安卓图片加载框架--Universal-Image-Loader

摘要: 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…阅读全文

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:

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	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:

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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.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:

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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。

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/**
* 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;
}