Gson Konvertierung zurückgeben null Java-Objekt

Question

Ich versuche, JSON-String in Java-Bean mit Gson zu konvertieren, aber es ist Rückgabe Nullwert.

public static void convert(String args) { 
    String json = 
       "{"body":{"response":{"total":"294","num":"294","filelist":[{"id":"56712","camname":"Camera1","camid":"514","start":"2016-07-08 12:00:38","end":"2016-07-08 12:03:00","stream":"3","recReason":"Activity","filename":"fs/514/2016-07-08/AD_1_1_3_2016_07_08_12_00_57.mrv","snapshot":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_12_00_57.jpg","nvrip":"192.168.0.200:8095"},{"id":"56708","camname":"Camera1","camid":"514","start":"2016-07-08 11:58:14","end":"2016-07-08 12:00:36","stream":"3","recReason":"Activity","filename":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_58_33.mrv","snapshot":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_58_33.jpg","nvrip":"192.168.0.200:8095"},{"id":"56705","camname":"Camera1","camid":"514","start":"2016-07-08 11:55:49","end":"2016-07-08 11:58:11","stream":"3","recReason":"Activity","filename":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_56_08.mrv","snapshot":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_56_08.jpg","nvrip":"192.168.0.200:8095"},{"id":"56702","camname":"Camera1","camid":"514","start":"2016-07-08 11:53:25","end":"2016-07-08 11:55:47","stream":"3","recReason":"Activity","filename":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_53_44.mrv","snapshot":"fs-/514/2016-07-08/AD_1_1_3_2016_07_08_11_53_44.jpg","nvrip":"192.168.0.200:8095"},{"id":"56699","camname":"Camera1","camid":"514","start":"2016-07-08 11:51:00","end":"2016-07-08 11:53:22","stream":"3","recReason":"Activity","filename":"fs/514/2016-07-08/AD_1_1_3_2016_07_08_11_51_19.mrv","snapshot":"fs-/514/2016-07-08/AD_1_1_3_2016_07_08_11_51_19.jpg","nvrip":"192.168.0.200:8095"}],"status":"OK"}}}"; 

    // Now do the magic. 
    RecordingListResponseDTO data = new Gson().fromJson(json, RecordingListResponseDTO .class); 

    // Show it. 
    System.out.println("converted data :"+data); 
} 

Meine Bohnenklasse folgt. RecordingListResponseDTO

public class RecordingListResponseDTO implements Serializable { 
    private String status; 
    private int total; 
    private int num; 
    List<FileListDTO> fileList; 

    public RecordingListResponseDTO(){ 

    } 
    public RecordingListResponseDTO(String status, int total, int num, List<FileListDTO> fileList) { 
     this.status = status; 
     this.total = total; 
     this.num = num; 
     this.fileList = fileList; 
    } 

    public String getStatus() { 
     return status; 
    } 

    public void setStatus(String status) { 
     this.status = status; 
    } 

    public int getTotal() { 
     return total; 
    } 

    public void setTotal(int total) { 
     this.total = total; 
    } 

    public int getNum() { 
     return num; 
    } 

    public void setNum(int num) { 
     this.num = num; 
    } 

    public List<FileListDTO> getFileList() { 
     return fileList; 
    } 

    public void setFileList(List<FileListDTO> fileList) { 
     this.fileList = fileList; 
    } 

    @Override 
    public String toString() { 
     return "RecordingListResponseDTO{" + 
       "status='" + status + '\'' + 
       ", total=" + total + 
       ", num=" + num + 

