Android UI-开源框架ImageLoader的完美例子(异步加载大量图片)

Android开源框架ImageLoader的完美例子

很多人都在讨论如何让图片能在异步加载更加流畅，可以显示大量图片，在拖动ListView的时候不会出现卡的现象。关于ImageLoader这个开源框架的使用有很多网友都介绍过，不过还不够清楚，这里有一个关于这个开源项目的完美例子，ListView的图片加载、GridView的图片加载、ViewPager的图片加载、Gallery画廊的图片加载、Widget的使用。很完善的一个例子，在这里我把所有界面效果做出博客分享出来，需要源码的朋友到我的资源页下载

下载地址：http://download.csdn.net/detail/wwj_748/5975847

要使用ImageLoader就要到这里下载jar包：

https://github.com/nostra13/Android-Universal-Image-Loader

然后导入项目中去就行了

项目文档结构图：

从界面说起，界面本身是没什么好说的，就是如何在xml当中进行定义罢了

有以下这么多个布局文件

一个一个来看呗

首先是这样的效果

这个在Android4.2.2比较好看，在Android2.3.3就显得比较挫。

/2013.8.19_Universal_Image_Loader_Demo/res/layout/ac_home.xml

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<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >

&lt;LinearLayout  
    android:layout_width=&quot;fill_parent&quot;  
    android:layout_height=&quot;fill_parent&quot;  
    android:orientation=&quot;vertical&quot; &gt;  

    &lt;TextView  
        android:layout_width=&quot;fill_parent&quot;  
        android:layout_height=&quot;wrap_content&quot;  
        android:gravity=&quot;center&quot;  
        android:paddingBottom=&quot;10dip&quot;  
        android:paddingTop=&quot;20dip&quot;  
        android:text=&quot;@string/label_activity_examples&quot;  
        android:textSize=&quot;24sp&quot; /&gt;  

    &lt;Button  
        android:layout_width=&quot;fill_parent&quot;  
        android:layout_height=&quot;wrap_content&quot;  
        android:layout_margin=&quot;10dip&quot;  
        android:onClick=&quot;onImageListClick&quot;  
        android:text=&quot;@string/button_image_list&quot; /&gt;  

    &lt;Button  
        android:layout_width=&quot;fill_parent&quot;  
        android:layout_height=&quot;wrap_content&quot;  
        android:layout_margin=&quot;10dip&quot;  
        android:onClick=&quot;onImageGridClick&quot;  
        android:text=&quot;@string/button_image_grid&quot; /&gt;  

    &lt;Button  
        android:layout_width=&quot;fill_parent&quot;  
        android:layout_height=&quot;wrap_content&quot;  
        android:layout_margin=&quot;10dip&quot;  
        android:onClick=&quot;onImagePagerClick&quot;  
        android:text=&quot;@string/button_image_pager&quot; /&gt;  

    &lt;Button  
        android:layout_width=&quot;fill_parent&quot;  
        android:layout_height=&quot;wrap_content&quot;  
        android:layout_margin=&quot;10dip&quot;  
        android:onClick=&quot;onImageGalleryClick&quot;  
        android:text=&quot;@string/button_image_gallery&quot; /&gt;  
&lt;/LinearLayout&gt;

</ScrollView>

列表异步加载图片效果

/2013.8.19_Universal_Image_Loader_Demo/res/layout/ac_image_list.xml

[html] view
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<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />

/2013.8.19_Universal_Image_Loader_Demo/res/layout/item_list_image.xml

[html] view
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >

&lt;ImageView  
    android:id=&quot;@&#43;id/image&quot;  
    android:layout_width=&quot;72dip&quot;  
    android:layout_height=&quot;72dip&quot;  
    android:layout_margin=&quot;3dip&quot;  
    android:adjustViewBounds=&quot;true&quot;  
    android:contentDescription=&quot;@string/descr_image&quot;  
    android:scaleType=&quot;centerCrop&quot; /&gt;  

