本文实例讲述了Android编程开发实现带进度条和百分比的多线程下载。分享给大家供大家参考，具体如下：
继上一篇《java多线程下载实例详解》之后，可以将它移植到我们的安卓中来，下面是具体实现源码：
DownActivity.java：
package com.example.downloads; import java.io.File; import java.io.IOException; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import com.example.downloads.utils.DownLoadThread; import android.os.Bundle; import android.os.Environment; import android.os.Handler; import android.os.Message; import android.annotation.SuppressLint; import android.app.Activity; import android.text.TextUtils; import android.view.Menu; import android.view.View; import android.widget.EditText; import android.widget.ProgressBar; import android.widget.TextView; import android.widget.Toast; public class DownActivity extends Activity { // 声明控件 // 路径与线程数量 public EditText et_url, et_num; // 进度条 public static ProgressBar pb_thread; // 显示进度的操作 public TextView tv_pb; // 线程的数量 public static int threadNum = 3; // 每个线程负责下载的大小 public int blockSize; public static int threadCount;// 数量 // 访问的path public String path; public static boolean flag = true; // 记录进度条的值 public static int pb_count = 0; public static Handler handler; public static final int TEXTVALUE = 1; public static int pb_num = 0; public static int size = 0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_down); et_url = (EditText) findViewById(R.id.et_path); et_num = (EditText) findViewById(R.id.et_threadNum); pb_thread = (ProgressBar) findViewById(R.id.pb_down); tv_pb = (TextView) findViewById(R.id.tv_pb); handler = new Handler() { @SuppressLint("HandlerLeak") @Override public void handleMessage(Message msg) { super.handleMessage(msg); switch (msg.what) { case TEXTVALUE: System.out.println("-------" + DownActivity.pb_count + "//////" + DownActivity.size); // 改变TEXTView pb_num = (DownActivity.pb_count * 100) / DownActivity.size; tv_pb.setText("当前进度是+" + pb_num + "%"); break; default: break; } } }; } @Override public 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; } public void downLoad(View v) { DownActivity.flag = true; DownActivity.pb_count = 0; path = et_url.getText().toString(); String threadNum_et = et_num.getText().toString(); if (TextUtils.isEmpty(path) || TextUtils.isEmpty(threadNum_et)) { Toast.makeText(this, "不能为空", Toast.LENGTH_LONG).show(); return; } Toast.makeText(this, "url:" + path + "--" + threadNum_et, Toast.LENGTH_LONG).show(); // 转换成数字 threadNum = Integer.valueOf(threadNum_et); new Thread(new Runnable() { @Override public void run() { try { // 创建出URL对象 URL url = new URL(path); // 创建出 HttpURLConnection对象 HttpURLConnection httpURLConnection = (HttpURLConnection) url .openConnection(); // 设置 发请求发送的方式 httpURLConnection.setRequestMethod("GET"); // 设置请求是否超时时间 httpURLConnection.setConnectTimeout(5000); // 设置 httpURLConnection .setRequestProperty("User-Agent", " Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)"); // 是否响应成功 if (httpURLConnection.getResponseCode() == 200) { // 获取文件的大小 size = httpURLConnection.getContentLength(); System.out.println("文件的大小" + size); // 设置进度条的最大值 pb_thread.setMax(size); // 创建文件 //保存到SD卡上 // 首先判断是否拥有sdcard if (Environment.getExternalStorageState().equals( Environment.MEDIA_MOUNTED)) { // 获取sdCard文件目录对象 File sdFile = Environment .getExternalStorageDirectory(); // 创建文件对象 File file = new File(sdFile, "youdao.exe"); RandomAccessFile accessFile = new RandomAccessFile( file, "rwd"); // 设置文件的大小 accessFile.setLength(size); // 每个线程下载的大小 blockSize = size / threadNum; // 开三个线程 操作此文件 for (int i = 1; i <= threadNum; i++) { // 1 2 3 // 计算出每个线程开始的位置 int startSize = (i - 1) * blockSize; // 结束位置 int endSize = (i) * blockSize; // 当线程是最后一个线程的时候 if (i == threadNum) { // 判断文件的大小是否大于计算出来的结束位置 if (size > endSize) { // 结束位置 等于 文件的大小 endSize = size; } } // 为每个线程创建一个随机的读取 RandomAccessFile threadAccessFile = new RandomAccessFile( file, "rwd"); new Thread(new DownLoadThread(i, threadAccessFile, startSize, endSize, path)).start(); } } } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }).start(); } /** * 暂停操作 * * @param v */ public void downPause(View v) { Toast.makeText(this, "暂停", Toast.LENGTH_LONG).show(); this.flag = false; } }
DownLoadThread.java：
package com.example.downloads.utils; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import com.example.downloads.DownActivity; import android.os.Environment; public class DownLoadThread implements Runnable { public RandomAccessFile accessFile; // 每个线程 都拥有一个accessFile的文件对象 线程1 线程2 线程3 // 线程下载文件的起始位置 public int startSize; public int endSize; // 文件下载的path路径 public String path; public int threadId; // 线程的标识 public DownLoadThread(int threadId, RandomAccessFile accessFile, int startSize, int endSize, String path) { this.threadId = threadId; this.accessFile = accessFile; this.startSize = startSize; this.endSize = endSize; this.path = path; } @Override public void run() { // 执行run方法 try { // 创建文件到SD卡上去 // 首先判断是否拥有sdcard if (Environment.getExternalStorageState().equals( Environment.MEDIA_MOUNTED)) { // 获取sdCard文件目录对象 File sdFile = Environment.getExternalStorageDirectory(); File threadFile = new File(sdFile, threadId + ".txt"); if (threadFile.exists()) { // 读取该文件的内容 // 创建文件的输入流对象 FileInputStream fis = new FileInputStream(threadFile); // 采用工具类读取 byte data[] = StreamTools.isToData(fis); // 转化成字符串 String threadLen = new String(data); if ((threadLen != null) && (!"".equals(threadLen))) { startSize = Integer.valueOf(threadLen); // 解决 416bug的错误 if (startSize > endSize) { startSize = endSize - 1; } } } // 创建文件 // 创建URL对象 URL url = new URL(path); // 创建HttpURLConnection对象 HttpURLConnection httpURLConnection = (HttpURLConnection) url .openConnection(); // 设置请求的头 httpURLConnection.setRequestMethod("GET"); // 设置请求是否超时时间 httpURLConnection.setConnectTimeout(5000); // 设置 httpURLConnection .setRequestProperty("User-Agent", " Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)"); // 关键的设置 httpURLConnection.setRequestProperty("Range", "bytes=" + startSize + "-" + endSize); // 输出当前线程 System.out.println("当前线程" + threadId + " 下载开始位置:" + startSize + " 下载结束位置:" + endSize); // 响应成功 // 设置随机读取文件的 开始位置 accessFile.seek(startSize); // 获取相应流对象 InputStream is = httpURLConnection.getInputStream(); // 创建输出流对象 byte buffer[] = new byte[1024]; int len = 0; int threadTotal = 0;// 每个线程下载后保存记录 / while ((len = is.read(buffer)) != -1) { accessFile.write(buffer, 0, len); threadTotal += len;// 记录你写入的长度 //xml文件 //改变进度条： setProgressBar(len); // 通过文件记录文件下载的长度 FileOutputStream fos = new FileOutputStream(threadFile); fos.write((threadTotal + "").getBytes()); fos.flush(); fos.close(); //发送handler消息 DownActivity.handler.sendEmptyMessage(DownActivity.TEXTVALUE); if(!DownActivity.flag){ return; } } accessFile.close(); is.close(); System.out.println(threadId + "线程执行完毕"); // 线程操作 synchronized (DownActivity.class) { DownActivity.threadCount++; if (DownActivity.threadCount >= DownActivity.threadNum) { for (int i = 1; i <= DownActivity.threadNum; i++) { // 获取sdCard上的文件 File deleteFile = new File(sdFile, i + ".txt"); if (deleteFile.exists()) { // 文件删除 deleteFile.delete(); } } } } } } catch (MalformedURLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public synchronized void setProgressBar(int len){ DownActivity.pb_count+=len; DownActivity.pb_thread.setProgress(DownActivity.pb_count); } }
StreamTools.java：
package com.example.downloads.utils; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; public class StreamTools { public static byte[] isToData(InputStream is) throws IOException{ // 字节输出流 ByteArrayOutputStream bops = new ByteArrayOutputStream(); // 读取数据的缓存区 byte buffer[] = new byte[1024]; // 读取长度的记录 int len = 0; // 循环读取 while ((len = is.read(buffer)) != -1) { bops.write(buffer, 0, len); } // 把读取的内容转换成byte数组 byte data[] = bops.toByteArray(); bops.flush(); bops.close(); is.close(); return data; } }
strings.xml：
<?xml version="1.0" encoding="utf-8"?> <resources> <string name="app_name">downloads</string> <string name="action_settings">Settings</string> <string name="tv_down">文件下载的地址</string> <string name="tv_threadNum">线程数量</string> <string name="tv_num">0%</string> <string name="btn_text">下载</string> <string name="btn_pause">暂停</string> <string name="et_path">http://172.22.64.8:8080/doudou/youdao.exe</string> <string name="et_threadNum">3</string> </resources>
布局文件：
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".DownActivity" > <TextView android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentTop="true" android:text="@string/tv_down" /> <EditText android:id="@+id/et_path" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_below="@+id/textView1" android:ems="10" android:inputType="none" android:text="@string/et_path" > <requestFocus /> </EditText> <TextView android:id="@+id/textView2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_below="@+id/et_path" android:text="@string/tv_threadNum" /> <EditText android:id="@+id/et_threadNum" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/textView2" android:layout_alignRight="@+id/et_path" android:layout_below="@+id/textView2" android:ems="10" android:inputType="number" android:text="@string/et_threadNum" /> <ProgressBar android:id="@+id/pb_down" style="?android:attr/progressBarStyleHorizontal" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/et_threadNum" android:layout_alignRight="@+id/et_threadNum" android:layout_below="@+id/et_threadNum" android:layout_marginTop="14dp" /> <TextView android:id="@+id/tv_pb" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignRight="@+id/textView1" android:layout_below="@+id/pb_down" android:layout_marginTop="24dp" android:text="@string/tv_num" /> <Button android:id="@+id/btn_down" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/pb_down" android:layout_below="@+id/tv_pb" android:layout_marginTop="32dp" android:onClick="downLoad" android:text="@string/btn_text" /> <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/btn_down" android:layout_below="@+id/btn_down" android:layout_marginTop="16dp" android:onClick="downPause" android:text="@string/btn_pause" /> </RelativeLayout>
效果如下：
最后要注意的是别忘了在项目清单文件中加入权限：
<!-- SDCard权限 --> <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <!-- 访问网络的权限 --> <uses-permission android:name="android.permission.INTERNET" />
希望本文所述对大家Android程序设计有所帮助。