Comment faire pour convertir la liste des chemins de fichier en un objet JSON en Java

Question

J'ai une exigence pour convertir un ensemble de structure de fichier obtenu à partir de DB dans un JSON. Par exemple: De DB, je reçois le chemin suivant et attributs de fichier:

Record 1: 
    "path": "/sd/card/camera/pics/selfie.jpg" 
    "fileName": "selfie.jpg", 
    "mimeType": "image/jpeg" 

Record 2: 
    "path": "/sd/card/camera/pics/personal/selfie1.jpg" 
    "fileName": "selfie1.jpg", 
    "mimeType": "image/jpeg" 

et ainsi de suite .. je dois convertir en un JSON comme:

[{ 
    "sd": [{ 
     "card": [{ 
      "camera": [{ 
       "pics": [{ 
         "fileName": "selfie.jpg", 
         "path": "/sd/card/camera/pics/selfie.jpg", 
         "mimeType": "image/jpeg" 
        }, 
        { 
         "personal": [{ 
          "fileName": "selfie1.jpg", 
          "path": "/sd/card/camera/pics/personal/selfie1.jpg", 
          "mimeType": "image/jpeg" 
         }] 
        } 
       ] 
      }] 
     }] 
    }] 
}] 

Answer 1

Je suis va vous donner une solution jackson. D'abord, construisez un objet (ou plus, Je vous laisse gérer l'héritage Java, ou utiliser n'importe quel type de structure que vous voulez utiliser). Comme celui-ci par exemple:

@JsonSerialize(using = CustomSerializer.class) 
public class Something { 

    private String currentFolder; // Name of the folder if this instance of something is a folder 
    private Something[] childs; 

    private Map<String,String> currentPicture; // Picture properties if this instance of something is a picture 

    public Something() {currentPicture = new HashMap<String,String>();} 

    public Something[] getChilds() { 
     return childs; 
    } 

    public void setContent(Something[] _childs) {this.childs = _childs;} 
    public String getCurrentFolder() {return currentFolder;} 
    public void setCurrentFolder(String _currentFolder) {this.currentFolder = _currentFolder;} 
    public Map<String,String> getCurrentPicture() {return currentPicture;} 
    public void setCurrentPicture(Map<String,String> currentPicture) {this.currentPicture = currentPicture;} 
} 

Ensuite, créez le CustomSerializer, qui vous aidera à faire tout ce que vous voulez faire:

public class CustomSerializer extends JsonSerializer<Something>{ 

    @Override 
    public void serialize(Something value, JsonGenerator jgen, SerializerProvider provider) 
      throws IOException, JsonProcessingException { 
     jgen.writeStartObject(); 
     // Adding the folder into the json, only if it exists 
     if(value.getCurrentFolder()!=null){ 
      jgen.writeObjectField(value.getCurrentFolder(), value.getChilds()); 
     } 

     // Adding properties of the picture, only if they exist 
     if(value.getCurrentPicture()!= null){ 
      for(String k : value.getCurrentPicture().keySet()){ 
       jgen.writeObjectField(k,value.getCurrentPicture().get(k)); 
      } 
     } 
     jgen.writeEndObject(); 
    } 

} 

Enfin (je l'ai pas fait, mais vous Je vais le faire, j'en suis sûr!) Créez un mappeur à partir de ce que vous avez lu jusqu'à la classe "Quelque chose". Je construire l'objet manuellement ici (rapidement, il est donc pas propre):

public static void main(String[] args) throws JsonGenerationException, JsonMappingException, IOException { 
    Something s = new Something(); 
    s.setCurrentFolder("toto"); 
    Something s2 = new Something(); 
    s2.setCurrentFolder("tata"); 

    Something s2bis = new Something(); 
    s2bis.setCurrentFolder("tataBis"); 

    Something[] s2Group = {s2bis}; 
    s2.setContent(s2Group); 
    Something s2bispic = new Something(); 
    s2bispic.getCurrentPicture().put("fileName", "ThatPictureOfMysSelfILikeSoMuch.jpg"); 
    s2bispic.getCurrentPicture().put("path", "toto/tata/tataBis/ThatPictureOfMysSelfILikeSoMuch.jpg"); 
    s2bispic.getCurrentPicture().put("mimeType", "image/jpeg"); 

    Something s2bispic2 = new Something(); 
    s2bispic2.getCurrentPicture().put("fileName", "ThatPictureOfMysSelfIDontLike.jpg"); 
    s2bispic2.getCurrentPicture().put("path", "toto/tata/tataBis/ThatPictureOfMysSelfIDontLike.jpg"); 
    s2bispic2.getCurrentPicture().put("mimeType", "image/jpeg"); 


    Something[] s2BisGroup = {s2bispic,s2bispic2}; 
    s2bis.setContent(s2BisGroup); 
    Something s3 = new Something(); 

    s3.getCurrentPicture().put("fileName", "selfie.jpg"); 
    s3.getCurrentPicture().put("path", "toto/selfie.jpg"); 
    s3.getCurrentPicture().put("mimeType", "image/jpeg"); 

    Something[] sGroup = {s2,s3}; 
    s.setContent(sGroup); 

    ObjectMapper mapper = new ObjectMapper(); 
    String temp = mapper.writeValueAsString(s); 
    System.out.println(temp); 
} 

Et voici ce que je reçois:

{ 
    "toto":[ 
     { 
     "tata":[ 
      { 
       "tataBis":[ 
        { 
        "path":"toto/tata/tataBis/ThatPictureOfMysSelfILikeSoMuch.jpg", 
        "fileName":"ThatPictureOfMysSelfILikeSoMuch.jpg", 
        "mimeType":"image/jpeg" 
        }, 
        { 
        "path":"toto/tata/tataBis/ThatPictureOfMysSelfIDontLike.jpg", 
        "fileName":"ThatPictureOfMysSelfIDontLike.jpg", 
        "mimeType":"image/jpeg" 
        } 
       ] 
      } 
     ] 
     }, 
     { 
     "path":"toto/selfie.jpg", 
     "fileName":"selfie.jpg", 
     "mimeType":"image/jpeg" 
     } 
    ] 
} 

Cordialement,