimeType;
  55.      * <pre>
  56.      * 支持的类型如下：
  57.      * gif : image/gif
  58.      * bmp : image/bmp
  59.      * ico : image/x-icon
  60.      * jpeg : image/jpeg
  61.      * jpg : image/jpeg
  62.      * png : image/png
  63.      * zip : application/x-zip-compressed
  64.      * jsp : null
  65.      * pdf : application/pdf
  66.      * png : image/png
  67.      * jpg : image/jpeg
  68.      * mp4 : video/mp4
  69.      * flv : null
  70.      * ppt : application/vnd.ms-powerpoint
  71.      * pptx : application/vnd.openxmlformats-officedocument.presentationml.presentation
  72.      * xlsx : application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
  73.      * xls : application/vnd.ms-excel
  74.      * doc : application/msword
  75.      * docx : application/vnd.openxmlformats-officedocument.wordprocessingml.document
  76.      * txt : text/plain
  77.      * </pre>
  78.      *
  79.      * @return
  80.      */
  81.     public static String get(String fileName) {
  82.         return get(Paths.get(fileName));
  83.     }
  85.     public static String get(String fileName, String defaultMimeType) {
  86.         final String mimeType = get(fileName);
  87.         return mimeType == null ? defaultMimeType : mimeType;
  88.     }
  90.     @SneakyThrows
  91.     public static String get(Path filePath) {
  92.         final String fileName = filePath.getFileName().toString();
  93.         final String extName = FileNameUtil.extName(fileName);
  94.         return map.get(extName);
  95.         //return Files.probeContentType(filePath);  // openJDK 无法获取到对应的类型
  96.     }
  98.     public static String get(Path filePath, String defaultMimeType) {
  99.         final String mimeType = get(filePath);
  100.         return mimeType == null ? defaultMimeType : mimeType;
  101.     }
  103.     public static void main(String[] args) {
  104.         final List<String> suffixs = Arrays.asList(
  105.                 "gif", "bmp", "ico", "jpeg", "jpg", "png", "zip", "jsp", "pdf", "png", "jpg", "mp4", "flv", "ppt", "pptx", "xlsx", "xls", "doc", "docx", "txt"
  106.         );
  107.         for (int i = 0; i < suffixs.size(); i++) {
  108.             final String suffix = suffixs.get(i);
  109. //            System.out.println(suffix + " : " + get(i + "." + suffix));
  110.             System.out.println(StrUtil.format("map.put(\"{}\",\"{}\");", suffix, get(i + "." + suffix)));
  111.         }
  112.     }
  113. }