断线续传——>断点续传核心代码

/** 
* 断点续传 
* @param url 
*/ 
private void duanDianXuChuan(final String url){ 
try { 
Runnable r = new Runnable() { 
@Override 
public void run() { 
getRemoteFile(url); 
} 
}; 
new Thread(r).start(); 
} catch (Exception e) { 
e.printStackTrace(); 
} 
} 
/** 
* 下载远端文件 
* @param urlString 
*/ 
private void getRemoteFile(String urlString){ 
try{ 
File file; 
if(mCurSize == 0){ 
file = File.createTempFile(fileNa, fileEx); 
currentTempFilePath = file.getAbsolutePath(); 
Log.e(“andy”,file.getName() + ” has exists.”); 
} else { 
file = new File(currentTempFilePath); 
FileInputStream fis = new FileInputStream(file); 
mCurSize = fis.available(); 
Log.e(“andy”,file.getName() + ” has ” + mCurSize + ” bytes.”); 
} 
URL url = new URL(urlString); 
HttpURLConnection httpConnection = (HttpURLConnection) url 

.openConnection(); 
httpConnection.setRequestProperty(“User-Agent”, “NetFox”); 
String sProperty = “bytes=” + mCurSize + “-”; 
httpConnection.setRequestProperty(“RANGE”, sProperty); 
InputStream is = httpConnection.getInputStream(); 
Log.e(“andy”,”mTempFileName = ” + mTempFileName); 
/*将文件写入暂存盘*/ 
FileOutputStream fos = new FileOutputStream(file, true); 
byte buf[] = new byte[512]; 
do 
{ 
int numread = is.read(buf); 
if (numread <= 0) 
{ 
mHandler.sendEmptyMessageDelayed(this.DOWNLOAD_FINISH, 0); 
break; 
} 
mCurSize += numread; 
mHandler.sendEmptyMessageDelayed(this.UPDATE_DOWNLOAD_PROGRESS, 0); 
Log.e(“andy”,”current size = ” + mCurSize); 
fos.write(buf, 0, numread); 
}while (mContinue); 
/*打开文件进行安装*/ 
if(mCurSize == mSize) { 
mCurSize = 0; 
openFile(file); 
} 
try 
{ 
is.close(); 
} 
catch (Exception ex) 
{ 
Log.e(“andy”, “error: ” + ex.getMessage(), ex); 
} 
}catch(Exception e){ 
e.printStackTrace(); 
} 
} 
/** 
* 获得文件长度 
* @param urlString 
* @return 
*/ 
public long getFileSize(String urlString) { 
int nFileLength = -1; 
try { 
URL url = new URL(urlString); 
HttpURLConnection httpConnection = (HttpURLConnection) url 
.openConnection(); 
httpConnection.setRequestProperty(“User-Agent”, “NetFox”); 
int responseCode = httpConnection.getResponseCode(); 
if (responseCode >= 400) { 
return -2; // -2 represent access is error 
} 
String sHeader; 
for (int i = 1;; i++) { 
sHeader = httpConnection.getHeaderFieldKey(i); 
if (sHeader != null) { 
if (sHeader.equals(“content-length”)) { 
nFileLength = Integer.parseInt(httpConnection 
.getHeaderField(sHeader)); 
break; 
} 
} else 
break; 
} 
} catch (IOException e) { 
e.printStackTrace(); 
} catch (Exception e) { 
e.printStackTrace(); 
} 
return nFileLength; 
} 
/** 
* 计算百分比 
* @param p1 
* @param p2 
* @return 
*/ 
public static String percent(double p1, double p2) { 
String str; 
double p3 = p1 / p2; 
NumberFormat nf = NumberFormat.getPercentInstance(); 
nf.setMinimumFractionDigits(2); 
str = nf.format(p3); 
Log.e(“andy”,”percentage = ” + str); 
return str; 
}