图片缓存

FileCache.java

 

[java]  view plain copy

 

1. import java.io.File;  
2. import android.content.Context;  
3.   
4. public class FileCache {  
5.   
6.     private File cacheDir;  
7.   
8.     public FileCache(Context context) {  
9.         // 找一个用来缓存图片的路径  
10.         if (android.os.Environment.getExternalStorageState().equals(  
11.                 android.os.Environment.MEDIA_MOUNTED))  
12.             cacheDir = new File(android.os.Environment.getExternalStorageDirectory(),  
13.                     "文件夹名称");  
14.         else  
15.             cacheDir = context.getCacheDir();  
16.         if (!cacheDir.exists())  
17.             cacheDir.mkdirs();  
18.     }  
19.   
20.     public File getFile(String url) {  
21.         String filename = String.valueOf(url.hashCode());  
22.         File f = new File(cacheDir, filename);  
23.         return f;  
24.     }  
25.   
26.     public void clear() {  
27.         File[] files = cacheDir.listFiles();  
28.         if (files == null)  
29.             return;  
30.         for (File f : files)  
31.             f.delete();  
32.     }  
33.   
34. }  

 

 

HttpUtil.java

 

[java]  view plain copy

 

1. import java.io.ByteArrayOutputStream;  
2. import java.io.File;  
3. import java.io.FileNotFoundException;  
4. import java.io.FileOutputStream;  
5. import java.io.IOException;  
6. import java.io.InputStream;  
7. import java.io.OutputStream;  
8. import java.io.UnsupportedEncodingException;  
9. import java.net.HttpURLConnection;  
10. import java.net.MalformedURLException;  
11. import java.net.ProtocolException;  
12. import java.net.URL;  
13. import java.net.URLEncoder;  
14. import java.util.Map;  
15.   
16. /** 
17.  * Http 请求工具类 
18.  *  
19.  * @author Scorpio.Liu 
20.  *  
21.  */  
22. public class HttpUtil {  
23.   
24.     /** 
25.      * 获取响应字符串 
26.      *  
27.      * @param path 
28.      *            路径 
29.      * @param parameters 
30.      *            参数 
31.      * @return 响应字符串 
32.      */  
33.     public static String getResponseStr(String path, Map<String, String> parameters) {  
34.         StringBuffer buffer = new StringBuffer();  
35.         URL url;  
36.         try {  
37.             if (parameters != null && !parameters.isEmpty()) {  
38.                 for (Map.Entry<String, String> entry : parameters.entrySet()) {  
39.                     // 完成转码操作  
40.                     buffer.append(entry.getKey()).append("=")  
41.                             .append(URLEncoder.encode(entry.getValue(), "UTF-8")).append("&");  
42.                 }  
43.                 buffer.deleteCharAt(buffer.length() - 1);  
44.             }  
45.             url = new URL(path);  
46.             HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();  
47.             urlConnection.setConnectTimeout(3000);  
48.             urlConnection.setRequestMethod("POST");  
49.             urlConnection.setDoInput(true);// 表示从服务器获取数据  
50.             urlConnection.setDoOutput(true);// 表示向服务器写数据  
51.             // 获得上传信息的字节大小以及长度  
52.             byte[] mydata = buffer.toString().getBytes();  
53.             // 表示设置请求体的类型是文本类型  
54.             urlConnection.setRequestProperty("Content-Type",  
55.                     "application/x-www-form-urlencoded");  
56.             urlConnection.setRequestProperty("Content-Length", String.valueOf(mydata.length));  
57.             // 获得输出流,向服务器输出数据  
58.             OutputStream outputStream = urlConnection.getOutputStream();  
59.             outputStream.write(mydata, 0, mydata.length);  
60.             outputStream.close();  
61.             int responseCode = urlConnection.getResponseCode();  
62.             if (responseCode == 200) {  
63.                 return changeInputStream(urlConnection.getInputStream());  
64.             }  
65.         } catch (UnsupportedEncodingException e) {  
66.             e.printStackTrace();  
67.         } catch (MalformedURLException e) {  
68.             e.printStackTrace();  
69.         } catch (ProtocolException e) {  
70.             e.printStackTrace();  
71.         } catch (IOException e) {  
72.             e.printStackTrace();  
73.         }  
74.         return null;  
75.     }  
76.   
77.     private static String changeInputStream(InputStream inputStream) {  
