java - 添加字符串资源而不是静态数据

Question

我正在尝试添加一些字符串资源来替换内容字符串，但我似乎无法访问它们，因为它是一个静态类。如何从非静态上下文向 DummyItem 添加项目？

我编辑添加了我在另一篇文章中看到的自定义上下文类。它现在可以工作，但自定义上下文类会抛出警告 - 不要将 Android 上下文类放在静态字段中；这是内存泄漏。

这实际上是内存泄漏吗？如何？我可以解决它吗？

//自定义上下文类

public class MyCustomContext extends Application {

    private static Context context;

    public void onCreate() {
        super.onCreate();
        MyCustomContext.context = getApplicationContext();
    }

    public static Context getAppContext() {
        return MyCustomContext.context;
    }
}

//虚拟内容类

public class DummyContent {

    public static final List<DummyItem> ITEMS = new ArrayList<>();

    public static final Map<String, DummyItem> ITEM_MAP = new HashMap<>(5);

    static {
        addItem(new DummyItem("1", R.drawable.p1, "Item #1", "Author A", res.MyCustomContext.getAppContext().getString(R.string.ContentA));
        addItem(new DummyItem("2", R.drawable.p2, "Item #2", "Author B", res.MyCustomContext.getAppContext().getString(R.string.ContentB));
        addItem(new DummyItem("3", R.drawable.p3, "Item #3", "Author C", res.MyCustomContext.getAppContext().getString(R.string.ContentC)));
    }

    private static void addItem(DummyItem item) {
        ITEMS.add(item);
        ITEM_MAP.put(item.id, item);
    }

    public static class DummyItem {
        public final String id;
        public final int photoId;
        public final String title;
        public final String author;
        public final String content;

        public DummyItem(String id, int photoId, String title, String author, String content) {
            this.id = id;
            this.photoId = photoId;
            this.title = title;
            this.author = author;
            this.content = content;
        }
    }
}

//列表 fragment

import android.annotation.TargetApi;
import android.app.Activity;
import android.app.ListFragment;
import android.content.Context;
import android.graphics.Bitmap;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.graphics.drawable.RoundedBitmapDrawable;
import android.support.v4.graphics.drawable.RoundedBitmapDrawableFactory;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

import com.bumptech.glide.Glide;
import com.bumptech.glide.request.target.BitmapImageViewTarget;

import com.app.test.R;
import com.app.test.DummyContent;

/**
 * Shows a list of all available quotes.
 */
public class PortfolioListFragment extends ListFragment {

    private Callback callback = dummyCallback;

    /**
     * A callback interface. Called whenever a item has been selected.
     */
    public interface Callback {
        void onItemSelected(String id);
    }

    /**
     * A dummy no-op implementation of the Callback interface. Only used when no active Activity is present.
     */
    private static final Callback dummyCallback = new Callback() {
        @Override
        public void onItemSelected(String id) {
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setListAdapter(new MyListAdapter());
        setHasOptionsMenu(true);
    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        // notify callback about the selected list item
        callback.onItemSelected(DummyContent.ITEMS.get(position).id);
    }

    /**
     * onAttach(Context) is not called on pre API 23 versions of Android.
     * onAttach(Activity) is deprecated but still necessary on older devices.
     */
    @TargetApi(23)
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        onAttachToContext(context);
    }

    /**
     * Deprecated on API 23 but still necessary for pre API 23 devices.
     */
    @SuppressWarnings("deprecation")
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            onAttachToContext(activity);
        }
    }

    /**
     * Called when the fragment attaches to the context
     */
    protected void onAttachToContext(Context context) {
        if (!(context instanceof Callback)) {
            throw new IllegalStateException("Activity must implement callback interface.");
        }

        callback = (Callback) context;
    }

    private class MyListAdapter extends BaseAdapter {

        @Override
        public int getCount() {
            return DummyContent.ITEMS.size();
        }

        @Override
        public Object getItem(int position) {
            return DummyContent.ITEMS.get(position);
        }

        @Override
        public long getItemId(int position) {
            return DummyContent.ITEMS.get(position).id.hashCode();
        }

