android多线程暂停下载-HttpURLConnection

android多线程暂停下载-HttpURLConnection

private EditText et_path;    private LinearLayout ll_pbs;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        et_path = (EditText) findViewById(R.id.et_path);        ll_pbs = (LinearLayout) findViewById(R.id.ll_pbs);    }    public void startDownload(View view){        //资源路径        final String path = et_path.getText().toString().trim();        new Thread(new Runnable() {            @Override            public void run() {                URL url;                try {                    url = new URL(path);                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();                    conn.connect();                    int totalSize = conn.getContentLength();                    int threadCount = 3;                    //计算每个线程下载的字节数                    int blockSize = totalSize/3;                    //目标路径                    String target = Environment.getExternalStorageDirectory().getAbsolutePath()+"/bbb.jpg";                    for (int i = 1; i <= threadCount; i++) {                        int id = i;                        int startIndex = (id-1)*blockSize;                        int endIndex = -1;                        if (id==threadCount) {                            //3*3-1                            endIndex = totalSize-1;                        }else {                            endIndex = id*blockSize-1;                        }                        final ProgressBar pb = (ProgressBar) View.inflate(MainActivity.this, R.layout.pb, null);                        runOnUiThread(new Runnable() {                            @Override                            public void run() {                                ll_pbs.addView(pb);                            }                        });                        DownloadThread downloadThread = new DownloadThread(id,startIndex,endIndex,path,target,pb);                        downloadThread.start();                    }                } catch (Exception e) {                    e.printStackTrace();                }            }        }).start();    }    class DownloadThread extends Thread{        private int id;        private int startIndex;        private int endIndex;        private String path;        private String target;        private File tempFile;        private ProgressBar pb;        private int newStartIndex;        public DownloadThread(int id, int startIndex, int endIndex,String path, String target,ProgressBar pb) {            super();            this.id = id;            this.startIndex = startIndex;            this.endIndex = endIndex;            this.path = path;            this.target = target;            this.pb = pb;            tempFile = new File(Environment.getExternalStorageDirectory(),"thread"+id+".tmp");            try {                BufferedReader br = new BufferedReader(new FileReader(tempFile));                String readLine = br.readLine();                br.close();                newStartIndex = Integer.parseInt(readLine);            } catch (Exception e) {                newStartIndex = startIndex;            }            pb.setMax(endIndex-startIndex);        }        @Override        public void run() {            try {                URL url = new URL(path);                HttpURLConnection conn = (HttpURLConnection) url.openConnection();                conn.setRequestProperty("Range", "bytes="+newStartIndex+"-"+endIndex);                conn.connect();                int code = conn.getResponseCode();                if (206==code) {                    InputStream inputStream = conn.getInputStream();                    File file = new File(target);                    RandomAccessFile raf = new RandomAccessFile(file ,"rwd");                    raf.seek(newStartIndex);                    int len=-1;                    byte[] buffer = new byte[1024];                    int total =0;                    while((len=inputStream.read(buffer))!=-1){                        FileWriter fileWriter = new FileWriter(tempFile);                        raf.write(buffer,0,len);                        total+=len;                        fileWriter.write(""+(newStartIndex+total));                        fileWriter.close();                        //当前线程下载的总百分比                        float process =(100.f* (total+newStartIndex-startIndex))/(endIndex-startIndex);                        System.out.println(id+"下载了"+process);                        pb.setProgress(total+newStartIndex-startIndex);                    }                    System.out.println(id+"已完成");                    raf.close();                }            } catch (Exception e) {                e.printStackTrace();            }        }    }