78.         ByteArrayOutputStream outputStream = new ByteArrayOutputStream();  
79.         byte[] data = new byte[1024];  
80.         int len = 0;  
81.         String result = "";  
82.         if (inputStream != null) {  
83.             try {  
84.                 while ((len = inputStream.read(data)) != -1) {  
85.                     outputStream.write(data, 0, len);  
86.                 }  
87.                 result = new String(outputStream.toByteArray(), "UTF-8");  
88.             } catch (IOException e) {  
89.                 e.printStackTrace();  
90.             }  
91.         }  
92.         return result;  
93.     }  
94.   
95.     public static InputStream getInputStream(String path) {  
96.         URL url;  
97.         try {  
98.             url = new URL(path);  
99.             HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();  
100.             urlConnection.setConnectTimeout(3000);  
101.             urlConnection.setRequestMethod("GET");  
102.             urlConnection.setDoInput(true);// 表示从服务器获取数据  
103.             urlConnection.connect();  
104.             if (urlConnection.getResponseCode() == 200)  
105.                 return urlConnection.getInputStream();  
106.         } catch (MalformedURLException e) {  
107.             // TODO Auto-generated catch block  
108.             e.printStackTrace();  
109.         } catch (IOException e) {  
110.             // TODO Auto-generated catch block  
111.             e.printStackTrace();  
112.         } catch (Exception e) {  
113.             // TODO Auto-generated catch block  
114.             e.printStackTrace();  
115.         }  
116.         return null;  
117.     }  
118.   
119.     public static byte[] readStream(InputStream inStream) throws Exception {  
120.         ByteArrayOutputStream outSteam = new ByteArrayOutputStream();  
121.         byte[] buffer = new byte[1024];  
122.         int len = -1;  
123.         while ((len = inStream.read(buffer)) != -1) {  
124.             outSteam.write(buffer, 0, len);  
125.   
126.         }  
127.         outSteam.close();  
128.         inStream.close();  
129.         return outSteam.toByteArray();  
130.     }  
131.   
132.     public static void CopyStream(String url, File f) {  
133.         FileOutputStream fileOutputStream = null;  
134.         InputStream inputStream = null;  
135.         try {  
136.             inputStream = getInputStream(url);  
137.             byte[] data = new byte[1024];  
138.             int len = 0;  
139.             fileOutputStream = new FileOutputStream(f);  
140.             while ((len = inputStream.read(data)) != -1) {  
141.                 fileOutputStream.write(data, 0, len);  
142.             }  
143.         } catch (FileNotFoundException e) {  
144.             e.printStackTrace();  
145.         } catch (IOException e) {  
146.             e.printStackTrace();  
147.         } finally {  
148.             if (inputStream != null) {  
149.                 try {  
150.                     inputStream.close();  
151.                 } catch (IOException e) {  
152.                     e.printStackTrace();  
153.                 }  
154.             }  
155.             if (fileOutputStream != null) {  
156.                 try {  
157.                     fileOutputStream.close();  
158.                 } catch (IOException e) {  
159.                     e.printStackTrace();  
160.                 }  
161.             }  
162.         }  
163.     }  
164.   
165. }  

MemoryCache.java

 

 

[java]  view plain copy

 

1. import java.lang.ref.SoftReference;  
2. import java.util.Collections;  
3. import java.util.HashMap;  
4. import java.util.Map;  
5. import android.graphics.Bitmap;  
6.   
7. public class MemoryCache {  
8.     private Map<String, SoftReference<Bitmap>> cache = Collections  
9.             .synchronizedMap(new HashMap<String, SoftReference<Bitmap>>());// 软引用  
10.   
11.     public Bitmap get(String id) {  
12.         if (!cache.containsKey(id))  
13.             return null;  
14.         SoftReference<Bitmap> ref = cache.get(id);  
15.         return ref.get();  
16.     }  
17.   
18.     public void put(String id, Bitmap bitmap) {  
19.         cache.put(id, new SoftReference<Bitmap>(bitmap));  
20.     }  
21.   
22.     public void clear() {  
23.         cache.clear();  
24.     }  
25. }  

