Java base64 添加data URI

　　任何语言生成的base64均不会携带data URI，而前端在读取base64时需要携带data URI头

 1     public String getContentType(Path path){
 2         try {
 3             return Files.probeContentType(path);
 4         } catch (IOException e) {
 5             e.printStackTrace();
 6         }
 7         return null;
 8     }
 9 
10     public String getContentType(byte[] bytes){
11         MagicMatch match = null;
12         try {
13             match = Magic.getMagicMatch(bytes);
14         } catch (MagicParseException e) {
15             e.printStackTrace();
16         } catch (MagicMatchNotFoundException e) {
17             e.printStackTrace();
18         } catch (MagicException e) {
19             e.printStackTrace();
20         }
21         return match.getMimeType();
22     }
23 
24     public String encryptToBase64(String filePath) {
25         if (filePath == null) {
26             return null;
27         }
28         try {
29             Path path = Paths.get(filePath);
30             if(Files.exists(path,new LinkOption[]{ LinkOption.NOFOLLOW_LINKS})){
31                 byte[] b = Files.readAllBytes(path);
32                 String contentType = getContentType(path);
33                 String contentType1 = getContentType(b);
34                 String base64str1 = DatatypeConverter.printBase64Binary(b);  //Java7
35                 String base64Str = Base64.getEncoder().encodeToString(b);
36                 // cretate "data URI"
37                 StringBuilder sb = new StringBuilder();
38                 sb.append("data:");
39                 sb.append(contentType);
40                 sb.append(";base64,");
41                 sb.append(base64Str);
42                 return sb.toString();
43             }
44             return null;
45         } catch (IOException e) {
46             e.printStackTrace();
47         }
48         return null;
49     }