Using Picasso library with ListView

问题

What I\'m trying to do is adapt my custom ListView adapter to use images fetched from the web by the Picasso library. I believe I have my adapter changed in order to accept an image from Picasso, but I am unsure how to change my implementation to accept it using a ListView. I believe I have to access holder.imageIcon, but I am not sure how to get it up and running. My code is as follows.

History.java

public class History {
    public String score;
    public String gametype;
    public Picasso icon;

    public History() {
        super();
    }

    public History(String score, String gametype, Picasso icon) {
        super();
        this.score = score;
        this.gametype = gametype;
        this.icon = icon;
    }
}

HistoryAdapter.java

public class HistoryAdapter extends ArrayAdapter<History> {

    Context context;
    int layoutResId;
    History data[] = null;

    public HistoryAdapter(Context context, int layoutResId, History[] data) {
        super(context, layoutResId, data);
        this.layoutResId = layoutResId;
        this.context = context;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        HistoryHolder holder = null;

        if(convertView == null)
        {
            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            convertView = inflater.inflate(layoutResId, parent, false);

            holder = new HistoryHolder();
            holder.imageIcon = (ImageView)convertView.findViewById(R.id.icon);
            holder.textTitle = (TextView)convertView.findViewById(R.id.gameType);
            holder.textScore = (TextView)convertView.findViewById(R.id.score);

            convertView.setTag(holder);
        }
        else
        {
            holder = (HistoryHolder)convertView.getTag();
        }

        History history = data[position];
        holder.textScore.setText(history.score);
        holder.textTitle.setText(history.gametype);
        holder.imageIcon.setImageResource(history.icon);


        return convertView;
    }

    static class HistoryHolder
    {
        ImageView imageIcon;
        TextView textTitle;
        TextView textScore;
    }
}

Implementation

History[] historyData = new History[games.length()];


for(int i = 0; i < games.length(); i++) {
                    JSONObject c = games.getJSONObject(i);
                    JSONObject gameStats = games.getJSONObject(i).getJSONObject(TAG_STATS);
                    type[i] = c.getString(TAG_TYPE);
                    champId[i] = c.getString(\"championId\");
                    cs[i] = gameStats.getString(\"minionsKilled\");
                    kills[i] = gameStats.getString(\"championsKilled\");
                    deaths[i] = gameStats.getString(\"numDeaths\");
                    assists[i] = gameStats.getString(\"assists\");
                    win[i] = gameStats.getString(\"win\");

                    if(win[i].equals(\"true\"))
                        win[i] = \"Victory\";
                    else
                        win[i] = \"Defeat\";

                    if(type[i].equals(\"RANKED_SOLO_5x5\"))
                        type[i] = \"Ranked (Solo)\";

                    if(type[i].equals(\"CAP_5x5\"))
                        type[i] = \"TeamBuilder\";

                    if(type[i].equals(\"NORMAL\"))
                        type[i] = \"Unranked\";

                    score[i] = kills[i] +\"/\" + deaths[i] + \"/\" + assists[i];

                    historyData[i] = new History(score[i], champId[i], R.drawable.ic_launcher); // Placeholder image

                }

                if(historyData == null) {
                    historyData[0] = new History(\"No game found\", \"N/A\", R.drawable.ic_launcher); // Use Picasso placeholder
                    Log.i(\"Data\", \"\" + historyData);
                }

                adapter = new HistoryAdapter(MatchHistoryActivity.this,
                        R.layout.list_adapter,
                        historyData);

                list.setAdapter(adapter);

list_item.xml

<RelativeLayout
    xmlns:android=\"http://schemas.android.com/apk/res/android\"
    android:layout_width=\"fill_parent\"
    android:layout_height=\"?android:attr/listPreferredItemHeight\"
    android:background=\"#111111\"
    android:padding=\"6dip\" >

    <ImageView
        android:id=\"@+id/icon\"
        android:layout_width=\"wrap_content\"
        android:layout_height=\"fill_parent\"
        android:layout_alignParentBottom=\"true\"
        android:layout_alignParentTop=\"true\"
        android:layout_marginRight=\"6dip\"
        android:contentDescription=\"TODO\"
        android:src=\"@drawable/ic_launcher\" />

    <TextView
        android:id=\"@+id/score\"
        android:textColor=\"#C49246\"
        android:layout_width=\"fill_parent\"
        android:layout_height=\"26dip\"
        android:layout_alignParentBottom=\"true\"
        android:layout_alignParentRight=\"true\"
        android:layout_marginLeft=\"5dp\"
        android:layout_toRightOf=\"@id/icon\"
        android:ellipsize=\"marquee\"
        android:singleLine=\"true\"
        android:text=\"0/0/0 KDA\"
        android:textSize=\"12sp\" />

    <TextView
        android:id=\"@+id/gameType\"
        android:textColor=\"#C49246\"
        android:layout_width=\"fill_parent\"
        android:layout_height=\"wrap_content\"
        android:layout_above=\"@id/score\"
        android:layout_alignParentRight=\"true\"
        android:layout_alignParentTop=\"true\"
        android:layout_alignWithParentIfMissing=\"true\"
        android:layout_marginLeft=\"5dp\"
        android:layout_toRightOf=\"@id/icon\"
        android:gravity=\"center_vertical\"
        android:textSize=\"16sp\" />

</RelativeLayout>

回答1:

There are 2 things you need to change: 1) History.icon should be the String url of the icon, not a Picasso object. You can also use a File, Uri, or int, but a String url is probably what you want.

2) Modify your Adapter's getView() method to load the icon using Picasso (see the last line before getView() returns the convertView):

public class HistoryAdapter extends ArrayAdapter<History> {

    Context context;
    int layoutResId;
    History data[] = null;

    public HistoryAdapter(Context context, int layoutResId, History[] data) {
        super(context, layoutResId, data);
        this.layoutResId = layoutResId;
        this.context = context;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        HistoryHolder holder = null;

        if(convertView == null)
        {
            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            convertView = inflater.inflate(layoutResId, parent, false);

            holder = new HistoryHolder();
            holder.imageIcon = (ImageView)convertView.findViewById(R.id.icon);
            holder.textTitle = (TextView)convertView.findViewById(R.id.gameType);
            holder.textScore = (TextView)convertView.findViewById(R.id.score);

            convertView.setTag(holder);
        }
        else
        {
            holder = (HistoryHolder)convertView.getTag();
        }

        History history = data[position];
        holder.textScore.setText(history.score);
        holder.textTitle.setText(history.gametype);
        Picasso.with(this.context).load(history.icon).into(holder.imageIcon)


        return convertView;
    }

    static class HistoryHolder
    {
        ImageView imageIcon;
        TextView textTitle;
        TextView textScore;
    }
}

来源：https://stackoverflow.com/questions/23120238/using-picasso-library-with-listview