开源项目之UniversalImageLoader(异步加载大量图片)

来源：互联网发布：python 任务计划编辑：程序博客网时间：2024/06/05 17:59

UniversalImageLoader是实现异步加载大量图片的源码和例子，包括缓存、硬盘缓存、容错机制等技术。

项目如图：

测试效果如图：

总共有四种格式效果！

第一种ImageList，效果如图：

关键测试代码如下：

[java] view plaincopy
public class ImageListActivity extends BaseActivity  
{  
  
    private String[] imageUrls;  
  
    private DisplayImageOptions options;  
  
    @Override  
    public void onCreate(Bundle savedInstanceState)  
    {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.ac_image_list);  
  
        Bundle bundle = getIntent().getExtras();  
        imageUrls = bundle.getStringArray(Extra.IMAGES);  
  
        options = new DisplayImageOptions.Builder()  
                .showStubImage(R.drawable.stub_image).cacheInMemory()  
                .cacheOnDisc().build();  
  
        ListView listView = (ListView) findViewById(android.R.id.list);  
        listView.setAdapter(new ItemAdapter());  
        listView.setOnItemClickListener(new OnItemClickListener()  
        {  
            @Override  
            public void onItemClick(AdapterView<?> parent, View view,  
                    int position, long id)  
            {  
                startImageGalleryActivity(position);  
            }  
        });  
    }  
  
    @Override  
    protected void onStop()  
    {  
        imageLoader.stop();  
        super.onStop();  
    }  
  
    private void startImageGalleryActivity(int position)  
    {  
        Intent intent = new Intent(this, ImagePagerActivity.class);  
        intent.putExtra(Extra.IMAGES, imageUrls);  
        intent.putExtra(Extra.IMAGE_POSITION, position);  
        startActivity(intent);  
    }  
  
    class ItemAdapter extends BaseAdapter  
    {  
  
        private class ViewHolder  
        {  
            public TextView text;  
            public ImageView image;  
        }  
  
        @Override  
        public int getCount()  
        {  
            return imageUrls.length;  
        }  
  
        @Override  
        public Object getItem(int position)  
        {  
            return position;  
        }  
  
        @Override  
        public long getItemId(int position)  
        {  
            return position;  
        }  
  
        @Override  
        public View getView(final int position, View convertView,  
                ViewGroup parent)  
        {  
            View view = convertView;  
            final ViewHolder holder;  
            if (convertView == null)  
            {  
                view = getLayoutInflater().inflate(R.layout.item_list_image,  
                        null);  
                holder = new ViewHolder();  
                holder.text = (TextView) view.findViewById(R.id.text);  
                holder.image = (ImageView) view.findViewById(R.id.image);  
                view.setTag(holder);  
            } else  
                holder = (ViewHolder) view.getTag();  
  
            holder.text.setText("Item " + position);  
  
            imageLoader  
                    .displayImage(imageUrls[position], holder.image, options);  
  
            return view;  
        }  
    }  
}  

第二种ImageGrid效果！如图：

测试关键代码如下：

[java] view plaincopy
public class ImageGridActivity extends BaseActivity  
{  
  
    private String[] imageUrls;  
  
    private DisplayImageOptions options;  
  
    @Override  
    public void onCreate(Bundle savedInstanceState)  
    {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.ac_image_grid);  
  
        Bundle bundle = getIntent().getExtras();  
        imageUrls = bundle.getStringArray(Extra.IMAGES);  
  
        options = new DisplayImageOptions.Builder()  
                .showStubImage(R.drawable.stub_image)  
                .showImageForEmptyUri(R.drawable.image_for_empty_url)  
                .cacheInMemory().cacheOnDisc().build();  
  
        GridView gridView = (GridView) findViewById(R.id.gridview);  
        gridView.setAdapter(new ImageAdapter());  
        gridView.setOnItemClickListener(new OnItemClickListener()  
        {  
            @Override  
            public void onItemClick(AdapterView<?> parent, View view,  
                    int position, long id)  
            {  
                startImageGalleryActivity(position);  
            }  
        });  
    }  
  
