5.文件下載功能設計與實現

【說明】比較復雜；

【增加參數】

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【新建downloadhandler】新建下載處理類；

【使用異步的下載方法】

【file工具類】沒有講解，課下編寫的

1 package com.flj.latte.util.file;2 3 import android.content.ContentResolver;4 import android.content.Context;5 import android.content.Intent;6 import android.content.res.AssetManager;7 import android.database.Cursor;8 import android.graphics.Bitmap;9 import android.graphics.Typeface;10 import android.media.MediaScannerConnection;11 import android.net.Uri;12 import android.os.Build;13 import android.os.Environment;14 import android.provider.MediaStore;15 import android.webkit.MimeTypeMap;16 import android.widget.TextView;17 18 import com.flj.latte.app.Latte;19 20 import java.io.BufferedInputStream;21 import java.io.BufferedOutputStream;22 import java.io.BufferedReader;23 import java.io.File;24 import java.io.FileNotFoundException;25 import java.io.FileOutputStream;26 import java.io.IOException;27 import java.io.InputStream;28 import java.io.InputStreamReader;29 import java.text.SimpleDateFormat;30 import java.util.Date;31 import java.util.Locale;32 33 34 public final class FileUtil {35 36 //格式化的模板37 private static final String TIME_FORMAT = "_yyyyMMdd_HHmmss";38 39 private static final String SDCARD_DIR =40 Environment.getExternalStorageDirectory().getPath();41 42 //默認本地上傳圖片目錄43 public static final String UPLOAD_PHOTO_DIR =44 Environment.getExternalStorageDirectory().getPath() + "/a_upload_photos/";45 46 //網頁緩存地址47 public static final String WEB_CACHE_DIR =48 Environment.getExternalStorageDirectory().getPath() + "/app_web_cache/";49 50 //系統相機目錄51 public static final String CAMERA_PHOTO_DIR =52 Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getPath() + "/Camera/";53 54 private static String getTimeFormatName(String timeFormatHeader) {55 final Date date = new Date(System.currentTimeMillis());56 //必須要加上單引號57 final SimpleDateFormat dateFormat = new SimpleDateFormat("'" + timeFormatHeader + "'" + TIME_FORMAT, Locale.getDefault());58 return dateFormat.format(date);59 }60 61 /**62 * @param timeFormatHeader 格式化的頭(除去時間部分)63 * @param extension 后綴名64 * @return 返回時間格式化后的文件名65 */66 public static String getFileNameByTime(String timeFormatHeader, String extension) {67 return getTimeFormatName(timeFormatHeader) + "." + extension;68 }69 70 @SuppressWarnings("ResultOfMethodCallIgnored")71 private static File createDir(String sdcardDirName) {72 //拼接成SD卡中完整的dir73 final String dir = SDCARD_DIR + "/" + sdcardDirName + "/";74 final File fileDir = new File(dir);75 if (!fileDir.exists()) {76 fileDir.mkdirs();77 }78 return fileDir;79 }80 81 @SuppressWarnings("ResultOfMethodCallIgnored")82 public static File createFile(String sdcardDirName, String fileName) {83 return new File(createDir(sdcardDirName), fileName);84 }85 86 private static File createFileByTime(String sdcardDirName, String timeFormatHeader, String extension) {87 final String fileName = getFileNameByTime(timeFormatHeader, extension);88 return createFile(sdcardDirName, fileName);89 }90 91 //獲取文件的MIME92 public static String getMimeType(String filePath) {93 final String extension = getExtension(filePath);94 return MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);95 }96 97 //獲取文件的后綴名98 public static String getExtension(String filePath) {99 String suffix = ""; 100 final File file = new File(filePath); 101 final String name = file.getName(); 102 final int idx = name.lastIndexOf('.'); 103 if (idx > 0) { 104 suffix = name.substring(idx + 1); 105 } 106 return suffix; 107 } 108 109 /** 110 * 保存Bitmap到SD卡中 111 * 112 * @param dir 目錄名,只需要寫自己的相對目錄名即可 113 * @param compress 壓縮比例 100是不壓縮,值約小壓縮率越高 114 * @return 返回該文件 115 */ 116 public static File saveBitmap(Bitmap mBitmap, String dir, int compress) { 117 118 final String sdStatus = Environment.getExternalStorageState(); 119 // 檢測sd是否可用 120 if (!sdStatus.equals(Environment.MEDIA_MOUNTED)) { 121 return null; 122 } 123 FileOutputStream fos = null; 124 BufferedOutputStream bos = null; 125 File fileName = createFileByTime(dir, "DOWN_LOAD", "jpg"); 126 try { 127 fos = new FileOutputStream(fileName); 128 bos = new BufferedOutputStream(fos); 129 mBitmap.compress(Bitmap.CompressFormat.JPEG, compress, bos);// 把數據寫入文件 130 } catch (FileNotFoundException e) { 131 e.printStackTrace(); 132 } finally { 133 try { 134 135 if (bos != null) { 136 bos.flush(); 137 } 138 if (bos != null) { 139 bos.close(); 140 } 141 //關閉流 142 if (fos != null) { 143 fos.flush(); 144 } 145 if (fos != null) { 146 fos.close(); 147 } 148 } catch (IOException e) { 149 e.printStackTrace(); 150 } 151 } 152 refreshDCIM(); 153 154 return fileName; 155 } 156 157 public static File writeToDisk(InputStream is, String dir, String name) { 158 final File file = FileUtil.createFile(dir, name); 159 BufferedInputStream bis = null; 160 FileOutputStream fos = null; 161 BufferedOutputStream bos = null; 162 163 try { 164 bis = new BufferedInputStream(is); 165 fos = new FileOutputStream(file); 166 bos = new BufferedOutputStream(fos); 167 168 byte data[] = new byte[1024 * 4]; 169 170 int count; 171 while ((count = bis.read(data)) != -1) { 172 bos.write(data, 0, count); 173 } 174 175 bos.flush(); 176 fos.flush(); 177 178 179 } catch (IOException e) { 180 e.printStackTrace(); 181 } finally { 182 try { 183 if (bos != null) { 184 bos.close(); 185 } 186 if (fos != null) { 187 fos.close(); 188 } 189 if (bis != null) { 190 bis.close(); 191 } 192 is.close(); 193 } catch (IOException e) { 194 e.printStackTrace(); 195 } 196 } 197 198 return file; 199 } 200 201 public static File writeToDisk(InputStream is, String dir, String prefix, String extension) { 202 final File file = FileUtil.createFileByTime(dir, prefix, extension); 203 BufferedInputStream bis = null; 204 FileOutputStream fos = null; 205 BufferedOutputStream bos = null; 206 207 try { 208 bis = new BufferedInputStream(is); 209 fos = new FileOutputStream(file); 210 bos = new BufferedOutputStream(fos); 211 212 byte data[] = new byte[1024 * 4]; 213 214 int count; 215 while ((count = bis.read(data)) != -1) { 216 bos.write(data, 0, count); 217 } 218 219 bos.flush(); 220 fos.flush(); 221 222 223 } catch (IOException e) { 224 e.printStackTrace(); 225 } finally { 226 try { 227 if (bos != null) { 228 bos.close(); 229 } 230 if (fos != null) { 231 fos.close(); 232 } 233 if (bis != null) { 234 bis.close(); 235 } 236 is.close(); 237 } catch (IOException e) { 238 e.printStackTrace(); 239 } 240 } 241 242 return file; 243 } 244 245 /** 246 * 通知系統刷新系統相冊，使照片展現出來 247 */ 248 private static void refreshDCIM() { 249 if (Build.VERSION.SDK_INT >= 19) { 250 //兼容android4.4版本，只掃描存放照片的目錄 251 MediaScannerConnection.scanFile(Latte.getApplicationContext(), 252 new String[]{Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getPath()}, 253 null, null); 