android之网络资源多线程下载

package com.example.threaddown;import java.util.Timer;import java.util.TimerTask;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.ProgressBar;public class MainActivity extends Activity {EditText url;EditText target;Button downBn;ProgressBar bar;DownUtil downUtil;private int mDownStatus;@Overrideprotected 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制url = (EditText) findViewById(R.id.url);target = (EditText) findViewById(R.id.target);downBn = (Button) findViewById(R.id.downBn);bar = (ProgressBar) findViewById(R.id.br);// 创建一个Handler对象final Handler handler = new Handler() {@Overridepublic void handleMessage(Message msg) {if (msg.what == 0x123) {bar.setProgress(mDownStatus);}}};downBn.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// 初始化DownUtil对象downUtil = new DownUtil(url.getText().toString(), target.getText().toString(), 6);new Thread() {@Overridepublic 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() {@Overridepublic void run() {// 获取下载任务的完成比例double completeRate = downUtil.getCompleteRate();mDownStatus = (int) (completeRate * 1000);// 发送消息通知届满更新的进度条handler.sendEmptyMessage(0x123);// 下载完成之后取消任务进度if (mDownStatus >= 100) {timer.cancel();}}}, 0, 1000);}}.start();}});}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}

package com.example.threaddown;import java.io.IOException;import java.io.InputStream;import java.io.RandomAccessFile;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;public class DownUtil {// 定义下载资源的路径private String path;// 指定所下载的文件的保存位置private String targetFile;// 定义需要使用多少线程下载资源private int threadNum;// 定义下载的线程对象private DownThread[] threads;// 定义下载的文件总大小private int fileSize;public DownUtil(String path, String targetFile, int threadNum) {this.path = path;this.targetFile = targetFile;this.threadNum = threadNum;}public void download() throws IOException {URL url = new URL(path);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setConnectTimeout(5000);conn.setRequestMethod("GET");conn.setRequestProperty("Accept", "*/*");conn.setRequestProperty("Accept-Language", "zh-CN");conn.setRequestProperty("Charset", "UTF-8");conn.setRequestProperty("Connection", "Keep-Alive");// 得到文件的大小fileSize = conn.getContentLength();conn.disconnect();int currentPartsSize = fileSize / threadNum + 1;RandomAccessFile file = new RandomAccessFile(targetFile, "rw");// 设置本地文件的大小file.setLength(fileSize);file.close();for (int i = 0; i < threadNum; i++) {// 计算每条线程的下载位置int startPos = i * currentPartsSize;// 每个线程使用一个RandomAccessFile进行下载RandomAccessFile current = new RandomAccessFile(targetFile, "rw");// 定义该线程的下载位置current.seek(startPos);// 创建下载线程threads[i] = new DownThread(startPos, currentPartsSize, current);// 启动线程下载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++) {sumSize += threads[i].length;}return sumSize * 1.0 / fileSize;}private class DownThread extends Thread {// 定义当前线程下载的位置private int startPos;// 定义当前线程下载文件的大小private int currentPartsSize;// 当前线程下载的文件块private RandomAccessFile currentPart;// 定义该线程已下载的字节数private int length;public DownThread(int startPos, int currentPartsSize,RandomAccessFile currentPart) {this.startPos = startPos;this.currentPart = currentPart;this.currentPartsSize = currentPartsSize;}@Overridepublic void run() {try {URL url = new URL(path);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setConnectTimeout(5000);conn.setRequestMethod("GET");conn.setRequestProperty("Accept", "*/*");conn.setRequestProperty("Accept-Language", "zh-CN");conn.setRequestProperty("Charset", "UTF-8");conn.setRequestProperty("Connection", "Keep-Alive");InputStream in = conn.getInputStream();in.skip(startPos);int hasRead = 0;byte[] buffer = new byte[1024];// 读取网络数据，并写入本地文件while (length < currentPartsSize&& (hasRead = in.read(buffer)) > 0) {currentPart.write(buffer, 0, hasRead);// 累计该线程下载的总大小length += hasRead;}currentPart.close();in.close();} catch (Exception e) {e.printStackTrace();}}}}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context=".MainActivity" >    <EditText        android:id="@+id/url"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="http://ksoap2-android.googlecode.com/svn/m2-repo/com/google/code/ksoap2-android/ksoap2-android-assembly/3.1.0/ksoap2-android-assembly-3.1.0-jar-with-dependencies.jar" />    <EditText        android:id="@+id/target"        android:layout_width="match_parent"        android:layout_height="wrap_content"         android:text="/mnt/sdcard/"/>    <Button        android:id="@+id/downBn"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="down" />    <ProgressBar        android:id="@+id/br"        style="?android:attr/progressBarStyleHorizontal"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>

    <!-- 在SD卡中创建与删除文件的权限 -->    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />    <!-- 在SD开中写入数据的权限 -->    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />    <!-- 访问网路的权限 -->    <uses-permission android:name="android.permission.INTERNET" />