java – Dagger 2：使用@Named获取同一对象的多个实例时出错
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我怎么能得到像光标一样的多个相同返回类型的实例
例如 ：-
Module
@CursorScope
public class CursorModule {
@Provides
Cursor provideSongCursor(
@Named("Song") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
new String[]{
BaseColumns._ID,
MediaStore.Audio.AudioColumns.TITLE,
MediaStore.Audio.AudioColumns.ARTIST,
MediaStore.Audio.AudioColumns.ALBUM,
MediaStore.Audio.AudioColumns.DURATION
}, MediaStore.Audio.AudioColumns.IS_MUSIC + "=1", null, null);
}
@Provides
Cursor provideAlbumCursor(
@Named("Album") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI,
new String[]{
BaseColumns._ID,
MediaStore.Audio.AlbumColumns.ALBUM,
MediaStore.Audio.AlbumColumns.ARTIST,
MediaStore.Audio.AlbumColumns.NUMBER_OF_SONGS,
MediaStore.Audio.AlbumColumns.FIRST_YEAR
}, null, null, null);
}
@Provides
Cursor provideArtistCursor(@Named("Artist") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Artists.EXTERNAL_CONTENT_URI,
new String[] {
BaseColumns._ID,
MediaStore.Audio.ArtistColumns.ARTIST,
MediaStore.Audio.ArtistColumns.NUMBER_OF_ALBUMS,
MediaStore.Audio.ArtistColumns.NUMBER_OF_TRACKS
}, null, null,null);
}
@Provides
Cursor provideGenreCursor(
@Named("Genres") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Genres.EXTERNAL_CONTENT_URI,
new String[] {
BaseColumns._ID,
MediaStore.Audio.GenresColumns.NAME
}, null, null, null);
}
@Provides
Cursor providePlaylistCursor(@Named("Playlist") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,
new String[] {
BaseColumns._ID,
MediaStore.Audio.PlaylistsColumns.NAME
}, null, null, null);
}
}
提供的
@CursorScope
@Subcomponent(modules = CursorModule.class)
public interface CursorComponent {
Cursor cursor();
}
我收到这个错误
Error:(17, 11) Gradle: error: android.database.Cursor is bound multiple times:
@Provides android.database.Cursor com.merkmod.musician.dependency.CursorModule.provideSongCursor(@Named("Song") com.merkmod.musician.application.Musician)
@Provides android.database.Cursor com.merkmod.musician.dependency.CursorModule.provideAlbumCursor(@Named("Album") com.merkmod.musician.application.Musician)
@Provides android.database.Cursor com.merkmod.musician.dependency.CursorModule.provideArtistCursor(@Named("Artist") com.merkmod.musician.application.Musician)
@Provides android.database.Cursor com.merkmod.musician.dependency.CursorModule.provideGenreCursor(@Named("Genres") com.merkmod.musician.application.Musician)
@Provides android.database.Cursor com.merkmod.musician.dependency.CursorModule.providePlaylistCursor(@Named("Playlist") com.merkmod.musician.application.Musician)
我创建了多个Cursor实例,并在提供程序级别使用@Named进行注释,然后它开始给我错误,无法提供@Provides注释,所以我转而在构造函数中使用它
就像上面的代码一样.问题是一次又一次地运行一个循环,我就像陷入完成光标的工作一样,任何帮助都会得到应用.
解决方法:
当你想提供一种类型的多个变量时,你必须使用如下所示的@Named注释：
Module
@CursorScope
public class CursorModule {
@Provides
@Named("songCursor")
Cursor provideSongCursor(
@Named("Song") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
new String[]{
BaseColumns._ID,
MediaStore.Audio.AudioColumns.TITLE,
MediaStore.Audio.AudioColumns.ARTIST,
MediaStore.Audio.AudioColumns.ALBUM,
MediaStore.Audio.AudioColumns.DURATION
}, MediaStore.Audio.AudioColumns.IS_MUSIC + "=1", null, null);
}
@Provides
@Named("albumCursor")
Cursor provideAlbumCursor(
@Named("Album") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI,
new String[]{
BaseColumns._ID,
MediaStore.Audio.AlbumColumns.ALBUM,
MediaStore.Audio.AlbumColumns.ARTIST,
MediaStore.Audio.AlbumColumns.NUMBER_OF_SONGS,
MediaStore.Audio.AlbumColumns.FIRST_YEAR
}, null, null, null);
}
@Provides
@Named("artistCursor")
Cursor provideArtistCursor(@Named("Artist") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Artists.EXTERNAL_CONTENT_URI,
new String[] {
BaseColumns._ID,
MediaStore.Audio.ArtistColumns.ARTIST,
MediaStore.Audio.ArtistColumns.NUMBER_OF_ALBUMS,
MediaStore.Audio.ArtistColumns.NUMBER_OF_TRACKS
}, null, null,null);
}
@Provides
@Named("genreCursor")
Cursor provideGenreCursor(
@Named("Genres") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Genres.EXTERNAL_CONTENT_URI,
new String[] {
BaseColumns._ID,
MediaStore.Audio.GenresColumns.NAME
}, null, null, null);
}
@Provides
@Named("playListCursor")
Cursor providePlaylistCursor(@Named("Playlist") Musician musician) {
return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,
new String[] {
BaseColumns._ID,
MediaStore.Audio.PlaylistsColumns.NAME
}, null, null, null);
}
}
那么当你想要像下面这样注入时：
@Inject
@Named("soundCursor")
Cursor soundCursor;
@Inject
@Named("albumCursor")
Cursor albumCursor;
@Inject
@Named("artistCursor")
Cursor artistCursor;
@Inject
@Named("genreCursor")
Cursor genreCursor;
@Inject
@Named("playListCursor")
Cursor playListCursor;
如果你想在构造函数注射中注射它们,请执行以下操作：
@Inject
public SomeClassConstructor(@Named("album") Cursor cursur)
以及你在你的子组件界面中写的东西我不能得到它是什么,它必须像：
@CursorScope
@Subcomponent(modules = CursorModule.class)
public interface CursorComponent {
void inject(TheClassThatWantsToUseInject1 obj);
void inject(TheClassThatWantsToUseInject2 obj);
}
在您的应用程序组件中：
YourSubComponentInterface plus(CursorModule module);
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