&lt;TextView  
    android:id=&quot;@&#43;id/text&quot;  
    android:layout_width=&quot;fill_parent&quot;  
    android:layout_height=&quot;wrap_content&quot;  
    android:layout_gravity=&quot;left|center_vertical&quot;  
    android:layout_marginLeft=&quot;20dip&quot;  
    android:textSize=&quot;22sp&quot; /&gt;

</LinearLayout>

GridView异步加载图片显示

/2013.8.19_Universal_Image_Loader_Demo/res/layout/ac_image_grid.xml

[html] view
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<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/gridview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center"
android:horizontalSpacing="4dip"
android:numColumns="3"
android:stretchMode="columnWidth"
android:verticalSpacing="4dip"
android:padding="4dip" />

/2013.8.19_Universal_Image_Loader_Demo/res/layout/item_grid_image.xml

[html] view
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<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/image"
android:layout_width="fill_parent"
android:layout_height="120dip"
android:adjustViewBounds="true"
android:contentDescription="@string/descr_image"
android:scaleType="centerCrop" />

ViewPager异步加载图片显示

/2013.8.19_Universal_Image_Loader_Demo/res/layout/ac_image_pager.xml

[html] view
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<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/pager"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />

/2013.8.19_Universal_Image_Loader_Demo/res/layout/item_pager_image.xml

[html] view
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<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="1dip" >

&lt;ImageView  
    android:id=&quot;@&#43;id/image&quot;  
    android:layout_width=&quot;wrap_content&quot;  
    android:layout_height=&quot;wrap_content&quot;  
    android:layout_gravity=&quot;center&quot;  
    android:adjustViewBounds=&quot;true&quot;  
    android:contentDescription=&quot;@string/descr_image&quot; /&gt;  

&lt;ProgressBar  
    android:id=&quot;@&#43;id/loading&quot;  
    android:layout_width=&quot;wrap_content&quot;  
    android:layout_height=&quot;wrap_content&quot;  
    android:layout_gravity=&quot;center&quot;  
    android:visibility=&quot;gone&quot; /&gt;

</FrameLayout>

Gallery画廊异步加载图片显示

/2013.8.19_Universal_Image_Loader_Demo/res/layout/ac_image_gallery.xml

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<?xml version="1.0" encoding="utf-8"?>
<Gallery xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/gallery"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:spacing="1dip" />

/2013.8.19_Universal_Image_Loader_Demo/res/layout/item_gallery_image.xml

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<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/image"
android:layout_width="120dip"
android:layout_height="120dip"
android:layout_gravity="center"
android:adjustViewBounds="true"
android:contentDescription="@string/descr_image"
android:scaleType="centerCrop" />

还有一个就是桌面小部件

以上只是布局文件，没有什么可以说，具体Activity代码实现如下：

先是这个：

/2013.8.19_Universal_Image_Loader_Demo/src/com/nostra13/example/universalimageloader/HomeActivity.java

主界面Activity代码

[java] view
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/***

Copyright 2011-2013 Sergey Tarasevich
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
package com.nostra13.example.universalimageloader;

import static com.nostra13.example.universalimageloader.Constants.IMAGES;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;

import com.nostra13.example.universalimageloader.Constants.Extra;
import com.nostra13.universalimageloader.utils.L;

/**

@author Sergey Tarasevich (nostra13[at]gmail[dot]com)
*/
public class HomeActivity extends BaseActivity {

private static final String TEST_FILENAME = "Universal Image Loader @#&=+-.,!()~'%20.png";

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.ac_home);
```
// 定义文件对象，目录：/mnt/sdcard, 文件名:TEST_FILE_NAME  
File testImageOnSdCard = new File(&quot;/mnt/sdcard&quot;, TEST_FILE_NAME);  
if (!testImageOnSdCard.exists()) {  // 如果文件不存在  
    // 把文件复制到SD卡  
    copyTestImageToSdCard(testImageOnSdCard);  
}  
```
}

// 点击进入ListView展示界面
public void onImageListClick(View view) {
Intent intent = new Intent(this, ImageListActivity.class);
intent.putExtra(Extra.IMAGES, IMAGES);
startActivity(intent);
}

