Android多线程文件下载

2022-10-22 09:58:09

版本信息

apply plugin: 'com.android.application'

android {

    compileSdkVersion 23

    buildToolsVersion "23.0.3"

    defaultConfig {

        applicationId "xidian.dy.com.chujia"

        minSdkVersion 15

        targetSdkVersion 23

        versionCode 1

        versionName "1.0"

    }

    buildTypes {

        release {

            minifyEnabled false

            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'

        }

    }

}

dependencies {

    compile fileTree(dir: 'libs', include: ['*.jar'])

    testCompile 'junit:junit:4.12'

    compile 'com.android.support:appcompat-v7:23.4.0'

}

亲测可用

布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical" >

        <LinearLayout

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:orientation="horizontal" >

                <TextView

                    android:layout_width="wrap_content"

                    android:layout_height="wrap_content"

                    android:text="输入url:" />

                <EditText

                    android:id="@+id/url"

                    android:layout_width="match_parent"

                    android:layout_height="wrap_content" />

        </LinearLayout>

        <LinearLayout

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:orientation="horizontal" >

                <TextView

                    android:layout_width="wrap_content"

                    android:layout_height="wrap_content"

                    android:text="输入保存的文件名:" />

                <EditText

                    android:id="@+id/target"

                    android:layout_width="match_parent"

                    android:layout_height="wrap_content" />

        </LinearLayout>

        <Button

            android:id="@+id/download"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="下载" />

        <ProgressBar

            android:id="@+id/progressBar"

            style="@android:style/Widget.ProgressBar.Horizontal"

            android:layout_width="match_parent"

            android:layout_height="wrap_content" />

</LinearLayout>

下载工具类

package xidian.dy.com.chujia;

/**

 * Created by dy on 2016/6/29.

 */

import android.os.Environment;

import android.os.StrictMode;

import android.util.Log;

import java.io.File;

import java.io.InputStream;

import java.io.RandomAccessFile;

import java.net.HttpURLConnection;

import java.net.URL;

/**

 * Description:

 * 创建ServerSocket监听的主类

 * @author  jph

 * Date：2014.08.27

 */

public class DownUtil

{

    /**下载资源的URL**/

    private String path;

    /**下载的文件的保存位置**/

    private String targetFile;

    /**需要使用多少线程下载资源**/

    private int threadNum;

    /**下载的线程对象**/

    private DownThread[] threads;

    /**下载的文件的总大小**/

    private int fileSize;

    public DownUtil(String path, String targetFile, int threadNum) {

        this.path = path;

        this.threadNum = threadNum;

        // 初始化threads数组

        threads = new DownThread[threadNum];

        this.targetFile = targetFile;

    }

    public void download() throws Exception {

        URL url = new URL(path);

        HttpURLConnection conn = (HttpURLConnection) url.openConnection();

        conn.setConnectTimeout(5 * 1000);

        conn.setReadTimeout(5*1000);

        conn.setRequestMethod("GET");

        conn.setRequestProperty(

                "Accept",

                "image/gif, image/jpeg, image/pjpeg, image/pjpeg, "

                        + "application/x-shockwave-flash, application/xaml+xml, "

                        + "application/vnd.ms-xpsdocument, application/x-ms-xbap, "

                        + "application/x-ms-application, application/vnd.ms-excel, "

                        + "application/vnd.ms-powerpoint, application/msword, */*");

        conn.setRequestProperty("Accept-Language", "zh-CN");

        conn.setRequestProperty("Charset", "UTF-8");

        conn.setRequestProperty("Connection", "Keep-Alive");

        conn.connect();

        if(conn.getResponseCode() == 200){

            // 得到文件大小

            fileSize = conn.getContentLength();

            //关闭连接

            conn.disconnect();

            //计算每个线程下载文件大小

            int currentPartSize = fileSize / threadNum;

            //创建本地文件

            File myfile = new File(Environment.getExternalStorageDirectory(), targetFile);

                if(myfile.exists())

                    myfile.delete();

                else

                    myfile.createNewFile();

                RandomAccessFile file = new RandomAccessFile(myfile, "rwd");

                // 设置本地文件的大小

                file.setLength(fileSize);

                file.close();

                for (int i = 0; i < threadNum; i++) {

                    // //计算线程下载的开始位置和结束位置

                    int startIndex = i * currentPartSize;

                    int endIndex = (i + 1) *currentPartSize - 1;

                    if(i == threadNum - 1){

                        endIndex = fileSize - 1;

                    }

                    // 每个线程使用一个RandomAccessFile进行下载

                    RandomAccessFile currentPart = new RandomAccessFile(myfile, "rwd");

                    threads[i] = new DownThread(currentPart,startIndex, endIndex);

                    threads[i].start();

                }

        }

    }

    // 获取下载的完成百分比

    public double getCompleteRate() {

        // 统计多条线程已经下载的总大小

        int sumSize = 0;

        for (int i = 0; i < threadNum; i++) {

            if(threads[i] == null)

                sumSize += 0;

            else

                sumSize += threads[i].length;

        }

        // 返回已经完成的百分比

        return sumSize * 1.0 / fileSize;