254 } else { 255 //掃描整個SD卡來更新系統圖庫，當文件很多時用戶體驗不佳，且不適合4.4以上版本 256 Latte.getApplicationContext().sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + 257 Environment.getExternalStorageDirectory()))); 258 } 259 } 260 261 /** 262 * 讀取raw目錄中的文件,并返回為字符串 263 */ 264 public static String getRawFile(int id) { 265 final InputStream is = Latte.getApplicationContext().getResources().openRawResource(id); 266 final BufferedInputStream bis = new BufferedInputStream(is); 267 final InputStreamReader isr = new InputStreamReader(bis); 268 final BufferedReader br = new BufferedReader(isr); 269 final StringBuilder stringBuilder = new StringBuilder(); 270 String str; 271 try { 272 while ((str = br.readLine()) != null) { 273 stringBuilder.append(str); 274 } 275 } catch (IOException e) { 276 e.printStackTrace(); 277 } finally { 278 try { 279 br.close(); 280 isr.close(); 281 bis.close(); 282 is.close(); 283 } catch (IOException e) { 284 e.printStackTrace(); 285 } 286 } 287 return stringBuilder.toString(); 288 } 289 290 291 public static void setIconFont(String path, TextView textView) { 292 final Typeface typeface = Typeface.createFromAsset(Latte.getApplicationContext().getAssets(), path); 293 textView.setTypeface(typeface); 294 } 295 296 /** 297 * 讀取assets目錄下的文件,并返回字符串 298 */ 299 public static String getAssetsFile(String name) { 300 InputStream is = null; 301 BufferedInputStream bis = null; 302 InputStreamReader isr = null; 303 BufferedReader br = null; 304 StringBuilder stringBuilder = null; 305 final AssetManager assetManager = Latte.getApplicationContext().getAssets(); 306 try { 307 is = assetManager.open(name); 308 bis = new BufferedInputStream(is); 309 isr = new InputStreamReader(bis); 310 br = new BufferedReader(isr); 311 stringBuilder = new StringBuilder(); 312 String str; 313 while ((str = br.readLine()) != null) { 314 stringBuilder.append(str); 315 } 316 } catch (IOException e) { 317 e.printStackTrace(); 318 } finally { 319 try { 320 if (br != null) { 321 br.close(); 322 } 323 if (isr != null) { 324 isr.close(); 325 } 326 if (bis != null) { 327 bis.close(); 328 } 329 if (is != null) { 330 is.close(); 331 } 332 assetManager.close(); 333 } catch (IOException e) { 334 e.printStackTrace(); 335 } 336 } 337 if (stringBuilder != null) { 338 return stringBuilder.toString(); 339 } else { 340 return null; 341 } 342 } 343 344 public static String getRealFilePath(final Context context, final Uri uri) { 345 if (null == uri) return null; 346 final String scheme = uri.getScheme(); 347 String data = null; 348 if (scheme == null) 349 data = uri.getPath(); 350 else if (ContentResolver.SCHEME_FILE.equals(scheme)) { 351 data = uri.getPath(); 352 } else if (ContentResolver.SCHEME_CONTENT.equals(scheme)) { 353 final Cursor cursor = context.getContentResolver().query(uri, new String[]{MediaStore.Images.ImageColumns.DATA}, null, null, null); 354 if (null != cursor) { 355 if (cursor.moveToFirst()) { 356 final int index = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA); 357 if (index > -1) { 358 data = cursor.getString(index); 359 } 360 } 361 cursor.close(); 362 } 363 } 364 return data; 365 } 366 }

?【保存文件類的封裝】

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【繼續封裝com.flj.latte.net.download.DownloadHandler】

【調用的方法】在后面的使用文件下載然后更新應用程序；

【提交代碼】

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總結

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