Android 使用开源xUtils来实现多线程下载（非原创）

<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" >

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="开始下载"
        android:onClick="click" />

    <ProgressBar 
        android:id="@+id/pb_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        style="@android:style/Widget.ProgressBar.Horizontal"
        />
    <TextView 
        android:id="@+id/tv_progress"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#A52A2A"
        android:textSize="25sp"
        />
    <TextView
        android:id="@+id/tv_failure"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#FF6347" />

</LinearLayout>

package com.example.xutilsmultithreaddownload;

import java.io.File;

import com.lidroid.xutils.HttpUtils;
import com.lidroid.xutils.exception.HttpException;
import com.lidroid.xutils.http.HttpHandler;
import com.lidroid.xutils.http.ResponseInfo;
import com.lidroid.xutils.http.callback.RequestCallBack;

import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.os.Bundle;
import android.os.Environment;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import android.os.Build;

public class MainActivity extends Activity {
    //错误提示的文本
    private TextView tv_failure;
    //进度条
    private ProgressBar pb_bar;
    //进度显示的文本
    private TextView tv_progress;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_main);
    tv_failure = (TextView) findViewById(R.id.tv_failure);
    pb_bar = (ProgressBar) findViewById(R.id.pb_bar);
    tv_progress = (TextView) findViewById(R.id.tv_progress);
    }

    public void click(View v) {
    // 文件名字
    String fileName = "ESurfing_V2.1.exe";
    // 路径
    String path = "http://192.168.1.66:8080/" + fileName;
    HttpUtils http = new HttpUtils();
    HttpHandler handler = http.download(path, Environment.getExternalStorageDirectory() + "/" + fileName, true, true, new RequestCallBack<File>() {
        //下载成功后调用
        @Override
        public void onSuccess(ResponseInfo<File> arg0) {
        // TODO Auto-generated method stub
        Toast.makeText(MainActivity.this, arg0.result.getPath(), 0).show();
        }
        //下载失败调用
        @Override
        public void onFailure(HttpException arg0, String arg1) {
        // TODO Auto-generated method stub
        tv_failure.setText(arg1);
        }
        //下载的时候调用
        @Override
        public void onLoading(long total, long current, boolean isUploading) {
        // TODO Auto-generated method stub
        super.onLoading(total, current, isUploading);
        //设置进度条的最大值
        pb_bar.setMax((int)total);
        //设置进度当前的进度
        pb_bar.setProgress((int)current);
        //文本显示当前的进度
        tv_progress.setText(current*100/total+"%");
        }
    });
    }
}

 <uses-permission android:name="android.permission.INTERNET"/>
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>