我正在尝试使用Gson在java bean中转换json字符串，但它是returnig null值。
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);
}
My Bean Class正在关注。 的 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 + '\'' +
'}';
}}
将Json字符串转换为Java对象后，我得到null值。 我建议你做错了。 提前谢谢。
答案 0 :(得分：2)
<强>先决条件：
使用了以下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"
}
}
}
第1步：
修改private List<FileListDTO> fileList中RecordingListResponseDTO.java的声明，如下所示：
@SerializedName("filelist")
private List<FileListDTO> fileList
第2步：
定义以下课程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);
}
}
}
第3步：
修改方法convert(String args)，如下所示：
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);
}
出于测试目的，您可以尝试将JSON存储在文件中，即D:/test.json，并通过以下方式调用方法：
String json = new String(Files.readAllBytes(Paths.get("D:/test.json")));
convert(json);
答案 1 :(得分：1)
您需要更改模型类，
最初在你的json响应中，数据包含代表object的“body”标签，最初需要为object标签创建类，然后所有数据都包含在你的“body”标签内，所以解析了body数据里面的所有数据，
可能有助于此代码，
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;
}
}
}
}