// 点击进入GridView展示界面
public void onImageGridClick(View view) {
Intent intent = new Intent(this, ImageGridActivity.class);
intent.putExtra(Extra.IMAGES, IMAGES);
startActivity(intent);
}

// 点击进入ViewPager展示界面
public void onImagePagerClick(View view) {
Intent intent = new Intent(this, ImagePagerActivity.class);
intent.putExtra(Extra.IMAGES, IMAGES);
startActivity(intent);
}

// 点击进入画廊展示界面
public void onImageGalleryClick(View view) {
Intent intent = new Intent(this, ImageGalleryActivity.class);
intent.putExtra(Extra.IMAGES, IMAGES);
startActivity(intent);
}

@Override
public void onBackPressed() {
imageLoader.stop(); // 停止加载图片
super.onBackPressed();
}

/**
- 开一个线程把assert目录下的图片复制到SD卡目录下
- @param testImageOnSdCard
  */
  private void copyTestImageToSdCard(final File testImageOnSdCard) {
  new Thread(new Runnable() {
  @Override
  public void run() {
  try {
  InputStream is = getAssets().open(TEST_FILE_NAME);
  FileOutputStream fos = new FileOutputStream(testImageOnSdCard);
  byte[] buffer = new byte[8192];
  int read;
  try {
  while ((read = is.read(buffer)) != -1) {
  fos.write(buffer, 0, read); // 写入输出流
  }
  } finally {
  fos.flush(); // 写入SD卡
  fos.close(); // 关闭输出流
  is.close(); // 关闭输入流
  }
  } catch (IOException e) {
  L.w("Can't copy test image onto SD card");
  }
  }
  }).start(); // 启动线程
  }
  }

/2013.8.19_Universal_Image_Loader_Demo/src/com/nostra13/example/universalimageloader/BaseActivity.java

[java] view
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/***

Copyright 2011-2013 Sergey Tarasevich
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
package com.nostra13.example.universalimageloader;

import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;

import com.nostra13.universalimageloader.core.ImageLoader;

/**

@author Sergey Tarasevich (nostra13[at]gmail[dot]com)
*/
public abstract class BaseActivity extends Activity {

protected ImageLoader imageLoader = ImageLoader.getInstance();

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// 加载菜单
getMenuInflater().inflate(R.menu.main_menu, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.item_clear_memory_cache:
imageLoader.clearMemoryCache(); // 清除内存缓存
return true;
case R.id.item_clear_disc_cache:
imageLoader.clearDiscCache(); // 清除SD卡中的缓存
return true;
default:
return false;
}
}
}

/2013.8.19_Universal_Image_Loader_Demo/src/com/nostra13/example/universalimageloader/AbsListViewBaseActivity.java

[java] view
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/***

Copyright 2011-2013 Sergey Tarasevich
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
package com.nostra13.example.universalimageloader;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.AbsListView;

import com.nostra13.universalimageloader.core.assist.PauseOnScrollListener;

/**

@author Sergey Tarasevich (nostra13[at]gmail[dot]com)
*/
public class AbsListViewBaseActivity extends BaseActivity {

protected static final String STATE_PAUSE_ON_SCROLL = "STATE_PAUSE_ON_SCROLL";
protected static final String STATE_PAUSE_ON_FLING = "STATE_PAUSE_ON_FLING";

protected AbsListView listView;

protected boolean pauseOnScroll = false;
protected boolean pauseOnFling = true;

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
pauseOnScroll = savedInstanceState.getBoolean(STATE_PAUSE_ON_SCROLL, false);
pauseOnFling = savedInstanceState.getBoolean(STATE_PAUSE_ON_FLING, true);
}

@Override
public void onResume() {
super.onResume();
applyScrollListener();
}

private void applyScrollListener() {
listView.setOnScrollListener(new PauseOnScrollListener(imageLoader, pauseOnScroll, pauseOnFling));
}

@Override
public void onSaveInstanceState(Bundle outState) {
outState.putBoolean(STATE_PAUSE_ON_SCROLL, pauseOnScroll);
outState.putBoolean(STATE_PAUSE_ON_FLING, pauseOnFling);
}

