網絡連接——文件下載（單線程/多線程）

單線程下載

package com.example.administrator.networkconnect;

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.os.PersistableBundle;
import android.util.Log;
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 FileDownLoad extends Activity implements View.OnClickListener{
    private Button mButtonSingle;
    private Button mButtonMulti;
    private ProgressBar mProgressBar;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_filedownload);
        mButtonSingle= (Button) findViewById(R.id.button_singlefile);
        mButtonSingle.setOnClickListener(this);
        mButtonMulti= (Button) findViewById(R.id.button_multifile);
        mButtonMulti.setOnClickListener(this);
        mProgressBar= (ProgressBar) findViewById(R.id.progressBar_download);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.button_singlefile:
                FileDownLoadAyscn filedown=new FileDownLoadAyscn();
                filedown.execute();              
                break;
            default:
                break;
        }
    }
    class FileDownLoadAyscn extends AsyncTask<String ,Integer,String >{

        @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 inputStream=connection.getInputStream();
                File file =new File(Environment.getExternalStorageDirectory(),"aa.mp3");
                if (!file.exists()){
                    file.createNewFile();
                }
                FileOutputStream outputStream=new FileOutputStream(file);
                byte[]array=new byte[1024];
                int index=inputStream.read(array);

                int current=0;
                while (index!=-1){
                    outputStream.write(array,0,index);
                    current+=index;
                    publishProgress(current,length);
                    index=inputStream.read(array);
                }
                outputStream.flush();
                inputStream.close();
                outputStream.close();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
        }

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

多線程下載

在主活動的監聽事件中，聲明要下載文件的服務器，並說明文件下載到的地址，然後利用for循環啓動多個線程，來進行下載，並將下載的進度通過handler發送，用handlerMessage進行處理並顯示到進度條上

package com.example.administrator.networkconnect;

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.os.PersistableBundle;
import android.util.Log;
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 FileDownLoad extends Activity implements View.OnClickListener{
    private Button mButtonSingle;
    private Button mButtonMulti;
    private ProgressBar mProgressBar;
    private int length;//返回的信息的長度
    private Handler handler=new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what){
                case 0x23:
                    mProgressBar.setProgress(msg.arg1*100/length);
                break;
            }
        }
    };
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_filedownload);
        mButtonMulti= (Button) findViewById(R.id.button_multifile);
        mButtonMulti.setOnClickListener(this);
        mProgressBar= (ProgressBar) findViewById(R.id.progressBar_download);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){

            case R.id.button_multifile:
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            String urlPath="http://192.168.0.30:8080/MyWebTest/music/aa.mp3";
                            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), 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();
                break;
            default:
                break;
        }
    }
}

然後在一個線程中進行文件的讀取和寫入，由於每個線程開始下載的文件的位置和下載結束的位置不一樣，這裏需要四個參數，分別是自己開始得和結束的文件的位置，還有服務器的地址和下載的文件的存儲位置。

package com.example.administrator.networkconnect;

import java.io.File;
import java.io.FileNotFoundException;
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 2015/9/12.
 */
public class MultiThread extends Thread {
    private long start;
    private long end;
    private String urlPath;
    private String filePath;
    private int sum=0;

    public int getSum() {
        return sum;
    }

    public MultiThread(long start, long end, String urlPath, String filePath) {

        this.start = start;
        this.end = end;
        this.urlPath = urlPath;
        this.filePath = filePath;
    }

    @Override
    public void run() {
        try {
            URL url=new URL(urlPath);
            URLConnection connection=url.openConnection();
            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();
        }
    }
}