android 图片库的封装

public class PictureLibrary {      /*       * 图片库的操作       */        File file;        URL url;      HttpURLConnection conn;      InputStream is;      FileOutputStream fos;        private Lock lock = new ReentrantLock();        private Condition downFile = lock.newCondition();        // 通过URL将数据下载到本地操作      private String toLocalFile(String strURL) {          String fileName = Utils.getFileName(strURL);          String path = Environment.getExternalStorageDirectory() + "/"                  + EcologicalTourism.FILE_PATH + "/images/" + fileName;            return path;      }        // 通过URL将数据下载到本地临时文件中      private String toLocalFileTemp(String strURL) {          String s = Utils.getFileName(strURL);          String fileName = s+"temp";          String path_url = Environment.getExternalStorageDirectory() + "/"                  + EcologicalTourism.FILE_PATH + "/tempimages/" + fileName;            return path_url;      }          /*       * 保存图片到本地，并返回本地url（此函数是阻塞的）       * main       * @参数：strURL，参数为图片的URL.返回值：该图片在本地SD卡暂存的位置       * 函数的工作是负责将图片从互联网上取得，存在本地存储中，并返回本地存储的文件路径，供调用者直接使用。如果文件已经存在本地，直接返回       * 如果文件未在本地，则直接从服务器下载，函数阻塞。       */      public String getReadSD(String strURL) {          Log.i("test", "拿到网络的地址是：" + strURL);          String strLocalFile = toLocalFile(strURL);  //k：把服务器URL转换为本地URL          String strLocalFileTemp = toLocalFileTemp(strURL); //k：把服务器URL转换为本地临时URL          while (true) {              File file = new File(strLocalFile);              Log.i("test", "本地文件是：" + strLocalFile);              File tfile = new File(strLocalFileTemp);              Log.i("test", "临时文件是：" + strLocalFileTemp);              // 1上锁              lock.lock();                if (file.exists()) {                  // 2if 本地文件存在                  // 解锁                  // 返回本地路径                  lock.unlock();                  Log.i("test", "返回本地路径：" + file);                  return strLocalFile;              } else if (tfile.exists()) {                  // if 对应的暂存文件存在                  // 解锁                  lock.unlock();                  try {                      // 睡眠                      downFile.await();                  } catch (Exception e) {                       e.printStackTrace();                      Log.i("test", "e 出现了异常1" + e);                  }                } else {                  try {                      // 创建对应的暂存文件                      tfile.createNewFile();                  } catch (IOException e) {                      Log.i("test", "e 出现了异常2" + e);                    }                  // 解锁                  lock.unlock();                  // 下载文件内容到暂存文件中                  downURL2(strURL, strLocalFile);                  // 上锁                  lock.lock();                  // 修改暂存文件名字为本地文件名                  tfile.renameTo(file);                  // 解锁                  lock.unlock();              }            }      }                    private void downURL2(String strURL, String strLocalFileTemp) {          // TODO Auto-generated method stub          URL url;          try {              url = new URL(strURL);              HttpURLConnection conn = (HttpURLConnection) url.openConnection();              conn.setConnectTimeout(5000);              conn.setRequestMethod("GET");              conn.setDoInput(true);              if (conn.getResponseCode() == 200) {                      InputStream is = conn.getInputStream();                      FileOutputStream fos = new FileOutputStream(strLocalFileTemp);                      byte[] buffer = new byte[1024];                      int len = 0;                      while ((len = is.read(buffer)) != -1) {                              fos.write(buffer, 0, len);                      }                      is.close();                      fos.close();                      // 返回一个URI对象              }          } catch (MalformedURLException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (ProtocolException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IOException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }                          }              /*       * 阻塞式下载url到文件 toFile中       */      private boolean downURL(String strURL, String toFile) {                   URL url;          try {              url = new URL(strURL);              HttpURLConnection httpUrl = (HttpURLConnection) url                      .openConnection();              httpUrl.setRequestMethod("GET");              int fileSize = httpUrl.getContentLength();// 文件大小              httpUrl.disconnect();// 关闭连接              int threadSize = 6;// 默认设置6个线程              threadSize = fileSize % threadSize == 0 ? threadSize                      : threadSize + 1;              int currentSize = fileSize / threadSize; // 每条线程下载大小                String dowloadir = Environment.getExternalStorageDirectory() + "/"                      + EcologicalTourism.FILE_PATH + "/images/";                File dir = new File(dowloadir);                if (!dir.exists()) {                  dir.mkdirs();              }              File file = new File(dir, toFile);              RandomAccessFile randomFile = new RandomAccessFile(file, "rw");              randomFile.setLength(fileSize);// 指定 file 文件的大小              for (int i = 0; i < threadSize; i++) {                  int startposition = i * currentSize;// 每条线程开始写入文件的位置                  RandomAccessFile threadFile = new RandomAccessFile(file, "rw");                  Log.i("syso", "toFile的内容是：" + toFile);                  threadFile.seek(startposition);                  new DownLoadThread(i, currentSize, threadFile, startposition,                          url).start();              }            } catch (Exception e) {              e.printStackTrace();              Log.i("syso", "download下载失败" + e);          }            return true;      }          /**       * 实现线程下载       *       */      private static class DownLoadThread extends Thread {          @SuppressWarnings("unused")          private int threadId;// 线程编号          private int currentSize;// 每条线程的大小          private RandomAccessFile threadFile; // 每条线程 要写入文件类          private int startposition;// 每条线程开始写入文件的位置          private URL url;  //网络地址            public DownLoadThread(int threadId, int currentSize,                  RandomAccessFile threadFile, int startposition, URL url) {              this.threadId = threadId;              this.currentSize = currentSize;              this.threadFile = threadFile;              this.startposition = startposition;              this.url = url;          }            public void run() {              try {                  HttpURLConnection httpUrl = (HttpURLConnection) url                          .openConnection();                  httpUrl.setRequestMethod("GET");                  httpUrl.setRequestProperty("range", "bytes=" + startposition                          + "-");// 指定服务器的位置                  InputStream is = httpUrl.getInputStream();                  byte[] data = new byte[1024];                  int len = -1;                  int threadFileSize = 0;                  while ((threadFileSize < currentSize)                          && ((len = is.read(data)) != -1)) {                      threadFile.write(data, 0, len);                      threadFileSize += len;                  }                  httpUrl.disconnect();                  is.close();              } catch (Exception e) {                  e.printStackTrace();              }          }      }                        /**      * 从本缓存中获取图片      */      public  Bitmap getBitmapFromCache(String imageURL) {  //        String bitmapName = imageURL.substring(imageURL.lastIndexOf("/") + 1);          String bitmapName = Utils.getFileName(imageURL);          File cacheDir = new File(Environment.getExternalStorageDirectory() + "/"                  + EcologicalTourism.FILE_PATH + "/images/");              File[] cacheFiles = cacheDir.listFiles();              int i = 0;              if(null!=cacheFiles){                for(; i<cacheFiles.length;i++){                      if(bitmapName.equals(cacheFiles[i].getName())){                          break;                      }                  }                                    if(i < cacheFiles.length)                  {                      return BitmapFactory.decodeFile(Environment.getExternalStorageDirectory() + "/"                          + EcologicalTourism.FILE_PATH + "/images/" + bitmapName);                  }                      }          return null;        }