GridView - 在新活动中打开图像

Question

目前我的项目有一个 GridView，其中每个下都有图像和描述。单击图像时，它应该在一个新活动中打开，其中包含完整的图像和描述。

它目前在模拟器上运行良好，但 onclick 在真实设备上没有任何作用。

如果我在 MainActivity 中将 intent.putExtra("image", item.getImage()) 更改为 intent.putExtra("image", bitmap)，它会打开新的辅助 DetailsActivity，但只显示文本而不显示图像。 Logcat 不会显示此更改的错误，只是说“java.lang.Integer 无法转换为 android.os.Parcelable”。

主活动：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    gridView = (GridView) findViewById(R.id.gridView);
    gridAdapter = new GridViewAdapter(this, R.layout.grid_item_layout, getData());
    gridView.setAdapter(gridAdapter);

    gridView.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {

            ImageItem item = (ImageItem) parent.getItemAtPosition(position);

                Intent intent = new Intent(MainActivity.this, DetailsActivity.class);
                intent.putExtra("title", item.getTitle());
                intent.putExtra("image", item.getImage());

            startActivity(intent);
        }
    });

}


private ArrayList<ImageItem> getData() {
    final ArrayList imageItems = new ArrayList();
    String[] itemsArray = getResources().getStringArray(R.array.grid_ids);

    TypedArray imgs = getResources().obtainTypedArray(R.array.image_ids);
    for (int i = 0; i < imgs.length(); i++) {
        Bitmap bitmap = BitmapFactory.decodeResource(this.getResources(), imgs.getResourceId(i, -1));
        imageItems.add(new ImageItem(bitmap, itemsArray[i]));
    }
    return imageItems;
}

详情活动：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_details);

    Intent intent = getIntent();

    String title = getIntent().getStringExtra("title");
    Bitmap image = getIntent().getParcelableExtra("image");

    TextView titleTextView = (TextView) findViewById(R.id.title);
    titleTextView.setText(title);

    ImageView imageView = (ImageView) findViewById(R.id.image);
    imageView.setImageBitmap(image);

ImageItem 类：

public class ImageItem {

public Bitmap image;
public String title;

public ImageItem(Bitmap image, String title) {
    super();
    this.image = image;
    this.title = title;
}

public Bitmap getImage() {
    return image;
}

public void setImage(Bitmap image) {
    this.image = image;
}

public String getTitle() {
    return title;
}

public void setTitle(String title) {
    this.title = title;
}

GridViewAdapter：

public class GridViewAdapter extends ArrayAdapter<ImageItem> {

private Context context;
private int layoutResourceId;
private ImageView imageView;
private ArrayList<ImageItem> data = new ArrayList<ImageItem>();

public GridViewAdapter(Context context, int layoutResourceId, ArrayList<ImageItem> data) {
    super(context, layoutResourceId, data);
    this.layoutResourceId = layoutResourceId;
    this.context = context;
    this.data = data;
}

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

    if (row == null) {
        LayoutInflater inflater = ((Activity) context).getLayoutInflater();
        row = inflater.inflate(layoutResourceId, parent, false);
        holder = new ViewHolder();
        holder.imageTitle = (TextView) row.findViewById(R.id.text);
        holder.image = (ImageView) row.findViewById(R.id.image);

        row.setTag(holder);
    } else {
        holder = (ViewHolder) row.getTag();
    }

    ImageItem item = data.get(position);
    holder.imageTitle.setText(item.getTitle());
    holder.image.setImageBitmap(item.getImage());
    return row;
}

static class ViewHolder {
    TextView imageTitle;
    ImageView image;
}

图像（在 R.drawable 中）和描述在 strings.xml 中的两个字符串数组中列出。

Answer 1

为了使您的实现更容易，您可以通过以下构造函数让该图像模型对象具有图像资源 ID。

public class ImageItem {

public int image;
public String title;

public ImageItem(int image, String title) {
    // image means your image resource id
    this.image = image;
    this.title = title;
}

public int getImage() {
    return image;
}

public void setImage(int image) {
    this.image = image;
}

public String getTitle() {
    return title;
}

public void setTitle(String title) {
    this.title = title;
}

}

在您的 onClick 方法中，您可以像下面这样操作

public void onItemClick(AdapterView<?> parent, View v, int position, long id) {

    ImageItem item = (ImageItem) parent.getItemAtPosition(position);

        Intent intent = new Intent(MainActivity.this, DetailsActivity.class);
        intent.putExtra("title", item.getTitle());
        // your image resource should be int
        intent.putExtra("imageId", item.getImage());

    startActivity(intent);
}

您的 DetailsActivity 将执行以下操作...

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_details);

    Intent intent = getIntent();

    String title = getIntent().getStringExtra("title");

    // here -1 is the default value for, if that extra isn't found
    int image = getIntent().getIntExtra("imageId", -1);

    TextView titleTextView = (TextView) findViewById(R.id.title);
    titleTextView.setText(title);

    ImageView imageView = (ImageView) findViewById(R.id.image);
    imageView.setImageResource(image);

Answer 2

有时，位图可能太大而无法编码和解码，或者在意图中作为字节数组传递。这可能会导致 OOM 或糟糕的 UI 体验。

由于您只使用可绘制文件，而不是位图，您可以在模型类中使用 int 值：

您可以在模型类中添加您的可绘制 ID，如下所示：

imageItems.add(new ImageItem(imgs.getResourceId(0, -1), itemsArray[i]));

在适配器中使用它时：

holder.image.setImageResource(imgs.getResourceId(0, -1));

您可以将此 int 发送到您的详细活动，然后您可以在那里设置：

int imageId = getIntent().getExtras().getInt("image"); imageView.setImageResource(imageId);

更新答案

你的模型类：

公共类 ImageItem {

// 代替位图使用 int public int image;公共字符串标题；

public ImageItem(int image, String title) { // 这里会显示你的资源 id this.image = image; this.title = 标题； }

public int getImage() { 返回图片； }

public void setImage(int image) { this.image = image; }

public String getTitle() { 返回标题； }

public void setTitle(String title) { this.title = title; }

}

在您的 MainActivity 中：

gridView.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView parent, View v, int position, long id) {

    ImageItem item = (ImageItem) parent.getItemAtPosition(position);

        Intent intent = new Intent(MainActivity.this, DetailsActivity.class);
        intent.putExtra("title", item.getTitle());
        intent.putExtra("image", item.getImage());

    startActivity(intent);
}
});

私有 ArrayList getData() { final ArrayList imageItems = new ArrayList(); String[] itemsArray = getResources().getStringArray(R.array.grid_ids);

TypedArray imgs = getResources().obtainTypedArray(R.array.image_ids);
for (int i = 0; i < imgs.length(); i++) {
imageItems.add(new ImageItem(imgs.getResourceId(0, -1), itemsArray[i]));
}
return imageItems;

}

在您的 DetailsActivity 中：

@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_details);

Intent intent = getIntent();

String title = getIntent().getStringExtra("title");
int image = getIntent().getExtras().getInt("image");

TextView titleTextView = (TextView) findViewById(R.id.title);
titleTextView.setText(title);

ImageView imageView = (ImageView) findViewById(R.id.image);
imageView.setImageResource(image);

在你的适配器中：

holder.image.setImageResource(imgs.getResourceId(0, -1));