Android编程开发实现带进度条和百分比的多线程下载

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"?>  downloads  Settings  文件下载的地址  线程数量  0%  下载  暂停  http://172.22.64.8:8080/doudou/youdao.exe  3

布局文件：

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：

希望本文所述对大家Android程序设计有所帮助。

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