使用HttpURLConnection（实现单线程多线程下载）

来源：互联网发布：铁翼雄风知乎编辑：程序博客网时间：2024/06/07 10:56

HttpURLConnection继承URLConnection因此也可向指定网站发送POST，GET请求

单线程下载

 class SingleDownloadTask extends AsyncTask<String, Integer, String> {        @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);            // int count= Integer.parseInt(values[1]*100.0/values[0]);            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");                URLConnection connection = url.openConnection();                int length = connection.getContentLength();                //publishProgress(length);                InputStream is = connection.getInputStream();                File file = new File(Environment.getExternalStorageDirectory(), "aa.mp3");                if (!file.exists()) {                    file.createNewFile();                }                FileOutputStream os = new FileOutputStream(file);                byte[] array = new byte[1024];                int sum = 0;                int index = is.read(array);                while (index != -1) {                    os.write(array, 0, index);                    sum += index;                    publishProgress(sum, length);                    index = is.read(array);                }                os.flush();                os.close();                is.close();            } catch (MalformedURLException e) {                e.printStackTrace();            } catch (IOException e) {                e.printStackTrace();            }            return null;        }        @Override        protected void onPostExecute(String s) {            super.onPostExecute(s);        }    }

多线程下载步骤

【1】创建URL对象
【2】获取指定URL对象指向的资源的大小,getContentLength()方法实现；
【3】在本地磁盘创建与资源大小相当的文件
【4】计算每个线程应该下载资源的分配（从那个字节开始，到哪个字节结束）
【5】依次创建启动多个线程下载

 private void MultiThreadDownload() {        new Thread() {            @Override            public void run() {                String urlPath = "http://192.168.0.30:8080/MyWebTest/music/aa.mp3";                try {                    URL url = new URL(urlPath);                    URLConnection connection = url.openConnection();                    length = connection.getContentLength();                    File file = new File(Environment.getExternalStorageDirectory(), "cc.mp3");                    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)-1, urlPath, file.getAbsolutePath());                        }                        thread.start();                        threads[i] = thread;                    }                    boolean isFinish = true;                    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 + 10 >= length) {                            isFinish = false;                        }                        Thread.sleep(1000);                    }                } catch (MalformedURLException e) {                    e.printStackTrace();                } catch (IOException e) {                    e.printStackTrace();                } catch (InterruptedException e) {                    e.printStackTrace();                }            }        }.start();    }

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

public class DownloadActivity extends Activity implements View.OnClickListener {    private Button mButtonSingle;    private Button mButtonMilti;    private ProgressBar mProgressBar;    private int length;    private Handler handler = new Handler() {        @Override        public void handleMessage(Message msg) {            switch (msg.what) {                case 0x23:                    mProgressBar.setProgress(msg.arg1 * 100 / length);                    break;                default:                    break;            }        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_download);        mButtonSingle = (Button) findViewById(R.id.button_download_single);        mButtonMilti = (Button) findViewById(R.id.button_download_milti);        mProgressBar = (ProgressBar) findViewById(R.id.progressbar);        mButtonMilti.setOnClickListener(this);        mButtonSingle.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button_download_single:                SingleDownloadTask task = new SingleDownloadTask();                task.execute();                break;            case R.id.button_download_milti:                MultiThreadDownload();                break;            default:                break;        }    }    private void MultiThreadDownload() {        new Thread() {            @Override            public void run() {                String urlPath = "http://192.168.0.30:8080/MyWebTest/music/aa.mp3";                try {                    URL url = new URL(urlPath);                    URLConnection connection = url.openConnection();                    length = connection.getContentLength();                    File file = new File(Environment.getExternalStorageDirectory(), "cc.mp3");                    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)-1, urlPath, file.getAbsolutePath());                        }                        thread.start();                        threads[i] = thread;                    }                    boolean isFinish = true;                    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 + 10 >= length) {                            isFinish = false;                        }                        Thread.sleep(1000);                    }                } catch (MalformedURLException e) {                    e.printStackTrace();                } catch (IOException e) {                    e.printStackTrace();                } catch (InterruptedException e) {                    e.printStackTrace();                }            }        }.start();    }    class SingleDownloadTask extends AsyncTask<String, Integer, String> {        @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);            // int count= Integer.parseInt(values[1]*100.0/values[0]);            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");                URLConnection connection = url.openConnection();                int length = connection.getContentLength();                //publishProgress(length);                InputStream is = connection.getInputStream();                File file = new File(Environment.getExternalStorageDirectory(), "aa.mp3");                if (!file.exists()) {                    file.createNewFile();                }                FileOutputStream os = new FileOutputStream(file);                byte[] array = new byte[1024];                int sum = 0;                int index = is.read(array);                while (index != -1) {                    os.write(array, 0, index);                    sum += index;                    publishProgress(sum, length);                    index = is.read(array);                }                os.flush();                os.close();                is.close();            } catch (MalformedURLException e) {                e.printStackTrace();            } catch (IOException e) {                e.printStackTrace();            }            return null;        }        @Override        protected void onPostExecute(String s) {            super.onPostExecute(s);        }    }}

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