ImageLoader.java

 

 

[java]  view plain copy

 

1. import java.io.File;  
2. import java.io.FileInputStream;  
3. import java.io.FileNotFoundException;  
4. import java.io.UnsupportedEncodingException;  
5. import java.net.URLEncoder;  
6. import java.util.Collections;  
7. import java.util.Map;  
8. import java.util.WeakHashMap;  
9. import java.util.concurrent.ExecutorService;  
10. import java.util.concurrent.Executors;  
11. import android.app.Activity;  
12. import android.content.Context;  
13. import android.graphics.Bitmap;  
14. import android.graphics.BitmapFactory;  
15. import android.graphics.drawable.BitmapDrawable;  
16. import android.widget.ImageView;  
17.   
18. public class ImageLoader {  
19.   
20.     private MemoryCache memoryCache = new MemoryCache();  
21.     private FileCache fileCache;  
22.     private Map<ImageView, String> imageViews = Collections  
23.             .synchronizedMap(new WeakHashMap<ImageView, String>());  
24.     private ExecutorService executorService;  
25.     private boolean isSrc;  
26.   
27.     /** 
28.      * @param context 
29.      *            上下文对象 
30.      * @param flag 
31.      *            true为source资源，false为background资源 
32.      */  
33.     public ImageLoader(Context context, boolean flag) {  
34.         fileCache = new FileCache(context);  
35.         executorService = Executors.newFixedThreadPool(5);  
36.         isSrc = flag;  
37.     }  
38.   
39.     final int stub_id = R.drawable.ic_launcher;  
40.   
41.     public void DisplayImage(String url, ImageView imageView) {  
42.         String u1 = url.substring(0, url.lastIndexOf("/") + 1);  
43.         String u2 = url.substring(url.lastIndexOf("/") + 1);  
44.         try {  
45.             u2 = URLEncoder.encode(u2, "UTF-8");  
46.         } catch (UnsupportedEncodingException e) {  
47.             e.printStackTrace();  
48.         }  
49.         url = u1 + u2;  
50.         imageViews.put(imageView, url);  
51.         Bitmap bitmap = memoryCache.get(url);  
52.         if (bitmap != null) {  
53.             if (isSrc)  
54.                 imageView.setImageBitmap(bitmap);  
55.             else  
56.                 imageView.setBackgroundDrawable(new BitmapDrawable(bitmap));  
57.         } else {  
58.             queuePhoto(url, imageView);  
59.             if (isSrc)  
60.                 imageView.setImageResource(stub_id);  
61.             else  
62.                 imageView.setBackgroundResource(stub_id);  
63.         }  
64.     }  
65.   
66.     private void queuePhoto(String url, ImageView imageView) {  
67.         PhotoToLoad p = new PhotoToLoad(url, imageView);  
68.         executorService.submit(new PhotosLoader(p));  
69.     }  
70.   
71.     private Bitmap getBitmap(String url) {  
72.         try {  
73.             File f = fileCache.getFile(url);  
74.             // 从sd卡  
75.             Bitmap b = onDecodeFile(f);  
76.             if (b != null)  
77.                 return b;  
78.             // 从网络  
79.             Bitmap bitmap = null;  
80.             System.out.println("ImageLoader-->download");  
81.             HttpUtil.CopyStream(url, f);  
82.             bitmap = onDecodeFile(f);  
83.   
84.             return bitmap;  
85.         } catch (Exception ex) {  
86.             ex.printStackTrace();  
87.             return null;  
88.         }  
89.     }  
90.   
91.     public Bitmap onDecodeFile(File f) {  
92.         try {  
93.             return BitmapFactory.decodeStream(new FileInputStream(f));  
94.         } catch (FileNotFoundException e) {  
95.             // TODO Auto-generated catch block  
96.             e.printStackTrace();  
97.         }  
98.         return null;  
99.     }  
100.   
101.     /** 
102.      * 解码图像用来减少内存消耗 
103.      *  
104.      * @param f 
105.      * @return 
