用冒號作爲字段名稱的一部分使用GSON創建JSON

Question

我創建了一組需要轉換爲json的類（pojos）。因爲我有一個約束條件，即json字段名稱遵循某種格式，我已經將gson作爲我選擇的庫，因爲它允許註釋字段名稱。

因此，我有json字段名稱，如asset_type，preview_image_thumbnail等，以及任何元數據字段必須具有格式metadata:<metadata-field-name>。根據gson的說法，至少，我的metadata:tags和metadata:site註釋不會被gson轉換，因爲它們不是有效的json字段名稱。

一切正常，除了那些夢幻般的元數據字段名稱。我的目標是有類似以下的輸出：

{ 
    "name": "Test Remote Asset", 
    "description": "test-remote-asset", 
    "asset_type": "remote_asset", 
    "duration": 172360, 
    "stream_urls": { 
    "flash": "http://www.test-site.com/videos/a-video.flv", 
    "iphone": "http://www.test-site.com/videos/a-video.3gp", 
    "ipad": "http://www.test-site.com/videos/a-video.3gp", 
    "source_file": "http://www.test-site.com/videos/a-video.mp4" 
    }, 
    "metadata:tags": "tag1,tag2,tag3", 
    "metadata:site": "test-site" 
} 

這裏是例外嘗試我的課轉化爲JSON當我得到：

java.lang.IllegalArgumentException: metadata:tags is not a valid JSON field name. 

，這裏是課堂上，我想變換：

public class RemoteAsset { 

/** The video's name **/ 
private String name; 

/** The video's description **/ 
private String description; 

/** The video asset type **/ 
@SerializedName("asset_type") 
private String assetType; 

/** The video's duration, in milliseconds **/ 
private long duration; 

/** The video's thumbnail preview URL **/ 
@SerializedName("preview_image_url") 
private String previewImageUrl; 

/** The video's OpenCms Structure ID **/ 
@SerializedName("external_id") 
private String externalId; 

/** The video's various streaming URLs **/ 
@SerializedName("stream_urls") 
private StreamUrls streamUrls; 

/** The video's tags, coma-separated **/ 
@SerializedName("metadata:tags") 
private String metadataTags; 

/** The video's host site **/ 
@SerializedName("metadata:site") 
private String metadataSite; 

public String getMetadataTags() { 
    return metadataTags; 
} 

public void setMetadataTags(String metadata_tags) { 
    this.metadataTags = metadata_tags; 
} 

public String getMetadataSite() { 
    return metadataSite; 
} 

public void setMetadataSite(String metadata_site) { 
    this.metadataSite = metadata_site; 
} 

public RemoteAsset() { 

    this.streamUrls = null; 
    this.assetType = null; 
    this.previewImageUrl = ""; 
    this.metadataSite = ""; 
    this.metadataTags = ""; 
    this.externalId = ""; 
    this.description = ""; 
    this.duration = 0L; 
    this.name = ""; 
} 

public String getName() { 
    return this.name; 
} 

public void setName(String name) { 
    this.name = name; 
} 

public String getDescription() { 
    return this.description; 
} 

public void setDescription(String description) { 
    this.description = description; 
} 

public String getAssetType() { 
    return this.assetType; 
} 

public void setAssetType(ASSET_TYPE asset_type) { 
    this.assetType = asset_type.getTypeName(); 
} 

public long getDuration() { 
    return this.duration; 
} 

public void setDuration(long duration) { 
    this.duration = duration; 
} 

public String getPreviewImageUrl() { 
    return this.previewImageUrl; 
} 

public void setPreviewImageUrl(String preview_image_url) { 
    this.previewImageUrl = preview_image_url; 
} 

public String getExternalId() { 
    return this.externalId; 
} 

public void setExternalId(String external_id) { 
    this.externalId = external_id; 
} 

public StreamUrls getStreamUrls() { 
    return this.streamUrls; 
} 

public void setStreamUrls(StreamUrls stream_urls) { 
    this.streamUrls = stream_urls; 
} 

@Override 
public String toString() { 
    StringBuilder builder = new StringBuilder(); 
    builder.append("RemoteAsset [name=").append(this.name) 
      .append(", description=").append(this.description) 
      .append(", assetType=").append(this.assetType) 
      .append(", duration=").append(this.duration) 
      .append(", previewImageUrl=").append(this.previewImageUrl) 
      .append(", externalId=").append(this.externalId) 
      .append(", streamUrls=").append(this.streamUrls).append("]"); 
    return builder.toString(); 
} 
} 

Answer 1

問題是那些無法直接映射到Java變量，因爲您不能在變量名中包含冒號。您需要使用Gson @SerializedName註釋。至少在GSON版本2.2.2以下工作：

public static void main(String[] args) 
{ 
    String json = "{\"some:field\":\"foo\"}"; 
    Gson gson = new Gson(); 

    MyClass mc = gson.fromJson(json, MyClass.class); 

    json = gson.toJson(mc); 
    System.out.println(json); 
} 

class MyClass 
{ 
    // String some:field; <- You can do that! 
    @SerializedName("some:field") 
    String someField; 
} 

輸出：

{ 「一些：場」： 「富」}