0913Android基础网络技术之下载（AsyncTask）

下载

　　通过urlconnection以及线程实现下载
　　下载之前要添加权限，以及在主线程中注册

    <uses-permission android:name="android.permission.INTERNET" />    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

　　注册

        <activity android:name=".MyDownloadActivity"></activity>

单线程下载

　　通过继承AsyncTask新开一个线程，将下载过程中的数据用来设置progressbar

 class MyAsynvTask extends AsyncTask<String,Integer,String>{        @Override        protected void onPostExecute(String s) {            super.onPostExecute(s);        }        @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);            int all=values[1];            int current=values[0];            int progress= (int) (current*100.0/all);            mProgressBar.setProgress(progress);        }        @Override        protected String doInBackground(String... params) {            try {                URL url=new URL("http://192.168.0.44:8080/MyServiceTest/music/aa.mp3");                URLConnection connection=url.openConnection();                int length=connection.getContentLength();                InputStream is=connection.getInputStream();                File file=new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC),"ee.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;        }    }

　　启动线程

new MyAsynvTask().execute();

多线程下载

　　新建线程类

package com.example.laowang.myinternet;import java.io.File;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 Administrator on 2015/9/13. */public class MultiThread extends Thread {    private int sum=0;    private long start;    private long end;    private String urlPath;    private String filePath;    public MultiThread(long start, long end, String url, String filePath) {        this.start = start;        this.end = end;        this.urlPath = url;        this.filePath = filePath;    }    public int getSum() {        return sum;    }    @Override    public void run() {        try {            URL url=new URL(urlPath);            URLConnection connection=url.openConnection();//            如果为true，则允许进行用户交互（即下载前访问是否下载）            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");//            只有RandomAccessFile才有seek搜寻方法，而这个方法也只适用于文件            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();        }    }}

　　在活动中运行线程

  new Thread(new Runnable() {                    @Override                    public void run() {                        try {                            String urlPath="http://192.168.0.44:8080/MyServiceTest/music/aa.mp3";                            URL  url = new URL(urlPath);                            URLConnection connection=url.openConnection();//                            获得文件的长度                            length=connection.getContentLength();//                            新建存放下载内容的文件。                            File file=new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC),"dd.mp3");                            if(!file.exists()){                                file.createNewFile();                            }//                            新建多线程对象，打开五个线程同时进行下载。                            MultiThread[] threads=new MultiThread[5];                            for (int i=0;i<5;i++){                                MultiThread thread=null;//                                最后一部分，由于极大的可能没有正处，所有这边设置结束长度为文件的长度。                                if(i==4){                                    thread = new MultiThread(length / 5*4, length , urlPath, file.getAbsolutePath());                                }else {//                                 传入起始位置，结束位置，下载路径，下载文件存放路径。因为包前包后所以减一                                    thread = new MultiThread(length / 5 * i, length / 5 * (i + 1)-1, urlPath, file.getAbsolutePath());                                }                                thread.start();                                threads[i]=thread;                            }//                          设置进度条                            boolean isFinish=true;                            while(isFinish){                                int sum=0;//                                获得五个线程的实时长度的和                                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();

单线程以及多线程下载运行gif

　　达到的效果

全部代码

　　活动
　　

package com.example.laowang.myinternet;import android.app.Activity;import android.os.AsyncTask;import android.os.Bundle;import android.os.Environment;import android.os.Handler;import android.os.Message;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 MyDownloadActivity extends Activity implements View.OnClickListener {    private Button mBtnSingelDownload;    private Button mBtnMulThreadDownload;    private ProgressBar mProgressBar;    int length;    private Handler handler=new Handler(){        @Override        public void handleMessage(Message msg) {            switch (msg.what){                case 0x23://                    将进度条最大值设为文件最大值。                    mProgressBar.setMax(length);                    mProgressBar.setProgress(msg.arg1);//                    mProgressBar.setProgress((int) (msg.arg1*100.0/length));                    break;            }        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_download);        mBtnSingelDownload = (Button) findViewById(R.id.button_signal_thread_download);        mBtnMulThreadDownload = (Button) findViewById(R.id.button_mul_thread_download);        mProgressBar= (ProgressBar) findViewById(R.id.progressBar);        mBtnSingelDownload.setOnClickListener(this);        mBtnMulThreadDownload.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()){            case R.id.button_signal_thread_download:                new MyAsynvTask().execute();                break;            case R.id.button_mul_thread_download:                new Thread(new Runnable() {                    @Override                    public void run() {                        try {                            String urlPath="http://192.168.0.44:8080/MyServiceTest/music/aa.mp3";                            URL  url = new URL(urlPath);                            URLConnection connection=url.openConnection();//                            获得文件的长度                            length=connection.getContentLength();//                            新建存放下载内容的文件。                            File file=new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC),"dd.mp3");                            if(!file.exists()){                                file.createNewFile();                            }//                            新建多线程对象，打开五个线程同时进行下载。                            MultiThread[] threads=new MultiThread[5];                            for (int i=0;i<5;i++){                                MultiThread thread=null;//                                最后一部分，由于极大的可能没有正处，所有这边设置结束长度为文件的长度。                                if(i==4){                                    thread = new MultiThread(length / 5*4, length , urlPath, file.getAbsolutePath());                                }else {//                                 传入起始位置，结束位置，下载路径，下载文件存放路径。因为包前包后所以减一                                    thread = new MultiThread(length / 5 * i, length / 5 * (i + 1)-1, urlPath, file.getAbsolutePath());                                }                                thread.start();                                threads[i]=thread;                            }//                          设置进度条                            boolean isFinish=true;                            while(isFinish){                                int sum=0;//                                获得五个线程的实时长度的和                                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();                break;            default:                break;        }    }    class MyAsynvTask extends AsyncTask<String,Integer,String>{        @Override        protected void onPostExecute(String s) {            super.onPostExecute(s);        }        @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);            int all=values[1];            int current=values[0];            int progress= (int) (current*100.0/all);            mProgressBar.setProgress(progress);        }        @Override        protected String doInBackground(String... params) {            try {                URL url=new URL("http://192.168.0.44:8080/MyServiceTest/music/aa.mp3");                URLConnection connection=url.openConnection();                int length=connection.getContentLength();                InputStream is=connection.getInputStream();                File file=new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC),"ee.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;        }    }}

　　多线程下载新开的线程类

package com.example.laowang.myinternet;import java.io.File;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 Administrator on 2015/9/13. */public class MultiThread extends Thread {    private int sum=0;    private long start;    private long end;    private String urlPath;    private String filePath;    public MultiThread(long start, long end, String url, String filePath) {        this.start = start;        this.end = end;        this.urlPath = url;        this.filePath = filePath;    }    public int getSum() {        return sum;    }    @Override    public void run() {        try {            URL url=new URL(urlPath);            URLConnection connection=url.openConnection();//            如果为true，则允许进行用户交互（即下载前访问是否下载）            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");//            只有RandomAccessFile才有seek搜寻方法，而这个方法也只适用于文件            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();        }    }}

　　布局

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:gravity="center"    android:orientation="vertical">    <Button        android:id="@+id/button_mul_thread_download"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="多线程下载" />    <Button        android:id="@+id/button_signal_thread_download"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="单线程下载" />    <ProgressBar        android:id="@+id/progressBar"        style="?android:attr/progressBarStyleHorizontal"        android:layout_margin="5dp"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>