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【Java】动态下载工具类

作者:weidi1989 / 发布于2013/10/24/ 496


	import java.io.File;
	import java.io.FileInputStream;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.util.zip.GZIPInputStream;

	import org.apache.http.Header;
	import org.apache.http.HttpResponse;
	import org.apache.http.HttpStatus;
	import org.apache.http.client.HttpClient;
	import org.apache.http.client.methods.HttpGet;
	import org.apache.http.impl.client.DefaultHttpClient;
	import org.apache.http.params.BasicHttpParams;
	import org.apache.http.params.HttpConnectionParams;
	import org.apache.http.params.HttpParams;

	public class DownloadUtils {
	 private static final int CONNECT_TIMEOUT = 10000;
	 private static final int DATA_TIMEOUT = 40000;
	 private final static int DATA_BUFFER = 8192;

	 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 {
	 int downloadProgress = 0;
	 long remoteSize = 0;
	 int currentSize = 0;
	 long totalSize = -1;

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

	 if(append && dest.exists() && dest.exists()) {
	 FileInputStream fis = null;
	 try {
	 fis = new FileInputStream(dest);
	 currentSize = fis.available();
	 } catch(IOException e) {
	 throw e;
	 } finally {
	 if(fis != null) {
	 fis.close();
	 }
	 }
	 }

	 HttpGet request = new HttpGet(urlStr);

	 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);
	 if(response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
	 is = response.getEntity().getContent();
	 remoteSize = response.getEntity().getContentLength();
	 Header contentEncoding = response.getFirstHeader("Content-Encoding");
	 if(contentEncoding != null && contentEncoding.getValue().equalsIgnoreCase("gzip")) {
	 is = new GZIPInputStream(is);
	 }
	 os = new FileOutputStream(dest, append);
	 byte buffer[] = new byte[DATA_BUFFER];
	 int readSize = 0;
	 while((readSize = is.read(buffer)) > 0){
	 os.write(buffer, 0, readSize);
	 os.flush();
	 totalSize += readSize;
	 if(downloadListener!= null){
	 downloadProgress = (int) (totalSize*100/remoteSize);
	 downloadListener.downloading(downloadProgress);
	 }
	 }
	 if(totalSize < 0) {
	 totalSize = 0;
	 }
	 }
	 } finally {
	 if(os != null) {
	 os.close();
	 }
	 if(is != null) {
	 is.close();
	 }
	 }

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

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

	 return totalSize;
	 }
	}

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