今天来介绍图片加载的框架Android-Universal-Image-Loader
GITHUB上的下载路径为：https://github.com/nostra13/Android-Universal-Image-Loader
也可以自行百度下载。
首先来封装的一个类CacheTool ，由于其他加载图片的方法有点繁琐，所以这里仅封装了一个简单实用的加载方法：
import android.content.Context; import android.graphics.Bitmap; import android.graphics.Bitmap.CompressFormat; import android.net.Uri; import android.os.Environment; import android.widget.ImageView; import java.io.File; import com.ncct.app.R; import com.nostra13.universalimageloader.cache.disc.impl.UnlimitedDiscCache; import com.nostra13.universalimageloader.cache.disc.naming.Md5FileNameGenerator; import com.nostra13.universalimageloader.cache.memory.impl.UsingFreqLimitedMemoryCache; import com.nostra13.universalimageloader.core.DisplayImageOptions; import com.nostra13.universalimageloader.core.ImageLoader; import com.nostra13.universalimageloader.core.ImageLoaderConfiguration; import com.nostra13.universalimageloader.core.assist.ImageLoadingListener; import com.nostra13.universalimageloader.core.assist.QueueProcessingType; import com.nostra13.universalimageloader.core.download.BaseImageDownloader; /** * 图片加载框架 * * @author jiang * */ public class CacheTool { private static File cacheDir = Environment.getDataDirectory(); private static DisplayImageOptions options = new DisplayImageOptions.Builder().showStubImage(R.drawable.loading_img) .showImageForEmptyUri(R.drawable.loading_error).showImageOnFail(R.drawable.loading_error) .cacheInMemory(true).cacheOnDisc(true).bitmapConfig(Bitmap.Config.RGB_565).build(); private static ImageLoaderConfiguration config; public static void Init(Context context) { config = new ImageLoaderConfiguration.Builder(context).memoryCacheExtraOptions(480, 800) // max // width, // max // height，即保存的每个缓存文件的最大长宽 .discCacheExtraOptions(480, 800, CompressFormat.JPEG, 75, null) // Can // slow // ImageLoader, // use // it // carefully // (Better // don't // use // it)/设置缓存的详细信息，最好不要设置这个 .threadPoolSize(3)// 线程池内加载的数量 .threadPriority(Thread.NORM_PRIORITY - 2).denyCacheImageMultipleSizesInMemory() .memoryCache(new UsingFreqLimitedMemoryCache(2 * 1024 * 1024)) // You // can // pass // your // own // memory // cache // implementation/你可以通过自己的内存缓存实现 .memoryCacheSize(2 * 1024 * 1024).discCacheSize(50 * 1024 * 1024) .discCacheFileNameGenerator(new Md5FileNameGenerator())// 将保存的时候的URI名称用MD5 // 加密 .tasksProcessingOrder(QueueProcessingType.LIFO).discCacheFileCount(100) // 缓存的文件数量 // .discCache(new UnlimitedDiscCache(cacheDir))// 自定义缓存路径 .defaultDisplayImageOptions(DisplayImageOptions.createSimple()) .imageDownloader(new BaseImageDownloader(context, 5 * 1000, 30 * 1000)) // connectTimeout // (5 // s), // readTimeout // (30 // s)超时时间 .writeDebugLogs() // Remove for release app .build();// 开始构建 // Initialize ImageLoader with configuration. ImageLoader.getInstance().init(config); } /** * 加载图片并监听回调结果 * * @param iv * @param url * @param mImageLoadingListener */ public static void displayImg(ImageView iv, String url, ImageLoadingListener mImageLoadingListener) { ImageLoader.getInstance().displayImage(url, iv, options, mImageLoadingListener); } /** * 加载图片 * * @param iv * @param url */ public static void displayImg(ImageView iv, String url) { ImageLoader.getInstance().displayImage(url, iv, options); } /** * 清除内存 */ public static void clearMemoryCache() { ImageLoader.getInstance().clearMemoryCache(); } /** * 清除缓存 */ public static void clearDiskCache() { ImageLoader.getInstance().clearDiscCache(); } /** * 得到某个图片的缓存路径 * * @param imageUrl * @return */ public static String getImagePath(String imageUrl) { return ImageLoader.getInstance().getDiscCache().get(imageUrl).getPath(); } }
封装好了，里面都有详细的介绍，这里介绍下上面的中的ImageLoadingListener 接口回调，按ctrl + 鼠标左键可以进入jar包里的java文件：
/******************************************************************************* * 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.universalimageloader.core.assist; import android.graphics.Bitmap; import android.view.View; /** * Listener for image loading process.<br /> * You can use {@link SimpleImageLoadingListener} for implementing only needed methods. * * @author Sergey Tarasevich (nostra13[at]gmail[dot]com) * @see SimpleImageLoadingListener * @see FailReason * @since 1.0.0 */ public interface ImageLoadingListener { /** * Is called when image loading task was started * * @param imageUri Loading image URI * @param view View for image */ void onLoadingStarted(String imageUri, View view); /** * Is called when an error was occurred during image loading * * @param imageUri Loading image URI * @param view View for image. Can be <b>null</b>. * @param failReason {@linkplain FailReason The reason} why image loading was failed */ void onLoadingFailed(String imageUri, View view, FailReason failReason); /** * Is called when image is loaded successfully (and displayed in View if one was specified) * * @param imageUri Loaded image URI * @param view View for image. Can be <b>null</b>. * @param loadedImage Bitmap of loaded and decoded image */ void onLoadingComplete(String imageUri, View view, Bitmap loadedImage); /** * Is called when image loading task was cancelled because View for image was reused in newer task * * @param imageUri Loading image URI * @param view View for image. Can be <b>null</b>. */ void onLoadingCancelled(String imageUri, View view); }
从以上代码中我们可以了解到接口中我们可以监听到开始、失败、完成、取消的动作。
现在开始使用吧：
private ImageView My_Head; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.personcenter); My_Head = (ImageView) findViewById(R.id.My_Head); String Url = "http://pic.nipic.com/2007-11-09/200711912453162_2.jpg"; CacheTool.displayImg(My_Head , Url ); }
Mark一下，暂存一个直接通过URL获取bitmap的函数，未作内存处理。
/** * 获取指定路径的图片 * * @param urlpath * @return * @throws Exception */ public Bitmap getImage(String urlpath) throws Exception { URL url = new URL(urlpath); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(5000); Bitmap bitmap = null; InputStream inputStream = conn.getInputStream(); bitmap = BitmapFactory.decodeStream(inputStream); return bitmap; }
遗失的拂晓
