網絡連接2 單線程和多線程下載 並更新progressbar

1，單線程下載     AsyncTask來更新UI 

case R.id.button_download_single:
new DownloadTask().execute();

private class DownloadTask extends AsyncTask<String,Integer,String>{

@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
mProgressBar.setProgress((int)(values[0]*100.0/values[1]));
        }

@Override
protected String doInBackground(String... params) {

try {

//                URL url = new URL("http://192.168.0.30:8080/MyWebTest/music/aa.mp3");
URL url = new URL("http://js.tudouui.com/bin/player2/olc_8.swf");
/**
                 * 用url.openConnection()獲得URLConnection
                 */
URLConnection urlConnection = url.openConnection();
/**
                 * 獲取總長度，用於設置進度條
                 */
int length = urlConnection.getContentLength();
                InputStream inputStream = urlConnection.getInputStream();
/**
                 * 在本地創建文件，別忘了設置寫的權限
                 */
File file = new File(Environment.getExternalStorageDirectory(),"aa.mp3");
if(!file.exists()){
                    file.createNewFile();
                }
                FileOutputStream fos = new FileOutputStream(file);
byte[] array = new byte[1024];
int sum = 0;
int index = inputStream.read(array);
while (index!=-1){
                    fos.write(array,0,index);
                    sum+=index;
                    publishProgress(sum,length);
                    index =inputStream.read(array);
                }
                fos.flush();
                fos.close();
                inputStream.close();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
return null;
        }
    }

2，多線程下載 

界面，數據部分

case R.id.button_download_multi:
//多線程下載

new Thread(new Runnable() {
@Override
public void run() {
try {
                String urlPath="http://filelx.liqucn.com/upload/2015/jiaotong/didi_psnger_test4_93_v395_94.ptada";
                URL  url = new URL(urlPath);
                URLConnection connection=url.openConnection();
length=connection.getContentLength();
                File file=new File(Environment.getExternalStorageDirectory(),"heinika.apk");
if(!file.exists()){
                    file.createNewFile();
                }
                MultiThread[] threads=new MultiThread[5];
for (int i=0;i<5;i++){
                    MultiThread thread=null;
if(i==4){
                        thread = new MultiThread(length / 5*4, length , urlPath, file.getAbsolutePath());
                    }else {
                        thread = new MultiThread(length / 5 * i, length / 5 * (i + 1), urlPath, file.getAbsolutePath());
                    }
                    thread.start();
                    threads[i]=thread;
                }
boolean isFinish=false;

while(!isFinish){
int sum=0;
for (MultiThread thread:threads){
                        sum+= thread.getSum();
                    }
                    Message msg=  handler.obtainMessage();
                    msg.what=0x23;
                    msg.arg1=sum;
handler.sendMessage(msg);
if(sum==length){
                        isFinish=true;
                    }
                    Thread.sleep(1000);
                }
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

        }
    }).start();
break;

接收消息的handler，用來更新UI

int length;
private Handler handler=new Handler(){
@Override
public void handleMessage(Message msg) {
switch (msg.what){
case 0x23:
mProgressBar.setMax(length);
mProgressBar.setProgress(msg.arg1);
break;
        }
    }
};

可以下載指定位置的線程

public class MultiThread extends Thread{
public MultiThread(long start, long end, String url, String filePath) {
this.start = start;
this.end = end;
this.urlPath = url;
this.filePath = filePath;
    }
private int sum=0;
private long start;
private long end;
private String urlPath;
private String filePath;

public int getSum() {
return sum;
    }

@Override
public void run() {
try {
            URL url=new URL(urlPath);
            URLConnection connection=url.openConnection();
/**
             * allowUserInteraction
             如果爲 true，則在允許用戶交互（例如彈出一個驗證對話框）的上下文中對此 URL 進行檢查。
             */
connection.setAllowUserInteraction(true);

            connection.setRequestProperty("Range", "bytes=" + start + "-"
+ end);
             InputStream is= connection.getInputStream();
byte [] array=new byte[1024];
            is.read(array);
            File file=new File(filePath);
            RandomAccessFile randomAccessFileile=new RandomAccessFile(file,"rw");
            randomAccessFileile.seek(start);
int index=is.read(array);
while (index!=-1){
                randomAccessFileile.write(array,0,index);
sum+=index;
                index=is.read(array);
            }
            randomAccessFileile.close();
            is.close();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}