如何使用BaseAdapter在ListView中显示远程图像？

Z时代
2024-01-10
分类：问答

我正在使用以下代码在BaseView上使用BaseAdapter显示图像。代码显示可绘制文件夹内的图像。但我想修改代码，使其显示从以下数组远程图像：如何使用BaseAdapter在ListView中显示远程图像？

String flags[] ={"http://www.website.com/images/usa.png","http://www.website.com/images/china.png","http://www.website.com/images/australia.png","http://www.website.com/images/portugle.png","http://www.website.com/images/norway.png","http://www.website.com/images/new_zealand.png"};

能否专家告诉我什么部分需要提前change.Thanks。

MainActivity.java：

public class MainActivity extends Activity { 
    ListView simpleList; 
    String countryList[] = {"USA", "China", "australia", "Portugle", "Norway", "NewZealand"}; 
    int flags[] = {R.drawable.usa, R.drawable.china, R.drawable.australia, R.drawable.portugle, R.drawable.norway, R.drawable.new_zealand}; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     simpleList = (ListView) findViewById(R.id.simpleListView); 
     CustomAdapter customAdapter = new CustomAdapter(getApplicationContext(), countryList, flags); 
     simpleList.setAdapter(customAdapter); 
     simpleList.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
      @Override 
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
       Toast.makeText(getApplicationContext(), "Hello " + countryList[position], Toast.LENGTH_LONG).show(); 
      } 
     }); 
    } 
}

CustomAdapter.java：

Public class CustomAdapter extends BaseAdapter { 
    Context context; 
    String countryList[]; 
    int flags[]; 
    LayoutInflater inflter; 
    public CustomAdapter(Context applicationContext, String[] countryList, int[] flags) { 
     this.context = context; 
     this.countryList = countryList; 
     this.flags = flags; 
     inflter = (LayoutInflater.from(applicationContext)); 
    } 
    @Override 
    public int getCount() { 
     return countryList.length; 
    } 
    @Override 
    public Object getItem(int i) { 
     return null; 
    } 
    @Override 
    public long getItemId(int i) { 
     return 0; 
    } 
    @Override 
    public View getView(int i, View view, ViewGroup viewGroup) { 
     view = inflter.inflate(R.layout.activity_listview, null); 
     TextView country = (TextView) view.findViewById(R.id.textView); 
     ImageView icon = (ImageView) view.findViewById(R.id.icon); 
     country.setText(countryList[i]); 
     icon.setImageResource(flags[i]); 
     return view; 
    } 
}

回答：

您需要：

1）获取这些图像在一个单独的线程，你可以使用抽射，改造，为此抢劫。

2）根据1）中的任何方法的响应，您必须将您从服务中获得的值的列表传递给适配器的构造函数。您需要为该模型创建一个POJO，该结构将包含来自REST Web服务的所有元素。

3）建议为您的listview的适配器使用一个viewholder，以避免反复膨胀视图。

回答：

最简单的事情是用Glide或Picasso：

@Override 
public View getView(int i, View view, ViewGroup viewGroup) { 
    view = inflter.inflate(R.layout.activity_listview, null); 
    TextView country = (TextView) view.findViewById(R.id.textView); 
    ImageView icon = (ImageView) view.findViewById(R.id.icon); 
    country.setText(countryList[i]); 
    // Assuming flags is now the list of Strings of image urls 
    GlideApp.with(view.getContext()).load(flags[i]).into(icon); 
    return view; 
}