java - 将 ImageView 添加到 LinearLayout 中

Question

我使用以下代码从互联网下载了一堆图像:

for(int i = 1; i < 12; i++) {
    try {
        URL imageURL = new URL("http://domain/drawimage.php?type=" + i + "&d1=" + this.d1 + "&d2=" + this.d2);
        Bitmap image = BitmapFactory.decodeStream(imageURL.openConnection().getInputStream());

        bitmaps.add(image);
    } catch (Exception e) {
        System.out.println(e);
        e.printStackTrace();
    }
}

稍后，当我尝试将它们插入 LinearLayout (ll) 时，即使 bitmaps.size() = 11，图像也不会出现。

for(int i = 0; i < bitmaps.size(); i++) {
    ImageView iv = new ImageView(c); // c = getApplicationContext()
    iv.setImageBitmap(bitmaps.get(i));
    iv.setVisibility(ImageView.VISIBLE);

    ll.addView(iv);
}

如果我尝试使用 TextView，它会起作用。

for(int i = 0; i < bitmaps.size(); i++) {
    TextView tv = new TextView(c); // c = getApplicationContext()
    tv.setText("image ");
    tv.setGravity(Gravity.CENTER_HORIZONTAL);

    ll.addView(tv);
}

是加载问题还是插入失败？如何修复？

Answer 1

据我了解，您正在尝试在垂直线性布局中添加图像列表？

我建议您使用具有自定义布局的 ListView 和 ArrayAdapter。

这是我为帮助您而编写的示例代码:

public class MainActivity extends ListActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activitymain);


        StrictMode.ThreadPolicy policy = new StrictMode.
             ThreadPolicy.Builder().permitAll().build();
             StrictMode.setThreadPolicy(policy);


        List<Bitmap> bitmaps= new ArrayList<Bitmap>();

        for(int i = 1; i < 12; i++) {
            try {
                URL imageURL = new URL("http://developer.android.com/assets/images/dac_logo.png");
                Bitmap image = BitmapFactory.decodeStream(imageURL.openConnection().getInputStream());

                bitmaps.add(image);
            } catch (Exception e) {
                System.out.println(e);
                e.printStackTrace();
            }
        }

        setListAdapter(new BitmapAdapter(this,R.layout.listview_item,bitmaps));

    }

自定义位图适配器:

public class BitmapAdapter extends ArrayAdapter<Bitmap>{

     Context context; 
      int layoutResourceId;  
      List<Bitmap> bitmaps;

    public BitmapAdapter(Context context, int textViewResourceId,
            List<Bitmap> objects) {
        super(context, textViewResourceId, objects);
        // TODO Auto-generated constructor stub

        this.layoutResourceId = textViewResourceId;
        this.bitmaps = objects;
        this.context = context;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        View rowView = inflater.inflate(this.layoutResourceId, parent, false);
        ImageView iv = (ImageView) rowView.findViewById(R.id.imageView1);

        iv.setImageBitmap(this.bitmaps.get(position));

        return rowView;
    }

}

activitymain.xml:

<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
     android:id="@android:id/list">

</ListView>

listview_item.xml:

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

<ImageView
    android:id="@+id/imageView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/ic_launcher" />