@Override
public boolean onPrepareOptionsMenu(Menu menu) {
MenuItem pauseOnScrollItem = menu.findItem(R.id.item_pause_on_scroll);
pauseOnScrollItem.setVisible(true);
pauseOnScrollItem.setChecked(pauseOnScroll);
```
MenuItem pauseOnFlingItem = menu.findItem(R.id.item_pause_on_fling);  
pauseOnFlingItem.setVisible(true);  
pauseOnFlingItem.setChecked(pauseOnFling);  
return true;  
```
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.item_pause_on_scroll:
pauseOnScroll = !pauseOnScroll;
item.setChecked(pauseOnScroll);
applyScrollListener();
return true;
case R.id.item_pause_on_fling:
pauseOnFling = !pauseOnFling;
item.setChecked(pauseOnFling);
applyScrollListener();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}

/2013.8.19_Universal_Image_Loader_Demo/src/com/nostra13/example/universalimageloader/Constants.java

常量类代码

[java] view
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/***

Copyright 2011-2013 Sergey Tarasevich
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
package com.nostra13.example.universalimageloader;

/**

/2013.8.19_Universal_Image_Loader_Demo/src/com/nostra13/example/universalimageloader/ImageListActivity.java

[java] view
plaincopy

/***

Copyright 2011-2013 Sergey Tarasevich
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
package com.nostra13.example.universalimageloader;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

import com.nostra13.example.universalimageloader.Constants.Extra;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.assist.ImageLoadingListener;
import com.nostra13.universalimageloader.core.assist.SimpleImageLoadingListener;
import com.nostra13.universalimageloader.core.display.FadeInBitmapDisplayer;
import com.nostra13.universalimageloader.core.display.RoundedBitmapDisplayer;

/**

@author Sergey Tarasevich (nostra13[at]gmail[dot]com)
*/
public class ImageListActivity extends AbsListViewBaseActivity {

DisplayImageOptions options; // DisplayImageOptions是用于设置图片显示的类

String[] imageUrls; // 图片路径

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.ac_image_list);
```
Bundle bundle = getIntent().getExtras();  
imageUrls = bundle.getStringArray(Extra.IMAGES);  

// 使用DisplayImageOptions.Builder()创建DisplayImageOptions  
options = new DisplayImageOptions.Builder()  
    .showStubImage(R.drawable.ic_stub)          // 设置图片下载期间显示的图片  
    .showImageForEmptyUri(R.drawable.ic_empty)  // 设置图片Uri为空或是错误的时候显示的图片  
    .showImageOnFail(R.drawable.ic_error)       // 设置图片加载或解码过程中发生错误显示的图片      
    .cacheInMemory(true)                        // 设置下载的图片是否缓存在内存中  
    .cacheOnDisc(true)                          // 设置下载的图片是否缓存在SD卡中  
    .displayer(new RoundedBitmapDisplayer(20))  // 设置成圆角图片  
    .build();                                   // 创建配置过得DisplayImageOption对象  

listView = (ListView) findViewById(android.R.id.list);  
((ListView) listView).setAdapter(new ItemAdapter());  
listView.setOnItemClickListener(new OnItemClickListener() {  
    @Override  
    public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position, long id) {  
        // 点击列表项转入ViewPager显示界面  
        startImagePagerActivity(position);        
    }  
});  
```
}

@Override
public void onBackPressed() {
AnimateFirstDisplayListener.displayedImages.clear();
super.onBackPressed();
}

private void startImagePagerActivity(int position) {
Intent intent = new Intent(this, ImagePagerActivity.class);
intent.putExtra(Extra.IMAGES, imageUrls);
intent.putExtra(Extra.IMAGE_POSITION, position);
startActivity(intent);
}

/**
- 自定义列表项适配器
- */
  class ItemAdapter extends BaseAdapter {
  
  private ImageLoadingListener animateFirstListener = new AnimateFirstDisplayListener();
  
