下载文件工具类

public class DownloadUtils {
	private static final int CONNECT_TIMEOUT = 10000;
	private static final int DATA_TIMEOUT = 40000;
	private final static int DATA_BUFFER = 1024 * 10;

	public interface DownloadListener {
		public void downloading(int progress);

		public void downloaded();
	}

	public static long download(String urlStr, File dest, boolean append,
			DownloadListener downloadListener) throws Exception {
		LogUtil.i("开始下载：" + urlStr);
		int downloadProgress = 0;
		long remoteSize = 0;
		long currentSize = 0;
		long totalSize = -1;

		File parentFile = dest.getParentFile();
		if (parentFile != null && !parentFile.exists()) {
			parentFile.mkdirs();
		}

		if (!append || !dest.isFile()) {
			dest.delete();
		}

		if (append && dest.exists()) {
			currentSize = dest.length();
		}

		HttpGet request = new HttpGet(urlStr);

		LogUtil.d("currentSize = " + currentSize);

		if (currentSize > 0) {
			request.addHeader("Range", "bytes=" + currentSize + "-");
		}

		HttpParams params = new BasicHttpParams();
		HttpConnectionParams.setConnectionTimeout(params, CONNECT_TIMEOUT);
		HttpConnectionParams.setSoTimeout(params, DATA_TIMEOUT);
		HttpClient httpClient = new DefaultHttpClient(params);

		InputStream is = null;
		FileOutputStream os = null;
		try {
			HttpResponse response = httpClient.execute(request);
			int statusCode = response.getStatusLine().getStatusCode();
			LogUtil.d("statusCode = " + statusCode);
			if (statusCode == HttpStatus.SC_OK|| statusCode == HttpStatus.SC_PARTIAL_CONTENT) {

				boolean isBreak = false;
				if (statusCode == HttpStatus.SC_PARTIAL_CONTENT) {
					isBreak = true;
				}
				Header[] hs = response.getAllHeaders();
				if (hs != null) {
					for (int i = 0; i < hs.length; i++) {
						String headerName = hs[i].getName();
						if ("Accept-Ranges".equalsIgnoreCase(headerName)
								|| "Accept-Range".equalsIgnoreCase(headerName)
								|| "Content-Ranges"
										.equalsIgnoreCase(headerName)
								|| "Content-Range".equalsIgnoreCase(headerName)) {
							isBreak = true;
						}
					}
				}

				remoteSize = response.getEntity().getContentLength(); // max
				LogUtil.d("old remoteSize = " + remoteSize);
				if (isBreak) {
					remoteSize += currentSize;
				}
				LogUtil.d("new remoteSize = " + remoteSize);

				is = response.getEntity().getContent();
				Header contentEncoding = response
						.getFirstHeader("Content-Encoding");
				if (contentEncoding != null
						&& contentEncoding.getValue().equalsIgnoreCase("gzip")) {
					is = new GZIPInputStream(is);
				}
				os = new FileOutputStream(dest, isBreak);
				byte buffer[] = new byte[DATA_BUFFER];
				int readSize = 0;
				while ((readSize = is.read(buffer)) != -1) {
					os.write(buffer, 0, readSize);
					os.flush();
					totalSize += readSize;
					currentSize += readSize;
					downloadProgress = (int) (currentSize * 100 / remoteSize);
					// LogUtil.d("currentSize = " + currentSize);
					if (downloadListener != null) {
						downloadListener.downloading(downloadProgress);
					}
					if (Thread.currentThread().isInterrupted()) {
						LogUtil.i("取消下载:" + urlStr);
						break;
					}
				}
				if (totalSize < 0) {
					totalSize = 0;
				}
				LogUtil.d("currentSize = " + currentSize);
			} else {
				throw new Exception("网络请求失败:" + urlStr);
			}

		} catch (Exception e) {
			throw e;
		} finally {
			httpClient.getConnectionManager().shutdown();
			if (os != null) {
				try {
					os.close();
				} catch (Exception e2) {
					e2.printStackTrace();
				}
			}
			if (is != null) {
				try {
					is.close();
				} catch (Exception e2) {
					e2.printStackTrace();
				}
			}
		}

		if (totalSize < 0) {
			throw new Exception("Download file fail: " + urlStr);
		}

		if (downloadListener != null) {
			downloadListener.downloaded();
		}

		return totalSize;
	}
}