    @Override  
    protected void onStop()  
    {  
        imageLoader.stop();  
        super.onStop();  
    }  
  
    private void startImageGalleryActivity(int position)  
    {  
        Intent intent = new Intent(this, ImagePagerActivity.class);  
        intent.putExtra(Extra.IMAGES, imageUrls);  
        intent.putExtra(Extra.IMAGE_POSITION, position);  
        startActivity(intent);  
    }  
  
    public class ImageAdapter extends BaseAdapter  
    {  
        @Override  
        public int getCount()  
        {  
            return imageUrls.length;  
        }  
  
        @Override  
        public Object getItem(int position)  
        {  
            return null;  
        }  
  
        @Override  
        public long getItemId(int position)  
        {  
            return position;  
        }  
  
        @Override  
        public View getView(int position, View convertView, ViewGroup parent)  
        {  
            final ImageView imageView;  
            if (convertView == null)  
            {  
                imageView = (ImageView) getLayoutInflater().inflate(  
                        R.layout.item_grid_image, parent, false);  
            } else  
            {  
                imageView = (ImageView) convertView;  
            }  
  
            imageLoader.displayImage(imageUrls[position], imageView, options,  
                    new SimpleImageLoadingListener()  
                    {  
                        @Override  
                        public void onLoadingComplete()  
                        {  
                            Animation anim = AnimationUtils.loadAnimation(  
                                    ImageGridActivity.this, R.anim.fade_in);  
                            imageView.setAnimation(anim);  
                            anim.start();  
                        }  
                    });  
  
            return imageView;  
        }  
    }  
}  

第三种ImagePager效果，如图：

测试关键实现如下：

[java] view plaincopy
public class ImagePagerActivity extends BaseActivity  
{  
  
    private ViewPager pager;  
  
    private DisplayImageOptions options;  
  
    public void onCreate(Bundle savedInstanceState)  
    {  
        super.onCreate(savedInstanceState);  
  
        setContentView(R.layout.ac_image_pager);  
        Bundle bundle = getIntent().getExtras();  
        String[] imageUrls = bundle.getStringArray(Extra.IMAGES);  
        int pagerPosition = bundle.getInt(Extra.IMAGE_POSITION, 0);  
  
        options = new DisplayImageOptions.Builder()  
                .showImageForEmptyUri(R.drawable.image_for_empty_url)  
                .cacheOnDisc().imageScaleType(ImageScaleType.EXACT).build();  
  
        pager = (ViewPager) findViewById(R.id.pager);  
        pager.setAdapter(new ImagePagerAdapter(imageUrls));  
        pager.setCurrentItem(pagerPosition);  
    }  
  
    @Override  
    protected void onStop()  
    {  
        imageLoader.stop();  
        super.onStop();  
    }  
  
    private class ImagePagerAdapter extends PagerAdapter  
    {  
  
        private String[] images;  
        private LayoutInflater inflater;  
  
        ImagePagerAdapter(String[] images)  
        {  
            this.images = images;  
            inflater = getLayoutInflater();  
        }  
  
        @Override  
        public void destroyItem(View container, int position, Object object)  
        {  
            ((ViewPager) container).removeView((View) object);  
        }  
  
        @Override  
        public void finishUpdate(View container)  
        {  
        }  
  
        @Override  
        public int getCount()  
        {  
            return images.length;  
        }  
  
        @Override  
        public Object instantiateItem(View view, int position)  
        {  
            final FrameLayout imageLayout = (FrameLayout) inflater.inflate(  
                    R.layout.item_pager_image, null);  
            final ImageView imageView = (ImageView) imageLayout  
                    .findViewById(R.id.image);  
            final ProgressBar spinner = (ProgressBar) imageLayout  
                    .findViewById(R.id.loading);  
  
            imageLoader.displayImage(images[position], imageView, options,  
                    new ImageLoadingListener()  
                    {  
                        @Override  
                        public void onLoadingStarted()  
                        {  
                            spinner.setVisibility(View.VISIBLE);  
                        }  
  