        @Override
        public View getView(int position, View convertView, ViewGroup container) {
            if (convertView == null) {
                convertView = LayoutInflater.from(getActivity()).inflate(R.layout.list_item_article, container, false);
            }

            final DummyContent.DummyItem item = (DummyContent.DummyItem) getItem(position);
            ((TextView) convertView.findViewById(R.id.article_title)).setText(item.title);
            ((TextView) convertView.findViewById(R.id.article_subtitle)).setText(item.author);
            final ImageView img = (ImageView) convertView.findViewById(R.id.thumbnail);
            Glide.with(getActivity()).load(item.photoId).asBitmap().into(new BitmapImageViewTarget(img) {
                @Override
                protected void setResource(Bitmap resource) {
                    RoundedBitmapDrawable circularBitmapDrawable = RoundedBitmapDrawableFactory.create(getActivity().getResources(), resource);
                    circularBitmapDrawable.setCircular(true);
                    img.setImageDrawable(circularBitmapDrawable);
                }
            });

            return convertView;
        }
    }

    public PortfolioListFragment() {
    }
}

Answer 1

检查下面的代码。从 Activity 调用此类时，您可以传递上下文，然后就可以访问字符串资源。

public class DummyContent {

    /**
     * An array of sample items.
     */
    private  Context context ;
    public DummyContent(Context context){
        this.context = context ;
        addStaticItem(); 
    }

    public static  List<DummyItem> ITEMS = new ArrayList<>();

    /**
     * A map of sample items. Key: sample ID; Value: Item.
     */
    public static  Map<String, DummyItem> ITEM_MAP = new HashMap<>(5);

     public void addStaticItem(){
         addItem(new DummyItem("1", R.drawable.ic_launcher, "Item #1", "Author A", "Content A"));
         addItem(new DummyItem("2", R.drawable.ic_launcher, "Item #2", "Author B","Content B"));
         addItem(new DummyItem("3", R.drawable.ic_launcher, "Item #3", "Author C", context.getResources().getString(R.string.text_ok) ));
     }



    private void addItem(DummyItem item) {
        ITEMS.add(item);
        ITEM_MAP.put(item.id, item);
    }

    public  class DummyItem {
        public  String id;
        public  int photoId;
        public  String title;
        public  String author;
        public  String content;

        public DummyItem(String id, int photoId, String title, String author, String content) {
            this.id = id;
            this.photoId = photoId;
            this.title = title;
            this.author = author;
            this.content = content;
        }
    }
}

下面是您的 PortfolioListFragment 类:

public class PortfolioListFragment extends ListFragment {

    private Callback callback = dummyCallback;

    /**
     * A callback interface. Called whenever a item has been selected.
     */
    public interface Callback {
        void onItemSelected(String id);
    }

    /**
     * A dummy no-op implementation of the Callback interface. Only used when no active Activity is present.
     */
    private static final Callback dummyCallback = new Callback() {
        @Override
        public void onItemSelected(String id) {
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        DummyContent dummyContent = new DummyContent(getContext());
        setListAdapter(new MyListAdapter());
        setHasOptionsMenu(true);
    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        // notify callback about the selected list item
        callback.onItemSelected(DummyContent.ITEMS.get(position).id);
    }

    /**
     * onAttach(Context) is not called on pre API 23 versions of Android.
     * onAttach(Activity) is deprecated but still necessary on older devices.
     */
    @TargetApi(23)
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        onAttachToContext(context);
    }

    /**
     * Deprecated on API 23 but still necessary for pre API 23 devices.
     */
    @SuppressWarnings("deprecation")
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            onAttachToContext(activity);
        }
    }

    /**
     * Called when the fragment attaches to the context
     */
    protected void onAttachToContext(Context context) {
        if (!(context instanceof Callback)) {
            throw new IllegalStateException("Activity must implement callback interface.");
        }

        callback = (Callback) context;
    }

    private class MyListAdapter extends BaseAdapter {

        @Override
        public int getCount() {
            return DummyContent.ITEMS.size();
        }

        @Override
        public Object getItem(int position) {
            return DummyContent.ITEMS.get(position);
        }

        @Override
        public long getItemId(int position) {
            return DummyContent.ITEMS.get(position).id.hashCode();
        }

        @Override
        public View getView(int position, View convertView, ViewGroup container) {
            if (convertView == null) {
                convertView = LayoutInflater.from(getActivity()).inflate(R.layout.list_item_article, container, false);
            }

            final DummyContent.DummyItem item = (DummyContent.DummyItem) getItem(position);
            ((TextView) convertView.findViewById(R.id.article_title)).setText(item.title);
            ((TextView) convertView.findViewById(R.id.article_subtitle)).setText(item.author);
            final ImageView img = (ImageView) convertView.findViewById(R.id.thumbnail);
            Glide.with(getActivity()).load(item.photoId).asBitmap().into(new BitmapImageViewTarget(img) {
                @Override
                protected void setResource(Bitmap resource) {
                    RoundedBitmapDrawable circularBitmapDrawable = RoundedBitmapDrawableFactory.create(getActivity().getResources(), resource);
                    circularBitmapDrawable.setCircular(true);
                    img.setImageDrawable(circularBitmapDrawable);
                }
            });

            return convertView;
        }
    }

    public PortfolioListFragment() {
    }
}