Android——单、多线程下载

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/***用于打开用于下载的界面.*/package com.example.administrator.myconnection;import android.content.Intent;import android.os.Bundle;import android.os.PersistableBundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;/** * Created by Administrator on 2015/9/11. */public class IndexActivity extends AppCompatActivity implements View.OnClickListener {    private Button mBtnUrlConnection;    private Button mBtnDownload;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_index);        mBtnUrlConnection= (Button) findViewById(R.id.btn_urlconnect);        mBtnDownload= (Button) findViewById(R.id.btn_download);        mBtnUrlConnection.setOnClickListener(this);        mBtnDownload.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()){            case R.id.btn_connect:                break;            case R.id.btn_download:                Intent intent=new Intent("com.example.administrator.myconnection.DownloadActivity");                startActivity(intent);                break;        }    }}

/***下载界面*/package com.example.administrator.myconnection;import android.os.AsyncTask;import android.os.Bundle;import android.os.Environment;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.ProgressBar;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.MalformedURLException;import java.net.URL;import java.net.URLConnection;/** * Created by Administrator on 2015/9/11. */public class DownloadActivity extends AppCompatActivity implements View.OnClickListener {    private Button mBtnSingleDownload;    private Button mBtnMoreDownload;    private ProgressBar progressBar;    int length;    /**     * 当Handler被创建会关联到创建它的当前线程的消息队列，该类用于往消息队列发送消息    * 消息队列中的消息由当前线程内部进行处理    */    private Handler handler=new Handler(){        @Override        public void handleMessage(Message msg) {            switch (msg.what){                case 0x23:                    progressBar.setProgress(msg.arg1*100/length);                    break;            }        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_download);        progressBar= (ProgressBar) findViewById(R.id.progressbar);        mBtnSingleDownload= (Button) findViewById(R.id.singledownload);        mBtnMoreDownload= (Button) findViewById(R.id.multidownload);        mBtnMoreDownload.setOnClickListener(this);        mBtnSingleDownload.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()){            case R.id.singledownload:                //单线程下载              new Singledownload().execute();                break;            case R.id.multidownload:                //多线程下载                multiDownload();                break;        }    }    private void multiDownload() {  //多线程下载        new Thread(new Runnable() {            @Override            public void run() {                try {                    //下载文件的地址                    String urlPath="http://192.168.0.30:8080/MyWebTest/music/aa.mp3";                    URL url = new URL(urlPath);                    URLConnection connection=url.openConnection();                    //获取下载文件的长度                    length=connection.getContentLength();                    //在本地新建的文件地址，保存下载的文件                    File file=new File(Environment.getExternalStorageDirectory(),"cc.mp3");                    if(!file.exists()){                        file.createNewFile();                    }                    //分成5个线程并设置每个线程下载的起始、结束位置                    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 Singledownload extends AsyncTask<String,Integer,String>{        @Override        protected void onPostExecute(String s) {            super.onPostExecute(s);        }        @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);            progressBar.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();                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);                }                is.close();                os.flush();                os.close();            } catch (MalformedURLException e) {                e.printStackTrace();            } catch (IOException e) {                e.printStackTrace();            }            return null;        }    }}

/***多线程下载的线程*/package com.example.administrator.myconnection;import android.os.Environment;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.RandomAccessFile;import java.net.MalformedURLException;import java.net.URL;import java.net.URLConnection;/** * Created by zhonghangIT on 2015/9/11. */public class MultiThread extends Thread{    public MultiThread(long start, long end, String url, String filePath) {//传入开始位置，结束位置，下载路径，保存文件路径        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 如果为 true，则在允许用户交互（例如弹出一个验证对话框）的上下文中对此 URL 进行检查。            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是用来访问那些保存数据记录的文件的，你就可以用seek( )方法来访问记录，            // 并进行读写了。这些记录的大小不必相同；但是其大小和位置必须是可知的。但是该类仅限于操作文件。            RandomAccessFile randomAccessFileile=new RandomAccessFile(file,"rw");            randomAccessFileile.seek(start); //找到下载的起始位置            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();        }    }}

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