    }

    private class DownThread extends Thread {

        /**当前线程的下载位置**/

        private int startPos;

        /**当前线程下载的结束位置**/

        private int endPos;

        /**当前线程需要下载的文件块**/

        private RandomAccessFile currentPart;

        /**定义该线程已下载的字节数**/

        public int length;

        public DownThread(RandomAccessFile currentPart, int startPos, int endPos) {

            this.startPos = startPos;

            this.currentPart = currentPart;

            this.endPos = endPos;

        }

        @Override

        public void run() {

            try {

                URL url = new URL(path);

                HttpURLConnection conn = (HttpURLConnection)url

                        .openConnection();

                conn.setConnectTimeout(5 * 1000);

                conn.setRequestMethod("GET");

                conn.setRequestProperty(

                        "Accept",

                        "image/gif, image/jpeg, image/pjpeg, image/pjpeg, "

                                + "application/x-shockwave-flash, application/xaml+xml, "

                                + "application/vnd.ms-xpsdocument, application/x-ms-xbap, "

                                + "application/x-ms-application, application/vnd.ms-excel, "

                                + "application/vnd.ms-powerpoint, application/msword, */*");

                conn.setRequestProperty("Accept-Language", "zh-CN");

                conn.setRequestProperty("Charset", "UTF-8");

                conn.setRequestProperty("Range", "bytes=" + startPos + "-" + endPos);

                conn.connect();

                if(conn.getResponseCode() == 206){

                    InputStream inStream = conn.getInputStream();

                    // 跳过startPos个字节，表明该线程只下载自己负责哪部分文件。

                    byte[] buffer = new byte[4*1024];

                    int hasRead;

                    currentPart.seek(startPos);

                    // 读取网络数据，并写入本地文件

                    while ((hasRead = inStream.read(buffer)) >0 ) {

                        currentPart.write(buffer, 0, hasRead);

                        // 累计该线程下载的总大小

                        length += hasRead;

                    }

                    Log.i(Thread.currentThread().getName(), String.valueOf(length));

                    currentPart.close();

                    inStream.close();

                }

            }

            catch (Exception e) {

                e.printStackTrace();

            }

        }

    }

}

主代码

package xidian.dy.com.chujia;

import android.content.Context;

import android.os.Bundle;

import android.os.Environment;

import android.os.Handler;

import android.os.Looper;

import android.os.Message;

import android.support.v7.app.AppCompatActivity;

import android.util.Log;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.ProgressBar;

import android.widget.Toast;

import java.util.Timer;

import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {

    EditText url;

    EditText target;

    Button downBn;

    ProgressBar bar;

    DownUtil downUtil;

    private int mDownStatus;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        // 获取程序界面中的三个界面控件

        url = (EditText) findViewById(R.id.url);

        target = (EditText) findViewById(R.id.target);

        downBn = (Button) findViewById(R.id.download);

        bar = (ProgressBar) findViewById(R.id.progressBar);

        // 创建一个Handler对象

        final Handler handler = new Handler() {

            @Override

            public void handleMessage(Message msg) {

                if (msg.what == 0x123) {

                    bar.setProgress(mDownStatus);

                }

            }

        };

        downBn.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))

                    return;

                // 初始化DownUtil对象（最后一个参数指定线程数）

                downUtil = new DownUtil(url.getText().toString(),

                        target.getText().toString(), 4);

                new Thread() {

                    @Override

                    public void run(){

                        try {

                            // 开始下载

                            downUtil.download();

                        }

                        catch (Exception e) {

                            e.printStackTrace();

                        }

                        // 定义每秒调度获取一次系统的完成进度

                        final Timer timer = new Timer();

                        timer.schedule(new TimerTask() {

                            @Override

                            public void run() {

                                // 获取下载任务的完成比率

                                double completeRate = downUtil.getCompleteRate();

                                mDownStatus = (int) (completeRate * 100);

                                // 发送消息通知界面更新进度条

                                Log.i(Thread.currentThread().getName(), String.valueOf(mDownStatus));

                                handler.sendEmptyMessage(0x123);

                                // 下载完全后取消任务调度

                                if (mDownStatus >= 100) {

                                    showToastByRunnable(MainActivity.this, "下载完成", 2000);

                                    timer.cancel();

                                }

                            }

                        }, 0, 100);

                    }

                }.start();

            }

        });

    }

    /**

     * 在非UI线程中使用Toast

     * @param context 上下文

     * @param text 用以显示的消息内容

     * @param duration 消息显示的时间

     * */

    private void showToastByRunnable(final Context context, final CharSequence text, final int duration) {

        Handler handler = new Handler(Looper.getMainLooper());

        handler.post(new Runnable() {

            @Override

            public void run() {

                Toast.makeText(context, text, duration).show();

            }

        });

    }

}

权限控制

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="xidian.dy.com.chujia">

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

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

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

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

    <application

        android:allowBackup="true"

        android:icon="@mipmap/ic_launcher"

        android:label="@string/app_name"

        android:supportsRtl="true"

        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>

码农公寓

版本信息

布局文件

下载工具类

主代码

权限控制

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