       ", fileList=" + fileList + 
       '}'; 
    }} 

FileListDTO.java

public class FileListDTO { 
private int id; 
private String camname; 
private int camid; 
private Date start; 
private Date end; 
private int stream; 
private String recReason; 
private String filename; 
private String snapshot; 
private String nvrip; 

public FileListDTO(int id, String camname, Date start, int camid, Date end, int stream, String recReason, String filename, String snapshot, String nvrip) { 
    this.id = id; 
    this.camname = camname; 
    this.start = start; 
    this.camid = camid; 
    this.end = end; 
    this.stream = stream; 
    this.recReason = recReason; 
    this.filename = filename; 
    this.snapshot = snapshot; 
    this.nvrip = nvrip; 
} 

public int getId() { 
    return id; 
} 

public void setId(int id) { 
    this.id = id; 
} 

public String getCamname() { 
    return camname; 
} 

public void setCamname(String camname) { 
    this.camname = camname; 
} 

public int getCamid() { 
    return camid; 
} 

public void setCamid(int camid) { 
    this.camid = camid; 
} 

public Date getStart() { 
    return start; 
} 

public void setStart(Date start) { 
    this.start = start; 
} 

public Date getEnd() { 
    return end; 
} 

public void setEnd(Date end) { 
    this.end = end; 
} 

public int getStream() { 
    return stream; 
} 

public void setStream(int stream) { 
    this.stream = stream; 
} 

public String getRecReason() { 
    return recReason; 
} 

public void setRecReason(String recReason) { 
    this.recReason = recReason; 
} 

public String getFilename() { 
    return filename; 
} 

public void setFilename(String filename) { 
    this.filename = filename; 
} 

public String getSnapshot() { 
    return snapshot; 
} 

public void setSnapshot(String snapshot) { 
    this.snapshot = snapshot; 
} 

public String getNvrip() { 
    return nvrip; 
} 

public void setNvrip(String nvrip) { 
    this.nvrip = nvrip; 
} 

@Override 
public String toString() { 
    return "FileListDTO{" + 
      "id=" + id + 
      ", camname='" + camname + '\'' + 
      ", camid=" + camid + 
      ", start=" + start + 
      ", end=" + end + 
      ", stream=" + stream + 
      ", recReason='" + recReason + '\'' + 
      ", filename='" + filename + '\'' + 
      ", snapshot='" + snapshot + '\'' + 
      ", nvrip='" + nvrip + '\'' + 
      '}'; 
}} 

Ich erhalte Nullwert nach JSON-String zu Java-Objekt zu konvertieren. was ich falsch mache, bitte schlage mich vor. Vielen Dank im Voraus.

Answer 1

Voraussetzungen helfen können:

Folge JSON wurde durchgeführt:

{ 
    "body":{ 
     "response":{ 
     "total":294, 
     "num":294, 
     "filelist":[ 
      { 
       "id":56712, 
       "camname":"Camera1", 
       "camid":514, 
       "start":"2016-07-08 12:00:38", 
       "end":"2016-07-08 12:03:00", 
       "stream":3, 
       "recReason":"Activity", 
       "filename":"fs/514/2016-07-08/AD_1_1_3_2016_07_08_12_00_57.mrv", 
       "snapshot":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_12_00_57.jpg", 
       "nvrip":"192.168.0.200:8095" 
      }, 
      { 
       "id":56708, 
       "camname":"Camera1", 
       "camid":514, 
       "start":"2016-07-08 11:58:14", 
       "end":"2016-07-08 12:00:36", 
       "stream":3, 
       "recReason":"Activity", 
       "filename":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_58_33.mrv", 
       "snapshot":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_58_33.jpg", 
       "nvrip":"192.168.0.200:8095" 
      }, 
      { 
       "id":56705, 
       "camname":"Camera1", 
       "camid":514, 
       "start":"2016-07-08 11:55:49", 
       "end":"2016-07-08 11:58:11", 
       "stream":3, 
       "recReason":"Activity", 
       "filename":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_56_08.mrv", 
       "snapshot":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_56_08.jpg", 
       "nvrip":"192.168.0.200:8095" 
      }, 
      { 
       "id":56702, 
       "camname":"Camera1", 
       "camid":514, 
       "start":"2016-07-08 11:53:25", 
       "end":"2016-07-08 11:55:47", 
       "stream":3, 
       "recReason":"Activity", 
       "filename":"fs-1/514/2016-07-08/AD_1_1_3_2016_07_08_11_53_44.mrv", 
       "snapshot":"fs-/514/2016-07-08/AD_1_1_3_2016_07_08_11_53_44.jpg", 
       "nvrip":"192.168.0.200:8095" 
      }, 
      { 
       "id":56699, 
       "camname":"Camera1", 
       "camid":514, 
       "start":"2016-07-08 11:51:00", 
       "end":"2016-07-08 11:53:22", 
       "stream":3, 
       "recReason":"Activity", 
       "filename":"fs/514/2016-07-08/AD_1_1_3_2016_07_08_11_51_19.mrv", 
       "snapshot":"fs-/514/2016-07-08/AD_1_1_3_2016_07_08_11_51_19.jpg", 
       "nvrip":"192.168.0.200:8095" 
      } 
     ], 
     "status":"OK" 
     } 
    } 
} 

