android加了进度条和进度文本多线程断点续传下载

package com.example.threaddownload;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;

import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MainActivity extends Activity {
    private static String path = "http://192.168.21.1:8080/ok/TGPSetup.exe";
    private static int threadCount = 3;
    private static int finishThread = 0;
    //添加进度条
    private ProgressBar pro;
    //进度数
    private int progress;
    //添加文本进度
    private TextView tv;
    private Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg) {
            //如果有的时候下载的文件过大会出现负数改成long表示就可以了
            tv.setText((long)pro.getProgress()*100/pro.getMax()+"%");
        
        };
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        pro = (ProgressBar) findViewById(R.id.pro);
        tv = (TextView) findViewById(R.id.tv);
        findViewById(R.id.start).setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                new Thread() {
                    @Override
                    public void run() {

                        try {
                            URL url = new URL(path);
                            HttpURLConnection conn = (HttpURLConnection) url
                                    .openConnection();
                            conn.setRequestMethod("GET");
                            conn.setReadTimeout(5000);
                            conn.setConnectTimeout(5000);
                            if (conn.getResponseCode() == 200) {
                                // 第一次请求要下载的长度
                                int length = conn.getContentLength();
                                
                                pro.setMax(length);
                                //给主线程发送消息
                                handler.sendEmptyMessage(1);
                                // 应该从字符串中截取文件名称
                                File file = new File(Environment.getExternalStorageDirectory(),"TGPSetup.exe");
                                // 在下载之前生成临时文件，占位置
                                RandomAccessFile rdm = new RandomAccessFile(
                                        file, "rwd");
                                // 给临时文件大小
                                rdm.setLength(length);
                                // 关闭
                                rdm.close();
                                // 计算每个线程应该下载的长度
                                int size = length / threadCount;
                                // 为每个线程分配开始位置和结束位置
                                for (int i = 0; i < threadCount; i++) {
                                    int start = i * size;
                                    int end = (i + 1) * size - 1;
                                    // 最后一个线程的结束位置为总长度
                                    if (i == threadCount - 1) {
                                        end = length;
                                    }
                                    // 每次都调用新的线程
                                    new DownThread(start, end, i).start();
                                }
                            }
                        } catch (Exception e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }

                    }
                }.start();

            }
        });

    }

    // 线程
    class DownThread extends Thread {
        private int start;
        private int end;
        private int threadId;

        public DownThread(int start, int end, int threadId) {
            this.start = start;
            this.end = end;
            this.threadId = threadId;
        }

        @Override
        public void run() {
            try {
                // 创建进度文件
                File progressFile = new File(Environment.getExternalStorageDirectory(),threadId + ".txt");
                // 判断是否有记录进度的文件,如果有的话把开始位置重新赋值
                if (progressFile.exists()) {
                    FileInputStream fis = new FileInputStream(progressFile);
                    BufferedReader br = new BufferedReader(
                            new InputStreamReader(fis));
                    int lastProgress =Integer.parseInt(br.readLine()); 
                    start += lastProgress;
                    //上次下载的显示到进度条
                    progress+=lastProgress;
                    pro.setProgress(progress);
                    
                    fis.close();

                }
                System.out.println(threadId + "线程下载区间" + start + "---" + end);
                // 再次请求网络
                URL url = new URL(path);
                HttpURLConnection conn = (HttpURLConnection) url
                        .openConnection();
                conn.setRequestMethod("GET");
                conn.setReadTimeout(5000);
                conn.setConnectTimeout(5000);
                // 设置本次请求的文件的长度
                conn.setRequestProperty("Range", "bytes=" + start + "-" + end);
                // 请求部分数据是206
                if (conn.getResponseCode() == 206) {
                    // 得到请求长度的文件输入流
                    InputStream is = conn.getInputStream();
                    byte[] b = new byte[1024];
                    int len = 0;
                    // 记录每一次下载字节数
                    int totle = 0;
                
                    // 应该从字符串中截取文件名称
                    File file = new File(Environment.getExternalStorageDirectory(),"TGPSetup.exe");
                    // 拿到之前占位置那个文件,相当于输出流
                    RandomAccessFile rdm = new RandomAccessFile(file, "rwd");
                    // 改变写入文件的开始位置
                    rdm.seek(start);
                    while ((len = is.read(b)) != -1) {
                        // 每次读取流里的数据写到临时文件里
                        rdm.write(b, 0, len);
                        totle += len;
                        progress+=len;
                        handler.sendEmptyMessage(1);
                        pro.setProgress(progress);
                        System.out.println(threadId + "线程" + "下载了" + totle);
                        // 把下载的总数存到进度文件里
                        RandomAccessFile rdm1 = new RandomAccessFile(
                                progressFile, "rwd");
                        rdm1.write((totle + "").getBytes());
                        rdm1.close();
                    }
                    rdm.close();
                    finishThread++;
                    // 下载结束删除进度文件
                    if (finishThread == threadCount) {
                        // 加同步锁
                        synchronized (path) {
                            for (int i = 0; i < threadCount; i++) {
                                File f = new File(Environment.getExternalStorageDirectory(),i + ".txt");
                                f.delete();
                            }
                            finishThread = 0;
                        }
                    }
                }
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

}