  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, parent, false);
  holder = new ViewHolder();
  holder.text = (TextView) view.findViewById(R.id.text);
  holder.image = (ImageView) view.findViewById(R.id.image);
  view.setTag(holder); // 给View添加一个格外的数据
  } else {
  holder = (ViewHolder) view.getTag(); // 把数据取出来
  }
```
holder.text.setText(&quot;Item &quot; &#43; (position &#43; 1));  // TextView设置文本  

/** 
 * 显示图片 
 * 参数1：图片url 
 * 参数2：显示图片的控件 
 * 参数3：显示图片的设置 
 * 参数4：监听器 
 */  
imageLoader.displayImage(imageUrls[position], holder.image, options, animateFirstListener);  

return view;  
```
  }
  }
/**
- 图片加载第一次显示监听器
- @author Administrator
- */
  private static class AnimateFirstDisplayListener extends SimpleImageLoadingListener {
  
  static final List<String> displayedImages = Collections.synchronizedList(new LinkedList<String>());
  
  @Override
  public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
  if (loadedImage != null) {
  ImageView imageView = (ImageView) view;
  // 是否第一次显示
  boolean firstDisplay = !displayedImages.contains(imageUri);
  if (firstDisplay) {
  // 图片淡入效果
  FadeInBitmapDisplayer.animate(imageView, 500);
  displayedImages.add(imageUri);
  }
  }
  }
  }
  }

/2013.8.19_Universal_Image_Loader_Demo/src/com/nostra13/example/universalimageloader/ImageGridActivity.java

网格视图Activity

[java] view
plaincopy

/***

Copyright 2011-2013 Sergey Tarasevich
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
package com.nostra13.example.universalimageloader;

import com.nostra13.example.universalimageloader.Constants.Extra;
import com.nostra13.universalimageloader.core.DisplayImageOptions;

/**

网格视图显示Activity

@author Sergey Tarasevich (nostra13[at]gmail[dot]com)
*/
public class ImageGridActivity extends AbsListViewBaseActivity {

String[] imageUrls; // 图片Url

DisplayImageOptions options; // 显示图片的设置

@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.ic_stub)  
    .showImageForEmptyUri(R.drawable.ic_empty)  
    .showImageOnFail(R.drawable.ic_error)  
    .cacheInMemory(true)  
    .cacheOnDisc(true)  
    .bitmapConfig(Bitmap.Config.RGB_565)     //设置图片的解码类型  
    .build();  

listView = (GridView) findViewById(R.id.gridview);  
((GridView) listView).setAdapter(new ImageAdapter());           // 填充数据  
listView.setOnItemClickListener(new OnItemClickListener() {  
    @Override  
    public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position, long id) {  
        startImagePagerActivity(position);  
    }  
});

}

private void startImagePagerActivity(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;  
    }  

    // 将图片显示任务增加到执行池，图片将被显示到ImageView当轮到此ImageView  
    imageLoader.displayImage(imageUrls[position], imageView, options);  

    return imageView;  
}

}
}

/2013.8.19_Universal_Image_Loader_Demo/src/com/nostra13/example/universalimageloader/ImagePagerActivity.java

ViewPager视图Activity

[java] view
plaincopy

/***

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
package com.nostra13.example.universalimageloader;

import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.Toast;

import com.nostra13.example.universalimageloader.Constants.Extra;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.assist.FailReason;
import com.nostra13.universalimageloader.core.assist.ImageScaleType;
import com.nostra13.universalimageloader.core.assist.SimpleImageLoadingListener;
import com.nostra13.universalimageloader.core.display.FadeInBitmapDisplayer;

/**

ViewPager页面显示Activity

@author Sergey Tarasevich (nostra13[at]gmail[dot]com)
*/
public class ImagePagerActivity extends BaseActivity {

private static final String STATE_POSITION = "STATE_POSITION";

DisplayImageOptions options;

ViewPager pager;

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.ac_image_pager);

Bundle bundle = getIntent().getExtras();  
String[] imageUrls = bundle.getStringArray(Extra.IMAGES);  
// 当前显示View的位置  
int pagerPosition = bundle.getInt(Extra.IMAGE_POSITION, 0);  

