Java 使用GSON将json解析为pojo，pojo由列表组成

当我试图将一个json字符串解析到我的自定义类（由另一个pojo的列表组成）时，我遇到了一个问题

我得到的错误是：

java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 226

我试图解析的类是：

package com.example.client.models;

import java.util.List;

public class Catalog {

private List<Artist> list;

public Catalog() {  }

/**
 * @param list
 */
public Catalog(List<Artist> list) {
    super();
    this.list = list;
}

/**
 * @return the list
 */
public List<Artist> getList() {
    return list;
}

/**
 * @param list the list to set
 */
public void setList(List<Artist> list) {
    this.list = list;
}
}

我已经验证了json字符串，因此我想我的问题在于GSON解析。我希望你能帮我解决我的问题

如果你能给我举个例子或者给我一点提示，那就太好了。 先谢谢你！；）

编辑 又来了 我已经包括了我正在使用的JSON字符串的一个示例：

{
 "list":[
  {
     "artistName":"tmpArtistName",
     "albumList":[
        {
           "albumName":"tmpAlbumName",
           "songList":[
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              },
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              }
           ],
           "albumFile":"/home/pi/tmpAlbumFile"
        },
        {
           "albumName":"tmpAlbumName",
           "songList":[
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              },
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              }
           ],
           "albumFile":"/home/pi/tmpAlbumFile"
        }
     ],
     "artistFile":"/home/pi/tmpArtistFile"
  },
  {
     "artistName":"tmpArtistName",
     "albumList":[
        {
           "albumName":"tmpAlbumName",
           "songList":[
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              },
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              }
           ],
           "albumFile":"/home/pi/tmpAlbumFile"
        },
        {
           "albumName":"tmpAlbumName",
           "songList":[
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              },
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              }
           ],
           "albumFile":"/home/pi/tmpAlbumFile"
        }
     ],
     "artistFile":"/home/pi/tmpArtistFile"
  }
]
}

---

Gson解析器显然无法将字符串直接反序列化到

文件

对象中。相反，它需要一个匹配的JSON对象（由

{

和

}

包围）来继续解组。为了解决这个问题，您只需注册一个类型适配器来处理文件属性：

public class FileTypeAdapter extends TypeAdapter<File> {

    @Override
    public void write(final JsonWriter out, final File value)
            throws IOException {
        if (value == null) {
            out.nullValue();
        } else {
            out.value(value.getAbsolutePath());
        }
    }

    @Override
    public File read(final JsonReader in) throws IOException {
        if (in.hasNext()) {
            final String name = in.nextString();
            return name != null ? new File(name) : null;
        }

        return null;
    }
}

为此：

final Gson gson = new GsonBuilder().registerTypeAdapter(File.class,
    new FileTypeAdapter()).create();

这应该可以解决问题

---

---

另一方面，如果您愿意并且能够切换，则库可以处理此类反序列化，而无需特殊定制

如果您包含（一个具有代表性的示例）您试图解析的JSON，这会很有帮助。@Perception我已经包含了一个JSON字符串示例

{
 "list":[
  {
     "artistName":"tmpArtistName",
     "albumList":[
        {
           "albumName":"tmpAlbumName",
           "songList":[
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              },
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              }
           ],
           "albumFile":"/home/pi/tmpAlbumFile"
        },
        {
           "albumName":"tmpAlbumName",
           "songList":[
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              },
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              }
           ],
           "albumFile":"/home/pi/tmpAlbumFile"
        }
     ],
     "artistFile":"/home/pi/tmpArtistFile"
  },
  {
     "artistName":"tmpArtistName",
     "albumList":[
        {
           "albumName":"tmpAlbumName",
           "songList":[
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              },
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              }
           ],
           "albumFile":"/home/pi/tmpAlbumFile"
        },
        {
           "albumName":"tmpAlbumName",
           "songList":[
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              },
              {
                 "songName":"tmpSongName",
                 "songFile":"/home/pi/tmpSongFile"
              }
           ],
           "albumFile":"/home/pi/tmpAlbumFile"
        }
     ],
     "artistFile":"/home/pi/tmpArtistFile"
  }
]
}

public class FileTypeAdapter extends TypeAdapter<File> {

    @Override
    public void write(final JsonWriter out, final File value)
            throws IOException {
        if (value == null) {
            out.nullValue();
        } else {
            out.value(value.getAbsolutePath());
        }
    }

    @Override
    public File read(final JsonReader in) throws IOException {
        if (in.hasNext()) {
            final String name = in.nextString();
            return name != null ? new File(name) : null;
        }

        return null;
    }
}

final Gson gson = new Gson();

final Gson gson = new GsonBuilder().registerTypeAdapter(File.class,
    new FileTypeAdapter()).create();