106.      */  
107.     public Bitmap decodeFile(File f) {  
108.         try {  
109.             // 解码图像大小  
110.             BitmapFactory.Options o = new BitmapFactory.Options();  
111.             o.inJustDecodeBounds = true;  
112.             BitmapFactory.decodeStream(new FileInputStream(f), null, o);  
113.             // 找到正确的刻度值，它应该是2的幂。  
114.             final int REQUIRED_SIZE = 70;  
115.             int width_tmp = o.outWidth, height_tmp = o.outHeight;  
116.             int scale = 1;  
117.             while (true) {  
118.                 if (width_tmp / 2 < REQUIRED_SIZE || height_tmp / 2 < REQUIRED_SIZE)  
119.                     break;  
120.                 width_tmp /= 2;  
121.                 height_tmp /= 2;  
122.                 scale *= 2;  
123.             }  
124.             BitmapFactory.Options o2 = new BitmapFactory.Options();  
125.             o2.inSampleSize = scale;  
126.             return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);  
127.         } catch (FileNotFoundException e) {  
128.         }  
129.         return null;  
130.     }  
131.   
132.     /** 
133.      * 任务队列 
134.      *  
135.      * @author Scorpio.Liu 
136.      *  
137.      */  
138.     private class PhotoToLoad {  
139.         public String url;  
140.         public ImageView imageView;  
141.   
142.         public PhotoToLoad(String u, ImageView i) {  
143.             url = u;  
144.             imageView = i;  
145.         }  
146.     }  
147.   
148.     class PhotosLoader implements Runnable {  
149.         PhotoToLoad photoToLoad;  
150.   
151.         PhotosLoader(PhotoToLoad photoToLoad) {  
152.             this.photoToLoad = photoToLoad;  
153.         }  
154.   
155.         @Override  
156.         public void run() {  
157.             if (imageViewReused(photoToLoad))  
158.                 return;  
159.             Bitmap bmp = getBitmap(photoToLoad.url);  
160.             memoryCache.put(photoToLoad.url, bmp);  
161.             if (imageViewReused(photoToLoad))  
162.                 return;  
163.             BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad);  
164.             Activity a = (Activity) photoToLoad.imageView.getContext();  
165.             a.runOnUiThread(bd);  
166.         }  
167.     }  
168.   
169.     boolean imageViewReused(PhotoToLoad photoToLoad) {  
170.         String tag = imageViews.get(photoToLoad.imageView);  
171.         if (tag == null || !tag.equals(photoToLoad.url))  
172.             return true;  
173.         return false;  
174.     }  
175.   
176.     /** 
177.      * 显示位图在UI线程 
178.      *  
179.      * @author Scorpio.Liu 
180.      *  
181.      */  
182.     class BitmapDisplayer implements Runnable {  
183.         Bitmap bitmap;  
184.         PhotoToLoad photoToLoad;  
185.   
186.         public BitmapDisplayer(Bitmap b, PhotoToLoad p) {  
187.             bitmap = b;  
188.             photoToLoad = p;  
189.         }  
190.   
191.         public void run() {  
192.             if (imageViewReused(photoToLoad))  
193.                 return;  
194.             if (bitmap != null) {  
195.                 if (isSrc)  
196.                     photoToLoad.imageView.setImageBitmap(bitmap);  
197.                 else  
198.                     photoToLoad.imageView.setBackgroundDrawable(new BitmapDrawable(bitmap));  
199.             } else {  
200.                 if (isSrc)  
201.                     photoToLoad.imageView.setImageResource(stub_id);  
202.                 else  
203.                     photoToLoad.imageView.setBackgroundResource(stub_id);  
204.             }  
205.         }  
206.     }  
207.   
208.     public void clearCache() {  
209.         memoryCache.clear();  
210.         fileCache.clear();  
211.     }  
212.   
213. }  

使用的时候用ImageLoader这个类就ok了，很方便~