// 如果之前有保存用户数据  
if (savedInstanceState != null) {  
    pagerPosition = savedInstanceState.getInt(STATE_POSITION);  
}  

options = new DisplayImageOptions.Builder()  
    .showImageForEmptyUri(R.drawable.ic_empty)  
    .showImageOnFail(R.drawable.ic_error)  
    .resetViewBeforeLoading(true)  
    .cacheOnDisc(true)  
    .imageScaleType(ImageScaleType.EXACTLY)  
    .bitmapConfig(Bitmap.Config.RGB_565)  
    .displayer(new FadeInBitmapDisplayer(300))  
    .build();  

pager = (ViewPager) findViewById(R.id.pager);  
pager.setAdapter(new ImagePagerAdapter(imageUrls));  
pager.setCurrentItem(pagerPosition);    // 显示当前位置的View

}

@Override
public void onSaveInstanceState(Bundle outState) {
// 保存用户数据
outState.putInt(STATE_POSITION, pager.getCurrentItem());
}

private class ImagePagerAdapter extends PagerAdapter {

private String[] images;  
private LayoutInflater inflater;  

ImagePagerAdapter(String[] images) {  
    this.images = images;  
    inflater = getLayoutInflater();  
}  

@Override  
public void destroyItem(ViewGroup 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(ViewGroup view, int position) {  
    View imageLayout = inflater.inflate(R.layout.item_pager_image, view, false);  
    ImageView imageView = (ImageView) imageLayout.findViewById(R.id.image);  
    final ProgressBar spinner = (ProgressBar) imageLayout.findViewById(R.id.loading);  

    imageLoader.displayImage(images[position], imageView, options, new SimpleImageLoadingListener() {  
        @Override  
        public void onLoadingStarted(String imageUri, View view) {  
            spinner.setVisibility(View.VISIBLE);  
        }  

        @Override  
        public void onLoadingFailed(String imageUri, View view, FailReason failReason) {  
            String message = null;  
            switch (failReason.getType()) {     // 获取图片失败类型  
                case IO_ERROR:              // 文件I/O错误  
                    message = &quot;Input/Output error&quot;;  
                    break;  
                case DECODING_ERROR:        // 解码错误  
                    message = &quot;Image can't be decoded&quot;;  
                    break;  
                case NETWORK_DENIED:        // 网络延迟  
                    message = &quot;Downloads are denied&quot;;  
                    break;  
                case OUT_OF_MEMORY:         // 内存不足  
                    message = &quot;Out Of Memory error&quot;;  
                    break;  
                case UNKNOWN:               // 原因不明  
                    message = &quot;Unknown error&quot;;  
                    break;  
            }  
            Toast.makeText(ImagePagerActivity.this, message, Toast.LENGTH_SHORT).show();  

            spinner.setVisibility(View.GONE);  
        }  

        @Override  
        public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {  
            spinner.setVisibility(View.GONE);       // 不显示圆形进度条  
        }  
    });  

    ((ViewPager) view).addView(imageLayout, 0);     // 将图片增加到ViewPager  
    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) {  
}

}
}

/2013.8.19_Universal_Image_Loader_Demo/src/com/nostra13/example/universalimageloader/ImageGalleryActivity.java

画廊视图的Activity

[java] view
plaincopy

/***

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
***/
package com.nostra13.example.universalimageloader;

import com.nostra13.example.universalimageloader.Constants.Extra;
import com.nostra13.universalimageloader.core.DisplayImageOptions;

/**

画廊视图Activity

@author Sergey Tarasevich (nostra13[at]gmail[dot]com)
*/
@SuppressWarnings("deprecation")
public class ImageGalleryActivity extends BaseActivity {

String[] imageUrls;

DisplayImageOptions options;

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.ac_image_gallery);

Bundle bundle = getIntent().getExtras();  
imageUrls = bundle.getStringArray(Extra.IMAGES);  

options = new DisplayImageOptions.Builder()  
    .showStubImage(R.drawable.ic_stub)  
    .showImageForEmptyUri(R.drawable.ic_empty)  
    .showImageOnFail(R.drawable.ic_error)  
    .cacheInMemory(true)  
    .cacheOnDisc(true)  
    .bitmapConfig(Bitmap.Config.RGB_565)  
    .build();  

// 自API 16之后就被抛弃了  
Gallery gallery = (Gallery) findViewById(R.id.gallery);  
gallery.setAdapter(new ImageGalleryAdapter());  
gallery.setOnItemClickListener(new OnItemClickListener() {  
    @Override  
    public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position, long id) {  
        startImagePagerActivity(position);  
    }  
});

}

private class ImageGalleryAdapter extends BaseAdapter {
@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(int position, View convertView, ViewGroup parent) {  
    ImageView imageView = (ImageView) convertView;  
    if (imageView == null) {  
        imageView = (ImageView) getLayoutInflater().inflate(R.layout.item_gallery_image, parent, false);  
    }  
    imageLoader.displayImage(imageUrls[position], imageView, options);  
    return imageView;  
}

}
}

关于桌面控件的代码我就不贴了，朋友们可以自己下载我这个Demo

还有就是Manifest文件代码

[html] view
plaincopy

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.nostra13.example.universalimageloader"
android:versionCode="35"
android:versionName="1.8.7" >

&lt;uses-sdk  
    android:minSdkVersion=&quot;5&quot;  
    android:targetSdkVersion=&quot;16&quot; /&gt;  

&lt;!-- 网络访问权限 --&gt;  
&lt;uses-permission android:name=&quot;android.permission.INTERNET&quot; /&gt;  
&lt;!-- 文件写入SD卡权限 --&gt;  
&lt;uses-permission android:name=&quot;android.permission.WRITE_EXTERNAL_STORAGE&quot; /&gt;  

&lt;application  
    android:name=&quot;.UILApplication&quot;  
    android:icon=&quot;@drawable/ic_launcher&quot;  
    android:label=&quot;@string/app_name&quot; &gt;  
    &lt;activity  
        android:name=&quot;.HomeActivity&quot;  
        android:label=&quot;@string/app_name&quot; &gt;  
        &lt;intent-filter&gt;  
            &lt;action android:name=&quot;android.intent.action.MAIN&quot; /&gt;  

            &lt;category android:name=&quot;android.intent.category.LAUNCHER&quot; /&gt;  
        &lt;/intent-filter&gt;  
    &lt;/activity&gt;  
    &lt;activity  
        android:name=&quot;.ImageListActivity&quot;  
        android:label=&quot;@string/ac_name_image_list&quot; /&gt;  
    &lt;activity  
        android:name=&quot;.ImageGridActivity&quot;  
        android:label=&quot;@string/ac_name_image_grid&quot; /&gt;  
    &lt;activity  
        android:name=&quot;.ImagePagerActivity&quot;  
        android:label=&quot;@string/ac_name_image_pager&quot; /&gt;  
    &lt;activity  
        android:name=&quot;.ImageGalleryActivity&quot;  
        android:label=&quot;@string/ac_name_image_gallery&quot; /&gt;  

    &lt;!-- Widget --&gt;  
    &lt;receiver android:name=&quot;.widget.UILWidgetProvider&quot; &gt;  
        &lt;meta-data  
            android:name=&quot;android.appwidget.provider&quot;  
            android:resource=&quot;@xml/widget_provider&quot; /&gt;  

        &lt;intent-filter&gt;  
            &lt;action android:name=&quot;android.appwidget.action.APPWIDGET_UPDATE&quot; /&gt;  
        &lt;/intent-filter&gt;  
    &lt;/receiver&gt;  
&lt;/application&gt;

</manifest>

以上的代码已经很详尽了，读者可以把它整合到你的项目当中，就可以实现完美异步加载图片。在这里要感谢那些为我们开源的大神们，他们的贡献让我们这些开发者更快更有效的完成工作，希望我们的开源会越做越好，我相信我们的开发者有这个能力。

Android UI-开源框架ImageLoader的完美例子(异步加载大量图片)

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