Schritt 1:

die Deklaration von private List<FileListDTO> fileList in RecordingListResponseDTO.java wie folgt ändern:

@SerializedName("filelist") 
private List<FileListDTO> fileList 

Schritt 2:

definieren folgende Klasse MyDateTypeAdapter.java:

import java.lang.reflect.Type; 
import java.text.DateFormat; 
import java.text.ParseException; 
import java.text.SimpleDateFormat; 
import java.util.Date; 
import java.util.Locale; 
import java.util.TimeZone; 

import com.google.gson.JsonDeserializationContext; 
import com.google.gson.JsonDeserializer; 
import com.google.gson.JsonElement; 
import com.google.gson.JsonParseException; 
import com.google.gson.JsonPrimitive; 
import com.google.gson.JsonSerializationContext; 
import com.google.gson.JsonSerializer; 

public class MyDateTypeAdapter implements JsonSerializer<Date>, JsonDeserializer<Date> { 

    private DateFormat dateFormat; 

    public MyDateTypeAdapter() { 
     dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.US); 
     dateFormat.setTimeZone(TimeZone.getTimeZone("UTC")); 
    } 

    @Override 
    public synchronized JsonElement serialize(Date date, Type type, JsonSerializationContext jsonSerializationContext) { 
     return new JsonPrimitive(dateFormat.format(date)); 
    } 

    @Override 
    public synchronized Date deserialize(JsonElement jsonElement, Type type, 
      JsonDeserializationContext jsonDeserializationContext) { 
     try { 
      return dateFormat.parse(jsonElement.getAsString()); 
     } catch (ParseException e) { 
      throw new JsonParseException(e); 
     } 
    } 

} 

Schritt 3:

die Methode ändern convert(String args) wie folgt:

public static void convert(String args) { 
     JsonParser parser = new JsonParser(); 
     String json = parser.parse(args) 
          .getAsJsonObject() 
          .getAsJsonObject("body") 
          .getAsJsonObject("response") 
          .toString(); 

     // Now do the magic. 
     RecordingListResponseDTO data = new GsonBuilder() 
       .registerTypeAdapter(Date.class, new MyDateTypeAdapter()) 
       .create().fromJson(json, RecordingListResponseDTO.class); 
     // Show it. 
     System.out.println("converted data :"+data); 
} 

Für Testzwecke können Sie versuchen, die JSON in einer Datei, dh die Speicherung D:/test.json und rufen Sie die Methode durch:

String json = new String(Files.readAllBytes(Paths.get("D:/test.json"))); 
convert(json); 

Answer 2

etwas, das man die Modelle Klasse ändern müssen wie,

zunächst in Ihrer json Antwortdaten enthält „body“ -Tag, der darstellt, zu widersprechen ist, zunächst müssen Sie die Klasse für das Objekt-Tag erstellen, dann sind alle Daten enthält innen Ihre "body" -Tag, analysieren so alle innerhalb von Daten von Körperdaten,

diesen Code,

public class RecordingListResponseDTO implements Serializable { 
    Recordinglist body; 

    public class Recordinglist(){ 
    Recordresponse response; 

    public class Recordresponse(){ 
     String total; 

     public int getTotal() { 
      return total; 
     } 

     public void setTotal(int total) { 
      this.total = total; 
     } 
    } 
    } 
}