Android编程开发实现带进度条和百分比的多线程下载

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;
  }
}

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);
  }
}

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;
  }
}

<&＃63;xml version="1.0" encoding="utf-8"&＃63;>

  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