Question

在我的gridView中，我想从url加载图像，因为我使用了ImageLoader库,,,,我使用了PhotoAdapter.class来设置adter到gridview，并且我已经保存了PhotoGallery.class中的所有URL。

但我的gridview显示空白。

GalleryViewActivity.class：

public class GalleryViewActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.photoview);

initViews（）; }

    public void initViews() {
        GridView gridView = (GridView) findViewById(R.id.photoview);
        gridView.setAdapter(new PhotosAdapter(GalleryViewActivity.this,
                (List<PhotoGallery>) gridView));
    }
}

PhotoAdapter.class

public class PhotosAdapter extends BaseAdapter {

    class PhotosViewHolder {
        ImageView imageView;

        public PhotosViewHolder(View convertView) {
            imageView = (ImageView) convertView.findViewById(R.id.images_child);
        }

        public void loadImageUrls(ImageLoader imageLoader, String url) {
            imageLoader.displayImage(url, imageView);
        }
    }

    private Activity activity;
    private ImageLoader imageLoader;
    private List<PhotoGallery> photoGalleries;

    public PhotosAdapter(Activity activity, List<PhotoGallery> galleries) {
        this.activity = activity;
        this.photoGalleries = galleries;
        this.imageLoader = new ImageLoader(activity);
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return photoGalleries.size();
    }

    @Override
    public PhotoGallery getItem(int position) {
        // TODO Auto-generated method stub
        return photoGalleries.get(position);
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup arg2) {
        PhotosViewHolder viewHolder;
        if (convertView == null) {
            convertView = View.inflate(activity, R.layout.gallery_child_layout,
                    null);
            viewHolder = new PhotosViewHolder(convertView);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (PhotosViewHolder) convertView.getTag();
        }
        PhotoGallery gallery = getItem(position);
        viewHolder.loadImageUrls(imageLoader, gallery.getImageUrl());
        return convertView;
    }

}

PhotoGallery.class：

public class PhotoGallery {
    private String imageUrl;

    public PhotoGallery(int i) {
        int index = i % 3;
        imageUrl = urls[index];
    }
    private String urls[] = {
            "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_1.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_2.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_3.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_4.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_5.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_6.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_7.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_8.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_9.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_10.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_11.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_12.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_13.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_14.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_15.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_16.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_17.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_18.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_19.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_20.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_21.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_22.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_23.jpg",
                "http://mobileapp.certifytechnologies.com/jumeirah/ju_gal_img/gal_24.jpg" };

    public String getImageUrl() {
        return imageUrl;
    }
}

photoview.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/splashscreen"
    android:orientation="vertical" >

    <GridView
        android:id="@+id/photoview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:background="#A3000000"
        android:horizontalSpacing="1dp"
        android:numColumns="3"
        android:paddingTop="20dp"
        android:stretchMode="columnWidth"
        android:verticalSpacing="15dp" />

</LinearLayout>

gallery_child_view.xml

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <ImageView 
        android:id="@+id/images_child"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:src="@drawable/splashscreen"
        android:scaleType="fitXY"/>

</LinearLayout>

Answer 1

您是否已向该应用授予了Internet权限？在AndroidManifest.xml中

<manifest xlmns:android...>
 ...
 <uses-permission android:name="android.permission.INTERNET"></uses-permission>
</manifest>

Answer 2

调用在onCreate（）

之后创建的initViews（）方法

解决方案：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.photoview);
        initViews();
    }

Answer 3

在您的GalleryViewActivity.class中，您似乎无法在onCreate方法上调用initViews（），因此您的网格永远不会被初始化。

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.photoview);
    // Add this one here.
    initViews();
}

作为额外的建议，您不应该保存对主要活动的引用。如果你想要扩展布局，你应该使用getContext（）（或getActivity（）。getContext（））而不是保存引用。

这部分代码完全错误：

gridView.setAdapter(new PhotosAdapter(GalleryViewActivity.this,
            (List<PhotoGallery>) gridView));

我建议您阅读GridView上的android文档以及Java Collections的一些主题，因为您无法将GridView强制转换为对象列表。如果你不了解基础知识，那么你就很难理解你想要达到的目标。

Android GridView不会从网址加载图片

3 个答案: