Android开源框架ImageLoader的完美例子

Android开源框架ImageLoader的完美例子

2013年8月19日开源框架之Universal_Image_Loader学习

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

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" >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical" >

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:paddingBottom="10dip"
            android:paddingTop="20dip"
            android:text="@string/label_activity_examples"
            android:textSize="24sp" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_margin="10dip"
            android:onClick="onImageListClick"
            android:text="@string/button_image_list" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_margin="10dip"
            android:onClick="onImageGridClick"
            android:text="@string/button_image_grid" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_margin="10dip"
            android:onClick="onImagePagerClick"
            android:text="@string/button_image_pager" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_margin="10dip"
            android:onClick="onImageGalleryClick"
            android:text="@string/button_image_gallery" />
    LinearLayout>

ScrollView>

列表异步加载图片效果

/2013.8.19_Universal_Image_Loader_Demo/res/layout/ac_image_list.xml

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

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" >

    <ImageView
        android:id="@+id/image"
        android:layout_width="72dip"
        android:layout_height="72dip"
        android:layout_margin="3dip"
        android:adjustViewBounds="true"
        android:contentDescription="@string/descr_image"
        android:scaleType="centerCrop" />

    <TextView
        android:id="@+id/text"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="left|center_vertical"
        android:layout_marginLeft="20dip"
        android:textSize="22sp" />

LinearLayout>

GridView异步加载图片显示

/2013.8.19_Universal_Image_Loader_Demo/res/layout/ac_image_grid.xml

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

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

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

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" >

    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:adjustViewBounds="true"
        android:contentDescription="@string/descr_image" />

    <ProgressBar
        android:id="@+id/loading"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:visibility="gone" />

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

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

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

/*******************************************************************************
 * 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_FILE_NAME = "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("/mnt/sdcard", 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

/*******************************************************************************
 * 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

/*******************************************************************************
 * 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

/*******************************************************************************
 * 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;

/**
 * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
 * 常量类
 */
public final class Constants {

    // 一堆图片链接
    public static final String[] IMAGES = new String[] {
            // Heavy images
            "https://lh6.googleusercontent.com/-jZgveEqb6pg/T3R4kXScycI/AAAAAAAAAE0/xQ7CvpfXDzc/s1024/sample_image_01.jpg",
            "https://lh4.googleusercontent.com/-K2FMuOozxU0/T3R4lRAiBTI/AAAAAAAAAE8/a3Eh9JvnnzI/s1024/sample_image_02.jpg",
            "https://lh5.googleusercontent.com/-SCS5C646rxM/T3R4l7QB6xI/AAAAAAAAAFE/xLcuVv3CUyA/s1024/sample_image_03.jpg",
            "https://lh6.googleusercontent.com/-f0NJR6-_Thg/T3R4mNex2wI/AAAAAAAAAFI/45oug4VE8MI/s1024/sample_image_04.jpg",
            "https://lh3.googleusercontent.com/-n-xcJmiI0pg/T3R4mkSchHI/AAAAAAAAAFU/EoiNNb7kk3A/s1024/sample_image_05.jpg",
            "https://lh3.googleusercontent.com/-X43vAudm7f4/T3R4nGSChJI/AAAAAAAAAFk/3bna6D-2EE8/s1024/sample_image_06.jpg",
            "https://lh5.googleusercontent.com/-MpZneqIyjXU/T3R4nuGO1aI/AAAAAAAAAFg/r09OPjLx1ZY/s1024/sample_image_07.jpg",
            "https://lh6.googleusercontent.com/-ql3YNfdClJo/T3XvW9apmFI/AAAAAAAAAL4/_6HFDzbahc4/s1024/sample_image_08.jpg",
            "https://lh5.googleusercontent.com/-Pxa7eqF4cyc/T3R4oasvPEI/AAAAAAAAAF0/-uYDH92h8LA/s1024/sample_image_09.jpg",
            "https://lh4.googleusercontent.com/-Li-rjhFEuaI/T3R4o-VUl4I/AAAAAAAAAF8/5E5XdMnP1oE/s1024/sample_image_10.jpg",
            "https://lh5.googleusercontent.com/-_HU4fImgFhA/T3R4pPVIwWI/AAAAAAAAAGA/0RfK_Vkgth4/s1024/sample_image_11.jpg",
            "https://lh6.googleusercontent.com/-0gnNrVjwa0Y/T3R4peGYJwI/AAAAAAAAAGU/uX_9wvRPM9I/s1024/sample_image_12.jpg",
            "https://lh3.googleusercontent.com/-HBxuzALS_Zs/T3R4qERykaI/AAAAAAAAAGQ/_qQ16FaZ1q0/s1024/sample_image_13.jpg",
            "https://lh4.googleusercontent.com/-cKojDrARNjQ/T3R4qfWSGPI/AAAAAAAAAGY/MR5dnbNaPyY/s1024/sample_image_14.jpg",
            "https://lh3.googleusercontent.com/-WujkdYfcyZ8/T3R4qrIMGUI/AAAAAAAAAGk/277LIdgvnjg/s1024/sample_image_15.jpg",
            "https://lh6.googleusercontent.com/-FMHR7Vy3PgI/T3R4rOXlEKI/AAAAAAAAAGs/VeXrDNDBkaw/s1024/sample_image_16.jpg",
            "https://lh4.googleusercontent.com/-mrR0AJyNTH0/T3R4rZs6CuI/AAAAAAAAAG0/UE1wQqCOqLA/s1024/sample_image_17.jpg",
            "https://lh6.googleusercontent.com/-z77w0eh3cow/T3R4rnLn05I/AAAAAAAAAG4/BaerfWoNucU/s1024/sample_image_18.jpg",
            "https://lh5.googleusercontent.com/-aWVwh1OU5Bk/T3R4sAWw0yI/AAAAAAAAAHE/4_KAvJttFwA/s1024/sample_image_19.jpg",
            "https://lh6.googleusercontent.com/-q-js52DMnWQ/T3R4tZhY2sI/AAAAAAAAAHM/A8kjp2Ivdqg/s1024/sample_image_20.jpg",
            "https://lh5.googleusercontent.com/-_jIzvvzXKn4/T3R4t7xpdVI/AAAAAAAAAHU/7QC6eZ10jgs/s1024/sample_image_21.jpg",
            "https://lh3.googleusercontent.com/-lnGi4IMLpwU/T3R4uCMa7vI/AAAAAAAAAHc/1zgzzz6qTpk/s1024/sample_image_22.jpg",
            "https://lh5.googleusercontent.com/-fFCzKjFPsPc/T3R4u0SZPFI/AAAAAAAAAHk/sbgjzrktOK0/s1024/sample_image_23.jpg",
            "https://lh4.googleusercontent.com/-8TqoW5gBE_Y/T3R4vBS3NPI/AAAAAAAAAHs/EZYvpNsaNXk/s1024/sample_image_24.jpg",
            "https://lh6.googleusercontent.com/-gc4eQ3ySdzs/T3R4vafoA7I/AAAAAAAAAH4/yKii5P6tqDE/s1024/sample_image_25.jpg",
            "https://lh5.googleusercontent.com/--NYOPCylU7Q/T3R4vjAiWkI/AAAAAAAAAH8/IPNx5q3ptRA/s1024/sample_image_26.jpg",
            "https://lh6.googleusercontent.com/-9IJM8so4vCI/T3R4vwJO2yI/AAAAAAAAAIE/ljlr-cwuqZM/s1024/sample_image_27.jpg",
            "https://lh4.googleusercontent.com/-KW6QwOHfhBs/T3R4w0RsQiI/AAAAAAAAAIM/uEFLVgHPFCk/s1024/sample_image_28.jpg",
            "https://lh4.googleusercontent.com/-z2557Ec1ctY/T3R4x3QA2hI/AAAAAAAAAIk/9-GzPL1lTWE/s1024/sample_image_29.jpg",
            "https://lh5.googleusercontent.com/-LaKXAn4Kr1c/T3R4yc5b4lI/AAAAAAAAAIY/fMgcOVQfmD0/s1024/sample_image_30.jpg",
            "https://lh4.googleusercontent.com/-F9LRToJoQdo/T3R4yrLtyQI/AAAAAAAAAIg/ri9uUCWuRmo/s1024/sample_image_31.jpg",
            "https://lh4.googleusercontent.com/-6X-xBwP-QpI/T3R4zGVboII/AAAAAAAAAIs/zYH4PjjngY0/s1024/sample_image_32.jpg",
            "https://lh5.googleusercontent.com/-VdLRjbW4LAs/T3R4zXu3gUI/AAAAAAAAAIw/9aFp9t7mCPg/s1024/sample_image_33.jpg",
            "https://lh6.googleusercontent.com/-gL6R17_fDJU/T3R4zpIXGjI/AAAAAAAAAI8/Q2Vjx-L9X20/s1024/sample_image_34.jpg",
            "https://lh3.googleusercontent.com/-1fGH4YJXEzo/T3R40Y1B7KI/AAAAAAAAAJE/MnTsa77g-nk/s1024/sample_image_35.jpg",
            "https://lh4.googleusercontent.com/-Ql0jHSrea-A/T3R403mUfFI/AAAAAAAAAJM/qzI4SkcH9tY/s1024/sample_image_36.jpg",
            "https://lh5.googleusercontent.com/-BL5FIBR_tzI/T3R41DA0AKI/AAAAAAAAAJk/GZfeeb-SLM0/s1024/sample_image_37.jpg",
            "https://lh4.googleusercontent.com/-wF2Vc9YDutw/T3R41fR2BCI/AAAAAAAAAJc/JdU1sHdMRAk/s1024/sample_image_38.jpg",
            "https://lh6.googleusercontent.com/-ZWHiPehwjTI/T3R41zuaKCI/AAAAAAAAAJg/hR3QJ1v3REg/s1024/sample_image_39.jpg",
            // Light images
            "http://tabletpcssource.com/wp-content/uploads/2011/05/android-logo.png",
            "http://simpozia.com/pages/images/stories/windows-icon.png",
            "https://si0.twimg.com/profile_images/1135218951/gmail_profile_icon3_normal.png",
            "http://www.krify.net/wp-content/uploads/2011/09/Macromedia_Flash_dock_icon.png",
            "http://radiotray.sourceforge.net/radio.png",
            "http://www.bandwidthblog.com/wp-content/uploads/2011/11/twitter-logo.png",
            "http://weloveicons.s3.amazonaws.com/icons/100907_itunes1.png",
            "http://weloveicons.s3.amazonaws.com/icons/100929_applications.png",
            "http://www.idyllicmusic.com/index_files/get_apple-iphone.png",
            "http://www.frenchrevolutionfood.com/wp-content/uploads/2009/04/Twitter-Bird.png",
            "http://3.bp.blogspot.com/-ka5MiRGJ_S4/TdD9OoF6bmI/AAAAAAAAE8k/7ydKtptUtSg/s1600/Google_Sky%2BMaps_Android.png",
            "http://www.desiredsoft.com/images/icon_webhosting.png",
            "http://goodereader.com/apps/wp-content/uploads/downloads/thumbnails/2012/01/hi-256-0-99dda8c730196ab93c67f0659d5b8489abdeb977.png",
            "http://1.bp.blogspot.com/-mlaJ4p_3rBU/TdD9OWxN8II/AAAAAAAAE8U/xyynWwr3_4Q/s1600/antivitus_free.png",
            "http://cdn3.iconfinder.com/data/icons/transformers/computer.png",
            "http://cdn.geekwire.com/wp-content/uploads/2011/04/firefox.png?7794fe",
            "https://ssl.gstatic.com/android/market/com.rovio.angrybirdsseasons/hi-256-9-347dae230614238a639d21508ae492302340b2ba",
            "http://androidblaze.com/wp-content/uploads/2011/12/tablet-pc-256x256.jpg",
            "http://www.theblaze.com/wp-content/uploads/2011/08/Apple.png",
            "http://1.bp.blogspot.com/-y-HQwQ4Kuu0/TdD9_iKIY7I/AAAAAAAAE88/3G4xiclDZD0/s1600/Twitter_Android.png",
            "http://3.bp.blogspot.com/-nAf4IMJGpc8/TdD9OGNUHHI/AAAAAAAAE8E/VM9yU_lIgZ4/s1600/Adobe%2BReader_Android.png",
            "http://cdn.geekwire.com/wp-content/uploads/2011/05/oovoo-android.png?7794fe",
            "http://icons.iconarchive.com/icons/kocco/ndroid/128/android-market-2-icon.png",
            "http://thecustomizewindows.com/wp-content/uploads/2011/11/Nicest-Android-Live-Wallpapers.png",
            "http://c.wrzuta.pl/wm16596/a32f1a47002ab3a949afeb4f",
            "http://macprovid.vo.llnwd.net/o43/hub/media/1090/6882/01_headline_Muse.jpg",
            // Special cases
            "http://cdn.urbanislandz.com/wp-content/uploads/2011/10/MMSposter-large.jpg", // very large image
            "file:///sdcard/Universal Image Loader @#&=+-_.,!()~'%20.png", // Image from SD card with encoded symbols
            "assets://Living Things @#&=+-_.,!()~'%20.jpg", // Image from assets
            "drawable://" + R.drawable.ic_launcher, // Image from drawables
            "http://upload.wikimedia.org/wikipedia/ru/b/b6/袣邪泻_泻芯褌_褋_屑褘褕邪屑懈_胁芯械胁邪谢.png", // Link with UTF-8
            "https://www.eff.org/sites/default/files/chrome150_0.jpg", // Image from HTTPS
            "http://bit.ly/soBiXr", // Redirect link
            "http://img001.us.expono.com/100001/100001-1bc30-2d736f_m.jpg", // EXIF
            "", // Empty link
            "http://wrong.site.com/corruptedLink", // Wrong link
    };

    private Constants() {
    }

    // 配置
    public static class Config {
        public static final boolean DEVELOPER_MODE = false;
    }

    // 额外类
    public static class Extra {
        public static final String IMAGES = "com.nostra13.example.universalimageloader.IMAGES";
        public static final String IMAGE_POSITION = "com.nostra13.example.universalimageloader.IMAGE_POSITION";
    }
}

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

/*******************************************************************************
 * 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 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("Item " + (position + 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 displayedImages = Collections.synchronizedList(new LinkedList());

        @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

/*******************************************************************************
 * 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.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.GridView;
import android.widget.ImageView;

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 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

/*******************************************************************************
 * 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.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 = "Input/Output error";
                            break;
                        case DECODING_ERROR:        // 解码错误
                            message = "Image can't be decoded";
                            break;
                        case NETWORK_DENIED:        // 网络延迟
                            message = "Downloads are denied";
                            break;
                        case OUT_OF_MEMORY:         // 内存不足
                            message = "Out Of Memory error";
                            break;
                        case UNKNOWN:               // 原因不明
                            message = "Unknown error";
                            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

/*******************************************************************************
 * 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.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.Gallery;
import android.widget.ImageView;

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 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);
    }

    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

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" >

    <uses-sdk
        android:minSdkVersion="5"
        android:targetSdkVersion="16" />


    <uses-permission android:name="android.permission.INTERNET" />

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application
        android:name=".UILApplication"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".HomeActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            intent-filter>
        activity>
        <activity
            android:name=".ImageListActivity"
            android:label="@string/ac_name_image_list" />
        <activity
            android:name=".ImageGridActivity"
            android:label="@string/ac_name_image_grid" />
        <activity
            android:name=".ImagePagerActivity"
            android:label="@string/ac_name_image_pager" />
        <activity
            android:name=".ImageGalleryActivity"
            android:label="@string/ac_name_image_gallery" />


        <receiver android:name=".widget.UILWidgetProvider" >
            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/widget_provider" />

            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            intent-filter>
        receiver>
    application>

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。