Android &引用；没有适用于简单类型的构造函数“；安卓系统中的杰克逊和其他系统中的对象_Android_Json_Parsing_Constructor_Jackson

Android &引用；没有适用于简单类型的构造函数“；安卓系统中的杰克逊和其他系统中的对象

android json parsing

Android &引用；没有适用于简单类型的构造函数“；安卓系统中的杰克逊和其他系统中的对象,android,json,parsing,constructor,jackson,Android,Json,Parsing,Constructor,Jackson,我在我的项目中使用Jackson来解析从服务器接收到的JSON，解析步骤非常有效，当尝试使用嵌套对象时，问题就出现了。下面是一些代码： @JsonIgnoreProperties(ignoreUnknown = true) public class Song { @JsonProperty("id") private int id = 0; @JsonProperty("title") private String title = ""; @JsonPr

我在我的项目中使用Jackson来解析从服务器接收到的JSON，解析步骤非常有效，当尝试使用嵌套对象时，问题就出现了。下面是一些代码：

@JsonIgnoreProperties(ignoreUnknown = true)
public class Song {

    @JsonProperty("id")
    private int id = 0;
    @JsonProperty("title")
    private String title = "";
    @JsonProperty("link")
    private String link = "";
    @JsonProperty("album")
    private Album album;

    public Song() {
    }

    public int getId() {
        return id;
    }

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

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getLink() {
       return link ;
    }

    public void setLink(String link ) {
        this.link = link ;
    }

    public Album getAlbum() {
        return album;
    }

    public void setAlbum(Album album) {
        this.album = album;
    }
}

Album类如下所示：

@JsonIgnoreProperties(ignoreUnknown = true)
public class Album {

    @JsonProperty("id")
    private int id;
    @JsonProperty("title")
    private String title;
    @JsonProperty("artist")
    private Artist artist;

    public Album(){}

    public int getId() {
        return id;
    }

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

    public String getTitle() {
        return title;
    }

    public void setTitle(String title){
        this.title = title;
    }

    public Artist getArtist() {
        return artist;
    }

    public void setArtist(Artist artist) {
        this.artist = artist;
    }
}

最后是“艺术家”课程：

因此，正如我在JSON解析工作正常之前所说的，问题是当我尝试访问其中一个“sub”对象时，例如，如果我尝试获取艺术家名称。当我这样做时：

getSong().getAlbum().getArtist().getName();

无论我在哪里做，Jackson都会停止解析JSON：

(IOException)Error: No suitable constructor found for type [simple type, class com.zarpamos.fandanztap.model.Album]: can not instantiate from JSON object (missing default constructor or creator, or perhaps need to add/enable type information?)

纯JSON输出：

{"categories":[{"id":"1","name":"Pop","packs":[{"id":"2","songs":[{"album":{"id":"2","title":"Sex And Love","artist":{"id":"2","name":"Enrique Iglesias"}},"id":"3","title":"Bailando","link":"song_1.mp3"},{"album":{"id":"1","title":"Peace Is The Mission","artist":{"id":"3","name":"Major Lazer"}},"id":"6","title":"Powerful","link":"song_2.mp3"},{"album":{"id":"2","title":"Sex And Love","artist":{"id":"2","name":"Enrique Iglesias"}},"id":"4","title":"Loco","link":"song_3.mp3"}, // More JSON elements...

解析“类别”和“包”效果很好，问题出在“相册”中

相同的JSON输出，但样式化：

以下是堆栈跟踪：

 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1080)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:295)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:142)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:523)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:101)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.impl.BeanPropertyMap.findDeserializeAndSet(BeanPropertyMap.java:285)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:248)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:136)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:245)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:217)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:25)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:523)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:101)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.impl.BeanPropertyMap.findDeserializeAndSet(BeanPropertyMap.java:285)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:248)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:136)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:245)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:217)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:25)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:523)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:101)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.impl.BeanPropertyMap.findDeserializeAndSet(BeanPropertyMap.java:285)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:248)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:136)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:245)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:217)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:25)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:523)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:101)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.impl.BeanPropertyMap.findDeserializeAndSet(BeanPropertyMap.java:285)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:248)
 W/System.err﹕ at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:136)
 W/System.err﹕ at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3562)
 W/System.err﹕ at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2578)
 W/System.err﹕ at com.dolphinziyo.myapp.tasks.GetPacksTask.onPostExecute(GetPacksTask.java:93)
 W/System.err﹕ at com.dolphinziyo.myapp.tasks.GetPacksTask.onPostExecute(GetPacksTask.java:38)
 W/System.err﹕ at android.os.AsyncTask.finish(AsyncTask.java:631)
 W/System.err﹕ at android.os.AsyncTask.access$600(AsyncTask.java:177)
 W/System.err﹕ at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
 W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:107)
 W/System.err﹕ at android.os.Looper.loop(Looper.java:194)
 W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5371)
 W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
 W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:525)
 W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
 W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
 W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)

这真的很奇怪，我不知道我做错了什么。谁能告诉我错误在哪里

提前感谢您

在您的

专辑

课程中，您必须为

艺术家

属性设置一个setter，如下所示：

 public void setArtist(Artist artist) {
    this.artist = artist;
 }

 public void setArtist(**Artista** artist) {
    this.artist = artist;
 }

不是这样的：

 public void setArtist(Artist artist) {
    this.artist = artist;
 }

 public void setArtist(**Artista** artist) {
    this.artist = artist;
 }

我最终手动解析了它，直到我有更多的时间来测试它

您的类是顶级类型还是嵌套在另一个类中？如果它们是嵌套的，则需要将它们标记为“static”

这是将代码转换为StackOverflow时的拼写错误，我用西班牙语编写了代码。我已经修复了我的帖子，谢谢这不是JSON输出，看起来更像PHP对象？奇怪的是，在访问对象时会出现错误，可以发布stacktrace吗？这是打印的JSON输出（来自PHP），为了更具可读性，我决定显示它，而不是普通的JSON。我想看看是否可以打印StackTrace我用同样的JSON代码更新了我的文章，但现在是纯文本。我刚刚添加了堆栈Trace，正如我在代码中所示，“艺术家”嵌套在“相册”中，“相册”嵌套在“歌曲”中，我将尝试静态执行它们，谢谢。对不起，它们是顶级的（如提供的代码中所示）没有嵌套。不管怎样，我尝试了静态操作，但应用程序失败，出现空指针异常。