如何在列表视图中显示从API下载的带有文本的图像

Question

我有一个ImageDownloader类，用于从API下载图像，该类的工作原理与我测试在activity_main.xml文件中使用ImageView显示图像一样。我现在想在Listview中显示这些图像，以便它使用Listview_images.xml布局为每个项目填充每个图像。我已经研究过需要一个自定义适配器文件来实现这一点，但我对自定义适配器类非常陌生，也不确定在使用下载的映像时应该如何配置它们。

保存图像并从ImageDownloaderService获取图像并将其设置为MainActivity的代码

for (int i = 0; i < displayFilmsNowShowingServiceActivity.getResults().length(); i++) {
try {
//Store each film result as a JSONObject in the Array
films.add(displayFilmsNowShowingServiceActivity.getResults().getJSONObject(i));
JSONObject getResults = displayFilmsNowShowingServiceActivity.getResults().getJSONObject(i);
result[i] = getResults.getString("film_name");
filmID[i] = getResults.getString("film_id");
filmArt[i] = getResults.getJSONObject("images").getJSONObject("poster").getJSONObject("1").getJSONObject("medium").getString("film_image");
//Create a file to save the image to using the imdb id of the film as a file name
String imagePath = this.getDir("MyfilmLib", Context.MODE_PRIVATE).getAbsoluteFile() + "/MyFilmLib/" + filmID[i] + ".jpg";
File file = new File(imagePath);
//If the file already exists then just display the image
if (file.exists()) {
ivFilmArt.setImageBitmap(BitmapFactory.decodeFile(imagePath));
} else {
//If the file doesn't exist then create and use an ImageDownloadService to download the image and
//save it to file
ImageDownloadService imageDownloadService = new ImageDownloadService(filmArt[i], imagePath);
//Call the addListener() method (which ImageDownloadService inherits from AbstractService) and pass this activity as an argument.
//The ImageDownloadService object can then call the ServiceComplete() method in this activity once the web service call has finished
imageDownloadService.addListener(this);
//Put the ImageDownloadService object on a new thread
imageThread = new Thread(imageDownloadService);
//Start the thread which will automatically call the run() method in the ImageDownloadService object
imageThread.start();
}
} catch (JSONException ex) {
result[i] = "Error";
ex.printStackTrace();
}
lvFilms.setAdapter(new ArrayAdapter<>(this, R.layout.listview_images, R.id.tv_images_text, result));
}

POJO类

public class DisplayFilmsNowShowingPOJO {
private int filmID;
private String filmName;
public DisplayFilmsNowShowingPOJO (int filmID, String filmName){
this.filmID = filmID;
this.filmName = filmName;
}
public int getFilmID() {
return filmID;
}
public void setFilmID(int filmID) {
this.filmID = filmID;
}
public String getFilmName() {
return filmName;
}
public void setFilmName(String filmName) {
this.filmName = filmName;
}
}

自定义适配器尝试

public class DisplayFilmsNowShowingAdapter extends ArrayAdapter<DisplayFilmsNowShowingPOJO> {
private Context mContext;
private List<DisplayFilmsNowShowingPOJO> filmsList = new ArrayList<>();
public DisplayFilmsNowShowingAdapter(@NonNull Context context, @LayoutRes ArrayList<DisplayFilmsNowShowingPOJO> list) {
super(context, 0 , list);
mContext = context;
filmsList = list;
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
View listItem = convertView;
if(listItem == null)
listItem = LayoutInflater.from(mContext).inflate(R.layout.listview_images,parent,false);
DisplayFilmsNowShowingPOJO currentFilm = filmsList.get(position);
ImageView iv_art = (ImageView)listItem.findViewById(R.id.iv_art);
iv_art.setImageResource(currentFilm.getFilmID());
TextView name = (TextView) listItem.findViewById(R.id.tv_images_text);
name.setText(currentFilm.getFilmName());
return listItem;
}
}

Answer 1

使用此库显示图像

implementation 'com.github.bumptech.glide:glide:4.11.0'
annotationProcessor 'com.github.bumptech.glide:compiler:4.11.0'

现在您的适配器

public class DisplayFilmsNowShowingAdapter extends ArrayAdapter<DisplayFilmsNowShowingPOJO> {
private Context mContext;
private List<DisplayFilmsNowShowingPOJO> filmsList = new ArrayList<>();
public DisplayFilmsNowShowingAdapter(@NonNull Context context, @LayoutRes ArrayList<DisplayFilmsNowShowingPOJO> list) {
super(context, 0 , list);
mContext = context;
filmsList = list;
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
View listItem = convertView;
if(listItem == null)
listItem = LayoutInflater.from(mContext).inflate(R.layout.listview_images,parent,false);
DisplayFilmsNowShowingPOJO currentFilm = filmsList.get(position);
ImageView iv_art = (ImageView)listItem.findViewById(R.id.iv_art);
//        iv_art.setImageResource(currentFilm.getFilmID());
Glide
.with(iv_art.getContext())
.load(currentFilm.getFilmID())
.centerCrop()
.into(iv_art );
TextView name = (TextView) listItem.findViewById(R.id.tv_images_text);
name.setText(currentFilm.getFilmName());
return listItem;
}

}

Answer 2

您应该为以上内容使用recyclerview。

查看这个关于如何实现上述的简短教程