                        @Override  
                        public void onLoadingFailed(FailReason failReason)  
                        {  
                            String message = null;  
                            switch (failReason)  
                            {  
                            case IO_ERROR:  
                                message = "Input/Output error";  
                                break;  
                            case OUT_OF_MEMORY:  
                                message = "Out Of Memory error";  
                                break;  
                            case UNKNOWN:  
                                message = "Unknown error";  
                                break;  
                            }  
                            Toast.makeText(ImagePagerActivity.this, message,  
                                    Toast.LENGTH_SHORT).show();  
  
                            spinner.setVisibility(View.GONE);  
                            imageView  
                                    .setImageResource(android.R.drawable.ic_delete);  
                        }  
  
                        @Override  
                        public void onLoadingComplete()  
                        {  
                            spinner.setVisibility(View.GONE);  
                            Animation anim = AnimationUtils.loadAnimation(  
                                    ImagePagerActivity.this, R.anim.fade_in);  
                            imageView.setAnimation(anim);  
                            anim.start();  
                        }  
  
                        @Override  
                        public void onLoadingCancelled()  
                        {  
                            // Do nothing  
                        }  
                    });  
  
            ((ViewPager) view).addView(imageLayout, 0);  
            return imageLayout;  
        }  
  
        @Override  
        public boolean isViewFromObject(View view, Object object)  
        {  
            return view.equals(object);  
        }  
  
        @Override  
        public void restoreState(Parcelable state, ClassLoader loader)  
        {  
        }  
  
        @Override  
        public Parcelable saveState()  
        {  
            return null;  
        }  
  
        @Override  
        public void startUpdate(View container)  
        {  
        }  
    }  
}  

第四种ImageGallery效果如图：

测试关键代码：

[java] view plaincopy
public class ImageGalleryActivity extends BaseActivity  
{  
  
    private Gallery gallery;  
  
    private DisplayImageOptions options;  
  
    public void onCreate(Bundle savedInstanceState)  
    {  
        super.onCreate(savedInstanceState);  
  
        setContentView(R.layout.ac_image_gallery);  
        Bundle bundle = getIntent().getExtras();  
        String[] imageUrls = bundle.getStringArray(Extra.IMAGES);  
        int galleryPosition = bundle.getInt(Extra.IMAGE_POSITION, 0);  
  
        options = new DisplayImageOptions.Builder()  
                .showImageForEmptyUri(R.drawable.image_for_empty_url)  
                .showStubImage(R.drawable.stub_image).cacheInMemory()  
                .cacheOnDisc().build();  
  
        gallery = (Gallery) findViewById(R.id.gallery);  
        gallery.setAdapter(new ImagePagerAdapter(imageUrls));  
        gallery.setSelection(galleryPosition);  
    }  
  
    @Override  
    protected void onStop()  
    {  
        imageLoader.stop();  
        super.onStop();  
    }  
  
    private class ImagePagerAdapter extends BaseAdapter  
    {  
  
        private String[] images;  
        private LayoutInflater inflater;  
  
        ImagePagerAdapter(String[] images)  
        {  
            this.images = images;  
            inflater = getLayoutInflater();  
        }  
  
        @Override  
        public int getCount()  
        {  
            return images.length;  
        }  
  
        @Override  
        public Object getItem(int position)  
        {  
            return position;  
        }  
  
        @Override  
        public long getItemId(int position)  
        {  
            return position;  
        }  
  
        @Override  
        public View getView(int position, View convertView, ViewGroup parent)  
        {  
            ImageView imageView = (ImageView) convertView;  
            if (imageView == null)  
            {  
                imageView = (ImageView) inflater.inflate(  
                        R.layout.item_gallery_image, parent, false);  
            }  
            imageLoader.displayImage(images[position], imageView, options);  
            return imageView;  
        }  
    }  
}  

实例中通过imageLoader成员负责图片操作！初始化如下：

[java] view plaincopy
protected ImageLoader imageLoader = ImageLoader.getInstance();  

此处主要是围绕UniversalImageLoader使用的介绍！~代码不难。

学习的目标是成熟！~

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