安卓图片异步加载工具类代码,Java代码库,德仔网

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【Java】安卓图片异步加载工具类

作者:mickelfeng / 发布于2015/7/9/ 668

随手写一个安卓图片异步加载工具类，支持多线程、文件缓存、可选临时和永久缓存、过程状态监听等。使用示例： AsyncImageLoader.INSTANCE.load(imageView, url); // 加载并临时缓存 AsyncImageLoader.INSTANCE.load(imageView, url, true, true); // 加载并永久缓存


	package me.lanfog.myandroid.utils;
	
	import java.io.File;
	import java.io.FileInputStream;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.net.URL;
	import java.util.concurrent.ExecutorService;
	import java.util.concurrent.Executors;
	
	import android.graphics.Bitmap;
	import android.graphics.BitmapFactory;
	import android.os.Environment;
	import android.os.Handler;
	import android.os.Looper;
	import android.util.Log;
	import android.view.View;
	import android.widget.ImageView;
	import android.widget.ProgressBar;
	
	public enum AsyncImageLoader {
	 INSTANCE;
	
	 private String TAG = AsyncImageLoader.class.getSimpleName();
	
	 private final ExecutorService executor;
	 private BitmapFactory.Options defaultOptions;
	 private final String cacheDir = "/sdcard/me.lanfog.myandroid/imagecache";
	
	 AsyncImageLoader() {
	 executor = Executors.newFixedThreadPool(10);
	 defaultOptions = new BitmapFactory.Options();
	 defaultOptions.inPreferredConfig = Bitmap.Config.RGB_565;
	 defaultOptions.inScaled = false;
	 defaultOptions.inPurgeable = true;
	 defaultOptions.inInputShareable = true;
	
	 // 启动时，清空上次缓存
	 File root = new File(cacheDir);
	 if(root.exists()){
	 File[] fs = root.listFiles();
	 for(File f:fs)
	 if(f.isFile())
	 f.delete();
	 }
	 }
	
	 public void stop() {
	 if (!executor.isTerminated())
	 executor.shutdownNow();
	 }
	
	
	 public void load(ImageView iv, String url){
	 this.load(iv, null, url, true, false, null, null, null); // 默认临时缓存
	 }
	
	 public void load(ImageView iv, String url, boolean cached, boolean permanent){
	 this.load(iv, null, url, cached, permanent, null, null, null);
	 }
	
	 /**
	 * 加载图片
	 *
	 * @param iv ImageView
	 * @param options BitmapFactory.Options
	 * @param url 下载地址
	 * @param cached 是否缓存
	 * @param permanent 是否永久缓存
	 * @param pb 进度条
	 * @param listener 状态监听器
	 * @param handler Handler
	 */
	 public void load(final ImageView iv, final BitmapFactory.Options options,
	 final String url, final boolean cached, final boolean permanent,
	 final ProgressBar pb, final LoadStateChangedListener listener, final Handler handler){
	
	 final Handler h = handler != null ? handler : new Handler(Looper.getMainLooper()); // 必要时构造Handler
	
	 executor.submit(new Runnable() {
	
	 @Override
	 public void run() {
	
	 Object tag = iv.getTag();
	 if(tag == null || tag instanceof LoadState){
	 iv.setTag(new LoadState(url, listener));
	 }
	
	 LoadState ls = (LoadState) iv.getTag();
	 if(ls.getState() == LoadState.STATE_LOADED && ls.getUrl().equals(url) && cached){
	 ls.setState(LoadState.STATE_LOADED); return; // 已经加载
	 }
	
	 /*显示进度条*/if(pb != null) h.post(new Runnable() { @Override public void run() { pb.setVisibility(View.VISIBLE); } });
	
	 Bitmap bitmap = null;
	 /*
	 * 使用缓存
	 */
	 if(cached){
	
	 if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
	
	 File f = new File(cacheDir + ( permanent ? "/permanent" : "" ) + "/" + digest(url));
	 if(f.exists()){
	
	 Log.i(TAG, "load from cached: " + url);
	 FileInputStream fis = null;
	 try {
	 fis = new FileInputStream(f);
	 bitmap = BitmapFactory.decodeStream(fis, null, options == null ? defaultOptions : options);
	 } catch (Exception e) {
	 e.printStackTrace();
	 } finally {
	 if(fis != null){
	 try { fis.close(); } catch (IOException e) {}
	 }
	 }
	 }
	 }
	 }
	
	 /*
	 * 下载文件
	 */
	 if(bitmap == null){
	
	 try {
	 Log.i(TAG, "load from network: " + url);
	 bitmap = BitmapFactory.decodeStream((InputStream) new URL(url).getContent(), null, options == null ? defaultOptions : options);
	
	 if (bitmap != null && cached
	 && Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { // 缓存到文件
	
	 File dir = new File(cacheDir + "/permanent");
	 if (!dir.exists()) {
	 dir.mkdirs();
	 }
	 File bitmapFile = new File(cacheDir + ( permanent ? "/permanent" : "" ) + "/" + digest(url));
	 if (!bitmapFile.exists()) {
	 bitmapFile.createNewFile();
	 }
	 FileOutputStream fos = new FileOutputStream(bitmapFile);
	 bitmap.compress(Bitmap.CompressFormat.JPEG, 80, fos);
	 fos.close();
	 }
	 } catch (Exception e) {
	 e.printStackTrace();
	 }
	 }
	
	 /*
	 * 处理结果
	 */
	 if(bitmap != null){
	
	 final Bitmap bm = bitmap;
	 h.post(new Runnable() { @Override public void run() { iv.setImageBitmap(bm);} });
	
	 ls.setState(LoadState.STATE_LOADED);
	 }else{
	 ls.setState(LoadState.STATE_ERROR);
	 }
	
	 /*隐藏进度条*/if(pb != null) h.post(new Runnable() { @Override public void run() { pb.setVisibility(View.GONE); } });
	 }
	
	 });
	 }
	
	 class LoadState {
	
	 public static final int STATE_LOADING = 0; // 加载中
	 public static final int STATE_LOADED = 1; // 已加载
	 public static final int STATE_ERROR = -1; // 失败
	 public static final int STATE_IDLE = -2; // 空闲
	
	 private String url; // 下载地址
	 private int state; // 加载状态
	 LoadStateChangedListener listener; // 状态监听
	
	 public LoadState(String url, LoadStateChangedListener listener) {
	 this.url = url;
	 this.listener = listener;
	 this.state = STATE_IDLE;
	 }
	
	 public String getUrl() {
	 return url;
	 }
	 public void setUrl(String url) {
	 this.url = url;
	 }
	 public int getState() {
	 return state;
	 }
	 public void setState(int state) {
	 this.state = state;
	 if(listener != null)
	 listener.onLoadStateChanged(state);
	 }
	 }
	
	 public static interface LoadStateChangedListener {
	 public void onLoadStateChanged(int state); // 加载状态改变事件
	 }
	
	 /**
	 * 对文本进行摘要
	 */
	 public String digest(String instr) {
	
	 String s = null;
	 char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
	 try {
	 java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
	 md.update(instr.getBytes());
	 byte tmp[] = md.digest();
	 char str[] = new char[16 * 2];
	 int k = 0;
	 for (int i = 0; i < 16; i++) {
	 byte byte0 = tmp[i];
	 str[k++] = hexDigits[byte0 >>> 4 & 0xf];
	 str[k++] = hexDigits[byte0 & 0xf];
	 }
	 s = new String(str).toLowerCase();
	 } catch (Exception e) {
	
	 }
	 return s;
	 }
	}

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　安卓图片　　异步加载　　工具类　

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