网上找到一个下载图片的工具类，下载到的图片是Drawable类型的。
1 package com.cn.gordon.exhibition.walk.utils;
2
3 import java.io.InputStream;
4 import java.lang.ref.SoftReference;
5 import java.net.URL;
6 import java.net.URLConnection;
7 import java.util.HashMap;
8 import java.util.concurrent.BlockingQueue;
9 import java.util.concurrent.LinkedBlockingQueue;
10 import java.util.concurrent.RejectedExecutionHandler;
11 import java.util.concurrent.ThreadPoolExecutor;
12 import java.util.concurrent.TimeUnit;
13
14 import android.graphics.drawable.Drawable;
15 import android.os.Handler;
16 import android.os.Looper;
17 /**
18 * 加载图片类
19 * @author jialg
20 *
21 */
22 public class AsyncImageLoader {
23 private static final String TAG = "AsyncImageLoader";
24 private ThreadPoolExecutor mPoolExecutor;
25 private HashMap<String, SoftReference<Drawable>> imageCache;
26 private Handler mMainThreadHandler;
27
28 /**
29 * 创建一个异步图片加载器，默认最大5个工作线程，最大等待队列20
30 */
31 public AsyncImageLoader() {
32 this(5, 20);
33 }
34
35 /**
36 * 创建一个异步图片加载器，当等待下载的图片超过设置的最大等待数量之后，会从等待队列中放弃一个最早加入队列的任务
37 *
38 * @param maxPoolSize 最大工作线程数
39 * @param queueSize 最大等待数
40 */
41 public AsyncImageLoader(int maxPoolSize, int queueSize) {
42 this(2, maxPoolSize, 3, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(queueSize),
43 new ThreadPoolExecutor.DiscardOldestPolicy());
44 }
45
46 /**
47 * 自定义线程池的加载器,请参考:{@link ThreadPoolExecutor}
48 *
49 * @param corePoolSize
50 * @param maximumPoolSize
51 * @param keepAliveTime
52 * @param unit
53 * @param workQueue
54 * @param handler
55 */
56 public AsyncImageLoader(int corePoolSize, int maximumPoolSize, long keepAliveTime,
57 TimeUnit unit, BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) {
58 imageCache = new HashMap<String, SoftReference<Drawable>>();
59 mPoolExecutor = new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepAliveTime, unit,
60 workQueue, handler);
61 mMainThreadHandler = new Handler(Looper.getMainLooper());
62 }
63
64 /**
65 * 异步加载一张图片
66 *
67 * @param imageUrl
68 * @param imageCallback
69 */
70 public void loadDrawable(final String imageUrl, final ImageCallback imageCallback) {
71 if (imageCache.containsKey(imageUrl)) {
72 SoftReference<Drawable> softReference = imageCache.get(imageUrl);
73 Drawable drawable = softReference.get();
74 if (drawable != null) {
75 imageCallback.onLoaded(drawable);
76 return;
77 }
78 }
79 LoadImageTask task = new LoadImageTask(imageUrl, this, mMainThreadHandler, imageCallback);
80 mPoolExecutor.execute(task);
81 }
82
83 /**
84 * 停止线程池运行，停止之后，将不能在继续调用 {@link #loadDrawable(String, ImageCallback)}
85 */
86 public void shutdown() {
87 mPoolExecutor.shutdown();
88 imageCache.clear();
89 }
90
91 private void cache(String url, Drawable drawable) {
92 imageCache.put(url, new SoftReference<Drawable>(drawable));
93 }
94
95 /**
96 * 下载任务
97 *
98 */
99 private static final class LoadImageTask implements Runnable {
100
101 private Handler mHandler;
102 private ImageCallback mCallback;
103 private AsyncImageLoader mLoader;
104 private String mPath;
105
106 /**
107 * @param imgPath 要下载的图片地址
108 * @param loader 图片加载器
109 * @param handler 主线程Handler
110 * @param imageCallback 图片加载回调
111 */
112 public LoadImageTask(String imgPath, AsyncImageLoader loader, Handler handler,
113 ImageCallback imageCallback) {
114 this.mHandler = handler;
115 this.mPath = imgPath;
116 this.mLoader = loader;
117 this.mCallback = imageCallback;
118 }
119
120 @Override
121 public void run() {
122 URL url;
123 InputStream is = null;
124 try {
125 url = new URL(mPath);
126 URLConnection conn = url.openConnection();
127 conn.connect();
128 is = conn.getInputStream();
129 final Drawable drawable = Drawable.createFromStream(is, "src");
130 mLoader.cache(mPath, drawable);
131 mHandler.post(new Runnable() {
132
133 @Override
134 public void run() {
135 mCallback.onLoaded(drawable);
136 }
137 });
138 } catch (final Exception e) {
139 mHandler.post(new Runnable() {
140
141 @Override
142 public void run() {
143 mCallback.onError(e);
144 }
145 });
146 }
147 }
148 }
149
150 /**
151 * 回调接口,在主线程中运行
152 *
153 */
154 public static interface ImageCallback {
155 /**
156 * 加载成功
157 *
158 * @param imageDrawable 下载下来的图片
159 */
160 public void onLoaded(Drawable drawable);
161
162 /**
163 * 加载失败
164 *
165 * @param e 异常
166 */
167 public void onError(Exception e);
168 }
169 }
图片下载之后，要进行存储，存储的类型是Bitmap，所以要将图片先转成BitmapDrawable,然后再转成Bitmap，运用上面的工具类进行图片的下载，并进行保存。
public class EntryActivity extends Activity {
private AsyncImageLoader asyncImageLoader;
private static String ALBUM_PATH = getSDPath() + java.io.File.separator + "exhibition_walk";
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.walkmain);
asyncImageLoader= new AsyncImageLoader();
init();
}
private void init(){
asyncImageLoader.loadDrawable(urlStr, new ImageCallback(){
@Override
public void onLoaded(Drawable imageDrawable) {
if(imageDrawable != null){
v1.setImageDrawable(imageDrawable);
BitmapDrawable draw = (BitmapDrawable) imageDrawable;
final Bitmap bitmap = draw.getBitmap();
try {
if (bitmap!=null) {
Toast.makeText(EntryActivity.this, "下载的图片可用", Toast.LENGTH_SHORT).show();
savePicture(bitmap, System.currentTimeMillis()+".jpg");
}else{
Toast.makeText(EntryActivity.this, "下载的图片不可用", Toast.LENGTH_SHORT).show();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public void onError(Exception e) {
}
});
}
private void savePicture(Bitmap bitmap,String fileName) throws IOException{
File dirFile = new File(ALBUM_PATH);
if(!dirFile.exists()){
dirFile.mkdirs();
Toast.makeText(EntryActivity.this, "创建文件夹", Toast.LENGTH_SHORT).show();
}
File myCaptureFile = new File(ALBUM_PATH + java.io.File.separator +fileName);
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(myCaptureFile));
bitmap.compress(Bitmap.CompressFormat.JPEG, 80, bos);
bos.flush();
bos.close();
}
/**
* 获取sd卡的路径
*
* @return 路径的字符串
*/
public static String getSDPath() {
File sdDir = null;
boolean sdCardExist = Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED); // 判断sd卡是否存在
if (sdCardExist) {
sdDir = Environment.getExternalStorageDirectory();// 获取外存目录
}
return sdDir.toString();
}
}
最后，图片存储到sd卡上，要进行权限的声明：
1 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 2 <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
时间： 2024-11-04 19:33:34